Changelogs » Asyncssh

Asyncssh

2.0.1

--------------------------

* Some API changes which should have been included in the 2.0.0 release
were missed. This release corrects that, but means that additional
changes may be needed in applications moving to 2.0.1. This should
hopefully be the last of such changes, but if any other issues are
discovered, additional changes will be limited to 2.0.x patch releases
and the API will stabilize again in the AsyncSSH 2.1 release. See the
next bullet for details about the additional incompatible change.

* To be consistent with other connect and listen functions, all methods
on SSHClientConnection which previously returned None on listen
failures have been changed to raise an exception instead. A new
ChannelListenError exception will now be raised when an SSH server
returns failure on a request to open a remote listener. This change
affects the following SSHClientConnection methods: create_server,
create_unix_server, start_server, start_unix_server,
forward_remote_port, and forward_remote_path.

* Restored the ability for SSHListener objects to be used as async
context managers. This previously worked in AsyncSSH 1.x and was
unintentionally broken in AsyncSSH 2.0.0.

* Added support for a number of additional functions to be called from
within an "async with" statement. These functions already returned
objects capable of being async context managers, but were not decorated
to allow them to be directly called from within "async with". This
change applies to the top level functions create_server, listen, and
listen_reverse and the SSHClientConnection methods create_server,
create_unix_server, start_server, start_unix_server, forward_local_port,
forward_local_path, forward_remote_port, forward_remote_path,
listen_ssh, and listen_reverse_ssh,

* Fixed a couple of issues in loading OpenSSH-format certificates which
were missing a trailing newline.

* Changed load_certificates() to allow multiple certificates to be loaded
from a single byte string argument, making it more consistent with
how load_certificates() works when reading from a file.

2.0.0

---------------------------

* NEW MAJOR VERSION: See below for potentially incompatible changes.

* Updated AsyncSSH to use the modern async/await syntax internally,
now requiring Python 3.6 or later. Those wishing to use AsyncSSH on
Python 3.4 or 3.5 should stick to the AsyncSSH 1.x releases.

* Changed first argument of SFTPServer constructor from an
SSHServerConnection (conn) to an SSHServerChannel (chan) to allow
custom SFTP server implementations to access environment variables
set on the channel that SFTP is run over. Applications which subclass
the SFTPServer class and implement an __init__ method will need to be
updated to account for this change and pass the new argument through
to the SFTPServer parent class. If the subclass has no __init__ and
just uses the connection, channel, and env properties of SFTPServer
to access this information, no changes should be required.

* Removed deprecated "session_encoding" and "session_errors" arguments
from create_server() and listen() functions. These arguments were
renamed to "encoding" and "errors" back in version 1.16.0 to be
consistent with other AsyncSSH APIs.

* Removed get_environment(), get_command(), and get_subsystem() methods
on SSHServerProcess class. This information was made available as
"env", "command", and "subsystem" properties of SSHServerProcess in
AsyncSSH 1.11.0.

* Removed optional loop argument from all public AsyncSSH APIs,
consistent with the deprecation of this argument in the asyncio
package in Python 3.8. Calls will now always use the event loop
which is active at the time of the call.

* Removed support for non-async context managers on AsyncSSH connections
and processes and SFTP client connections and file objects. Callers
should use "async with" to invoke the async the context managers on
these objects.

* Added support for SSHAgentClient being an async context manager. To
be consistent with other connect calls, connect_agent() will now
raise an exception when no agent is found or a connection failure
occurs, rather than logging a warning and returning None. Callers
should catch OSError or ChannelOpenError exceptions rather than
looking for a return value of None when calling this function.

* Added set_input() and clear_input() methods on SSHLineEditorChannel
to change the value of the current input line when line editing is
enabled.

* Added is_closing() method to the SSHChannel, SSHProcess, SSHWriter,
and SSHSubprocessTransport classes. mirroring the asyncio
BaseTransport and StreamWriter methods added in Python 3.7.

* Added wait_closed() async method to the SSHWriter class, mirroring
the asyncio StreamWriter method added in Python 3.7.

1.18.0

----------------------------

* Added support for GSSAPI ECDH and Edwards DH key exchange algorithms.

* Fixed gssapi-with-mic authentication to work with GSS key exchanges,
in cases where gssapi-keyex is not supported.

* Made connect_ssh and connect_reverse_ssh methods into async context
managers, simplifying the syntax needed to use them to create tunneled
SSH connections.

* Fixed a couple of issues with known hosts matching on tunneled SSH
connections.

* Improved flexibility of key/certificate parser automatic format
detection to properly recognize PEM even when other arbitrary text
is present at the beginning of the file. With this change, the
parser can also now handle mixing of multiple key formats in a
single file.

* Added support for OpenSSL "TRUSTED" PEM certificates. For now, no
enforcement is done of the additional trust restrictions, but such
certificates can be loaded and used by AsyncSSH without converting
them back to regular PEM format.

* Fixed some additional SFTP and SCP issues related to parsing of
Windows paths with drive letters and paths with multiple colons.

* Made AsyncSSH tolerant of a client which sends multiple service
requests for the "ssh-userauth" service. This is needed by the
Paramiko client when it tries more than one form of authentication
on a connection.

1.17.1

----------------------------

* Improved construction of file paths in SFTP to better handle native
Windows source paths containing backslashes or drive letters.

* Improved SFTP parallel I/O for large reads and file copies to better
handle the case where a read returns less data than what was requested
when not at the end of the file, allowing AsyncSSH to get back the
right result even if the requested block size is larger than the
SFTP server can handle.

* Fixed an issue where the requested SFTP block_size wasn't used in the
get, copy, mget, and mcopy functions if it was larger than the
default size of 16 KB.

* Fixed a problem where the list of client keys provided in an
SSHClientConnectionOptions object wasn't always preserved properly
across the opening of multiple SSH connections.

* Changed SSH agent client code to avoid printing a warning on Windows
when unable to connect to the SSH agent using the default path. A
warning will be printed if the agent_path or SSH_AUTH_SOCK is
explicitly set, but AsyncSSH will remain quiet if no agent path is
set and no SSH agent is running.

* Made AsyncSSH tolerant of unexpected authentication success/failure
messages sent after authentication completes. AsyncSSH previously
treated this as a protocol error and dropped the connection, while
most other SSH implementations ignored these messages and allowed
the connection to continue.

* Made AsyncSSH tolerant of SFTP status responses which are missing
error message and language tag fields, improving interoperability
with servers that omit these fields. When missing, AsyncSSH treats
these fields as if they were set to empty strings.

1.17.0

----------------------------

* Added support for "reverse direction" SSH connections, useful to
support applications like NETCONF Call Home, described in RFC 8071.

* Added support for the PyCA implementation of Chacha20-Poly1305,
eliminating the dependency on libnacl/libsodium to provide this
functionality, as long as OpenSSL 1.1.1b or later is installed.

