CVE-2022-24302: Changelog — Paramiko documentation

Next 2.x bugfix release

• [Bug]: bug:1637 (via #1599) Raise SSHException explicitly when blank private key data is loaded, instead of the natural result of IndexError. This should help more bits of Paramiko or Paramiko-adjacent codebases to correctly handle this class of error. Credit: Nicholas Dietz.

Next 1.x feature release

• [Support] #866: (also #838) Remove an old test-related file we don’t support, and add PyPy to Travis-CI config. Thanks to Pierce Lopez for the final patch and Pedro Rodrigues for an earlier edition.

• [Support] #956: Switch code coverage service from coveralls.io to codecov.io (& then disable the latter’s auto-comments.) Thanks to Nikolai Røed Kristiansen for the patch.

• [Support] #906: Clean up a handful of outdated imports and related tweaks. Thanks to Pierce Lopez.

• [Support] #1291: Backport pytest support and application of the black code formatter (both of which previously only existed in the 2.4 branch and above) to everything 2.0 and newer. This makes back/forward porting bugfixes significantly easier.

• [Support] #1292: Backport changes from #979 (added in Paramiko 2.3) to Paramiko 2.0-2.2, using duck-typing to preserve backwards compatibility. This allows these older versions to use newer Cryptography sign/verify APIs when available, without requiring them (as is the case with Paramiko 2.3+).

  Practically speaking, this change prevents spamming of CryptographyDeprecationWarning notices which pop up in the above scenario (older Paramiko, newer Cryptography).

  Note

  This is a no-op for Paramiko 2.3+, which have required newer Cryptography releases since they were released.

Next 1.x bugfix release

• [Support] #1291: Backport pytest support and application of the black code formatter (both of which previously only existed in the 2.4 branch and above) to everything 2.0 and newer. This makes back/forward porting bugfixes significantly easier.

• [Support] #1292: Backport changes from #979 (added in Paramiko 2.3) to Paramiko 2.0-2.2, using duck-typing to preserve backwards compatibility. This allows these older versions to use newer Cryptography sign/verify APIs when available, without requiring them (as is the case with Paramiko 2.3+).

  Practically speaking, this change prevents spamming of CryptographyDeprecationWarning notices which pop up in the above scenario (older Paramiko, newer Cryptography).

  Note

  This is a no-op for Paramiko 2.3+, which have required newer Cryptography releases since they were released.

2.11.0 2022-05-16

• [Feature] #1951: Add SSH config token expansion (eg %h, %p) when parsing ProxyJump directives. Patch courtesy of Bruno Inec.
• [Support] #2004: (via #2011) Apply unittest skipIf to tests currently using SHA1 in their critical path, to avoid failures on systems starting to disable SHA1 outright in their crypto backends (eg RHEL 9). Report & patch via Paul Howarth.
• [Support] #1838: (via #1870/#2028) Update camelCase method calls against the threading module to be snake_case; this and related tweaks should fix some deprecation warnings under Python 3.10. Thanks to Karthikeyan Singaravelan for the report, @Narendra-Neerukonda for the patch, and to Thomas Grainger and Jun Omae for patch workshopping.
• [Support] #2038: (via #2039) Recent versions of Cryptography have deprecated Blowfish algorithm support; in lieu of an easy method for users to remove it from the list of algorithms Paramiko tries to import and use, we’ve decided to remove it from our “preferred algorithms” list. This will both discourage use of a weak algorithm, and avoid warnings. Credit for report/patch goes to Mike Roest.

2.10.5 2022-05-16

• [Bug] #2008: (via #2010) Windows-native SSH agent support as merged in 2.10 could encounter Errno 22 OSError exceptions in some scenarios (eg server not cleanly closing a relevant named pipe). This has been worked around and should be less problematic. Reported by Danilo Campana Fuchs and patched by Jun Omae.
• [Bug] #2017: OpenSSH 7.7 and older has a bug preventing it from understanding how to perform SHA2 signature verification for RSA certificates (specifically certs - not keys), so when we added SHA2 support it broke all clients using RSA certificates with these servers. This has been fixed in a manner similar to what OpenSSH’s own client does: a version check is performed and the algorithm used is downgraded if needed. Reported by Adarsh Chauhan, with fix suggested by Jun Omae.
• [Bug] #1933: Align signature verification algorithm with OpenSSH re: zero-padding signatures which don’t match their nominal size/length. This shouldn’t affect most users, but will help Paramiko-implemented SSH servers handle poorly behaved clients such as PuTTY. Thanks to Jun Omae for catch & patch.

2.9.5 2022-05-16

• [Bug] #2008: (via #2010) Windows-native SSH agent support as merged in 2.10 could encounter Errno 22 OSError exceptions in some scenarios (eg server not cleanly closing a relevant named pipe). This has been worked around and should be less problematic. Reported by Danilo Campana Fuchs and patched by Jun Omae.
• [Bug] #2017: OpenSSH 7.7 and older has a bug preventing it from understanding how to perform SHA2 signature verification for RSA certificates (specifically certs - not keys), so when we added SHA2 support it broke all clients using RSA certificates with these servers. This has been fixed in a manner similar to what OpenSSH’s own client does: a version check is performed and the algorithm used is downgraded if needed. Reported by Adarsh Chauhan, with fix suggested by Jun Omae.
• [Bug] #1933: Align signature verification algorithm with OpenSSH re: zero-padding signatures which don’t match their nominal size/length. This shouldn’t affect most users, but will help Paramiko-implemented SSH servers handle poorly behaved clients such as PuTTY. Thanks to Jun Omae for catch & patch.

2.10.4 2022-04-25

• [Bug] #2035: Servers offering certificate variants of hostkey algorithms (eg [email protected]) could not have their host keys verified by Paramiko clients, as it only ever considered non-cert key types for that part of connection handshaking. This has been fixed.
• [Bug] #1964: (via #2024 as also reported in #2023) PKey instances’ eq did not have the usual safety guard in place to ensure they were being compared to another PKey object, causing occasional spurious BadHostKeyException (among other things). This has been fixed. Thanks to Shengdun Hua for the original report/patch and to Christopher Papke for the final version of the fix.
• [Support] #1838: (via #1870/#2028) Update camelCase method calls against the threading module to be snake_case; this and related tweaks should fix some deprecation warnings under Python 3.10. Thanks to Karthikeyan Singaravelan for the report, @Narendra-Neerukonda for the patch, and to Thomas Grainger and Jun Omae for patch workshopping.

2.9.4 2022-04-25

• [Bug] #2035: Servers offering certificate variants of hostkey algorithms (eg [email protected]) could not have their host keys verified by Paramiko clients, as it only ever considered non-cert key types for that part of connection handshaking. This has been fixed.
• [Bug] #1964: (via #2024 as also reported in #2023) PKey instances’ eq did not have the usual safety guard in place to ensure they were being compared to another PKey object, causing occasional spurious BadHostKeyException (among other things). This has been fixed. Thanks to Shengdun Hua for the original report/patch and to Christopher Papke for the final version of the fix.
• [Support] #1838: (via #1870/#2028) Update camelCase method calls against the threading module to be snake_case; this and related tweaks should fix some deprecation warnings under Python 3.10. Thanks to Karthikeyan Singaravelan for the report, @Narendra-Neerukonda for the patch, and to Thomas Grainger and Jun Omae for patch workshopping.

2.10.3 2022-03-18

• [Bug] #2002: (via #2003) Switch from module-global to thread-local storage when recording thread IDs for a logging helper; this should avoid one flavor of memory leak for long-running processes. Catch & patch via Richard Kojedzinszky.
• [Bug] #1963: (via #1977) Certificate-based pubkey auth was inadvertently broken when adding SHA2 support; this has been fixed. Reported by Erik Forsberg and fixed by Jun Omae.

2.9.3 2022-03-18

• [Bug]: (CVE-2022-24302) Creation of new private key files using PKey subclasses was subject to a race condition between file creation & mode modification, which could be exploited by an attacker with knowledge of where the Paramiko-using code would write out such files.

  This has been patched by using os.open and os.fdopen to ensure new files are opened with the correct mode immediately. We’ve left the subsequent explicit chmod in place to minimize any possible disruption, though it may get removed in future backwards-incompatible updates.

  Thanks to Jan Schejbal for the report & feedback on the solution, and to Jeremy Katz at Tidelift for coordinating the disclosure.

• [Bug] #2001: Fix Python 2 compatibility breakage introduced in 2.10.1. Spotted by Christian Hammond.

  Warning

  This is almost certainly the last time we will fix Python 2 related errors! Please see the roadmap.

• [Bug] #2002: (via #2003) Switch from module-global to thread-local storage when recording thread IDs for a logging helper; this should avoid one flavor of memory leak for long-running processes. Catch & patch via Richard Kojedzinszky.

• [Bug] #1963: (via #1977) Certificate-based pubkey auth was inadvertently broken when adding SHA2 support; this has been fixed. Reported by Erik Forsberg and fixed by Jun Omae.

2.10.2 2022-03-14

• [Bug] #2001: Fix Python 2 compatibility breakage introduced in 2.10.1. Spotted by Christian Hammond.

  Warning

  This is almost certainly the last time we will fix Python 2 related errors! Please see the roadmap.

2.10.1 2022-03-11

• [Bug]: (CVE-2022-24302) Creation of new private key files using PKey subclasses was subject to a race condition between file creation & mode modification, which could be exploited by an attacker with knowledge of where the Paramiko-using code would write out such files.

  This has been patched by using os.open and os.fdopen to ensure new files are opened with the correct mode immediately. We’ve left the subsequent explicit chmod in place to minimize any possible disruption, though it may get removed in future backwards-incompatible updates.

  Thanks to Jan Schejbal for the report & feedback on the solution, and to Jeremy Katz at Tidelift for coordinating the disclosure.

2.10.0 2022-03-11

• [Feature] #1509: (via #1868, #1837) Add support for OpenSSH’s Windows agent as a fallback when Putty/WinPageant isn’t available or functional. Reported by @benj56 with patches/PRs from @lewgordon and Patrick Spendrin.

• [Feature] #1976: Add support for the %C token when parsing SSH config files. Foundational PR submitted by @jbrand42.

• [Bug] #892: Significantly speed up low-level read/write actions on SFTPFile objects by using bytearray/memoryview. This is unlikely to change anything for users of the higher level methods like SFTPClient.get or SFTPClient.getfo, but users of SFTPClient.open will likely see orders of magnitude improvements for files larger than a few megabytes in size.

  Thanks to @jkji for the original report and to Sevastian Tchernov for the patch.

• [Support] #1985: Add six explicitly to install-requires; it snuck into active use at some point but has only been indicated by transitive dependency on bcrypt until they somewhat-recently dropped it. This will be short-lived until we drop Python 2 support. Thanks to Sondre Lillebø Gundersen for catch & patch.

2.9.2 2022-01-08

• [Bug]: Enhanced log output when connecting to servers that do not support server-sig-algs extensions, making the new-as-of-2.9 defaulting to SHA2 pubkey algorithms more obvious when it kicks in.
• [Bug]: Connecting to servers which support server-sig-algs but which have no overlap between that list and what a Paramiko client supports, now raise an exception instead of defaulting to rsa-sha2-512 (since the use of server-sig-algs allows us to know what the server supports).

2.9.1 2021-12-24

• [Bug] #1955: Server-side support for rsa-sha2-256 and ssh-rsa wasn’t fully operable after 2.9.0’s release (signatures for RSA pubkeys were always run through rsa-sha2-512 instead). Report and early stab at a fix courtesy of Jun Omae.

2.9.0 2021-12-23

• [Feature] #1643: (also #1925, #1644, #1326) Add support for SHA-2 variants of RSA key verification algorithms (as described in RFC 8332) as well as limited SSH extension negotiation (RFC 8308).

  Warning

  This change is slightly backwards incompatible, insofar as action is required if your target systems do not support either RSA2 or the server-sig-algs protocol extension.

  Specifically, you need to specify disabled_algorithms={’keys’: ['rsa-sha2-256’, ‘rsa-sha2-512’]} in either SSHClient or Transport. See below for details on why.

  How SSH servers/clients decide when and how to use this functionality can be complicated; Paramiko’s support is as follows:

  • Client verification of server host key during key exchange will now prefer rsa-sha2-512, rsa-sha2-256, and legacy ssh-rsa algorithms, in that order, instead of just ssh-rsa.

    • Note that the preference order of other algorithm families such as ed25519 and ecdsa has not changed; for example, those two groups are still preferred over RSA.

  • Server mode will now offer all 3 RSA algorithms for host key verification during key exchange, similar to client mode, if it has been configured with an RSA host key.

  • Client mode key exchange now sends the ext-info-c flag signaling support for MSG_EXT_INFO, and support for parsing the latter (specifically, its server-sig-algs flag) has been added.

  • Client mode, when performing public key authentication with an RSA key or cert, will act as follows:

    • In all cases, the list of algorithms to consider is based on the new preferred_pubkeys list (see below) and disabled_algorithms (specifically, its pubkeys key); this list, like with host keys, prefers SHA2-512, SHA2-256 and SHA1, in that order.
    • When the server does not send server-sig-algs, Paramiko will attempt the first algorithm in the above list. Clients connecting to legacy servers should thus use disabled_algorithms to turn off SHA2.
    • When the server does send server-sig-algs, the first algorithm supported by both ends is used, or if there is none, it falls back to the previous behavior.

  • SSH agent support grew the ability to specify algorithm flags when requesting private key signatures; this is now used to forward SHA2 algorithms when appropriate.

  • Server mode is now capable of pubkey auth involving SHA-2 signatures from clients, provided one’s server implementation actually provides for doing so.

    • This includes basic support for sending MSG_EXT_INFO (containing server-sig-algs only) to clients advertising ext-info-c in their key exchange list.

  In order to implement the above, the following API additions were made:

  • PKey.sign_ssh_data: Grew an extra, optional algorithm keyword argument (defaulting to None for most subclasses, and to “ssh-rsa” for RSAKey).
  • A new SSHException subclass was added, IncompatiblePeer, and is raised in all spots where key exchange aborts due to algorithmic incompatibility.
    • Like all other exceptions in that module, it inherits from SSHException, and as we did not change anything else about the raising (i.e. the attributes and message text are the same) this change is backwards compatible.
  • Transport grew a _preferred_pubkeys attribute and matching preferred_pubkeys property to match the other, kex-focused, such members. This allows client pubkey authentication to honor the disabled_algorithms feature.

  Thanks to Krisztián Kovács for the report and an early stab at a patch, as well as the numerous users who submitted feedback on the issue, including but not limited to: Christopher Rabotin, Sam Bull, and Manfred Kaiser.

2.8.1 2021-11-28

• [Bug]: (also #908) Update PKey and subclasses to compare (eq) via direct field/attribute comparison instead of hashing (while retaining the existing behavior of hash via a slight refactor). Big thanks to Josh Snyder and Jun Omae for the reports, and to Josh Snyder for reproduction details & patch.

