OpenSSH（Open Secure Shell）是使用SSH透过计算机网络加密通讯的实现。它是取代由SSH Communications Security所提供的商用版本的开放源代码方案。目前OpenSSH是OpenBSD的子计划。

2013-03-22发布6.2正式版。上一个版本是2012-08-29的6.1 此版本增加了AES-GCM认证加密支持，encrypt-then-mac (EtM) MAC模式支持，总算支持了多种加密方式支持（如Key+口令），支持了Key Revocation Lists(KRLs)等及Bug改进。

完全改进：

Changes since OpenSSH 6.1
=========================

This release introduces a number of new features:

Features:

 * ssh(1)/sshd(8): Added support for AES-GCM authenticated encryption in
   SSH protocol 2. The new cipher is available as aes128-gcm@openssh.com
   and aes256-gcm@openssh.com. It uses an identical packet format to the
   AES-GCM mode specified in RFC 5647, but uses simpler and different
   selection rules during key exchange.

 * ssh(1)/sshd(8): Added support for encrypt-then-mac (EtM) MAC modes
   for SSH protocol 2. These modes alter the packet format and compute
   the MAC over the packet length and encrypted packet rather than over
   the plaintext data. These modes are considered more secure and are
   used by default when available.

 * ssh(1)/sshd(8): Added support for the UMAC-128 MAC as
   "umac-128@openssh.com" and "umac-128-etm@openssh.com". The latter
   being an encrypt-then-mac mode.

 * sshd(8): Added support for multiple required authentication in SSH
   protocol 2 via an AuthenticationMethods option. This option lists
   one or more comma-separated lists of authentication method names.
   Successful completion of all the methods in any list is required for
   authentication to complete. This allows, for example, requiring a
   user having to authenticate via public key or GSSAPI before they
   are offered password authentication.

 * sshd(8)/ssh-keygen(1): Added support for Key Revocation Lists
   (KRLs), a compact binary format to represent lists of revoked keys
   and certificates that take as little as one bit per certificate when
   revoking by serial number. KRLs may be generated using ssh-keygen(1)
   and are loaded into sshd(8) via the existing RevokedKeys sshd_config
   option.

 * ssh(1): IdentitiesOnly now applies to keys obtained from a
   PKCS11Provider. This allows control of which keys are offered from
   tokens using IdentityFile.

 * sshd(8): sshd_config(5)'s AllowTcpForwarding now accepts "local"
   and "remote" in addition to its previous "yes"/"no" keywords to allow
   the server to specify whether just local or remote TCP forwarding is
   enabled.

 * sshd(8): Added a sshd_config(5) option AuthorizedKeysCommand to
   support fetching authorized_keys from a command in addition to (or
   instead of) from the filesystem. The command is run under an account
   specified by an AuthorizedKeysCommandUser sshd_config(5) option.

 * sftp-server(8): Now supports a -d option to allow the starting
   directory to be something other than the user's home directory.

 * ssh-keygen(1): Now allows fingerprinting of keys hosted in PKCS#11
   tokens using "ssh-keygen -lD pkcs11_provider".

 * ssh(1): When SSH protocol 2 only is selected (the default), ssh(1)
   now immediately sends its SSH protocol banner to the server without
   waiting to receive the server's banner, saving time when connecting.

 * ssh(1): Added ~v and ~V escape sequences to raise and lower the
   logging level respectively.

 * ssh(1): Made the escape command help (~?) context sensitive so that
   only commands that will work in the current session are shown.

 * ssh-keygen(1): When deleting host lines from known_hosts using
   "ssh-keygen -R host", ssh-keygen(1) now prints details of which lines
   were removed.
    
Bugfixes:

 * ssh(1): Force a clean shutdown of ControlMaster client sessions when
   the ~. escape sequence is used. This means that ~. should now work in
   mux clients even if the server is no longer responding.

 * ssh(1): Correctly detect errors during local TCP forward setup in
   multiplexed clients. bz#2055

 * ssh-add(1): Made deleting explicit keys "ssh-add -d" symmetric with
   adding keys with respect to certificates. It now tries to delete the
   corresponding certificate and respects the -k option to allow deleting
   of the key only.

 * sftp(1): Fix a number of parsing and command-editing bugs, including
   bz#1956

 * ssh(1): When muxmaster is run with -N, ensured that it shuts down
   gracefully when a client sends it "-O stop" rather than hanging around.
   bz#1985

 * ssh-keygen(1): When screening moduli candidates, append to the file
   rather than overwriting to allow resumption. bz#1957

 * ssh(1): Record "Received disconnect" messages at ERROR rather than
   INFO priority. bz#2057.

 * ssh(1): Loudly warn if explicitly-provided private key is unreadable.
   bz#1981

Portable OpenSSH:

 * sshd(8): The Linux seccomp-filter sandbox is now supported on ARM
   platforms where the kernel supports it.

 * sshd(8): The seccomp-filter sandbox will not be enabled if the system
   headers support it at compile time, regardless of whether it can be
   enabled then. If the run-time system does not support seccomp-filter,
   sshd will fall back to the rlimit pseudo-sandbox.

 * ssh(1): Don't link in the Kerberos libraries. They aren't necessary
   on the client, just on sshd(8). bz#2072

 * Fix GSSAPI linking on Solaris, which uses a differently-named GSSAPI
   library. bz#2073

 * Fix compilation on systems with openssl-1.0.0-fips.

 * Fix a number of errors in the RPM spec files.

下载：ftp://ftp.openbsd.com/pub/OpenBSD/OpenSSH/portable/openssh-6.2p1.tar.gz