* Restored libnacl support for Curve25519/Ed25519 on systems which
have an older version of OpenSSL that doesn't have that support.
This fallback also applies to Chacha20-Poly1305.

* Fixed Pageant support on Windows to use the Pageant agent by default
when it is available and client keys are not explicitly configured.

* Disabled the use of RSA SHA-2 signatures when using the Pageant
or Windows 10 OpenSSH agent on Windows, since neither of those
support the signature flags options to request them.

* Fixed a regression where a callable was no longer usable in the
sftp_factory argument of create_server.

1.16.1

----------------------------

* Added channel, connection, and env properties to SFTPServer instances,
so connection and channel information can be used to influence the
SFTP server's behavior. Previously, connection information was made
avaiable through the constructor, but channel and environment
information was not. Now, all of these are available as properties
on the SFTPServer instance without the need to explicitly store anything
in a custom constructor.

* Optimized SFTP glob matching when the glob pattern contains directory
names without glob characters in them. Thanks go to Mikhail Terekhov
for contributing this improvement!

* Added support for PurePath in a few places that were missed when this
support was originally added. Once again, thanks go to Mikhail Terehkov
for these fixes.

* Fixed bug in SFTP parallel I/O file reader where it sometimes returned
EOF prematurely. Thanks go to David G for reporting this problem and
providing a reproducible test case.

* Fixed test failures seen on Fedora Rawhide. Thanks go to Georg Sauthof
for reporting this issue and providing a test environment to help debug
it.

* Updated Ed25519/448 and Curve25519/448 tests to only run when these
algorithms are available. Thanks go to Ondřej Súkup for reporting
this issue and providing a suggested fix.

1.16.0

---------------------------

* Added support for Ed448 host/client keys and certificates and
rewrote Ed25519 support to use the PyCA implementation, reducing
the dependency on libnacl and libsodium to only be needed to
support the chacha20-poly1305 cipher.

* Added support for PKCS8 format Ed25519 and Ed448 private and
public keys (in addition to the OpenSSH format previously
supported).

* Added support for multiple delimiters in SSHReader's readuntil()
function, causing it to return data as soon as any of the
specified delimiters are matched.

* Added the ability to register custom key handlers in the line
editor which can modify the input line, extending the built-in
editing functionality.

* Added SSHSubprocessProtocol and SSHSubprocessTransport classes
to provide compatibility with asyncio.SubprocessProtocol and
asyncio.SubprocessTransport. Code which is designed to call
BaseEventLoop.subprocess_shell() or BaseEventLoop.subprocess_exec()
can be easily adapted to work against a remote process by calling
SSHClientConnection.create_subprocess().

* Added support for sending keepalive messages when the SSH
connection is idle, with an option to automatically disconnect
the connection if the remote system doesn't respond to these
keepalives.

* Changed AsyncSSH to ignore errors when loading unsupported key
types from the default file locations.

* Changed the reuse_port option to only be available on Python
releases which support it (3.4.4 and later).

* Fixed an issue where MSG_IGNORE packets could sometimes be sent
between MSG_NEWKEYS and MSG_EXT_INFO, which caused some SSH
implementations to fail to properly parse the MSG_EXT_INFO.

* Fixed a couple of errors in the handling of disconnects occurring
prior to authentication completing.

* Renamed "session_encoding" and "session_errors" arguments in
asyncssh.create_server() to "encoding" and "errors", to match
the names used for these arguments in other AsyncSSH APIs. The
old names are still supported for now, but they are marked as
deprecated and will be removed in a future release.

1.15.1

----------------------------

* Added callback-based host validation in SSHClient, allowing callers
to decide programmatically whether to trust server host keys and
certificates rather than having to provide a list of trusted values
in advance.

* Changed SSH client code to only load the default known hosts file if
if exists. Previously an error was returned if a known_hosts value
wasn't specified and the default known_hosts file didn't exist. For
host validate to work in this case, verification callbacks must be
implemented or other forms of validation such as X.509 trusted CAs
or GSS-based key exchange must be used.

* Fixed known hosts validation to completely disable certificate checks
when known_hosts is set to None. Previously, key checking was disabled
in this case but other checks for certificate expiration and hostname
mismatch were still performed, causing connections to fail even when
checking was supposed to be disabled.

* Switched curve25519 key exchange to use the PyCA implementation,
avoiding a dependency on libnacl/libsodium. For now, support for
Ed25519 keys still requires these libraries.

* Added get_fingerprint() method to return a fingerprint of an SSHKey.

1.15.0

----------------------------

* Added the ability to pass keyword arguments provided in the scp()
command through to asyncssh.connect() calls it makes, allowing
things like custom credentials to be specified.

* Added support for a reuse_port argument in create_server(). If
set, this will be passed to the asyncio loop.create_server() call
which creates listening sockets.

* Added support for "soft" EOF when line editing in enabled so that
EOF can be signalled multiple times on a channel. When Ctrl-D is
received on a channel with line editing enabled, EOF is returned
to the application but the channel remains open and capable of
accepting more input, allowing an interactive shell to process
the EOF for one command but still accept input for subsequent
commands.

* Added support for the Windows 10 OpenSSH ssh-agent. Thanks go to
SamP20 for providing an initial proof of concept and a suggested
implementation.

* Reworked scoped link-local IPv6 address normalization to work
better on Linux systems.

* Fixed a problem preserving directory structure in recursive scp().

* Fixed SFTP chmod tests to avoid attempting to set the sticky bit on
a plain file, as this caused test failures on FreeBSD.

* Updated note in SSHClientChannel's send_signal() documentation to
reflect that OpenSSH 7.9 and later should now support processing
of signal messages.

1.14.0

---------------------------

* Changed license from EPL 1.0 to EPL 2.0 with GPL 2.0 or later as an
available secondary license.

* Added support for automatically parallelizing large reads and write
made using the SFTPClientFile class, similar to what was already
available in the get/put/copy methods of SFTPClient.

* Added support for get_extra_info() in SSH process classes, returning
information associated with the channel the process is tied to.

* Added new set_extra_info() method on SSH connection and channel
classes, allowing applications to store additional information on
these objects.

* Added handlers for OpenSSH keepalive global & channel requests to
avoid messages about unknown requests in the debug log. These requests
are still logged, but at debug level 2 instead of 1 and they are not
labeled as unknown.

* Fixed race condition when closing sockets associated with forwarded
connections.

* Improved error handling during connection close in SFTPClient.

* Worked around issues with integer overflow on systems with a
32-bit time_t value when dates beyond 2038 are used in X.509
certificates.

* Added guards around some imports and tests which were causing
problems on Fedora 27.

* Changed debug level for reporting PTY modes from 1 to 2 to reduce
noise in the logs.

* Improved SFTP debug log output when sending EOF responses.