  Warning

  This fixes a security flaw! If you are running Paramiko on 32-bit systems with low entropy (such as any 32-bit Python 2, or a 32-bit Python 3 which is running with PYTHONHASHSEED=0) it is possible for an attacker to craft a new keypair from an exfiltrated public key, which Paramiko would consider equal to the original key.

  This could enable attacks such as, but not limited to, the following:

  • Paramiko server processes would incorrectly authenticate the attacker (using their generated private key) as if they were the victim. We see this as the most plausible attack using this flaw.
  • Paramiko client processes would incorrectly validate a connected server (when host key verification is enabled) while subjected to a man-in-the-middle attack. This impacts more users than the server-side version, but also carries higher requirements for the attacker, namely successful DNS poisoning or other MITM techniques.

• [Bug] #1257: (also #1266) Update RSA and ECDSA key decoding subroutines to correctly catch exception types thrown by modern versions of Cryptography (specifically TypeError and its internal UnsupportedAlgorithm). These exception classes will now become SSHException instances instead of bubbling up. Thanks to Ignat Semenov for the report and @tylergarcianet for an early patch.

• [Bug] #1024: Deleting items from HostKeys would incorrectly raise KeyError even for valid keys, due to a logic bug. This has been fixed. Report & patch credit: Jia Zhang.

• [Bug] #985: (via #992) Fix listdir failure when server uses a locale. Now on Python 2.7 SFTPAttributes will decode abbreviated month names correctly rather than raise UnicodeDecodeError`. Patch courtesy of Martin Packman.

2.8.0 2021-10-09

• [Feature] #1846: Add a prefetch keyword argument to SFTPClient.get/SFTPClient.getfo so users who need to skip SFTP prefetching are able to conditionally turn it off. Thanks to Github user @h3ll0r for the PR.
• [Bug] #1462: (via #1882) Newer server-side key exchange algorithms not intended to use SHA1 (diffie-hellman-group14-sha256, diffie-hellman-group16-sha512) were incorrectly using SHA1 after all, due to a bug causing them to ignore the hash_algo class attribute. This has been corrected. Big thanks to @miverson for the report and to Benno Rice for the patch.
• [Support] #1722: Remove leading whitespace from OpenSSH RSA test suite static key fixture, to conform better to spec. Credit: Alex Gaynor.
• [Support] #1727: Add missing test suite fixtures directory to MANIFEST.in, reinstating the ability to run Paramiko’s tests from an sdist tarball. Thanks to Sandro Tosi for reporting the issue and to Blazej Michalik for the PR.
• [Support]: Update our CI to catch issues with sdist generation, installation and testing.
• [Support]: Administrivia overhaul, including but not limited to:
  • Migrate CI to CircleCI
  • Primary dev branch is now main (renamed)
  • Many README edits for clarity, modernization etc; including a bunch more (and consistent) status badges & unification with main project site index
  • PyPI page much more fleshed out (long_description is now filled in with the README; sidebar links expanded; etc)
  • flake8, pytest configs split out of setup.cfg into their own files
  • Invoke/invocations (used by maintainers/contributors) upgraded to modern versions

2.7.2 2020-08-30

• [Bug] #1723: Fix incorrectly swapped order of p and q numbers when loading OpenSSH-format RSA private keys. At minimum this should address a slowdown when using such keys, and it also means Paramiko works with Cryptography 3.1 and above (which complains strenuously when this problem appears). Thanks to Alex Gaynor for the patch.
• [Bug]: Fix incorrect string formatting causing unhelpful error message annotation when using Kerberos/GSSAPI. (Thanks, newer version of flake8!)
• [Support] #1722: Remove leading whitespace from OpenSSH RSA test suite static key fixture, to conform better to spec. Credit: Alex Gaynor.
• [Support] #1727: Add missing test suite fixtures directory to MANIFEST.in, reinstating the ability to run Paramiko’s tests from an sdist tarball. Thanks to Sandro Tosi for reporting the issue and to Blazej Michalik for the PR.
• [Support]: Update our CI to catch issues with sdist generation, installation and testing.

2.7.1 2019-12-09

• [Bug] #1565: (via #1566) Fix a bug in support for ECDSA keys under the newly supported OpenSSH key format. Thanks to Pierce Lopez for the patch.
• [Bug] #1567: The new-style private key format (added in 2.7) suffered from an unpadding bug which had been fixed earlier for Ed25519 (as that key type has always used the newer format). That fix has been refactored and applied to the base key class, courtesy of Pierce Lopez.

2.7.0 2019-12-03

• [Feature]: Add new convenience classmethod constructors to SSHConfig: from_text, from_file, and from_path. No more annoying two-step process!

• [Feature] #897: Implement most ‘canonical hostname’ ssh_config functionality (CanonicalizeHostname, CanonicalDomains, CanonicalizeFallbackLocal, and CanonicalizeMaxDots; CanonicalizePermittedCNAMEs has not yet been implemented). All were previously silently ignored. Reported by Michael Leinartas.

• [Feature] #717: Implement support for the Match keyword in ssh_config files. Previously, this keyword was simply ignored & keywords inside such blocks were treated as if they were part of the previous block. Thanks to Michael Leinartas for the initial patchset.

• [Feature]: A couple of outright SSHConfig parse errors were previously represented as vanilla Exception instances; as part of recent feature work a more specific exception class, ConfigParseError, has been created. It is now also used in those older spots, which is naturally backwards compatible.

• [Feature] #602: (via #1343, #1313, #618) Implement support for OpenSSH 6.5-style private key files (typically denoted as having BEGIN OPENSSH PRIVATE KEY headers instead of PEM format’s BEGIN RSA PRIVATE KEY or similar). If you were getting any sort of weird auth error from “modern” keys generated on newer operating system releases (such as macOS Mojave), this is the first update to try.

  Major thanks to everyone who contributed or tested versions of the patch, including but not limited to: Kevin Abel, Michiel Tiller, Pierce Lopez, and Jared Hobbs.

• [Bug]: Perform deduplication of IdentityFile contents during ssh_config parsing; previously, if your config would result in the same value being encountered more than once, IdentityFile would contain that many copies of the same string.

• [Bug]: Paramiko’s use of subprocess for ProxyCommand support is conditionally imported to prevent issues on limited interpreter platforms like Google Compute Engine. However, any resulting ImportError was lost instead of preserved for raising (in the rare cases where a user tried leveraging ProxyCommand in such an environment). This has been fixed.

• [Bug]: ssh_config token expansion used a different method of determining the local username ($USER env var), compared to what the (much older) client connection code does (getpass.getuser, which includes $USER but may check other variables first, and is generally much more comprehensive). Both modules now use getpass.getuser.

• [Support]: Explicitly document which ssh_config features we currently support. Previously users just had to guess, which is simply no good.

• [Support]: Additional installation extras_require “flavors” (ed25519, invoke, and all) have been added to our packaging metadata; see the install docs for details.

2.6.0 2019-06-23

• [Feature] #1463: Add a new keyword argument to SSHClient.connect and Transport, disabled_algorithms, which allows selectively disabling one or more kex/key/cipher/etc algorithms. This can be useful when disabling algorithms your target server (or client) does not support cleanly, or to work around unpatched bugs in Paramiko’s own implementation thereof.

• [Bug] #322: SSHClient.exec_command previously returned a naive ChannelFile object for its stdin value; such objects don’t know to properly shut down the remote end’s stdin when they .close(). This lead to issues (such as hangs) when running remote commands that read from stdin.

  A new subclass, ChannelStdinFile, has been created which closes remote stdin when it itself is closed. exec_command has been updated to use that class for its stdin return value.

  Thanks to Brandon Rhodes for the report & steps to reproduce.

• [Support] #1311: (for #584, replacing #1166) Add backwards-compatible support for the gssapi GSSAPI library, as the previous backend (python-gssapi) has since become defunct. This change also includes tests for the GSSAPI functionality.

  Big thanks to Anselm Kruis for the patch and to Sebastian Deiß (author of our initial GSSAPI functionality) for review.

  Note

  This feature also adds setup.py ‘extras’ support for installing Paramiko as paramiko[gssapi], which pulls in the optional dependencies you had to get by hand previously.

  Note

  To be very clear, this patch does not remove support for the older python-gssapi library. We may remove that support in a later release, but for now, either library will work. Please upgrade to gssapi when you can, however, as python-gssapi is no longer maintained upstream.

• [Support] #1440: (with initial fixes via #1460) Tweak many exception classes so their string representations are more human-friendly; this also includes incidental changes to some super() calls.

  The definitions of exceptions’ init methods have not changed, nor have any log messages been altered, so this should be backwards compatible for everything except the actual exceptions’ str() outputs.

  Thanks to Fabian Büchler for original report & Pierce Lopez for the foundational patch.

2.5.1 2019-06-23

• [Bug] #1306: (via #1400) Fix Ed25519 key handling so certain key comment lengths don’t cause SSHException(“Invalid key”) (this was technically a bug in how padding, or lack thereof, is calculated/interpreted). Thanks to @parke for the bug report & Pierce Lopez for the patch.

2.4.3 2019-06-23

• [Bug] #1306: (via #1400) Fix Ed25519 key handling so certain key comment lengths don’t cause SSHException(“Invalid key”) (this was technically a bug in how padding, or lack thereof, is calculated/interpreted). Thanks to @parke for the bug report & Pierce Lopez for the patch.
• [Support] #1378: Add support for the modern (as of Python 3.3) import location of MutableMapping (used in host key management) to avoid the old location becoming deprecated in Python 3.8. Thanks to Josh Karpel for catch & patch.

2.5.0 2019-06-09

• [Feature] #1212: Updated SSHConfig.lookup so it returns a new, type-casting-friendly dict subclass (SSHConfigDict) in lieu of dict literals. This ought to be backwards compatible, and allows an easier way to check boolean or int type ssh_config values. Thanks to Chris Rose for the patch.

• [Feature] #532: (via #1384 and #1258) Add support for Curve25519 key exchange (aka [email protected]). Thanks to Alex Gaynor and Dan Fuhry for supplying patches.

• [Feature] #1233: (also #1229, #1332) Add support for encrypt-then-MAC (ETM) schemes ([email protected], [email protected]) and two newer Diffie-Hellman group key exchange algorithms (group14, using SHA256; and group16, using SHA512). Patch courtesy of Edgar Sousa.

• [Support] #1191: Update our install docs with (somewhat) recently added additional dependencies; we previously only required Cryptography, but the docs never got updated after we incurred bcrypt and pynacl requirements for Ed25519 key support.

  Additionally, pyasn1 was never actually hard-required; it was necessary during a development branch, and is used by the optional GSSAPI support, but is not required for regular installation. Thus, it has been removed from our setup.py and its imports in the GSSAPI code made optional.

  Credit to @stevenwinfield for highlighting the outdated install docs.

• [Support] #1262: Add *.pub files to the MANIFEST so distributed source packages contain some necessary test assets. Credit: Alexander Kapshuna.

• [Support] #1378: Add support for the modern (as of Python 3.3) import location of MutableMapping (used in host key management) to avoid the old location becoming deprecated in Python 3.8. Thanks to Josh Karpel for catch & patch.

• [Support] #1379: (also #1369) Raise Cryptography dependency requirement to version 2.5 (from 1.5) and update some deprecated uses of its API.

  This removes a bunch of warnings of the style CryptographyDeprecationWarning: encode_point has been deprecated on EllipticCurvePublicNumbers and will be removed in a future version. Please use EllipticCurvePublicKey.public_bytes to obtain both compressed and uncompressed point encoding and similar, which users who had eventually upgraded to Cryptography 2.x would encounter.

  Warning

  This change is backwards incompatible if you are unable to upgrade your version of Cryptography. Please see Cryptography’s own changelog for details on what may change when you upgrade; for the most part the only changes involved dropping older Python versions (such as 2.6, 3.3, or some PyPy editions) which Paramiko itself has already dropped.

2.4.2 2018-09-18

• [Bug] #1283: Fix exploit (CVE-2018-1000805) in Paramiko’s server mode (not client mode) where hostile clients could trick the server into thinking they were authenticated without actually submitting valid authentication.

  Specifically, steps have been taken to start separating client and server related message types in the message handling tables within Transport and AuthHandler; this work is not complete but enough has been performed to close off this particular exploit (which was the only obvious such exploit for this particular channel).

  Thanks to Daniel Hoffman for the detailed report.

• [Bug]: Modify protocol message handling such that Transport does not respond to MSG_UNIMPLEMENTED with its own MSG_UNIMPLEMENTED. This behavior probably didn’t cause any outright errors, but it doesn’t seem to conform to the RFCs and could cause (non-infinite) feedback loops in some scenarios (usually those involving Paramiko on both ends).

• [Support] #1262: Add *.pub files to the MANIFEST so distributed source packages contain some necessary test assets. Credit: Alexander Kapshuna.

2.3.3 2018-09-18

• [Bug] #1283: Fix exploit (CVE-2018-1000805) in Paramiko’s server mode (not client mode) where hostile clients could trick the server into thinking they were authenticated without actually submitting valid authentication.

  Specifically, steps have been taken to start separating client and server related message types in the message handling tables within Transport and AuthHandler; this work is not complete but enough has been performed to close off this particular exploit (which was the only obvious such exploit for this particular channel).

  Thanks to Daniel Hoffman for the detailed report.

• [Bug]: Modify protocol message handling such that Transport does not respond to MSG_UNIMPLEMENTED with its own MSG_UNIMPLEMENTED. This behavior probably didn’t cause any outright errors, but it doesn’t seem to conform to the RFCs and could cause (non-infinite) feedback loops in some scenarios (usually those involving Paramiko on both ends).

• [Support] #1262: Add *.pub files to the MANIFEST so distributed source packages contain some necessary test assets. Credit: Alexander Kapshuna.

2.2.4 2018-09-18

• [Bug] #1283: Fix exploit (CVE-2018-1000805) in Paramiko’s server mode (not client mode) where hostile clients could trick the server into thinking they were authenticated without actually submitting valid authentication.

  Specifically, steps have been taken to start separating client and server related message types in the message handling tables within Transport and AuthHandler; this work is not complete but enough has been performed to close off this particular exploit (which was the only obvious such exploit for this particular channel).

  Thanks to Daniel Hoffman for the detailed report.

• [Bug]: Modify protocol message handling such that Transport does not respond to MSG_UNIMPLEMENTED with its own MSG_UNIMPLEMENTED. This behavior probably didn’t cause any outright errors, but it doesn’t seem to conform to the RFCs and could cause (non-infinite) feedback loops in some scenarios (usually those involving Paramiko on both ends).

• [Support] #1262: Add *.pub files to the MANIFEST so distributed source packages contain some necessary test assets. Credit: Alexander Kapshuna.

