OpenSSH 6.8 发布，内部代码重构

OpenSSH 6.8 发布，此版本镜像很快提供在 http://www.openssh.com/。此版本是个重要版本，包括新特性和大量内部重构。

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。

OpenSSH 是 100% 的完整 SSH 协议版本 1.3, 1.5 和 2.0
实现，包括 sftp 客户端和服务器支持。

相比 OpenSSH 6.7 的更新内容
=========================

潜在不兼容改进
--------------------------------

 * sshd(8): UseDNS 默认为 'no'

新特性
------------

 * 大部分 OpenSSH 的内部代码被重构，现在更像库。

 * 添加 FingerprintHash 选项到 ssh(1) 和 sshd(8)；添加 equivalent
   命令行标记到其他工具来控制密钥指纹算法。

 * ssh(1), sshd(8): Experimental host key rotation support. Add a
   protocol extension for a server to inform a client of all its
   available host keys after authentication has completed. The client
   may record the keys in known_hosts, allowing it to upgrade to better
   host key algorithms and a server to gracefully rotate its keys.

   The client side of this is controlled by a UpdateHostkeys config
   option (default off).

 * ssh(1): Add a ssh_config HostbasedKeyType option to control which
   host public key types are tried during host-based authentication.

 * ssh(1), sshd(8): fix connection-killing host key mismatch errors
   when sshd offers multiple ECDSA keys of different lengths.

 * ssh(1): when host name canonicalisation is enabled, try to
   parse host names as addresses before looking them up for
   canonicalisation. fixes bz#2074 and avoiding needless DNS
   lookups in some cases.

 * ssh-keygen(1), sshd(8): Key Revocation Lists (KRLs) no longer
   require OpenSSH to be compiled with OpenSSL support.

 * ssh(1), ssh-keysign(8): Make ed25519 keys work for host based
   authentication.

 * sshd(8): SSH protocol v.1 workaround for the Meyer, et al,
   Bleichenbacher Side Channel Attack. Fake up a bignum key before
   RSA decryption.

 * sshd(8): Remember which public keys have been used for
   authentication and refuse to accept previously-used keys.
   This allows AuthenticationMethods=publickey,publickey to require
   that users authenticate using two _different_ public keys.

 * sshd(8): add sshd_config HostbasedAcceptedKeyTypes and
   PubkeyAcceptedKeyTypes options to allow sshd to control what
   public key types will be accepted. Currently defaults to all.

 * sshd(8): Don't count partial authentication success as a failure
   against MaxAuthTries.

 * ssh(1): Add RevokedHostKeys option for the client to allow
   text-file or KRL-based revocation of host keys.

 * ssh-keygen(1), sshd(8): Permit KRLs that revoke certificates by
   serial number or key ID without scoping to a particular CA.

 * ssh(1): Add a "Match canonical" criteria that allows ssh_config
   Match blocks to trigger only in the second config pass.

 * ssh(1): Add a -G option to ssh that causes it to parse its
   configuration and dump the result to stdout, similar to "sshd -T".

 * ssh(1): Allow Match criteria to be negated. E.g. "Match !host".

 * The regression test suite has been extended to cover more OpenSSH
   features. The unit tests have been expanded and now cover key
   exchange.

BUG 修复

 * ssh-keyscan(1): ssh-keyscan has been made much more robust again
   servers that hang or violate the SSH protocol.

 * ssh(1), ssh-keygen(1): Fix regression bz#2306: Key path names were
   being lost as comment fields.

 * ssh(1): Allow ssh_config Port options set in the second config
   parse phase to be applied (they were being ignored). bz#2286

 * ssh(1): Tweak config re-parsing with host canonicalisation - make
   the second pass through the config files always run when host name
   canonicalisation is enabled (and not whenever the host name
   changes) bz#2267

 * ssh(1): Fix passing of wildcard forward bind addresses when
   connection multiplexing is in use; bz#2324;

 * ssh-keygen(1): Fix broken private key conversion from non-OpenSSH
   formats; bz#2345.

 * ssh-keygen(1): Fix KRL generation bug when multiple CAs are in
   use.

 * Various fixes to manual pages: bz#2288, bz#2316, bz#2273

Portable OpenSSH

 * Support --without-openssl at configure time

   Disables and removes dependency on OpenSSL. Many features,
   including SSH protocol 1 are not supported and the set of crypto
   options is greatly restricted. This will only work on systems
   with native arc4random or /dev/urandom.

   Considered highly experimental for now.

 * Support --without-ssh1 option at configure time

   Allows disabling support for SSH protocol 1.

 * sshd(8): Fix compilation on systems with IPv6 support in utmpx; bz#2296

 * Allow custom service name for sshd on Cygwin. Permits the use of
   multiple sshd running with different service names.