1.13.3

----------------------------

* Added support for setting the Unicode error handling strategy in
conjunction with setting an encoding when creating new SSH sessions,
streams, and processes. This strategy can also be set when specifying
a session encoding in create_server(), and when providing an encoding
in the get_comment() and set_comment() functions on private/public
keys and certificates.

* Changed handling of Unicode in channels to use incrmeental codec,
similar to what was previously done in process redirection.

* Added Python 3.7 to the list of classifiers in setup.py, now that it
has been released.

* Updated Travis CI configuration to add Python 3.7 builds, and moved
Linux builds on never versions of Python up to xenial.

* Added missing coroutine decorator in test_channel.

1.13.2

---------------------------

* Added support for accessing client host keys via the OpenSSH
ssh-keysign program when doing host-based authentication. If
ssh-keysign is present and enabled on the system, an AsyncSSH
based SSH client can use host-based authentication without
access to the host private keys.

* Added support for using pathlib path objects when reading and
writing private and public keys and certificates.

* Added support for auth_completed() callback in the SSHServer
class which runs when authentication completes successfully
on each new connection.

* Fixed host-based authentication unit tests to mock out calls
to getnameinfo() to avoid failures on systems with restricted
network functionality.

1.13.1

----------------------------

* Added client and server support for host-based SSH authentication.
If enabled, this will allow all users from a given host to be
authenticated by a shared host key, rather than each user needing
their own key. This should only be used with hosts which are trusted
to keep their host keys secure and provide accurate client usernames.

* Added support for RSA key exchange algorithms (rsa2048-sha256 and
rsa1024-sha1) available in PuTTY and some mobile SSH clients.

* Added support for the SECP256K1 elliptic curve for ECDSA keys and
ECDH key exchange. This curve is supported by the Bitvise SSH client
and server.

* Added debug logging of the algorithms listed in a received kexinit
message.

1.13.0

----------------------------

* Added support for dynamic port forwarding via SOCKS, where AsyncSSH
will open a listener which understands SOCKS connect requests and
for each request open a TCP/IP tunnel over SSH to the requested host
and port.

* Added support in SSHProcess for I/O redirection to file objects that
implement read(), write(), and close() functions as coroutines, such
as the "aiofiles" package. In such cases, AsyncSSH will automaically
detect that it needs to make async calls to these methods when it
performs I/O.

* Added support for using pathlib objects in SSHProcess I/O redirection.

* Added multiple improvements to pattern matching support in the SFTPClient
glob(), mget(), mput(), and mcopy() methods. AsyncSSH now allows you
to use '**' in a pattern to do a recursive directory search, allows
character ranges in square brackets in a pattern, and allows a trailing
slash in a pattern to be specified to request that only directories
matching the pattern should be returned.

* Fixed an issue with calling readline() and readuntil() with a timeout,
where partial data received before the timeout was sometimes discarded.
Any partial data which was received when a timeout occurs will now be
left in the input buffer, so it is still available to future read()
calls.

* Fixed a race condition where trying to restart a read() after a timeout
could sometimes raise an exception about multiple simultaneous reads.

* Changed readuntil() in SSHReader to raise IncompleteReadError if the
receive window fills up before a delimiter match is found. This also
applies to readline(), which will return a partial line without a
newline at the end when this occurs. To support longer lines, a caller
can call readuntil() or readline() as many times as they'd like,
appending the data returned to the previous partial data until a
delimiter is found or some maximum size is exceeded. Since the default
window size is 2 MBytes, though, it's very unlikely this will be needed
in most applications.

* Reworked the crypto support in AsyncSSH to separate packet encryption
and decryption into its own module and simplified the directory
structure of the asyncssh.crypto package, eliminating a pyca subdirectory
that was created back when AsyncSSH used a mix of PyCA and PyCrypto.

1.12.2

----------------------------

* Added support for using pathlib objects as paths in calls to SFTP
methods, in addition to Unicode and byte strings. This is mainly
intended for use in constructing local paths, but it can also be
used for remote paths as long as POSIX-style pathlib objects are
used and an appropriate path encoding is set to handle the
conversion from Unicode to bytes.

* Changed server EXT_INFO message to only be sent after the first SSH key
exchange, to match the specification recently published in RFC 8308.

* Fixed edge case in TCP connection forwarding where data received
on a forward TCP connection was not delivered if the connection was
closed or half-closed before the corresponding SSH tunnel was fully
established.

* Made note about OpenSSH not properly handling send_signal more visible.

1.12.1

----------------------------

* Implemented a fix for CVE-2018-7749, where a modified SSH client could
request that an AsyncSSH server perform operations before authentication
had completed. Thanks go to Matthijs Kooijman for discovering and
reporting this issue and helping to review the fix.

* Added a non-blocking collect_output() method to SSHClientProcess to
allow applications to retrieve data received on an output stream
without blocking. This call can be called multiple times and freely
intermixed with regular read calls with a guarantee that output will
always be returned in order and without duplication.

* Updated debug logging implementation to make it more maintainable, and
to fix an issue where unprocessed packets were not logged in some cases.

* Extended the support below for non-ASCII characters in comments to apply
to X.509 certificates, allowing an optional encoding to be passed in to
get_comment() and set_comment() and a get_comment_bytes() function to
get the raw comment bytes without performing Unicode decoding.

* Fixed an issue where a UnicodeDecodeError could be reported in some
cases instead of a KeyEncryptionError when a private key was imported
using the wrong passphrase.

* Fixed the reporting of the MAC algorithm selected during key exchange to
properly report the cipher name for GCM and Chacha ciphers that don't
use a separate MAC algorithm. The correct value was being returned in
queries after the key exchange was complete, but the logging was being
done before this adjustment was made.

* Fixed the documentation of connection_made() in SSHSession subclasses
to properly reflect the type of SSHChannel objects passed to them.

1.12.0

---------------------------

* Enhanced AsyncSSH logging framework to provide detailed logging of
events in the connection, channel, key exchange, authentication,
sftp, and scp modules. Both high-level information logs and more
detailed debug logs are available, and debug logging supports
multiple debug levels with different amounts of verboseness.
Logger objects are also available on various AsyncSSH classes to
allow applications to report their own log events in a manner that
can be tied back to a specific SSH connection or channel.

* Added support for begin_auth() to be a coroutine, so asynchronous
operations can be performed within it to load state needed to
perform SSH authentication.

* Adjusted key usage flags set on generated X.509 certificates to be more
RFC compliant and work around an issue with OpenSSL validation of
self-signed non-CA certificates.

* Updated key and certificate comment handling to be less sensitive to
the encoding of non-ASCII characters. The get_comment() and set_comment()
functions now take an optional encoding paramter, defaulting to UTF-8
but allowing for others encodings. There's also a get_comment_bytes()
function to get the comment data as bytes without performing Unicode
decoding.

* Updated AsyncSSH to be compatible with beta release of Python 3.7.

* Updated code to address warnings reported by the latest version of pylint.