2.1.6 2018-09-18

• [Bug] #1283: Fix exploit (CVE-2018-1000805) in Paramiko’s server mode (not client mode) where hostile clients could trick the server into thinking they were authenticated without actually submitting valid authentication.

  Specifically, steps have been taken to start separating client and server related message types in the message handling tables within Transport and AuthHandler; this work is not complete but enough has been performed to close off this particular exploit (which was the only obvious such exploit for this particular channel).

  Thanks to Daniel Hoffman for the detailed report.

• [Bug]: Modify protocol message handling such that Transport does not respond to MSG_UNIMPLEMENTED with its own MSG_UNIMPLEMENTED. This behavior probably didn’t cause any outright errors, but it doesn’t seem to conform to the RFCs and could cause (non-infinite) feedback loops in some scenarios (usually those involving Paramiko on both ends).

• [Support] #1262: Add *.pub files to the MANIFEST so distributed source packages contain some necessary test assets. Credit: Alexander Kapshuna.

2.0.9 2018-09-18

• [Bug] #1283: Fix exploit (CVE-2018-1000805) in Paramiko’s server mode (not client mode) where hostile clients could trick the server into thinking they were authenticated without actually submitting valid authentication.

  Specifically, steps have been taken to start separating client and server related message types in the message handling tables within Transport and AuthHandler; this work is not complete but enough has been performed to close off this particular exploit (which was the only obvious such exploit for this particular channel).

  Thanks to Daniel Hoffman for the detailed report.

• [Bug]: Modify protocol message handling such that Transport does not respond to MSG_UNIMPLEMENTED with its own MSG_UNIMPLEMENTED. This behavior probably didn’t cause any outright errors, but it doesn’t seem to conform to the RFCs and could cause (non-infinite) feedback loops in some scenarios (usually those involving Paramiko on both ends).

• [Support] #1262: Add *.pub files to the MANIFEST so distributed source packages contain some necessary test assets. Credit: Alexander Kapshuna.

2.4.1 2018-03-12

• [Bug] #1039: Ed25519 auth key decryption raised an unexpected exception when given a unicode password string (typical in python 3). Report by Theodor van Nahl and fix by Pierce Lopez.
• [Bug] #1168: Add newer key classes for Ed25519 and ECDSA to paramiko.all so that code introspecting that attribute, or using from paramiko import * (such as some IDEs) sees them. Thanks to @patriksevallius for the patch.
• [Bug] #1175: Fix a security flaw (CVE-2018-7750) in Paramiko’s server mode (emphasis on server mode; this does not impact client use!) where authentication status was not checked before processing channel-open and other requests typically only sent after authenticating. Big thanks to Matthijs Kooijman for the report.

2.3.2 2018-03-12

• [Bug] #1108: Rename a private method keyword argument (which was named async) so that we’re compatible with the upcoming Python 3.7 release (where async is a new keyword.) Thanks to @vEpiphyte for the report.
• [Bug] #1039: Ed25519 auth key decryption raised an unexpected exception when given a unicode password string (typical in python 3). Report by Theodor van Nahl and fix by Pierce Lopez.
• [Bug] #1168: Add newer key classes for Ed25519 and ECDSA to paramiko.all so that code introspecting that attribute, or using from paramiko import * (such as some IDEs) sees them. Thanks to @patriksevallius for the patch.
• [Bug] #1175: Fix a security flaw (CVE-2018-7750) in Paramiko’s server mode (emphasis on server mode; this does not impact client use!) where authentication status was not checked before processing channel-open and other requests typically only sent after authenticating. Big thanks to Matthijs Kooijman for the report.
• [Support]: Include LICENSE file in wheel archives.

2.2.3 2018-03-12

• [Bug] #1071: Certificate support broke the no-certificate case for Ed25519 keys (symptom is an AttributeError about public_blob.) This went uncaught due to cert autoload behavior (i.e. our test suite never actually ran the no-cert case, because the cert existed!) Both issues have been fixed. Thanks to John Hu for the report.
• [Bug] #1108: Rename a private method keyword argument (which was named async) so that we’re compatible with the upcoming Python 3.7 release (where async is a new keyword.) Thanks to @vEpiphyte for the report.
• [Bug] #1039: Ed25519 auth key decryption raised an unexpected exception when given a unicode password string (typical in python 3). Report by Theodor van Nahl and fix by Pierce Lopez.
• [Bug] #1168: Add newer key classes for Ed25519 and ECDSA to paramiko.all so that code introspecting that attribute, or using from paramiko import * (such as some IDEs) sees them. Thanks to @patriksevallius for the patch.
• [Bug] #1175: Fix a security flaw (CVE-2018-7750) in Paramiko’s server mode (emphasis on server mode; this does not impact client use!) where authentication status was not checked before processing channel-open and other requests typically only sent after authenticating. Big thanks to Matthijs Kooijman for the report.
• [Support]: Include LICENSE file in wheel archives.

2.1.5 2018-03-12

• [Bug] #1071: Certificate support broke the no-certificate case for Ed25519 keys (symptom is an AttributeError about public_blob.) This went uncaught due to cert autoload behavior (i.e. our test suite never actually ran the no-cert case, because the cert existed!) Both issues have been fixed. Thanks to John Hu for the report.
• [Bug] #1108: Rename a private method keyword argument (which was named async) so that we’re compatible with the upcoming Python 3.7 release (where async is a new keyword.) Thanks to @vEpiphyte for the report.
• [Bug] #1039: Ed25519 auth key decryption raised an unexpected exception when given a unicode password string (typical in python 3). Report by Theodor van Nahl and fix by Pierce Lopez.
• [Bug] #1168: Add newer key classes for Ed25519 and ECDSA to paramiko.all so that code introspecting that attribute, or using from paramiko import * (such as some IDEs) sees them. Thanks to @patriksevallius for the patch.
• [Bug] #1175: Fix a security flaw (CVE-2018-7750) in Paramiko’s server mode (emphasis on server mode; this does not impact client use!) where authentication status was not checked before processing channel-open and other requests typically only sent after authenticating. Big thanks to Matthijs Kooijman for the report.
• [Support]: Include LICENSE file in wheel archives.

2.0.8 2018-03-12

• [Bug] #1071: Certificate support broke the no-certificate case for Ed25519 keys (symptom is an AttributeError about public_blob.) This went uncaught due to cert autoload behavior (i.e. our test suite never actually ran the no-cert case, because the cert existed!) Both issues have been fixed. Thanks to John Hu for the report.
• [Bug] #1108: Rename a private method keyword argument (which was named async) so that we’re compatible with the upcoming Python 3.7 release (where async is a new keyword.) Thanks to @vEpiphyte for the report.
• [Bug] #1039: Ed25519 auth key decryption raised an unexpected exception when given a unicode password string (typical in python 3). Report by Theodor van Nahl and fix by Pierce Lopez.
• [Bug] #1168: Add newer key classes for Ed25519 and ECDSA to paramiko.all so that code introspecting that attribute, or using from paramiko import * (such as some IDEs) sees them. Thanks to @patriksevallius for the patch.
• [Bug] #1175: Fix a security flaw (CVE-2018-7750) in Paramiko’s server mode (emphasis on server mode; this does not impact client use!) where authentication status was not checked before processing channel-open and other requests typically only sent after authenticating. Big thanks to Matthijs Kooijman for the report.
• [Support]: Include LICENSE file in wheel archives.

1.18.5 2018-03-12

• [Bug] #1108: Rename a private method keyword argument (which was named async) so that we’re compatible with the upcoming Python 3.7 release (where async is a new keyword.) Thanks to @vEpiphyte for the report.
• [Bug] #1175: Fix a security flaw (CVE-2018-7750) in Paramiko’s server mode (emphasis on server mode; this does not impact client use!) where authentication status was not checked before processing channel-open and other requests typically only sent after authenticating. Big thanks to Matthijs Kooijman for the report.

1.17.6 2018-03-12

• [Bug] #1055: (also #1056, #1057, #1058, #1059) Fix up host-key checking in our GSSAPI support, which was previously using an incorrect API call. Thanks to Anselm Kruis for the patches.
• [Bug] #1108: Rename a private method keyword argument (which was named async) so that we’re compatible with the upcoming Python 3.7 release (where async is a new keyword.) Thanks to @vEpiphyte for the report.
• [Bug] #1175: Fix a security flaw (CVE-2018-7750) in Paramiko’s server mode (emphasis on server mode; this does not impact client use!) where authentication status was not checked before processing channel-open and other requests typically only sent after authenticating. Big thanks to Matthijs Kooijman for the report.

2.4.0 2017-11-14

• [Feature]: Add a new passphrase kwarg to SSHClient.connect so users may disambiguate key-decryption passphrases from password-auth passwords. (This is a backwards compatible change; password will still pull double duty as a passphrase when passphrase is not given.)

• [Support] #1070: Drop Python 2.6 and Python 3.3 support; now only 2.7 and 3.4+ are supported. If you’re unable to upgrade from 2.6 or 3.3, please stick to the Paramiko 2.3.x (or below) release lines.

• [Support]: Include LICENSE file in wheel archives.

• [Support] #1100: Updated the test suite & related docs/metadata/config to be compatible with pytest instead of using the old, custom, crufty unittest-based test.py.

  This includes marking known-slow tests (mostly the SFTP ones) so they can be filtered out by inv test’s default behavior; as well as other minor tweaks to test collection and/or display (for example, GSSAPI tests are collected, but skipped, instead of not even being collected by default as in test.py.)

• [Support]: Update tearDown of client test suite to avoid hangs due to eternally blocking accept() calls on the internal server thread (which can occur when test code raises an exception before actually connecting to the server.)

2.3.1 2017-09-22

• [Bug] #1071: Certificate support broke the no-certificate case for Ed25519 keys (symptom is an AttributeError about public_blob.) This went uncaught due to cert autoload behavior (i.e. our test suite never actually ran the no-cert case, because the cert existed!) Both issues have been fixed. Thanks to John Hu for the report.

2.3.0 2017-09-18

• [Feature] #1042: (also partially #531) Implement basic client-side certificate authentication (as per the OpenSSH vendor extension.)

  The core implementation is PKey.load_certificate and its corresponding .public_blob attribute on key objects, which is honored in the auth and transport modules. Additionally, SSHClient.connect will now automatically load certificate data alongside private key data when one has appropriately-named cert files (e.g. id_rsa-cert.pub) - see its docstring for details.

  Thanks to Jason Rigby for a first draft (#531) and to Paul Kapp for the second draft, upon which the current functionality has been based (with modifications.)

  Note

  This support is client-focused; Paramiko-driven server code is capable of handling cert-bearing pubkey auth packets, but it does not interpret any cert-specific fields, so the end result is functionally identical to a vanilla pubkey auth process (and thus requires e.g. prepopulated authorized-keys data.) We expect full server-side cert support to follow later.

• [Feature] #1013: Added pre-authentication banner support for the server interface (ServerInterface.get_banner plus related support in Transport/AuthHandler.) Patch courtesy of Dennis Kaarsemaker.

• [Feature] #1026: Update Ed25519Key so its constructor offers the same file_obj parameter as its sibling key classes. Credit: Michal Kuffa.

• [Feature] #1063: Add a gss_trust_dns option to Client and Transport to allow explicitly setting whether or not DNS canonicalization should occur when using GSSAPI. Thanks to Richard E. Silverman for the report & Sebastian Deiß for initial patchset.

• [Bug] #60: (via #1037) Paramiko originally defaulted to zlib compression level 9 (when one connects with compression=True; it defaults to off.) This has been found to be quite wasteful and tends to cause much longer transfers in most cases, than is necessary.

  OpenSSH defaults to compression level 6, which is a much more reasonable setting (nearly identical compression characteristics but noticeably, sometimes significantly, faster transmission); Paramiko now uses this value instead.

  Thanks to Damien Dubé for the report and @DrNeutron for investigating & submitting the patch.

• [Support] #1012: (via #1016) Enhance documentation around the new SFTP.posix_rename method so it’s referenced in the ‘standard’ rename method for increased visibility. Thanks to Marius Flage for the report.

• [Support] #1041: Modify logic around explicit disconnect messages, and unknown-channel situations, so that they rely on centralized shutdown code instead of running their own. This is at worst removing some unnecessary code, and may help with some situations where Paramiko hangs at the end of a session. Thanks to Paul Kapp for the patch.

• [Support]: Display exception type and message when logging auth-rejection messages (ones reading Auth rejected: unsupported or mangled public key); previously this error case had a bare except and did not display exactly why the key failed. It will now append info such as KeyError: ‘some-unknown-type-string’ or similar.

• [Support]: Ed25519 keys never got proper API documentation support; this has been fixed.

• [Support] #979: Update how we use Cryptography’s signature/verification methods so we aren’t relying on a deprecated API. Thanks to Paul Kehrer for the patch.

  Warning

  This bumps the minimum Cryptography version from 1.1 to 1.5. Such an upgrade should be backwards compatible and easy to do. See their changelog for additional details.

2.2.2 2017-09-18

• [Bug] #945: (backport of #910 and re: #865) SSHClient now requests the type of host key it has (e.g. from known_hosts) and does not consider a different type to be a “Missing” host key. This fixes a common case where an ECDSA key is in known_hosts and the server also has an RSA host key. Thanks to Pierce Lopez.
• [Bug] #1055: (also #1056, #1057, #1058, #1059) Fix up host-key checking in our GSSAPI support, which was previously using an incorrect API call. Thanks to Anselm Kruis for the patches.
• [Bug] #1060: Fix key exchange (kex) algorithm list for GSSAPI authentication; previously, the list used solely out-of-date algorithms, and now contains newer ones listed preferentially before the old. Credit: Anselm Kruis.
• [Bug] #1061: Clean up GSSAPI authentication procedures so they do not prevent normal fallback to other authentication methods on failure. (In other words, presence of GSSAPI functionality on a target server precluded use of _any_ other auth type if the user was unable to pass GSSAPI auth.) Patch via Anselm Kruis.
• [Bug] #1065: Add rekeying support to GSSAPI connections, which was erroneously missing. Without this fix, any attempt to renegotiate the transport keys for a gss-kex-authed Transport would cause a MIC failure and terminate the connection. Thanks to Sebastian Deiß and Anselm Kruis for the patch.

