Call for testing: OpenSSH 6.8

[Damien Miller]

Hi,

OpenSSH 6.8 is almost ready for release, so we would appreciate testing
on as many platforms and systems as possible. This release contains
some substantial new features and a number of bugfixes.

Snapshot releases for portable OpenSSH are available from
http://www.mindrot.org/openssh_snap/

The OpenBSD version is available in CVS HEAD:
http://www.openbsd.org/anoncvs.html

Portable OpenSSH is also available via anonymous CVS using the
instructions at http://www.openssh.com/portable.html#cvs or
via Git at https://anongit.mindrot.org/openssh.git/

Running the regression tests supplied with Portable OpenSSH does not
require installation and is a simply:

$ ./configure && make tests

Live testing on suitable non-production systems is also
appreciated. Please send reports of success or failure to
openssh-unix-dev at mindrot.org.

Below is a summary of changes. More detail may be found in the ChangeLog
in the portable OpenSSH tarballs.

Thanks to the many people who contributed to this release.

Changes since OpenSSH 6.7
=========================

This is a major release, containing a number of new features as
well as a large internal re-factoring.

Potentially-incompatible changes
--------------------------------

 * sshd(8): UseDNS now defaults to 'no'. Configurations that match
   against the client host name (via sshd_config or authorized_keys)
   may need to re-enable it or convert to matching against addresses.

New Features
------------

 * Much of OpenSSH's internal code has been re-factored to be more
   library-like. These changes are mostly not user-visible, but
   have greatly improved OpenSSH's testability and internal layout.

 * Add FingerprintHash option to ssh(1) and sshd(8), and equivalent
   command-line flags to the other tools to control algorithm used
   for key fingerprints. The default changes from MD5 to SHA256 and
   format from hex to base64.

   Fingerprints now have the hash algorithm prepended. An example of
   the new format: SHA256:mVPwvezndPv/ARoIadVY98vAC0g+P/5633yTC4d/wXE
   Please note that visual host keys will also be different.

 * ssh(1), sshd(8): 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 on).

 * 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.

Bugfixes
--------

 * 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 fixed 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 system 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.

   Still experimental - not all regression and unit tests have been
   been adapted for the absence of 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.

Reporting Bugs:
===============

- Please read http://www.openssh.com/report.html
  Security bugs should be reported directly to openssh at openssh.com

OpenSSH is brought to you by Markus Friedl, Niels Provos, Theo de Raadt,
Kevin Steves, Damien Miller, Darren Tucker, Jason McIntyre, Tim Rice and
Ben Lindstrom.