* Cleaned up various formatting issues in Sphinx documentation.

* Significantly reduced time it takes to run unit tests by decreasing
the rounds of bcrypt encryption used when unit testing encrypted
OpenSSH private keys.

* Added support for testing against uvloop in Travis CI.

1.11.1

----------------------------

* Switched to using PBKDF2 implementation provided by PyCA, replacing a
much slower pure-Python implementation used in earlier releases.

* Improved support for file-like objects in process I/O redirection,
properly handling objects which don't support fileno() and allowing
both text and binary file objects based on whether they have an
'encoding' member.

* Changed PEM parser to be forgiving of trailing blank lines.

* Updated documentation to note lack of support in OpenSSH for send_signal(),
terminate(), and kill() channel requests.

* Updated unit tests to work better with OpenSSH 7.6.

* Updated Travis CI config to test with more recent Python versions.

1.11.0

---------------------------

* Added support for X.509 certificate based client and server authentication,
as defined in RFC 6187.

* DSA, RSA, and ECDSA keys are supported.
* New methods are available on SSHKey private keys to generate X.509
user, host, and CA certificates.
* Authorized key and known host support has been enhanced to support
matching on X.509 certificates and X.509 subject names.
* New arguments have been added to create_connection() and create_server()
to specify X.509 trusted root CAs, X.509 trusted root CA hash directories,
and allowed X.509 certificate purposes.
* A new load_certificates() function has been added to more easily pre-load
a list of certificates from byte strings or files.
* Support for including and validating OCSP responses is not yet available,
but may be added in a future release.
* This support adds a new optional dependency on pyOpenSSL in setup.py.

* Added command, subsystem, and environment properties to SSHProcess,
SSHCompletedProcess, and ProcessError classes, as well as stdout and
stderr properties in ProcessError which mirror what is already present
in SSHCompletedProcess. Thanks go to iforapsy for suggesting this.

* Worked around a datetime.max bug on Windows.

* Increased the build timeout on TravisCI to avoid build failures.

1.10.1

----------------------------

* Fixed SCP to properly call exit() on SFTPServer when the copy completes.
Thanks go to Arthur Darcet for discovering this and providing a
suggested fix.

* Added support for passphrase to be specified when loading default client
keys, and to ignore encrypted default keys if no passphrase is specified.

* Added additional known hosts test cases. Thanks go to Rafael Viotti
for providing these.

* Increased the default number of rounds for OpenSSH-compatible bcrypt
private key encryption to avoid a warning in the latest version of the
bcrypt module, and added a note that the encryption strength scale
linearly with the rounds value, not logarithmically.

* Fixed SCP unit test errors on Windows.

* Fixed some issues with Travis and Appveyor CI builds.

1.10.0

---------------------------

* Added SCP client and server support, The new asyncssh.scp() function
can get and put files on a remote SCP server and copy files between
two or more remote SCP servers, with options similar to what was
previously supported for SFTP. On the server side, an SFTPServer used
to serve files over SFTP can also serve files over SCP by simply
setting allow_scp to True in the call to create_server().

* Added a new SSHServerProcess class which supports I/O redirection on
inbound connections to an SSH server, mirroring the SSHClientProcess
class added previously for outbound SSH client connections.

* Enabled TCP keepalive on SSH client and server connections.

* Enabled Python 3 highlighting in Sphinx documentation.

* Fixed a bug where a previously loaded SSHKnownHosts object wasn't
properly accepted as a known_hosts value in create_connection() and
enhanced known_hosts to accept a callable to allow applications to
provide their own function to return trusted host keys.

* Fixed a bug where an exception was raised if the connection closed
while waiting for an asynchronous authentication callback to complete.

* Fixed a bug where empty passwords weren't being properly supported.

1.9.0

---------------------------

* Added support for GSSAPI key exchange and authentication when the
"gssapi" module is installed on UNIX or the "sspi" module from pypiwin32
is installed on Windows.

* Added support for additional Diffie Hellman groups, and added the ability
for Diffie Hellman and GSS group exchange to select larger group sizes.

* Added overridable methods format_user() and format_group() to format user
and group names in the SFTP server, defaulting to the previous behavior of
using pwd.getpwuid() and grp.getgrgid() on platforms that support those.

* Added an optional progress reporting callback on SFTP file transfers,
and made the block size for these transfers configurable.

* Added append_private_key(), append_public_key(), and append_certificate()
methods on the corresponding key and certificate classes to simplify
the creating of files containing a list of keys/certificates.

* Updated readdir to break responses into chunks to avoid hitting maximum
message size limits on large directories.

* Updated SFTP to work better on Windows, properly handling drive letters
and conversion between forward and back slashes in paths and handling
setting of attributes on open files and proper support for POSIX rename.
Also, file closes now block until the close completes, to avoid issues
with file locking.

* Updated the unit tests to run on Windows, and enabled continuous
integration builds for Windows to automatically run on Appveyor.

1.8.1

---------------------------

* Fix an issue in attempting to load the 'nettle' library on Windows.

1.8.0

---------------------------

* Added support for forwarding X11 connections. When requested, AsyncSSH
clients will allow remote X11 applications to tunnel data back to a local
X server and AsyncSSH servers can request an X11 DISPLAY value to export
to X11 applications they launch which will tunnel data back to an X
server associated with the client.

* Improved ssh-agent forwarding support on UNIX to allow AsyncSSH
servers to request an SSH_AUTH_SOCK value to export to applications
they launch in order to access the client's ssh-agent. Previously,
there was support for agent forwarding on server connections within
AsyncSSH itself, but they did not provide this forwarding to other
applications.

* Added support for PuTTY's Pageant agent on Windows systems, providing
functionality similar to the OpenSSH agent on UNIX. AsyncSSH client
connections from Windows can now access keys stored in the Pageant
agent when they perform public key authentication.

* Added support for the umac-64 and umac-128 MAC algorithms, compatible
with the implementation in OpenSSH. These algorithms are preferred
over the HMAC algorithms when both are available and the cipher chosen
doesn't already include a MAC.

* Added curve25519-sha256 as a supported key exchange algorithm. This
algorithm is identical to the previously supported algorithm named
'curve25519-sha256\libssh.org', matching what was done in OpenSSH 7.3.
Either name may now be used to request this type of key exchange.

* Changed the default order of key exchange algorithms to prefer the
curve25519-sha256 algorithm over the ecdh-sha2-nistp algorithms.

* Added support for a readuntil() function in SSHReader, modeled after
the readuntil() function in asyncio.StreamReader added in Python 3.5.2.
Thanks go to wwjiang for suggesting this and providing an example
implementation.

* Fixed issues where the explicitly provided event loop value was not
being passed through to all of the places which needed it. Thanks go
to Vladimir Rutsky for pointing out this problem and providing some
initial fixes.

* Improved error handling when port forwarding is requested for a port
number outside of the range 0-65535.