2.1.4 2017-09-18

• [Bug] #990: The (added in 2.2.0) bcrypt dependency should have been on version 3.1.3 or greater (was initially set to 3.0.0 or greater.) Thanks to Paul Howarth for the report.
• [Bug] #993: Ed25519 host keys were not comparable/hashable, causing an exception if such a key existed in a known_hosts file. Thanks to Oleh Prypin for the report and Pierce Lopez for the fix.
• [Bug] #945: (backport of #910 and re: #865) SSHClient now requests the type of host key it has (e.g. from known_hosts) and does not consider a different type to be a “Missing” host key. This fixes a common case where an ECDSA key is in known_hosts and the server also has an RSA host key. Thanks to Pierce Lopez.
• [Bug] #1055: (also #1056, #1057, #1058, #1059) Fix up host-key checking in our GSSAPI support, which was previously using an incorrect API call. Thanks to Anselm Kruis for the patches.
• [Bug] #1060: Fix key exchange (kex) algorithm list for GSSAPI authentication; previously, the list used solely out-of-date algorithms, and now contains newer ones listed preferentially before the old. Credit: Anselm Kruis.
• [Bug] #1061: Clean up GSSAPI authentication procedures so they do not prevent normal fallback to other authentication methods on failure. (In other words, presence of GSSAPI functionality on a target server precluded use of _any_ other auth type if the user was unable to pass GSSAPI auth.) Patch via Anselm Kruis.
• [Bug] #1065: Add rekeying support to GSSAPI connections, which was erroneously missing. Without this fix, any attempt to renegotiate the transport keys for a gss-kex-authed Transport would cause a MIC failure and terminate the connection. Thanks to Sebastian Deiß and Anselm Kruis for the patch.

2.0.7 2017-09-18

• [Bug] #990: The (added in 2.2.0) bcrypt dependency should have been on version 3.1.3 or greater (was initially set to 3.0.0 or greater.) Thanks to Paul Howarth for the report.
• [Bug] #993: Ed25519 host keys were not comparable/hashable, causing an exception if such a key existed in a known_hosts file. Thanks to Oleh Prypin for the report and Pierce Lopez for the fix.
• [Bug] #945: (backport of #910 and re: #865) SSHClient now requests the type of host key it has (e.g. from known_hosts) and does not consider a different type to be a “Missing” host key. This fixes a common case where an ECDSA key is in known_hosts and the server also has an RSA host key. Thanks to Pierce Lopez.
• [Bug] #1055: (also #1056, #1057, #1058, #1059) Fix up host-key checking in our GSSAPI support, which was previously using an incorrect API call. Thanks to Anselm Kruis for the patches.
• [Bug] #1060: Fix key exchange (kex) algorithm list for GSSAPI authentication; previously, the list used solely out-of-date algorithms, and now contains newer ones listed preferentially before the old. Credit: Anselm Kruis.
• [Bug] #1061: Clean up GSSAPI authentication procedures so they do not prevent normal fallback to other authentication methods on failure. (In other words, presence of GSSAPI functionality on a target server precluded use of _any_ other auth type if the user was unable to pass GSSAPI auth.) Patch via Anselm Kruis.
• [Bug] #1065: Add rekeying support to GSSAPI connections, which was erroneously missing. Without this fix, any attempt to renegotiate the transport keys for a gss-kex-authed Transport would cause a MIC failure and terminate the connection. Thanks to Sebastian Deiß and Anselm Kruis for the patch.

1.18.4 2017-09-18

• [Bug] #945: (backport of #910 and re: #865) SSHClient now requests the type of host key it has (e.g. from known_hosts) and does not consider a different type to be a “Missing” host key. This fixes a common case where an ECDSA key is in known_hosts and the server also has an RSA host key. Thanks to Pierce Lopez.
• [Bug] #1055: (also #1056, #1057, #1058, #1059) Fix up host-key checking in our GSSAPI support, which was previously using an incorrect API call. Thanks to Anselm Kruis for the patches.

2.2.1 2017-06-13

• [Bug] #990: The (added in 2.2.0) bcrypt dependency should have been on version 3.1.3 or greater (was initially set to 3.0.0 or greater.) Thanks to Paul Howarth for the report.
• [Bug] #993: Ed25519 host keys were not comparable/hashable, causing an exception if such a key existed in a known_hosts file. Thanks to Oleh Prypin for the report and Pierce Lopez for the fix.

2.2.0 2017-06-09

• [Feature] #325: (via #972) Add Ed25519 support, for both host keys and user authentication. Big thanks to Alex Gaynor for the patch.

  Note

  This change adds the bcrypt and pynacl Python libraries as dependencies. No C-level dependencies beyond those previously required (for Cryptography) have been added.

• [Feature] #951: Add support for ECDH key exchange (kex), specifically the algorithms ecdh-sha2-nistp256, ecdh-sha2-nistp384, and ecdh-sha2-nistp521. They now come before the older diffie-hellman-* family of kex algorithms in the preferred-kex list. Thanks to Shashank Veerapaneni for the patch & Pierce Lopez for a follow-up.

• [Feature] #857: Allow SSHClient.set_missing_host_key_policy to accept policy classes _or_ instances, instead of only instances, thus fixing a long-standing gotcha for unaware users.

• [Feature] #869: Add an auth_timeout kwarg to SSHClient.connect (default: 30s) to avoid hangs when the remote end becomes unresponsive during the authentication step. Credit to @timsavage.

  Note

  This technically changes behavior, insofar as very slow auth steps >30s will now cause timeout exceptions instead of completing. We doubt most users will notice; those affected can simply give a higher value to auth_timeout.

• [Feature] #65: (via #471) Add support for OpenSSH’s SFTP posix-rename protocol extension (section 3.3 of OpenSSH’s protocol extension document), via a new posix_rename method in SFTPClient and SFTPServerInterface. Thanks to Wren Turkal for the initial patch & Mika Pflüger for the enhanced, merged PR.

• [Support] #866: (also #838) Remove an old test-related file we don’t support, and add PyPy to Travis-CI config. Thanks to Pierce Lopez for the final patch and Pedro Rodrigues for an earlier edition.

• [Support] #974: Overhaul the codebase to be PEP-8, etc, compliant (i.e. passes the maintainer’s preferred flake8 configuration) and add a flake8 step to the Travis config. Big thanks to Dorian Pula!

• [Support]: A big formatting pass to clean up an enormous number of invalid Sphinx reference links, discovered by switching to a modern, rigorous nitpicking doc-building mode.

• [Support] #956: Switch code coverage service from coveralls.io to codecov.io (& then disable the latter’s auto-comments.) Thanks to Nikolai Røed Kristiansen for the patch.

• [Support] #921: Tighten up the hash implementation for various key classes; less code is good code. Thanks to Francisco Couzo for the patch.

• [Support] #906: Clean up a handful of outdated imports and related tweaks. Thanks to Pierce Lopez.

2.1.3 2017-06-09

• [Bug] #683: Make util.log_to_file append instead of replace. Thanks to @vlcinsky for the report.

• [Bug] #949: SSHClient and Transport could cause a memory leak if there’s a connection problem or protocol error, even if Transport.close() is called. Thanks Kyle Agronick for the discovery and investigation, and Pierce Lopez for assistance.

• [Bug] #794: (via #981) Prior support for ecdsa-sha2-nistp(384|521) algorithms didn’t fully extend to covering host keys, preventing connection to hosts which only offer these key types and no others. This is now fixed. Thanks to @ncoult and @kasdoe for reports and Pierce Lopez for the patch.

• [Bug] #900: (via #911) Prefer newer ecdsa-sha2-nistp keys over RSA and DSA keys during host key selection. This improves compatibility with OpenSSH, both in terms of general behavior, and also re: ability to properly leverage OpenSSH-modified known_hosts files. Credit: @kasdoe for original report/PR and Pierce Lopez for the second draft.

• [Bug] #667: The RC4/arcfour family of ciphers has been broken since version 2.0; but since the algorithm is now known to be completely insecure, we are opting to remove support outright instead of fixing it. Thanks to Alex Gaynor for catch & patch.

• [Bug] #983: Move sha1 above the now-arguably-broken md5 in the list of preferred MAC algorithms, as an incremental security improvement for users whose target systems offer both. Credit: Pierce Lopez.

• [Bug] #741: (also #809, #772; all via #912) Writing encrypted/password-protected private key files was silently broken since 2.0 due to an incorrect API call; this has been fixed.

  Includes a directly related fix, namely adding the ability to read AES-256-CBC ciphered private keys (which is now what we tend to write out as it is Cryptography’s default private key cipher.)

  Thanks to @virlos for the original report, Chris Harris and @ibuler for initial draft PRs, and @jhgorrell for the final patch.

• [Bug] #971: Allow any type implementing the buffer API to be used with BufferedFile, Channel, and SFTPFile. This resolves a regression introduced in 1.13 with the Python 3 porting changes, when using types such as memoryview. Credit: Martin Packman.

• [Bug] #984: Enhance default cipher preference order such that aes(192|256)-cbc are preferred over blowfish-cbc. Thanks to Alex Gaynor.

• [Bug] #865: SSHClient now requests the type of host key it has (e.g. from known_hosts) and does not consider a different type to be a “Missing” host key. This fixes a common case where an ECDSA key is in known_hosts and the server also has an RSA host key. Thanks to Pierce Lopez.

• [Support] #974: Overhaul the codebase to be PEP-8, etc, compliant (i.e. passes the maintainer’s preferred flake8 configuration) and add a flake8 step to the Travis config. Big thanks to Dorian Pula!

• [Support]: A big formatting pass to clean up an enormous number of invalid Sphinx reference links, discovered by switching to a modern, rigorous nitpicking doc-building mode.

• [Support] #956: Switch code coverage service from coveralls.io to codecov.io (& then disable the latter’s auto-comments.) Thanks to Nikolai Røed Kristiansen for the patch.

2.0.6 2017-06-09

• [Bug] #683: Make util.log_to_file append instead of replace. Thanks to @vlcinsky for the report.

• [Bug] #949: SSHClient and Transport could cause a memory leak if there’s a connection problem or protocol error, even if Transport.close() is called. Thanks Kyle Agronick for the discovery and investigation, and Pierce Lopez for assistance.

• [Bug] #794: (via #981) Prior support for ecdsa-sha2-nistp(384|521) algorithms didn’t fully extend to covering host keys, preventing connection to hosts which only offer these key types and no others. This is now fixed. Thanks to @ncoult and @kasdoe for reports and Pierce Lopez for the patch.

• [Bug] #900: (via #911) Prefer newer ecdsa-sha2-nistp keys over RSA and DSA keys during host key selection. This improves compatibility with OpenSSH, both in terms of general behavior, and also re: ability to properly leverage OpenSSH-modified known_hosts files. Credit: @kasdoe for original report/PR and Pierce Lopez for the second draft.

• [Bug] #667: The RC4/arcfour family of ciphers has been broken since version 2.0; but since the algorithm is now known to be completely insecure, we are opting to remove support outright instead of fixing it. Thanks to Alex Gaynor for catch & patch.

• [Bug] #983: Move sha1 above the now-arguably-broken md5 in the list of preferred MAC algorithms, as an incremental security improvement for users whose target systems offer both. Credit: Pierce Lopez.

• [Bug] #741: (also #809, #772; all via #912) Writing encrypted/password-protected private key files was silently broken since 2.0 due to an incorrect API call; this has been fixed.

  Includes a directly related fix, namely adding the ability to read AES-256-CBC ciphered private keys (which is now what we tend to write out as it is Cryptography’s default private key cipher.)

  Thanks to @virlos for the original report, Chris Harris and @ibuler for initial draft PRs, and @jhgorrell for the final patch.

• [Bug] #971: Allow any type implementing the buffer API to be used with BufferedFile, Channel, and SFTPFile. This resolves a regression introduced in 1.13 with the Python 3 porting changes, when using types such as memoryview. Credit: Martin Packman.

• [Bug] #984: Enhance default cipher preference order such that aes(192|256)-cbc are preferred over blowfish-cbc. Thanks to Alex Gaynor.

• [Bug] #865: SSHClient now requests the type of host key it has (e.g. from known_hosts) and does not consider a different type to be a “Missing” host key. This fixes a common case where an ECDSA key is in known_hosts and the server also has an RSA host key. Thanks to Pierce Lopez.

• [Support] #974: Overhaul the codebase to be PEP-8, etc, compliant (i.e. passes the maintainer’s preferred flake8 configuration) and add a flake8 step to the Travis config. Big thanks to Dorian Pula!

• [Support]: A big formatting pass to clean up an enormous number of invalid Sphinx reference links, discovered by switching to a modern, rigorous nitpicking doc-building mode.

• [Support] #956: Switch code coverage service from coveralls.io to codecov.io (& then disable the latter’s auto-comments.) Thanks to Nikolai Røed Kristiansen for the patch.

1.18.3 2017-06-09

• [Bug] #683: Make util.log_to_file append instead of replace. Thanks to @vlcinsky for the report.
• [Bug] #949: SSHClient and Transport could cause a memory leak if there’s a connection problem or protocol error, even if Transport.close() is called. Thanks Kyle Agronick for the discovery and investigation, and Pierce Lopez for assistance.
• [Bug] #971: Allow any type implementing the buffer API to be used with BufferedFile, Channel, and SFTPFile. This resolves a regression introduced in 1.13 with the Python 3 porting changes, when using types such as memoryview. Credit: Martin Packman.
• [Support] #956: Switch code coverage service from coveralls.io to codecov.io (& then disable the latter’s auto-comments.) Thanks to Nikolai Røed Kristiansen for the patch.

1.17.5 2017-06-09

• [Bug] #683: Make util.log_to_file append instead of replace. Thanks to @vlcinsky for the report.
• [Bug] #949: SSHClient and Transport could cause a memory leak if there’s a connection problem or protocol error, even if Transport.close() is called. Thanks Kyle Agronick for the discovery and investigation, and Pierce Lopez for assistance.
• [Bug] #971: Allow any type implementing the buffer API to be used with BufferedFile, Channel, and SFTPFile. This resolves a regression introduced in 1.13 with the Python 3 porting changes, when using types such as memoryview. Credit: Martin Packman.
• [Support] #956: Switch code coverage service from coveralls.io to codecov.io (& then disable the latter’s auto-comments.) Thanks to Nikolai Røed Kristiansen for the patch.

2.1.2 2017-02-20

• [Bug] #895: Fix a bug in server-mode concerning multiple interactive auth steps (which were incorrectly responded to). Thanks to Dennis Kaarsemaker for catch & patch.
• [Bug] #44: (via #891) SSHClient now gives its internal Transport a handle on itself, preventing garbage collection of the client until the session is closed. Without this, some code which returns stream or transport objects without the client that generated them, would result in premature session closure when the client was GCd. Credit: @w31rd0 for original report, Omer Anson for the patch.
• [Bug] #862: (via #863) Avoid test suite exceptions on platforms lacking errno.ETIME (which seems to be some FreeBSD and some Windows environments.) Thanks to Sofian Brabez.
• [Bug] #853: Tweak how RSAKey.str behaves so it doesn’t cause TypeError under Python 3. Thanks to Francisco Couzo for the report.
• [Support] #866: (also #838) Remove an old test-related file we don’t support, and add PyPy to Travis-CI config. Thanks to Pierce Lopez for the final patch and Pedro Rodrigues for an earlier edition.

