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。
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 email@example.com and firstname.lastname@example.org. 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 "email@example.com" and "firstname.lastname@example.org". 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.