* Disabled use of IPv6 in unit tests when opening local loopback sockets
to avoid issues with incomplete IPv6 support in TravisCI.

* Changed the unit tests to always start with a known set of environment
variables rather than inheriting the environment from the shell
running the tests. This was leading to test breakage in some cases.

1.7.3

---------------------------

* Updated unit tests to run properly in environments where OpenSSH
and OpenSSL are not installed.

* Updated a process unit test to not depend on the system's default
file encoding being UTF-8.

* Updated Mac TravisCI builds to use Xcode 8.1.

* Cleaned up some wording in the documentation.

1.7.2

---------------------------

* Fixed an issue with preserving file access times in SFTP, and update
the unit tests to more accurate detect this kind of failure.

* Fixed some markup errors in the documentation.

* Fixed a small error in the change log for release 1.7.0 regarding
the newly added Diffie Hellman key exchange algorithms.

1.7.1

--------------------------

* Fix an error that prevented the docs from building.

1.7.0

--------------------------

* Added support for group 14, 16, and 18 Diffie Hellman key exchange
algorithms which use SHA-256 and SHA-512.

* Added support for using SHA-256 and SHA-512 based signature algorithms
for RSA keys and support for OpenSSH extension negotiation to advertise
these signature algorithms.

* Added new load_keypairs and load_public_keys API functions which
support expicitly loading keys using the same syntax that was
previously available for specifying client_keys, authorized_client_keys,
and server_host_keys arguments when creating SSH clients and servers.

* Enhanced the SSH agent client to support adding and removing keys
and certificates (including support for constraints) and locking and
unlocking the agent. Support has also been added for adding and
removing smart card keys in the agent.

* Added support for getting and setting a comment value when generating
keys and certificates, and decoding and encoding this comment when
importing and exporting keys that support it. Currently, this is
available for OpenSSH format private keys and OpenSSH and RFC 4716
format public keys. These comment values are also passed on to the
SSH agent when keys are added to it.

* Fixed a bug in the generation of ECDSA certificates that showed up
when trying to use the nistp384 or nistp521 curves.

* Updated unit tests to use the new key and certificate generation
functions, eliminating the dependency on the ssh-keygen program.

* Updated unit tests to use the new SSH agent support when adding keys
to the SSH agent, eliminating the dependency on the ssh-add program.

* Incorporated a fix from Vincent Bernat for an issue with launching
ssh-agent on some systems during unit testing.

* Fixed some typos in the documentation found by Jakub Wilk.

1.6.2

--------------------------

* Added generate_user_certificate() and generate_host_certificate() methods
to SSHKey class to generate SSH certificates, and export_certificate()
and write_certificate() methods on SSHCertificate class to export
certificates for use in other tools.

* Improved editor unit tests to eliminate timing dependency.

* Cleaned up a few minor documentation issues.

1.6.1

---------------------------

* Added generate_private_key() function to create new DSA, RSA, ECDSA, or
Ed25519 private keys which can be used as SSH user and host keys.

* Removed an unintended dependency in the SSHLineEditor on session objects
keep a private member which referenced the corresponding channel.

* Fixed a race condition in SFTP unit tests.

* Updated dependencies to require version 1.5 of the cryptography module
and started to take advantage of the new one-shot sign and verify
APIs it now supports.

* Clarified the documentation of the default return value of eof_received().

* Added new multi-user client and server examples, showing a single
process opening multiple SSH connections in parallel.

* Updated development status and Python versions listed in setup.py.

1.6.0

---------------------------

* Added new create_process() and run() APIs modeled after the "subprocess"
module to simplify redirection of stdin, stdout, and stderr and
collection of output from remote SSH processes.

* Added input line editing and echoing capabilities to better support
interactive SSH server applications. AsyncSSH server sessions will now
automatically perform input echoing and provide basic line editing
capabilities to clients which request a pseudo-terminal, avoiding the
need for applications to provide this functionality.

* Added the ability to use SSHReader objects as async iterators in
Python 3.5, returning input a line at a time.

* Added support for the IUTF8 terminal mode now recognized by OpenSSH 7.3.

* Fixed a bug where an SSHReader read() call could return an empty string
when it followed a call to readline() instead of blocking until more
input was available.

* Updated AsyncSSH to use the bcrypt package from PyCA, now that it
has support for the kdf function.

* Updated the documentation and examples to show how to take advantage
of the new features listed here.

1.5.6

---------------------------

* Added support for Python 3.5 asynchronous context managers in
SSHConnection, SFTPClient, and SFTPFile, while still maintaining
backward compatibility with older Python 3.4 syntax.

* Updated bcrypt check in test code to only test features that depend
on it when the right version is available.

* Switched testing over to using tox to better support testing on
multiple versions of Python.

* Added tests of new Python 3.5 async syntax.

* Expanded Travis CI coverage to test both Python 3.4 and 3.5 on MacOS.

* Updated documentation and examples to use Python 3.5 syntax.

1.5.5

---------------------------

* Updated public_key module to make sure the right version of bcrypt is
installed before attempting to use it.

* Updated forward and sftp module unit tests to work better on Linux.

* Changed README links to point at new readthedocs.io domain.

1.5.4

--------------------------

* Added support for setting custom SSH client and server version strings.

* Added unit tests for the sftp module, bringing AsyncSSH up to 100%
code coverage under test on all modules.

* Added new wait_closed() method in SFTPClient class to wait for an
SFTP client session to be fully closed.

* Fixed an issue with error handling in new parallel SFTP file copy code.

* Fixed some other minor issues in SFTP found during unit tests.

* Fixed some minor documentation issues.

1.5.3

--------------------------

* Added support for opening tunneled SSH connections, where an SSH
connection is opened over another SSH connection's direct TCP/IP
channel.

* Improve performance of SFTP over high latency connections by having
the internal copy method issue multiple read requests in parallel.

* Reworked SFTP to mark all coroutine functions explicitly, to provide
better compatibility with the new Python 3.5 "await" syntax.

* Reworked create_connection() and create_server() functions to do
argument checking immediately rather than in the SSHConnection
constructors, improving error reporting and avoiding a bug in
asyncio which can leak socket objects.

* Fixed a hang which could occur when attempting to close an SSH
connection with a listener still active.

* Fixed an error related to passing keys in via public_key_auth_requested().

* Fixed a potential leak of an SSHAgentClient object when an error occurs
while opening a client connection.

* Fixed some race conditions related to channel and connection closes.

* Fixed some minor documentation issues.

* Continued to expand unit test coverage, completing coverage of the
connection module.

1.5.2

---------------------------

* Fixed a bug in UNIX domain socket forwarding introduced in 1.5.1 by the
TCP_NODELAY change.

* Fixed channel code to report when a channel is closed with incomplete
Unicode data in the receive buffer. This was previously reported
correctly when EOF was received on a channel, but not when it was
closed without sending EOF.