2.0.5 2017-02-20

• [Bug] #895: Fix a bug in server-mode concerning multiple interactive auth steps (which were incorrectly responded to). Thanks to Dennis Kaarsemaker for catch & patch.
• [Bug] #44: (via #891) SSHClient now gives its internal Transport a handle on itself, preventing garbage collection of the client until the session is closed. Without this, some code which returns stream or transport objects without the client that generated them, would result in premature session closure when the client was GCd. Credit: @w31rd0 for original report, Omer Anson for the patch.
• [Bug] #862: (via #863) Avoid test suite exceptions on platforms lacking errno.ETIME (which seems to be some FreeBSD and some Windows environments.) Thanks to Sofian Brabez.
• [Bug] #853: Tweak how RSAKey.str behaves so it doesn’t cause TypeError under Python 3. Thanks to Francisco Couzo for the report.
• [Support] #866: (also #838) Remove an old test-related file we don’t support, and add PyPy to Travis-CI config. Thanks to Pierce Lopez for the final patch and Pedro Rodrigues for an earlier edition.

1.18.2 2017-02-20

• [Bug] #895: Fix a bug in server-mode concerning multiple interactive auth steps (which were incorrectly responded to). Thanks to Dennis Kaarsemaker for catch & patch.
• [Bug] #713: (via #714 and #889) Don’t pass initialization vectors to PyCrypto when dealing with counter-mode ciphers; newer PyCrypto versions throw an exception otherwise (older ones simply ignored this parameter altogether). Thanks to @jmh045000 for report & patches.
• [Bug] #44: (via #891) SSHClient now gives its internal Transport a handle on itself, preventing garbage collection of the client until the session is closed. Without this, some code which returns stream or transport objects without the client that generated them, would result in premature session closure when the client was GCd. Credit: @w31rd0 for original report, Omer Anson for the patch.
• [Bug] #862: (via #863) Avoid test suite exceptions on platforms lacking errno.ETIME (which seems to be some FreeBSD and some Windows environments.) Thanks to Sofian Brabez.
• [Bug] #853: Tweak how RSAKey.str behaves so it doesn’t cause TypeError under Python 3. Thanks to Francisco Couzo for the report.
• [Support] #866: (also #838) Remove an old test-related file we don’t support, and add PyPy to Travis-CI config. Thanks to Pierce Lopez for the final patch and Pedro Rodrigues for an earlier edition.

1.17.4 2017-02-20

• [Bug] #895: Fix a bug in server-mode concerning multiple interactive auth steps (which were incorrectly responded to). Thanks to Dennis Kaarsemaker for catch & patch.
• [Bug] #713: (via #714 and #889) Don’t pass initialization vectors to PyCrypto when dealing with counter-mode ciphers; newer PyCrypto versions throw an exception otherwise (older ones simply ignored this parameter altogether). Thanks to @jmh045000 for report & patches.
• [Bug] #44: (via #891) SSHClient now gives its internal Transport a handle on itself, preventing garbage collection of the client until the session is closed. Without this, some code which returns stream or transport objects without the client that generated them, would result in premature session closure when the client was GCd. Credit: @w31rd0 for original report, Omer Anson for the patch.
• [Bug] #862: (via #863) Avoid test suite exceptions on platforms lacking errno.ETIME (which seems to be some FreeBSD and some Windows environments.) Thanks to Sofian Brabez.
• [Bug] #853: Tweak how RSAKey.str behaves so it doesn’t cause TypeError under Python 3. Thanks to Francisco Couzo for the report.
• [Support] #866: (also #838) Remove an old test-related file we don’t support, and add PyPy to Travis-CI config. Thanks to Pierce Lopez for the final patch and Pedro Rodrigues for an earlier edition.

2.1.1 2016-12-12

• [Bug] #859: (via #860) A tweak to the original patch implementing #398 was not fully applied, causing calls to invoke_shell to fail with AttributeError. This has been fixed. Patch credit: Kirk Byers.
• [Bug]: Accidentally merged the new features from 1.18.0 into the 2.0.x bugfix-only branch. This included merging a bug in one of those new features (breaking invoke_shell with an AttributeError.) The offending code has been stripped out of the 2.0.x line (but of course, remains in 2.1.x and above.)
• [Bug] #859: (via #860) A tweak to the original patch implementing #398 was not fully applied, causing calls to invoke_shell to fail with AttributeError. This has been fixed. Patch credit: Kirk Byers.

2.0.4 2016-12-12

• [Bug] #859: (via #860) A tweak to the original patch implementing #398 was not fully applied, causing calls to invoke_shell to fail with AttributeError. This has been fixed. Patch credit: Kirk Byers.
• [Bug]: Accidentally merged the new features from 1.18.0 into the 2.0.x bugfix-only branch. This included merging a bug in one of those new features (breaking invoke_shell with an AttributeError.) The offending code has been stripped out of the 2.0.x line (but of course, remains in 2.1.x and above.)
• [Bug] #859: (via #860) A tweak to the original patch implementing #398 was not fully applied, causing calls to invoke_shell to fail with AttributeError. This has been fixed. Patch credit: Kirk Byers.

1.18.1 2016-12-12

• [Bug] #859: (via #860) A tweak to the original patch implementing #398 was not fully applied, causing calls to invoke_shell to fail with AttributeError. This has been fixed. Patch credit: Kirk Byers.

2.1.0 2016-12-09

• [Feature] #398: Add an environment dict argument to Client.exec_command (plus the lower level Channel.update_environment and Channel.set_environment_variable methods) which implements the env SSH message type. This means the remote shell environment can be set without the use of VARNAME=value shell tricks, provided the server’s AcceptEnv lists the variables you need to set. Thanks to Philip Lorenz for the pull request.
• [Feature] #780: (also #779, and may help users affected by #520) Add an optional timeout parameter to Transport.start_client (and feed it the value of the configured connection timeout when used within SSHClient.) This helps prevent situations where network connectivity isn’t timing out, but the remote server is otherwise unable to service the connection in a timely manner. Credit to @sanseihappa.
• [Support] #854: Fix incorrect docstring/param-list for Transport.auth_gssapi_keyex so it matches the real signature. Caught by @Score_Under.
• [Support] #792: Minor updates to the README and demos; thanks to Alan Yee.
• [Support] #801: Skip a Unix-only test when on Windows; thanks to Gabi Davar.

2.0.3 2016-12-09

• [Bug] #681: Fix a Python3-specific bug re: the handling of read buffers when using ProxyCommand. Thanks to Paul Kapp for catch & patch.
• [Bug] #334: Make the subprocess import in proxy.py lazy so users on platforms without it (such as Google App Engine) can import Paramiko successfully. (Relatedly, make it easier to tweak an active socket check timeout [in Transport] which was previously hardcoded.) Credit: Shinya Okano.
• [Bug] #789: Add a missing .closed attribute (plus ._closed because reasons) to ProxyCommand so the earlier partial fix for #520 works in situations where one is gatewaying via ProxyCommand.
• [Bug] #742: (also re: #559) Catch AssertionError thrown by Cryptography when attempting to load bad ECDSA keys, turning it into an SSHException. This moves the behavior in line with other “bad keys” situations, re: Paramiko’s main auth loop. Thanks to MengHuan Yu for the patch.
• [Bug] #824: Fix the implementation of PKey.write_private_key_file (this method is only publicly defined on subclasses; the fix was in the private real implementation) so it passes the correct params to open(). This bug apparently went unnoticed and unfixed for 12 entire years. Congrats to John Villalovos for noticing & submitting the patch!
• [Bug] #802: (via #804) Update our vendored Windows API module to address errors of the form AttributeError: ‘module’ object has no attribute 'c_ssize_t’. Credit to Jason R. Coombs.
• [Support] #854: Fix incorrect docstring/param-list for Transport.auth_gssapi_keyex so it matches the real signature. Caught by @Score_Under.
• [Support] #792: Minor updates to the README and demos; thanks to Alan Yee.
• [Support] #801: Skip a Unix-only test when on Windows; thanks to Gabi Davar.

1.18.0 2016-12-09

• [Feature] #398: Add an environment dict argument to Client.exec_command (plus the lower level Channel.update_environment and Channel.set_environment_variable methods) which implements the env SSH message type. This means the remote shell environment can be set without the use of VARNAME=value shell tricks, provided the server’s AcceptEnv lists the variables you need to set. Thanks to Philip Lorenz for the pull request.
• [Feature] #780: (also #779, and may help users affected by #520) Add an optional timeout parameter to Transport.start_client (and feed it the value of the configured connection timeout when used within SSHClient.) This helps prevent situations where network connectivity isn’t timing out, but the remote server is otherwise unable to service the connection in a timely manner. Credit to @sanseihappa.
• [Support] #819: Document how lacking gmp headers at install time can cause a significant performance hit if you build PyCrypto from source. (Most system-distributed packages already have this enabled.)
• [Support] #854: Fix incorrect docstring/param-list for Transport.auth_gssapi_keyex so it matches the real signature. Caught by @Score_Under.
• [Support] #792: Minor updates to the README and demos; thanks to Alan Yee.
• [Support] #801: Skip a Unix-only test when on Windows; thanks to Gabi Davar.

1.17.3 2016-12-09

• [Bug] #681: Fix a Python3-specific bug re: the handling of read buffers when using ProxyCommand. Thanks to Paul Kapp for catch & patch.
• [Bug] #334: Make the subprocess import in proxy.py lazy so users on platforms without it (such as Google App Engine) can import Paramiko successfully. (Relatedly, make it easier to tweak an active socket check timeout [in Transport] which was previously hardcoded.) Credit: Shinya Okano.
• [Bug] #789: Add a missing .closed attribute (plus ._closed because reasons) to ProxyCommand so the earlier partial fix for #520 works in situations where one is gatewaying via ProxyCommand.
• [Bug] #824: Fix the implementation of PKey.write_private_key_file (this method is only publicly defined on subclasses; the fix was in the private real implementation) so it passes the correct params to open(). This bug apparently went unnoticed and unfixed for 12 entire years. Congrats to John Villalovos for noticing & submitting the patch!
• [Bug] #802: (via #804) Update our vendored Windows API module to address errors of the form AttributeError: ‘module’ object has no attribute 'c_ssize_t’. Credit to Jason R. Coombs.
• [Support] #819: Document how lacking gmp headers at install time can cause a significant performance hit if you build PyCrypto from source. (Most system-distributed packages already have this enabled.)
• [Support] #854: Fix incorrect docstring/param-list for Transport.auth_gssapi_keyex so it matches the real signature. Caught by @Score_Under.
• [Support] #792: Minor updates to the README and demos; thanks to Alan Yee.
• [Support] #801: Skip a Unix-only test when on Windows; thanks to Gabi Davar.

2.0.2 2016-07-25

• [Bug] #758: Apply type definitions to _winapi module from jaraco.windows 3.6.1. This should address issues on Windows platforms that often result in errors like ArgumentError: […] int too long to convert. Thanks to @swohlerLL for the report and Jason R. Coombs for the patch.
• [Bug] #774: Add a _closed private attribute to Channel objects so that they continue functioning when used as proxy sockets under Python 3 (e.g. as direct-tcpip gateways for other Paramiko connections.)
• [Bug] #673: (via #681) Fix protocol banner read errors (SSHException) which would occasionally pop up when using ProxyCommand gatewaying. Thanks to @Depado for the initial report and Paul Kapp for the fix.

1.17.2 2016-07-25

• [Bug] #758: Apply type definitions to _winapi module from jaraco.windows 3.6.1. This should address issues on Windows platforms that often result in errors like ArgumentError: […] int too long to convert. Thanks to @swohlerLL for the report and Jason R. Coombs for the patch.
• [Bug] #774: Add a _closed private attribute to Channel objects so that they continue functioning when used as proxy sockets under Python 3 (e.g. as direct-tcpip gateways for other Paramiko connections.)
• [Bug] #673: (via #681) Fix protocol banner read errors (SSHException) which would occasionally pop up when using ProxyCommand gatewaying. Thanks to @Depado for the initial report and Paul Kapp for the fix.

1.16.3 2016-07-25

• [Bug] #758: Apply type definitions to _winapi module from jaraco.windows 3.6.1. This should address issues on Windows platforms that often result in errors like ArgumentError: […] int too long to convert. Thanks to @swohlerLL for the report and Jason R. Coombs for the patch.
• [Bug] #774: Add a _closed private attribute to Channel objects so that they continue functioning when used as proxy sockets under Python 3 (e.g. as direct-tcpip gateways for other Paramiko connections.)
• [Bug] #673: (via #681) Fix protocol banner read errors (SSHException) which would occasionally pop up when using ProxyCommand gatewaying. Thanks to @Depado for the initial report and Paul Kapp for the fix.

2.0.1 2016-06-21

• [Bug] #537: Fix a bug in BufferedPipe.set_event which could cause deadlocks/hangs when one uses select.select against Channel objects (or otherwise calls Channel.fileno after the channel has closed). Thanks to Przemysław Strzelczak for the report & reproduction case, and to Krzysztof Rusek for the fix.
• [Bug] #520: (Partial fix) Fix at least one instance of race condition driven threading hangs at end of the Python interpreter session. (Includes a docs update as well - always make sure to .close() your clients!)

1.17.1 2016-06-21

• [Bug] #537: Fix a bug in BufferedPipe.set_event which could cause deadlocks/hangs when one uses select.select against Channel objects (or otherwise calls Channel.fileno after the channel has closed). Thanks to Przemysław Strzelczak for the report & reproduction case, and to Krzysztof Rusek for the fix.
• [Bug] #520: (Partial fix) Fix at least one instance of race condition driven threading hangs at end of the Python interpreter session. (Includes a docs update as well - always make sure to .close() your clients!)

1.16.2 2016-06-21

• [Bug] #537: Fix a bug in BufferedPipe.set_event which could cause deadlocks/hangs when one uses select.select against Channel objects (or otherwise calls Channel.fileno after the channel has closed). Thanks to Przemysław Strzelczak for the report & reproduction case, and to Krzysztof Rusek for the fix.
• [Bug] #520: (Partial fix) Fix at least one instance of race condition driven threading hangs at end of the Python interpreter session. (Includes a docs update as well - always make sure to .close() your clients!)

2.0.0 2016-04-28

• [Feature] #394: Replace PyCrypto with the Python Cryptographic Authority (PyCA) ‘Cryptography’ library suite. This improves security, installability, and performance; adds PyPy support; and much more.

  There aren’t enough ways to thank Alex Gaynor for all of his work on this, and then his patience while the maintainer let his PR grow moss for a year and change. Paul Kehrer came in with an assist, and I think I saw Olle Lundberg, @techtonik and @johnthagen supplying backup as well. Thanks to all!

  Warning

  This is a backwards incompatible change.

  However, it should only affect installation requirements; no API changes are intended or expected. Please report any such breakages as bugs.

  See our updated installation docs for details on what is now required to install Paramiko; many/most users should be able to simply pip install -U paramiko (especially if you upgrade to pip 8).

• [Feature] #731: (working off the earlier #611) Add support for 384- and 512-bit elliptic curve groups in ECDSA key types (aka ecdsa-sha2-nistp384 / ecdsa-sha2-nistp521). Thanks to Michiel Tiller and @CrazyCasta for the patches.

1.17.0 2016-04-28

• [Feature] #588: Add missing file-like object methods for BufferedFile and SFTPFile. Thanks to Adam Meily for the patch.
• [Bug] #649: Update the module in charge of handling SSH moduli so it’s consistent with OpenSSH behavior re: prime number selection. Thanks to Damien Tournoud for catch & patch.
• [Support] #636: Clean up and enhance the README (and rename it to README.rst from just README). Thanks to @LucasRMehl.
• [Support] #697: Remove whitespace in our setup.py’s install_requires as it triggers occasional bugs in some versions of setuptools. Thanks to Justin Lecher for catch & original patch.
• [Support] #612: Identify & work around a race condition in the test for handshake timeouts, which was causing frequent test failures for a subset of contributors as well as Travis-CI (usually, but not always, limited to Python 3.5). Props to Ed Kellett for assistance during some of the troubleshooting.
• [Support] #621: Annotate some public attributes on Channel such as .closed. Thanks to Sergey Vasilyev for the report.
• [Support] #729: Clean up setup.py to always use setuptools, not doing so was a historical artifact from bygone days. Thanks to Alex Gaynor.

1.16.1 2016-04-28

• [Bug] #652: Fix behavior of gssapi-with-mic auth requests so they fail gracefully (allowing followup via other auth methods) instead of raising an exception. Patch courtesy of @jamercee.
• [Bug] #499: Strip trailing/leading whitespace from lines when parsing SSH config files - this brings things in line with OpenSSH behavior. Thanks to Alfredo Esteban for the original report and Nick Pillitteri for the patch.
• [Bug] #632: Fix logic bug in the SFTP client’s callback-calling functionality; previously there was a chance the given callback would fire twice at the end of a transfer. Thanks to @ab9-er for catch & original patch.
• [Bug] #613: (via #619) Update to jaraco.windows 3.4.1 to fix some errors related to ctypes on Windows platforms. Credit to Jason R. Coombs.
• [Bug] #617: (aka fabric/fabric#1429; via #679; related: #678, #685, #615 & #616) Fix up NoValidConnectionsError so it pickles correctly, and fix a related Python 3 compatibility issue. Thanks to Rebecca Schlussel for the report & Marius Gedminas for the patch.
• [Bug] #716: Fix a Python 3 compatibility issue when handling two-factor authentication. Thanks to Mateusz Kowalski for the catch & original patch.
• [Bug] #577: (via #578; should also fix #718, #560) Fix stalled/hung SFTP downloads by cleaning up some threading lock issues. Thanks to Stephen C. Pope for the patch.
• [Bug] #676: (via #677) Fix a backwards incompatibility issue that cropped up in SFTPFile.prefetch re: the erroneously non-optional file_size parameter. Should only affect users who manually call prefetch. Thanks to @stevevanhooser for catch & patch.
• [Bug] #670: Due to an earlier bugfix, less-specific Host blocks’ ProxyCommand values were overriding ProxyCommand none in more-specific Host blocks. This has been fixed in a backwards compatible manner (i.e. ProxyCommand none continues to appear as a total lack of any proxycommand key in parsed config structures). Thanks to Pat Brisbin for the catch.
• [Support] #636: Clean up and enhance the README (and rename it to README.rst from just README). Thanks to @LucasRMehl.
• [Support] #697: Remove whitespace in our setup.py’s install_requires as it triggers occasional bugs in some versions of setuptools. Thanks to Justin Lecher for catch & original patch.
• [Support] #612: Identify & work around a race condition in the test for handshake timeouts, which was causing frequent test failures for a subset of contributors as well as Travis-CI (usually, but not always, limited to Python 3.5). Props to Ed Kellett for assistance during some of the troubleshooting.
• [Support] #621: Annotate some public attributes on Channel such as .closed. Thanks to Sergey Vasilyev for the report.
• [Support] #729: Clean up setup.py to always use setuptools, not doing so was a historical artifact from bygone days. Thanks to Alex Gaynor.

1.15.5 2016-04-28

• [Bug] #401: Fix line number reporting in log output regarding invalid known_hosts line entries. Thanks to Dylan Thacker-Smith for catch & patch.
• [Bug] #652: Fix behavior of gssapi-with-mic auth requests so they fail gracefully (allowing followup via other auth methods) instead of raising an exception. Patch courtesy of @jamercee.
• [Bug] #499: Strip trailing/leading whitespace from lines when parsing SSH config files - this brings things in line with OpenSSH behavior. Thanks to Alfredo Esteban for the original report and Nick Pillitteri for the patch.
• [Bug] #632: Fix logic bug in the SFTP client’s callback-calling functionality; previously there was a chance the given callback would fire twice at the end of a transfer. Thanks to @ab9-er for catch & original patch.
• [Bug] #613: (via #619) Update to jaraco.windows 3.4.1 to fix some errors related to ctypes on Windows platforms. Credit to Jason R. Coombs.
• [Bug] #617: (aka fabric/fabric#1429; via #679; related: #678, #685, #615 & #616) Fix up NoValidConnectionsError so it pickles correctly, and fix a related Python 3 compatibility issue. Thanks to Rebecca Schlussel for the report & Marius Gedminas for the patch.
• [Bug] #716: Fix a Python 3 compatibility issue when handling two-factor authentication. Thanks to Mateusz Kowalski for the catch & original patch.
• [Bug] #577: (via #578; should also fix #718, #560) Fix stalled/hung SFTP downloads by cleaning up some threading lock issues. Thanks to Stephen C. Pope for the patch.
• [Bug] #676: (via #677) Fix a backwards incompatibility issue that cropped up in SFTPFile.prefetch re: the erroneously non-optional file_size parameter. Should only affect users who manually call prefetch. Thanks to @stevevanhooser for catch & patch.
• [Bug] #670: Due to an earlier bugfix, less-specific Host blocks’ ProxyCommand values were overriding ProxyCommand none in more-specific Host blocks. This has been fixed in a backwards compatible manner (i.e. ProxyCommand none continues to appear as a total lack of any proxycommand key in parsed config structures). Thanks to Pat Brisbin for the catch.
• [Support] #525: Update the vendored Windows API addon to a more recent edition. Also fixes #193, #488, #498. Thanks to Jason Coombs.
• [Support] #636: Clean up and enhance the README (and rename it to README.rst from just README). Thanks to @LucasRMehl.
• [Support] #697: Remove whitespace in our setup.py’s install_requires as it triggers occasional bugs in some versions of setuptools. Thanks to Justin Lecher for catch & original patch.
• [Support] #612: Identify & work around a race condition in the test for handshake timeouts, which was causing frequent test failures for a subset of contributors as well as Travis-CI (usually, but not always, limited to Python 3.5). Props to Ed Kellett for assistance during some of the troubleshooting.
• [Support] #621: Annotate some public attributes on Channel such as .closed. Thanks to Sergey Vasilyev for the report.
• [Support] #729: Clean up setup.py to always use setuptools, not doing so was a historical artifact from bygone days. Thanks to Alex Gaynor.

1.16.0 2015-11-04

• [Feature] #167: Add get_hostnames for easier introspection of a loaded SSH config file or object. Courtesy of Søren Løvborg.

• [Feature] #356: (also #596, #365, #341, #164, #581, and a bunch of other duplicates besides) Add support for SHA-2 based key exchange (kex) algorithm diffie-hellman-group-exchange-sha256 and (H)MAC algorithms hmac-sha2-256 and hmac-sha2-512.

  This change includes tweaks to debug-level logging regarding algorithm-selection handshakes; the old all-in-one log line is now multiple easier-to-read, printed-at-handshake-time log lines.

  Thanks to the many people who submitted patches for this functionality and/or assisted in testing those patches. That list includes but is not limited to, and in no particular order: Matthias Witte, Dag Wieers, Ash Berlin, Etienne Perot, Gert van Dijk, @GuyShaanan, Aaron Bieber, @cyphase, and Eric Brown.

• [Feature] #604: Add support for the aes192-ctr and aes192-cbc ciphers. Thanks to Michiel Tiller for noticing it was as easy as tweaking some key sizes :D

• [Feature] #467: (also #139, #412) Fully enable two-factor authentication (e.g. when a server requires AuthenticationMethods pubkey,keyboard-interactive). Thanks to @perryjrandall for the patch and to @nevins-b and Matt Robenolt for additional support.

• [Bug] #22: Try harder to connect to multiple network families (e.g. IPv4 vs IPv6) in case of connection issues; this helps with problems such as hosts which resolve both IPv4 and IPv6 addresses but are only listening on IPv4. Thanks to Dries Desmet for original report and Torsten Landschoff for the foundational patchset.

• [Bug] #502: Fix ‘exec’ requests in server mode to use get_string instead of get_text to avoid UnicodeDecodeError on non-UTF-8 input. Thanks to Anselm Kruis for the patch & discussion.

• [Bug] #194: (also #562, #530, #576) Streamline use of stat when downloading SFTP files via SFTPClient.get; this avoids triggering bugs in some off-spec SFTP servers such as IBM Sterling. Thanks to @muraleee for the initial report and to Torkil Gustavsen for the patch.

• [Support] #419: Modernize a bunch of the codebase internals to leverage decorators. Props to @beckjake for realizing we’re no longer on Python 2.2 :D

• [Support] #421: Modernize threading calls to use newer API. Thanks to Olle Lundberg.

• [Support] #422: Clean up some unused imports. Courtesy of Olle Lundberg.

• [Support] #431: Replace handrolled ssh_config parsing code with use of the shlex module. Thanks to Yan Kalchevskiy.

• [Support] #582: Fix some old setup.py related helper code which was breaking bdist_dumb on Mac OS X. Thanks to Peter Odding for the patch.

• [Support] #516: Document AgentRequestHandler. Thanks to @toejough for report & suggestions.

• [Support] #554: Fix inaccuracies in the docstring for the ECDSA key class. Thanks to Jared Hance for the patch.

• [Support] #594: Correct some post-Python3-port docstrings to specify bytes type instead of str. Credit to @redixin.

• [Support] #525: Update the vendored Windows API addon to a more recent edition. Also fixes #193, #488, #498. Thanks to Jason Coombs.

1.15.4 2015-11-02

• [Bug] #565: Don’t explode with IndexError when reading private key files lacking an -----END <type> PRIVATE KEY----- footer. Patch courtesy of Prasanna Santhanam.
• [Bug] #359: Use correct attribute name when trying to use Python 3’s int.bit_length method; prior to fix, the Python 2 custom fallback implementation was always used, even on Python 3. Thanks to Alex Gaynor.
• [Bug] #366: Fix SFTPAttributes so its string representation doesn’t raise exceptions on empty/initialized instances. Patch by Ulrich Petri.
• [Support] #594: Correct some post-Python3-port docstrings to specify bytes type instead of str. Credit to @redixin.

1.14.3 2015-11-02

• [Bug] #402: Check to see if an SSH agent is actually present before trying to forward it to the remote end. This replaces what was usually a useless TypeError with a human-readable AuthenticationException. Credit to Ken Jordan for the fix and Yvan Marques for original report.
• [Bug] #353: (via #482) Fix a bug introduced in the Python 3 port which caused OverFlowError (and other symptoms) in SFTP functionality. Thanks to @dboreham for leading the troubleshooting charge, and to Scott Maxwell for the final patch.
• [Bug] #469: (also #488, #461 and like a dozen others) Fix a typo introduced in the 1.15 release which broke WinPageant support. Thanks to everyone who submitted patches, and to Steve Cohen who was the lucky winner of the cherry-pick lottery.
• [Bug] #404: Print details when displaying BadHostKeyException objects (expected vs received data) instead of just “hey shit broke”. Patch credit: Loic Dachary.
• [Bug] #490: Skip invalid/unparseable lines in known_hosts files, instead of raising SSHException. This brings Paramiko’s behavior more in line with OpenSSH, which silently ignores such input. Catch & patch courtesy of Martin Topholm.
• [Bug] #491: (combines #62 and #439) Implement timeout functionality to address hangs from dropped network connections and/or failed handshakes. Credit to @vazir and @dacut for the original patches and to Olle Lundberg for reimplementation.
• [Bug] #565: Don’t explode with IndexError when reading private key files lacking an -----END <type> PRIVATE KEY----- footer. Patch courtesy of Prasanna Santhanam.
• [Bug] #359: Use correct attribute name when trying to use Python 3’s int.bit_length method; prior to fix, the Python 2 custom fallback implementation was always used, even on Python 3. Thanks to Alex Gaynor.
• [Bug] #366: Fix SFTPAttributes so its string representation doesn’t raise exceptions on empty/initialized instances. Patch by Ulrich Petri.
• [Support] #516: Document AgentRequestHandler. Thanks to @toejough for report & suggestions.
• [Support] #554: Fix inaccuracies in the docstring for the ECDSA key class. Thanks to Jared Hance for the patch.
• [Support] #594: Correct some post-Python3-port docstrings to specify bytes type instead of str. Credit to @redixin.

1.13.4 2015-11-02

• [Bug] #402: Check to see if an SSH agent is actually present before trying to forward it to the remote end. This replaces what was usually a useless TypeError with a human-readable AuthenticationException. Credit to Ken Jordan for the fix and Yvan Marques for original report.
• [Bug] #353: (via #482) Fix a bug introduced in the Python 3 port which caused OverFlowError (and other symptoms) in SFTP functionality. Thanks to @dboreham for leading the troubleshooting charge, and to Scott Maxwell for the final patch.
• [Bug] #469: (also #488, #461 and like a dozen others) Fix a typo introduced in the 1.15 release which broke WinPageant support. Thanks to everyone who submitted patches, and to Steve Cohen who was the lucky winner of the cherry-pick lottery.
• [Bug] #404: Print details when displaying BadHostKeyException objects (expected vs received data) instead of just “hey shit broke”. Patch credit: Loic Dachary.
• [Bug] #490: Skip invalid/unparseable lines in known_hosts files, instead of raising SSHException. This brings Paramiko’s behavior more in line with OpenSSH, which silently ignores such input. Catch & patch courtesy of Martin Topholm.
• [Bug] #491: (combines #62 and #439) Implement timeout functionality to address hangs from dropped network connections and/or failed handshakes. Credit to @vazir and @dacut for the original patches and to Olle Lundberg for reimplementation.
• [Bug] #565: Don’t explode with IndexError when reading private key files lacking an -----END <type> PRIVATE KEY----- footer. Patch courtesy of Prasanna Santhanam.
• [Bug] #359: Use correct attribute name when trying to use Python 3’s int.bit_length method; prior to fix, the Python 2 custom fallback implementation was always used, even on Python 3. Thanks to Alex Gaynor.
• [Bug] #366: Fix SFTPAttributes so its string representation doesn’t raise exceptions on empty/initialized instances. Patch by Ulrich Petri.
• [Support] #516: Document AgentRequestHandler. Thanks to @toejough for report & suggestions.
• [Support] #554: Fix inaccuracies in the docstring for the ECDSA key class. Thanks to Jared Hance for the patch.
• [Support] #594: Correct some post-Python3-port docstrings to specify bytes type instead of str. Credit to @redixin.