* Added unit tests for channel, forward, and stream modules, partial
unit tests for the connection module, and a placeholder for unit
tests for the sftp module.

1.5.1

---------------------------

* Added basic support for running AsyncSSH on Windows. Some functionality
such as UNIX domain sockets will not work there, and the test suite will
not run there yet, but basic functionality has been tested and seems
to work. This includes features like bcrypt and support for newer
ciphers provided by libnacl when these optional packages are installed.

* Greatly improved the performance of known_hosts matching on exact
hostnames and addresses. Full wildcard pattern matching is still
supported, but entries involving exact hostnames or addresses are
now matched thousands of times faster.

* Split known_hosts parsing and matching into separate calls so that a
known_hosts file can be parsed once and used to make connections to
several different hosts. Thanks go to Josh Yudaken for suggesting
this and providing a sample implementation.

* Updated AsyncSSH to allow SSH agent forwarding when it is requested
even when local client keys are used to perform SSH authentication.

* Updaded channel state machine to better handle close being received
while the channel is paused for reading. Previously, some data would
not be delivered in this case.

* Set TCP_NODELAY on sockets to avoid latency problems caused by TCP
delayed ACK.

* Fixed a bug where exceptions were not always returned properly when
attempting to drain writes on a stream.

* Fixed a bug which could leak a socket object after an error opening
a local TCP listening socket.

* Fixed a number of race conditions uncovered during unit testing.

1.5.0

---------------------------

* Added support for OpenSSH-compatible direct and forwarded UNIX domain
socket channels and local and remote UNIX domain socket forwarding.

* Added support for client and server side ssh-agent forwarding.

* Fixed the open_connection() method on SSHServerConnection to not include
a handler_factory argument. This should only have been present on the
start_server() method.

* Fixed wait_closed() on SSHForwardListener to work properly when a
close is in progress at the time of the call.

1.4.1

---------------------------

* Fixed a bug in SFTP introduced in 1.4.0 related to handling of
responses to non-blocking file closes.

* Updated code to avoid calling asyncio.async(), deprecated in
Python 3.4.4.

* Updated unit tests to avoid errors on systems with an older version
of OpenSSL installed.

1.4.0

---------------------------

* Added ssh-agent client support, automatically using it when SSH_AUTH_SOCK
is set and client private keys aren't explicitly provided.

* Added new wait_closed() API on SSHConnection to allow applications to wait
for a connection to be fully closed and updated examples to use it.

* Added a new login_timeout argument when create an SSH server.

* Added a missing acknowledgement response when canceling port forwarding
and fixed a few other issues related to cleaning up port forwarding
listeners.

* Added handlers to improve the catching and reporting of exceptions that
are raised in asynchronous tasks.

* Reworked channel state machine to perform clean up on a channel only
after a close is both sent and received.

* Fixed SSHChannel to run the connection_lost() handler on the SSHSession
before unblocking callers of wait_closed().

* Fixed wait_closed() on SSHListener to wait for the acknowledgement from
the SSH server before returning.

* Fixed a race condition in port forwarding code.

* Fixed a bug related to sending a close on a channel which got a failure
when being opened.

* Fixed a bug related to handling term_type being set without term_size.

* Fixed some issues related to the automatic conversion of client
keyboard-interactive auth to password auth. With this change, automatic
conversion will only occur if the application doesn't override the
kbdint_challenge_received() method and it will only attempt to
authenticate once with the password provided.

1.3.2

---------------------------

* Added server-side support for handling password changes during password
authentication, and fixed a few other auth-related bugs.

* Added the ability to override the automatic support for keyboard-interactive
authentication when password authentication is supported.

* Fixed a race condition in unblocking streams.

* Removed support for OpenSSH v00 certificates now that OpenSSH no longer
supports them.

* Added unit tests for auth module.

1.3.1

--------------------------

* Updated AsyncSSH to depend on version 1.1 or later of PyCA and added
support for using its new Elliptic Curve Diffie Hellman (ECDH)
implementation, replacing the previous AsyncSSH native Python
version.

* Added support for specifying a passphrase in the create_connection,
create_server, connect, and listen functions to allow file names
or byte strings containing encrypted client and server host keys
to be specified in those calls.

* Fixed handling of cancellation in a few AsyncSSH calls, so it is
now possible to make calls to things like stream read or drain which
time out.

* Fixed a bug in keyboard-interactive fallback to password auth which
was introduced when support was added for auth functions optionally
being coroutines.

* Move bcrypt check in encrypted key handling until it is needed so
better errors can be returned if a passphrase is not specified or the
key derivation function used in a key is unknown.

* Added unit tests for the auth_keys module.

* Updated unit tests to better handle bcrypt or libnacl not being
installed.

1.3.0

---------------------------

* Updated AsyncSSH dependencies to make PyCA version 1.0.0 or later
mandatory and remove the older PyCrypto support. This change also
adds support for the PyCA implementation of ECDSA and removes support
for RC2-based private key encryption that was only supported by
PyCrypto.

* Refactored ECDH and Curve25519 key exchange code so they can share an
implementation, and prepared the code for adding a PyCA shim for this
as soon as support for that is released.

* Hardened the DSA and RSA implementations to do stricter checking of the
key exchange response, and sped up the RSA implementation by taking
advantage of optional RSA private key parameters when they are present.

* Added support for asynchronous client and server authentication,
allowing auth-related callbacks in SSHClient and SSHServer to optionally
be defined as coroutines.

* Added support for asynchronous SFTP server processing, allowing callbacks
in SFTPServer to optionally be defined as coroutines.

* Added support for a broader set of open mode flags in the SFTP server.
Note that this change is not completely backward compatible with previous
releases. If you have application code which expects a Python mode
string as an argument to SFTPServer open method, it will need to be
changed to expect a pflags value instead.

* Fixed handling of eof_received() when it returns false to close the
half-open connection but still allow sending or receiving of exit status
and exit signals.

* Added unit tests for the asn1, cipher, compression, ec, kex, known_hosts,
mac, and saslprep modules and expended the set of pbe and public_key
unit tests.

* Fixed a set of issues uncovered by ASN.1 unit tests:

* Removed extra 0xff byte when encoding integers of the form -128*256^n
* Fixed decoding error for OIDs beginning with 2.n where n >= 40
* Fixed range check for second component of ObjectIdentifier
* Added check for extraneous 0x80 bytes in ObjectIdentifier components
* Added check for negative component values in ObjectIdentifier
* Added error handling for ObjectIdentifier components being non-integer
* Added handling for missing length byte after extended tag
* Raised ASN1EncodeError instead of TypeError on unsupported types

* Added validation on asn1_class argument, and equality and hash methods
to BitString, RawDERObject, and TaggedDERObject. Also, reordered
RawDERObject arguments to be consistent with TaggedDERObject and added
str method to ObjectIdentifier.