1.15.3 2015-10-02

• [Bug] #402: Check to see if an SSH agent is actually present before trying to forward it to the remote end. This replaces what was usually a useless TypeError with a human-readable AuthenticationException. Credit to Ken Jordan for the fix and Yvan Marques for original report.
• [Bug] #353: (via #482) Fix a bug introduced in the Python 3 port which caused OverFlowError (and other symptoms) in SFTP functionality. Thanks to @dboreham for leading the troubleshooting charge, and to Scott Maxwell for the final patch.
• [Bug] #469: (also #488, #461 and like a dozen others) Fix a typo introduced in the 1.15 release which broke WinPageant support. Thanks to everyone who submitted patches, and to Steve Cohen who was the lucky winner of the cherry-pick lottery.
• [Bug] #404: Print details when displaying BadHostKeyException objects (expected vs received data) instead of just “hey shit broke”. Patch credit: Loic Dachary.
• [Bug] #490: Skip invalid/unparseable lines in known_hosts files, instead of raising SSHException. This brings Paramiko’s behavior more in line with OpenSSH, which silently ignores such input. Catch & patch courtesy of Martin Topholm.
• [Bug] #491: (combines #62 and #439) Implement timeout functionality to address hangs from dropped network connections and/or failed handshakes. Credit to @vazir and @dacut for the original patches and to Olle Lundberg for reimplementation.
• [Bug] #496: Fix a handful of small but critical bugs in Paramiko’s GSSAPI support (note: this includes switching from PyCrypo’s Random to os.urandom). Thanks to Anselm Kruis for catch & patch.
• [Support] #516: Document AgentRequestHandler. Thanks to @toejough for report & suggestions.
• [Support] #554: Fix inaccuracies in the docstring for the ECDSA key class. Thanks to Jared Hance for the patch.

1.15.2 2014-12-19

• [Bug] #320: Update our win_pageant module to be Python 3 compatible. Thanks to @sherbang and @adamkerz for the patches.
• [Bug] #429: Server-level debug message logging was overlooked during the Python 3 compatibility update; Python 3 clients attempting to log SSH debug packets encountered type errors. This is now fixed. Thanks to @mjmaenpaa for the catch.
• [Bug] #459: Tighten up agent connection closure behavior to avoid spurious ResourceWarning display in some situations. Thanks to @tkrapp for the catch.
• [Bug] #266: Change numbering of Transport channels to start at 0 instead of 1 for better compatibility with OpenSSH & certain server implementations which break on 1-indexed channels. Thanks to @egroeper for catch & patch.
• [Bug] #415: Fix ssh_config parsing to correctly interpret ProxyCommand none as the lack of a proxy command, instead of as a literal command string of "none". Thanks to Richard Spiers for the catch & Sean Johnson for the fix.
• [Bug] #428: Fix an issue in BufferedFile (primarily used in the SFTP modules) concerning incorrect behavior by readlines on files whose size exceeds the buffer size. Thanks to @achapp for catch & patch.
• [Bug] #455: Tweak packet size handling to conform better to the OpenSSH RFCs; this helps address issues with interactive program cursors. Courtesy of Jeff Quast.
• [Bug] #413: (also #414, #420, #454) Be significantly smarter about polling & timing behavior when running proxy commands, to avoid unnecessary (often 100%!) CPU usage. Major thanks to Jason Dunsmore for report & initial patchset and to Chris Adams & John Morrissey for followup improvements.
• [Support] #419: Modernize a bunch of the codebase internals to leverage decorators. Props to @beckjake for realizing we’re no longer on Python 2.2 :D
• [Support] #421: Modernize threading calls to use newer API. Thanks to Olle Lundberg.
• [Support] #422: Clean up some unused imports. Courtesy of Olle Lundberg.
• [Support] #431: Replace handrolled ssh_config parsing code with use of the shlex module. Thanks to Yan Kalchevskiy.

1.14.2 2014-12-19

• [Bug] #399: SSH agent forwarding (potentially other functionality as well) would hang due to incorrect values passed into the new window size arguments for Transport (thanks to a botched merge). This has been corrected. Thanks to Dylan Thacker-Smith for the report & patch.
• [Bug] #320: Update our win_pageant module to be Python 3 compatible. Thanks to @sherbang and @adamkerz for the patches.
• [Bug] #429: Server-level debug message logging was overlooked during the Python 3 compatibility update; Python 3 clients attempting to log SSH debug packets encountered type errors. This is now fixed. Thanks to @mjmaenpaa for the catch.
• [Bug] #459: Tighten up agent connection closure behavior to avoid spurious ResourceWarning display in some situations. Thanks to @tkrapp for the catch.
• [Bug] #266: Change numbering of Transport channels to start at 0 instead of 1 for better compatibility with OpenSSH & certain server implementations which break on 1-indexed channels. Thanks to @egroeper for catch & patch.
• [Bug] #415: Fix ssh_config parsing to correctly interpret ProxyCommand none as the lack of a proxy command, instead of as a literal command string of "none". Thanks to Richard Spiers for the catch & Sean Johnson for the fix.
• [Bug] #428: Fix an issue in BufferedFile (primarily used in the SFTP modules) concerning incorrect behavior by readlines on files whose size exceeds the buffer size. Thanks to @achapp for catch & patch.
• [Bug] #455: Tweak packet size handling to conform better to the OpenSSH RFCs; this helps address issues with interactive program cursors. Courtesy of Jeff Quast.
• [Bug] #413: (also #414, #420, #454) Be significantly smarter about polling & timing behavior when running proxy commands, to avoid unnecessary (often 100%!) CPU usage. Major thanks to Jason Dunsmore for report & initial patchset and to Chris Adams & John Morrissey for followup improvements.
• [Support] #249: Consolidate version information into one spot. Thanks to Gabi Davar for the reminder.
• [Support] #378: Minor code cleanup in the SSH config module courtesy of Olle Lundberg.
• [Support] #419: Modernize a bunch of the codebase internals to leverage decorators. Props to @beckjake for realizing we’re no longer on Python 2.2 :D
• [Support] #421: Modernize threading calls to use newer API. Thanks to Olle Lundberg.
• [Support] #422: Clean up some unused imports. Courtesy of Olle Lundberg.
• [Support] #431: Replace handrolled ssh_config parsing code with use of the shlex module. Thanks to Yan Kalchevskiy.

1.13.3 2014-12-19

• [Bug] #399: SSH agent forwarding (potentially other functionality as well) would hang due to incorrect values passed into the new window size arguments for Transport (thanks to a botched merge). This has been corrected. Thanks to Dylan Thacker-Smith for the report & patch.
• [Bug] #320: Update our win_pageant module to be Python 3 compatible. Thanks to @sherbang and @adamkerz for the patches.
• [Bug] #429: Server-level debug message logging was overlooked during the Python 3 compatibility update; Python 3 clients attempting to log SSH debug packets encountered type errors. This is now fixed. Thanks to @mjmaenpaa for the catch.
• [Bug] #459: Tighten up agent connection closure behavior to avoid spurious ResourceWarning display in some situations. Thanks to @tkrapp for the catch.
• [Bug] #266: Change numbering of Transport channels to start at 0 instead of 1 for better compatibility with OpenSSH & certain server implementations which break on 1-indexed channels. Thanks to @egroeper for catch & patch.
• [Bug] #415: Fix ssh_config parsing to correctly interpret ProxyCommand none as the lack of a proxy command, instead of as a literal command string of "none". Thanks to Richard Spiers for the catch & Sean Johnson for the fix.
• [Bug] #428: Fix an issue in BufferedFile (primarily used in the SFTP modules) concerning incorrect behavior by readlines on files whose size exceeds the buffer size. Thanks to @achapp for catch & patch.
• [Bug] #455: Tweak packet size handling to conform better to the OpenSSH RFCs; this helps address issues with interactive program cursors. Courtesy of Jeff Quast.
• [Bug] #413: (also #414, #420, #454) Be significantly smarter about polling & timing behavior when running proxy commands, to avoid unnecessary (often 100%!) CPU usage. Major thanks to Jason Dunsmore for report & initial patchset and to Chris Adams & John Morrissey for followup improvements.
• [Support] #249: Consolidate version information into one spot. Thanks to Gabi Davar for the reminder.
• [Support] #378: Minor code cleanup in the SSH config module courtesy of Olle Lundberg.
• [Support] #419: Modernize a bunch of the codebase internals to leverage decorators. Props to @beckjake for realizing we’re no longer on Python 2.2 :D
• [Support] #421: Modernize threading calls to use newer API. Thanks to Olle Lundberg.
• [Support] #422: Clean up some unused imports. Courtesy of Olle Lundberg.
• [Support] #431: Replace handrolled ssh_config parsing code with use of the shlex module. Thanks to Yan Kalchevskiy.

1.15.1 2014-09-22

• [Bug] #399: SSH agent forwarding (potentially other functionality as well) would hang due to incorrect values passed into the new window size arguments for Transport (thanks to a botched merge). This has been corrected. Thanks to Dylan Thacker-Smith for the report & patch.

1.15.0 2014-09-18

• [Feature] #131: Add a listdir_iter method to SFTPClient allowing for more efficient, async/generator based file listings. Thanks to John Begeman.

• [Feature] #184: Support quoted values in SSH config file parsing. Credit to Yan Kalchevskiy.

• [Feature] #218: Add support for ECDSA private keys on the client side. Thanks to @aszlig for the patch.

• [Feature] #372: Update default window & packet sizes to more closely adhere to the pertinent RFC; also expose these settings in the public API so they may be overridden by client code. This should address some general speed issues such as #175. Big thanks to Olle Lundberg for the update.

• [Feature] #362: Allow users to control the SSH banner timeout. Thanks to Cory Benfield.

• [Feature] #267: (also #250, #241, #228) Add GSS-API / SSPI (e.g. Kerberos) key exchange and authentication support (installation docs here). Mega thanks to Sebastian Deiß, with assist by Torsten Landschoff.

  Note

  Unix users should be aware that the python-gssapi library (a requirement for using this functionality) only appears to support Python 2.7 and up at this time.

• [Bug] #335: Fix ECDSA key generation (generation of brand new ECDSA keys was broken previously). Thanks to @solarw for catch & patch.

• [Bug] #234: Lower logging levels for a few overly-noisy log messages about secure channels. Thanks to David Pursehouse for noticing & contributing the fix.

• [Bug] #298: Don’t perform point validation on ECDSA keys in known_hosts files, since a) this can cause significant slowdown when such keys exist, and b) known_hosts files are implicitly trustworthy. Thanks to Kieran Spear for catch & patch.

  Note

  This change bumps up the version requirement for the ecdsa library to 0.11.

• [Bug] #373: Attempt to fix a handful of issues (such as #354) related to infinite loops and threading deadlocks. Thanks to Olle Lundberg as well as a handful of community members who provided advice & feedback via IRC.

• [Bug] #346: Fix an issue in private key files’ encryption salts that could cause tracebacks and file corruption if keys were re-encrypted. Credit to Xavier Nunn.

• [Support] #371: Add Travis support & docs update for Python 3.4. Thanks to Olle Lundberg.

• [Support] #169: Minor refactor of paramiko.sftp_client.SFTPClient.put thanks to Abhinav Upadhyay.

• [Support] #229: Fix a couple of incorrectly-copied docstrings’ … versionadded:: RST directives. Thanks to Aarni Koskela for the catch.

• [Support] #324: A bevvy of documentation typo fixes, courtesy of Roy Wellington.

• [Support] #249: Consolidate version information into one spot. Thanks to Gabi Davar for the reminder.

• [Support] #378: Minor code cleanup in the SSH config module courtesy of Olle Lundberg.

• [Support] #377: Factor Channel openness sanity check into a decorator. Thanks to Olle Lundberg for original patch.

• [Support] #374: (also #375) Old code cleanup courtesy of Olle Lundberg.

• [Support] #393: Replace internal use of PyCrypto’s SHA.new with the stdlib’s hashlib.sha1. Thanks to Alex Gaynor.

1.14.1 2014-08-25

• [Bug] #285: (also #352) Update our Python 3 b() compatibility shim to handle buffer objects correctly; this fixes a frequently reported issue affecting many users, including users of the bzr software suite. Thanks to @basictheprogram for the initial report, Jelmer Vernooij for the fix and Andrew Starr-Bochicchio & Jeremy T. Bouse (among others) for discussion & feedback.
• [Bug] #239: Add Windows-style CRLF support to SSH config file parsing. Props to Christopher Swenson.
• [Bug] #272: Fix a bug where known_hosts parsing hashed the input hostname as well as the hostnames from the known_hosts file, on every comparison. Thanks to @sigmunau for final patch and @ostacey for the original report.
• [Bug] #312: paramiko.transport.Transport had a bug in its repr which surfaces during errors encountered within its init, causing problematic tracebacks in such situations. Thanks to Simon Percivall for catch & patch.
• [Bug] #376: Be less aggressive about expanding variables in ssh_config files, which results in a speedup of SSH config parsing. Credit to Olle Lundberg.
• [Support] #169: Minor refactor of paramiko.sftp_client.SFTPClient.put thanks to Abhinav Upadhyay.
• [Support] #229: Fix a couple of incorrectly-copied docstrings’ … versionadded:: RST directives. Thanks to Aarni Koskela for the catch.
• [Support] #324: A bevvy of documentation typo fixes, courtesy of Roy Wellington.

1.13.2 2014-08-25

• [Bug] #285: (also #352) Update our Python 3 b() compatibility shim to handle buffer objects correctly; this fixes a frequently reported issue affecting many users, including users of the bzr software suite. Thanks to @basictheprogram for the initial report, Jelmer Vernooij for the fix and Andrew Starr-Bochicchio & Jeremy T. Bouse (among others) for discussion & feedback.
• [Bug] #239: Add Windows-style CRLF support to SSH config file parsing. Props to Christopher Swenson.
• [Bug] #272: Fix a bug where known_hosts parsing hashed the input hostname as well as the hostnames from the known_hosts file, on every comparison. Thanks to @sigmunau for final patch and @ostacey for the original report.
• [Bug] #312: paramiko.transport.Transport had a bug in its repr which surfaces during errors encountered within its init, causing problematic tracebacks in such situations. Thanks to Simon Percivall for catch & patch.
• [Bug] #376: Be less aggressive about expanding variables in ssh_config files, which results in a speedup of SSH config parsing. Credit to Olle Lundberg.
• [Support] #169: Minor refactor of paramiko.sftp_client.SFTPClient.put thanks to Abhinav Upadhyay.
• [Support] #229: Fix a couple of incorrectly-copied docstrings’ … versionadded:: RST directives. Thanks to Aarni Koskela for the catch.
• [Support] #324: A bevvy of documentation typo fixes, courtesy of Roy Wellington.

1.14.0 2014-05-07

• [Support] #284: Add Python language trove identifiers to setup.py. Thanks to Alex Gaynor for catch & patch.
• [Support] #290: (also #292) Add support for building universal (Python 2+3 compatible) wheel files during the release process. Courtesy of Alex Gaynor.
• [Support] #295: Swap out a bunch of PyCrypto hash functions with use of hashlib. Thanks to Alex Gaynor.
• [Support] #297: Replace PyCrypto’s Random with os.urandom for improved speed and security. Thanks again to Alex.
• [Support] #299: Use deterministic signatures for ECDSA keys for improved security. Thanks to Alex Gaynor.

1.13.1 2014-05-07

• [Bug] #235: Improve string type testing in a handful of spots (e.g. s/if type(x) is str/if isinstance(x, basestring)/g.) Thanks to @ksamuel for the report.

• [Bug] #308: Fix regression in dsskey.py that caused sporadic signature verification failures. Thanks to Chris Rose.

• [Bug]: Fix logging error in sftp_client for filenames containing the ‘%’ character. Thanks to Antoine Brenner.

• [Bug]: Added self.args for exception classes. Used for unpickling. Related to (Fabric #986, Fabric #714). Thanks to Alex Plugaru.

• [Bug]: paramiko.file.BufferedFile.read incorrectly returned text strings after the Python 3 migration, despite bytes being more appropriate for file contents (which may be binary or of an unknown encoding.) This has been addressed.

  This should fix this issue raised on the Obnam mailing list. Thanks to Antoine Brenner for the patch.

1.12.4 2014-05-07

• [Bug] #235: Improve string type testing in a handful of spots (e.g. s/if type(x) is str/if isinstance(x, basestring)/g.) Thanks to @ksamuel for the report.

• [Bug] #308: Fix regression in dsskey.py that caused sporadic signature verification failures. Thanks to Chris Rose.

• [Bug]: Fix logging error in sftp_client for filenames containing the ‘%’ character. Thanks to Antoine Brenner.

• [Bug]: Added self.args for exception classes. Used for unpickling. Related to (Fabric #986, Fabric #714). Thanks to Alex Plugaru.

• [Bug]: paramiko.file.BufferedFile.read incorrectly returned text strings after the Python 3 migration, despite bytes being more appropriate for file contents (which may be binary or of an unknown encoding.) This has been addressed.

  This should fix this issue raised on the Obnam mailing list. Thanks to Antoine Brenner for the patch.

1.11.6 2014-05-07

• [Bug] #235: Improve string type testing in a handful of spots (e.g. s/if type(x) is str/if isinstance(x, basestring)/g.) Thanks to @ksamuel for the report.

• [Bug] #308: Fix regression in dsskey.py that caused sporadic signature verification failures. Thanks to Chris Rose.

• [Bug]: Fix logging error in sftp_client for filenames containing the ‘%’ character. Thanks to Antoine Brenner.

• [Bug]: Added self.args for exception classes. Used for unpickling. Related to (Fabric #986, Fabric #714). Thanks to Alex Plugaru.

• [Bug]: paramiko.file.BufferedFile.read incorrectly returned text strings after the Python 3 migration, despite bytes being more appropriate for file contents (which may be binary or of an unknown encoding.) This has been addressed.

  This should fix this issue raised on the Obnam mailing list. Thanks to Antoine Brenner for the patch.

1.13.0 2014-03-13

• [Feature] #58: Allow client code to access the stored SSH server banner via Transport.get_banner. Thanks to @Jhoanor for the patch.

• [Feature] #16: Python 3 support! Our test suite passes under Python 3, and it (& Fabric’s test suite) continues to pass under Python 2. Python 2.5 is no longer supported with this change!

  The merged code was built on many contributors’ efforts, both code & feedback. In no particular order, we thank Daniel Goertzen, Ivan Kolodyazhny, Tomi Pieviläinen, Jason R. Coombs, Jan N. Schulze, @Lazik, Dorian Pula, Scott Maxwell, Tshepang Lekhonkhobe, Aaron Meurer, and Dave Halter.

• [Support] #256: Convert API documentation to Sphinx, yielding a new API docs website to replace the old Epydoc one. Thanks to Olle Lundberg for the initial conversion work.

1.12.3 2014-03-13

• [Bug]: Use constant-time hash comparison operations where possible, to protect against timing-based attacks. Thanks to Alex Gaynor for the patch.
• [Support] #256: Convert API documentation to Sphinx, yielding a new API docs website to replace the old Epydoc one. Thanks to Olle Lundberg for the initial conversion work.

1.11.5 2014-03-13

• [Bug]: Use constant-time hash comparison operations where possible, to protect against timing-based attacks. Thanks to Alex Gaynor for the patch.
• [Support] #256: Convert API documentation to Sphinx, yielding a new API docs website to replace the old Epydoc one. Thanks to Olle Lundberg for the initial conversion work.

1.10.7 2014-03-13

• [Bug]: Use constant-time hash comparison operations where possible, to protect against timing-based attacks. Thanks to Alex Gaynor for the patch.
• [Support] #256: Convert API documentation to Sphinx, yielding a new API docs website to replace the old Epydoc one. Thanks to Olle Lundberg for the initial conversion work.

1.12.2 2014-02-14

• [Bug] #193: (and its attentant PRs #230 & #253) Fix SSH agent problems present on Windows. Thanks to David Hobbs for initial report and to Aarni Koskela & Olle Lundberg for the patches.
• [Bug] #34: (PR #35) Fix SFTP prefetching incompatibility with some SFTP servers regarding request/response ordering. Thanks to Richard Kettlewell.
• [Bug] #268: Fix some missed renames of ProxyCommand related error classes. Thanks to Marius Gedminas for catch & patch.
• [Bug] #252: (Fabric #1020) Enhanced the implementation of ProxyCommand to avoid a deadlock/hang condition that frequently occurs at Transport shutdown time. Thanks to Mateusz Kobos, Matthijs van der Vleuten and Guillaume Zitta for the original reports and to Marius Gedminas for helping test nontrivial use cases.

1.11.4 2014-02-14

• [Bug] #193: (and its attentant PRs #230 & #253) Fix SSH agent problems present on Windows. Thanks to David Hobbs for initial report and to Aarni Koskela & Olle Lundberg for the patches.
• [Bug] #34: (PR #35) Fix SFTP prefetching incompatibility with some SFTP servers regarding request/response ordering. Thanks to Richard Kettlewell.
• [Bug] #268: Fix some missed renames of ProxyCommand related error classes. Thanks to Marius Gedminas for catch & patch.
• [Bug] #252: (Fabric #1020) Enhanced the implementation of ProxyCommand to avoid a deadlock/hang condition that frequently occurs at Transport shutdown time. Thanks to Mateusz Kobos, Matthijs van der Vleuten and Guillaume Zitta for the original reports and to Marius Gedminas for helping test nontrivial use cases.

1.10.6 2014-02-14

• [Bug] #193: (and its attentant PRs #230 & #253) Fix SSH agent problems present on Windows. Thanks to David Hobbs for initial report and to Aarni Koskela & Olle Lundberg for the patches.
• [Bug] #34: (PR #35) Fix SFTP prefetching incompatibility with some SFTP servers regarding request/response ordering. Thanks to Richard Kettlewell.
• [Bug] #268: Fix some missed renames of ProxyCommand related error classes. Thanks to Marius Gedminas for catch & patch.
• [Bug] #252: (Fabric #1020) Enhanced the implementation of ProxyCommand to avoid a deadlock/hang condition that frequently occurs at Transport shutdown time. Thanks to Mateusz Kobos, Matthijs van der Vleuten and Guillaume Zitta for the original reports and to Marius Gedminas for helping test nontrivial use cases.

1.12.1 2014-01-08

• [Bug] #176: Fix AttributeError bugs in known_hosts file (re)loading. Thanks to Nathan Scowcroft for the patch & Martin Blumenstingl for the initial test case.
• [Bug] #225: Note ecdsa requirement in README. Thanks to Amaury Rodriguez for the catch.

1.11.3 2014-01-08

• [Bug] #176: Fix AttributeError bugs in known_hosts file (re)loading. Thanks to Nathan Scowcroft for the patch & Martin Blumenstingl for the initial test case.

1.10.5 2014-01-08

• [Bug] #176: Fix AttributeError bugs in known_hosts file (re)loading. Thanks to Nathan Scowcroft for the patch & Martin Blumenstingl for the initial test case.

1.12.0 2013-09-27

• [Feature] #136: Add server-side support for the SSH protocol’s ‘env’ command. Thanks to Benjamin Pollack for the patch.

• [Feature] #152: Add tentative support for ECDSA keys. This adds the ecdsa module as a new dependency of Paramiko. The module is available at warner/python-ecdsa on Github and ecdsa on PyPI.

  • Note that you might still run into problems with key negotiation – Paramiko picks the first key that the server offers, which might not be what you have in your known_hosts file.
  • Mega thanks to Ethan Glasser-Camp for the patch.

1.11.2 2013-09-27

• [Bug] #199: Typo fix in the license header cross-project. Thanks to Armin Ronacher for catch & patch.
• [Bug] #200: Fix an exception-causing typo in demo_simple.py. Thanks to Alex Buchanan for catch & Dave Foster for patch.
• [Bug] #179: Fix a missing variable causing errors when an ssh_config file has a non-default AddressFamily set. Thanks to Ed Marshall & Tomaz Muraus for catch & patch.
• [Bug] #156: Fix potential deadlock condition when using Channel objects as sockets (e.g. when using SSH gatewaying). Thanks to Steven Noonan and Frank Arnold for catch & patch.

1.10.4 2013-09-27

• [Bug] #199: Typo fix in the license header cross-project. Thanks to Armin Ronacher for catch & patch.
• [Bug] #200: Fix an exception-causing typo in demo_simple.py. Thanks to Alex Buchanan for catch & Dave Foster for patch.
• [Bug] #179: Fix a missing variable causing errors when an ssh_config file has a non-default AddressFamily set. Thanks to Ed Marshall & Tomaz Muraus for catch & patch.

1.11.1 2013-09-20

• [Bug] #168: Update config handling to properly handle multiple ‘localforward’ and ‘remoteforward’ keys. Thanks to Emre Yılmaz for the patch.
• [Bug] #36: Fix the port-forwarding demo to avoid file descriptor errors. Thanks to Jonathan Halcrow for catch & patch.
• [Bug] #162: Clean up HMAC module import to avoid deadlocks in certain uses of SSHClient. Thanks to Gernot Hillier for the catch & suggested fix.

1.10.3 2013-09-20

• [Bug] #168: Update config handling to properly handle multiple ‘localforward’ and ‘remoteforward’ keys. Thanks to Emre Yılmaz for the patch.
• [Bug] #36: Fix the port-forwarding demo to avoid file descriptor errors. Thanks to Jonathan Halcrow for catch & patch.
• [Bug] #162: Clean up HMAC module import to avoid deadlocks in certain uses of SSHClient. Thanks to Gernot Hillier for the catch & suggested fix.

1.11.0 2013-07-26

• [Bug] #87: Ensure updates to known_hosts files account for any updates to said files after Paramiko initially read them. (Includes related fix to guard against duplicate entries during subsequent known_hosts loads.) Thanks to @sunweaver for the contribution.
• [Bug] #98: On Windows, when interacting with the PuTTY PAgeant, Paramiko now creates the shared memory map with explicit Security Attributes of the user, which is the same technique employed by the canonical PuTTY library to avoid permissions issues when Paramiko is running under a different UAC context than the PuTTY Ageant process. Thanks to Jason R. Coombs for the patch.
• [Support] #100: Remove use of PyWin32 in win_pageant module. Module was already dependent on ctypes for constructing appropriate structures and had ctypes implementations of all functionality. Thanks to Jason R. Coombs for the patch.

1.10.2 2013-07-26

• [Bug] #146: Indentation fixes for readability. Thanks to Abhinav Upadhyay for catch & patch.
• [Bug] #153: (also #67) Warn on parse failure when reading known_hosts file. Thanks to @glasserc for patch.

1.10.1 2013-04-05

• [Bug] #154: (Fabric #876) Forwarded SSH agent connections left stale local pipes lying around, which could cause local (and sometimes remote or network) resource starvation when running many agent-using remote commands. Thanks to Kevin Tegtmeier for catch & patch.
• [Bug] #142: (Fabric #811) SFTP put of empty file will still return the attributes of the put file. Thanks to Jason R. Coombs for the patch.

1.10.0 2013-03-01

• [Feature] #80: Expose the internal “is closed” property of the file transfer class BufferedFile as .closed, better conforming to Python’s file interface. Thanks to @smunaut and James Hiscock for catch & patch.
• [Feature] #113: Add timeout parameter to SSHClient.exec_command for easier setting of the command’s internal channel object’s timeout. Thanks to Cernov Vladimir for the patch.
• [Feature] #71: Add SFTPClient.putfo and .getfo methods to allow direct uploading/downloading of file-like objects. Thanks to Eric Buehl for the patch.
• [Feature] #115: Add convenience get_pty kwarg to Client.exec_command so users not manually controlling a channel object can still toggle PTY creation. Thanks to Michael van der Kolff for the patch.
• [Feature] #116: Limit Message.get_bytes to an upper bound of 1MB to protect against potential DoS vectors. Thanks to @mvschaik for catch & patch.
• [Feature] #127: Turn SFTPFile into a context manager. Thanks to Michael Williamson for the patch.
• [Feature] #128: Defer FQDN resolution until needed, when parsing SSH config files. Thanks to Parantapa Bhattacharya for catch & patch.
• [Feature] #110: Honor SSH config AddressFamily setting when looking up local host’s FQDN. Thanks to John Hensley for the patch.
• [Feature] #93: Overhaul SSH config parsing to be in line with man ssh_config (& the behavior of ssh itself), including addition of parameter expansion within config values. Thanks to Olle Lundberg for the patch.
• [Feature] #66: Batch SFTP writes to help speed up file transfers. Thanks to Olle Lundberg for the patch.
• [Bug] #102: Forego random padding for packets when running under *-ctr ciphers. This corrects some slowdowns on platforms where random byte generation is inefficient (e.g. Windows). Thanks to @warthog618 for catch & patch, and Michael van der Kolff for code/technique review.
• [Bug] #133: Fix handling of window-change events to be on-spec and not attempt to wait for a response from the remote sshd; this fixes problems with less common targets such as some Cisco devices. Thanks to Phillip Heller for catch & patch.
• [Support] #94: Remove duplication of SSH port constant. Thanks to Olle Lundberg for the catch.