* Fixed a set of issues uncovered by additional pbe unit tests:

* Encoding and decoding of PBES2-encrypted keys with a PRF other than
SHA1 is now handled correctly.
* Some exception messages were made more specific.
* Additional checks were put in for empty salt or zero iteration count
in encryption parameters.

* Fixed a set of issues uncovered by additional public key unit tests:

* Properly handle PKCS8 keys with invalid ASN.1 data
* Properly handle PKCS8 DSA & RSA keys with non-sequence for arg_params
* Properly handle attempts to import empty string as a public key
* Properly handle encrypted PEM keys with missing DEK-Info header
* Report check byte mismatches for encrypted OpenSSH keys as bad passphrase
* Return KeyImportError instead of KeyEncryptionError when passphrase
is needed but not provided

* Added information about branches to CONTRIBUTING guide.

* Performed a bunch of code cleanup suggested by pylint.

1.2.1

---------------------------

* Fixed a problem with passing in client_keys=None to disable public
key authentication in the SSH client.

* Updated Unicode handling to allow multi-byte Unicode characters to be
split across successive SSH data messages.

* Added a note to the documentation for AsyncSSH create_connection()
explaining how to perform the equivalent of a connect with a timeout.

1.2.0

--------------------------

* Fixed a problem with the SSHConnection context manager on Python versions
older than 3.4.2.

* Updated the documentation for get_extra_info() in the SSHConnection,
SSHChannel, SSHReader, and SSHWriter classes to contain pointers
to get_extra_info() in their parent transports to make it easier to
see all of the attributes which can be queried.

* Clarified the legal return values for the session_requested(),
connection_requested(), and server_requested() methods in
SSHServer.

* Eliminated calls to the deprecated importlib.find_loader() method.

* Made improvements to README suggested by Nicholas Chammas.

* Fixed a number of issues identified by pylint.

1.1.1

---------------------------

* Added new start_sftp_server method on SSHChannel to allow applications
using the non-streams API to start an SFTP server.

* Enhanced the default format_longname() method in SFTPServer to properly
handle the case where not all of the file attributes are returned by
stat().

* Fixed a bug related to the new allow_pty parameter in create_server.

* Fixed a bug in the hashed known_hosts support introduced in some recent
refactoring of the host pattern matching code.

1.1.0

---------------------------

* SFTP is now supported!

* Both client and server support is available.
* SFTP version 3 is supported, with OpenSSH extensions.
* Recursive transfers and glob matching are supported in the client.
* File I/O APIs allow files to be accessed without downloading them.

* New simplified connect and listen APIs have been added.

* SSHConnection can now be used as a context manager.

* New arguments to create_server now allow the specification of a
session_factory and encoding or sftp_factory as well as controls
over whether a pty is allowed and the window and max packet size,
avoiding the need to create custom SSHServer subclasses or custom
SSHServerChannel instances.

* New examples have been added for SFTP and to show the use of the new
connect and listen APIs.

* Copyrights in changed files have all been updated to 2015.

1.0.1

---------------------------

* Fixed a bug in OpenSSH private key encryption introduced in some
recent cipher refactoring.

* Added bcrypt and libnacl as optional dependencies in setup.py.

* Changed test_keys test to work properly when bcrypt or libnacl aren't
installed.

1.0.0

---------------------------

* This release finishes adding a number of major features, finally making
it worthy of being called a "1.0" release.

* Host and user certificates are now supported!

* Enforcement is done on principals in certificates.
* Enforcement is done on force-command and source-address critical options.
* Enforcement is done on permit-pty and permit-port-forwarding extensions.

* OpenSSH-style known hosts files are now supported!

* Positive and negative wildcard and CIDR-style patterns are supported.
* HMAC-SHA1 hashed host entries are supported.
* The cert-authority and revoked markers are supported.

* OpenSSH-style authorized keys files are now supported!

* Both client keys and certificate authorities are supported.
* Enforcement is done on from and principals options during key matching.
* Enforcement is done on no-pty, no-port-forwarding, and permitopen.
* The command and environment options are supported.
* Applications can query for their own non-standard options.

* Support has been added for OpenSSH format private keys.

* DSA, RSA, and ECDSA keys in this format are now supported.
* Ed25519 keys are supported when libnacl and libsodium are installed.
* OpenSSH private key encryption is supported when bcrypt is installed.

* Curve25519 Diffie-Hellman key exchange is now available via either the
curve25519-donna or libnacl and libsodium packages.

* ECDSA key support has been enhanced.

* Support is now available for PKCS8 ECDSA v2 keys.
* Support is now available for both NamedCurve and explicit ECParameter
versions of keys, as long as the parameters match one of the supported
curves (nistp256, nistp384, or nistp521).

* Support is now available for the OpenSSH chacha20-poly1305 cipher when
libnacl and libsodium are installed.

* Cipher names specified in private key encryption have been changed to be
consistent with OpenSSH cipher naming, and all SSH ciphers can now be
used for encryption of keys in OpenSSH private key format.

* A couple of race conditions in SSHChannel have been fixed and channel
cleanup is now delayed to allow outstanding message handling to finish.

* Channel exceptions are now properly delivered in the streams API.

* A bug in SSHStream read() where it could sometimes return more data than
requested has been fixed. Also, read() has been changed to properly block
and return all data until EOF or a signal is received when it is called
with no length.

* A bug in the default implementation of keyboard-interactive authentication
has been fixed, and the matching of a password prompt has been loosened
to allow it to be used for password authentication on more devices.

* Missing code to resume reading after a stream is paused has been added.

* Improvements have been made in the handling of canceled requests.

* The test code has been updated to test Ed25519 and OpenSSH format
private keys.

* Examples have been updated to reflect some of the new capabilities.

0.9.2

---------------------------

* Fixed a bug in PyCrypto CipherFactory introduced during PyCA refactoring.

0.9.1

--------------------------

* Added some missing items in setup.py and MANIFEST.in.

* Fixed the install to work even when cryptographic dependencies aren't
yet installed.

* Fixed an issue where get_extra_info calls could fail if called when
a connection or session was shutting down.

0.9.0

---------------------------

* Added support to use PyCA (0.6.1 or later) for cryptography. AsyncSSH
will automatically detect and use either PyCA, PyCrypto, or both depending
on which is installed and which algorithms are requested.

* Added support for AES-GCM ciphers when PyCA is installed.

0.8.4

---------------------------

* Fixed an error in the encode/decode functions for PKCS1 DSA public keys.

* Fixed a bug in the unit test code for import/export of RFC4716 public keys.

0.8.3

---------------------------

* Added a missing import in the curve25519 implementation.

0.8.2

---------------------------

* Provided a better long description for PyPI.

* Added link to PyPI in documentation sidebar.

0.8.1

---------------------------

* Added a note in the :meth:`validate_public_key()
<SSHServer.validate_public_key>` documentation clarifying that AsyncSSH
will verify that the client possesses the corresponding private key before
authentication is allowed to succeed.

* Switched from setuptools to distutils and added an initial set of unit
tests.

* Prepared the package to be uploaded to PyPI.

0.8.0

---------------------------

* Added support for Curve25519 Diffie Hellman key exchange on systems with
the curve25519-donna Python package installed.

* Updated the examples to more clearly show what values are returned even
when not all of the return values are used.

0.7.0

--------------------------

* This release adds support for the "high-level" ``asyncio`` streams API,
in the form of the :class:`SSHReader` and :class:`SSHWriter` classes
and wrapper methods such as :meth:`open_session()
<SSHClientConnection.open_session>`, :meth:`open_connection()
<SSHClientConnection.open_connection>`, and :meth:`start_server()
<SSHClientConnection.start_server>`. It also allows the callback
methods on :class:`SSHServer` to return either SSH session objects or
handler functions that take :class:`SSHReader` and :class:`SSHWriter`
objects as arguments. See :meth:`session_requested()
<SSHServer.session_requested>`, :meth:`connection_requested()
<SSHServer.connection_requested>`, and :meth:`server_requested()
<SSHServer.server_requested>` for more information.

* Added new exceptions :exc:`BreakReceived`, :exc:`SignalReceived`, and
:exc:`TerminalSizeChanged` to report when these messages are received
while trying to read from an :class:`SSHServerChannel` using the new
streams API.

* Changed :meth:`create_server() <SSHClientConnection.create_server>` to
accept either a callable or a coroutine for its ``session_factory``
argument, to allow asynchronous operations to be used when deciding
whether to accept a forwarded TCP connection.

* Renamed ``accept_connection()`` to :meth:`create_connection()
<SSHServerConnection.create_connection>` in the :class:`SSHServerConnection`
class for consistency with :class:`SSHClientConnection`, and added a
corresponding :meth:`open_connection() <SSHServerConnection.open_connection>`
method as part of the streams API.

* Added :meth:`get_exit_status() <SSHClientChannel.get_exit_status>` and
:meth:`get_exit_signal() <SSHClientChannel.get_exit_signal>` methods
to the :class:`SSHClientChannel` class.

* Added :meth:`get_command() <SSHServerChannel.get_command>` and
:meth:`get_subsystem() <SSHServerChannel.get_subsystem>` methods to
the :class:`SSHServerChannel` class.

* Fixed the name of the :meth:`write_stderr() <SSHServerChannel.write_stderr>`
method and added the missing :meth:`writelines_stderr()
<SSHServerChannel.writelines_stderr>` method to the :class:`SSHServerChannel`
class for outputting data to the stderr channel.

* Added support for a return value in the :meth:`eof_received()
<SSHClientSession.eof_received>` of :class:`SSHClientSession`,
:class:`SSHServerSession`, and :class:`SSHTCPSession` to support
half-open channels. By default, the channel is automatically closed
after :meth:`eof_received() <SSHClientSession.eof_received>` returns,
but returning ``True`` will now keep the channel open, allowing output
to still be sent on the half-open channel. This is done automatically
when the new streams API is used.

* Added values ``'local_peername'`` and ``'remote_peername'`` to the set
of information available from the :meth:`get_extra_info()
<SSHTCPChannel.get_extra_info>` method in the :class:`SSHTCPChannel` class.

* Updated functions returning :exc:`IOError` or :exc:`socket.error` to
return the new :exc:`OSError` exception introduced in Python 3.3.

* Cleaned up some errors in the documentation.

* The :ref:`API`, :ref:`ClientExamples`, and :ref:`ServerExamples` have
all been updated to reflect these changes, and new examples showing the
streams API have been added.

0.6.0

---------------------------

* This release is a major revamp of the code to migrate from the
``asyncore`` framework to the new ``asyncio`` framework in Python
3.4. All the APIs have been adapted to fit the new ``asyncio``
paradigm, using coroutines wherever possible to avoid the need
for callbacks when performing asynchronous operations.

So far, this release only supports the "low-level" ``asyncio`` API.

* The :ref:`API`, :ref:`ClientExamples`, and :ref:`ServerExamples` have
all been updated to reflect these changes.

0.5.0

---------------------------

* Added the following new classes to support fully asynchronous
connection forwarding, replacing the methods previously added in

0.4.0

---------------------------

* Added support in :class:`SSHTCPConnection` for the following methods
to allow asynchronous operations to be used when accepting inbound
connection requests:

* :meth:`handle_open_request() <SSHTCPConnection.handle_open_request>`
* :meth:`report_open() <SSHTCPConnection.report_open>`
* :meth:`report_open_error() <SSHTCPConnection.report_open_error>`

These new methods are used to implement asynchronous connect
support for local and remote port forwarding, and to support
trying multiple destination addresses when connection failures
occur.

* Cleaned up a few minor documentation errors.

0.3.0

---------------------------

* Added support in :class:`SSHClient` and :class:`SSHServer` for setting
the key exchange, encryption, MAC, and compression algorithms allowed
in the SSH handshake.

* Refactored the algorithm selection code to pull a common matching
function back into ``_SSHConnection`` and simplify other modules.

* Extended the listener class to open multiple listening sockets when
necessary, fixing a bug where sockets opened to listen on ``localhost``
were not properly accepting both IPv4 and IPv6 connections.

Now, any listen request which resolves to multiple addresses will open
listening sockets for each address.

* Fixed a bug related to tracking of listeners opened on dynamic ports.

0.2.0

---------------------------

* Added support in :class:`SSHClient` for the following methods related
to performing standard SSH port forwarding:

* :meth:`forward_local_port() <SSHClient.forward_local_port>`
* :meth:`cancel_local_port_forwarding() <SSHClient.cancel_local_port_forwarding>`
* :meth:`forward_remote_port() <SSHClient.forward_remote_port>`
* :meth:`cancel_remote_port_forwarding() <SSHClient.cancel_remote_port_forwarding>`
* :meth:`handle_remote_port_forwarding() <SSHClient.handle_remote_port_forwarding>`
* :meth:`handle_remote_port_forwarding_error() <SSHClient.handle_remote_port_forwarding_error>`

* Added support in :class:`SSHServer` for new return values in
:meth:`handle_direct_connection() <SSHServer.handle_direct_connection>`
and :meth:`handle_listen() <SSHServer.handle_listen>` to activate
standard SSH server-side port forwarding.

* Added a client_addr argument and member variable to :class:`SSHServer`
to hold the client's address information.

* Added and updated examples related to port forwarding and using
:class:`SSHTCPConnection` to open direct and forwarded TCP
connections in :ref:`ClientExamples` and :ref:`ServerExamples`.

* Cleaned up some of the other documentation.

* Removed a debug print statement accidentally left in related to
SSH rekeying.

0.1.0

---------------------------

* Initial release