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• Changes since OpenSSH 5.8

Changes since OpenSSH 5.8

Features:

• Introduce sandboxing of the pre-auth privsep child using an optional sshd_config(5) "UsePrivilegeSeparation=sandbox" mode that enables mandatory restrictions on the syscalls the privsep child can perform. This intention is to prevent a compromised privsep child from being used to attack other hosts (by opening sockets and proxying) or probing local kernel attack surface.

Three concrete sandbox implementation are provided (selected at
configure time): systrace, seatbelt and rlimit.

The systrace sandbox uses systrace(4) in unsupervised "fast-path"
mode, where a list of permitted syscalls is supplied. Any syscall not
on the list results in SIGKILL being sent to the privsep child. Note
that this requires a kernel with the new SYSTR_POLICY_KILL option
(only OpenBSD has this mode at present).

The seatbelt sandbox uses OS X/Darwin sandbox(7) facilities with a
strict (kSBXProfilePureComputation) policy that disables access to
filesystem and network resources.

The rlimit sandbox is a fallback choice for platforms that don't
support a better one; it uses setrlimit() to reset the hard-limit
of file descriptors and processes to zero, which should prevent
the privsep child from forking or opening new network connections.

Sandboxing of the privilege separated child process is currently
experimental but should become the default in a future release.
Native sandboxes for other platforms are welcome (e.g. Capsicum,
Linux pid/net namespaces, etc.)

• Add new SHA256-based HMAC transport integrity modes from
  http://www.ietf.org/id/draft-dbider-sha2-mac-for-ssh-02.txt
  These modes are hmac-sha2-256, hmac-sha2-256-96, hmac-sha2-512,
  and hmac-sha2-512-96, and are available by default in ssh(1) and
  sshd(8)

• The pre-authentication sshd(8) privilege separation slave process
  now logs via a socket shared with the master process, avoiding the
  need to maintain /dev/log inside the chroot.

• ssh(1) now warns when a server refuses X11 forwarding

• sshd_config(5)'s AuthorizedKeysFile now accepts multiple paths,
  separated by whitespace. The undocumented AuthorizedKeysFile2
  option is deprecated (though the default for AuthorizedKeysFile
  includes .ssh/authorized_keys2)

• sshd_config(5): similarly deprecate UserKnownHostsFile2 and
  GlobalKnownHostsFile2 by making UserKnownHostsFile and
  GlobalKnownHostsFile accept multiple options and default to
  include known_hosts2

• Retain key comments when loading v.2 keys. These will be visible
  in "ssh-add -l" and other places. bz#439

• ssh(1) and sshd(8): set IPv6 traffic class from IPQoS (as well as
  IPv4 ToS/DSCP). bz#1855

• ssh_config(5)'s ControlPath option now expands %L to the host
  portion of the destination host name.

• ssh_config(5) "Host" options now support negated Host matching, e.g.

  Host *.example.org !c.example.org
  User mekmitasdigoat

Will match "a.example.org", "b.example.org", but not "c.example.org"

• ssh_config(5): a new RequestTTY option provides control over when a
  TTY is requested for a connection, similar to the existing -t/-tt/-T
  ssh(1) commandline options.

• sshd(8): allow GSSAPI authentication to detect when a server-side
  failure causes authentication failure and don't count such failures
  against MaxAuthTries; bz#1244

• ssh-keygen(1): Add -A option. For each of the key types (rsa1, rsa,
  dsa and ecdsa) for which host keys do not exist, generate the host
  keys with the default key file path, an empty passphrase, default
  bits for the key type, and default comment. This is useful for
  system initialisation scripts.

• ssh(1): Allow graceful shutdown of multiplexing: request that a mux
  server removes its listener socket and refuse future multiplexing
  requests but don't kill existing connections. This may be requested
  using "ssh -O stop ..."

• ssh-add(1) now accepts keys piped from standard input. E.g.
  "ssh-add - < /path/to/key"

• ssh-keysign(8) now signs hostbased authentication
  challenges correctly using ECDSA keys; bz#1858

• sftp(1): document that sftp accepts square brackets to delimit
  addresses (useful for IPv6); bz#1847a

• ssh(1): when using session multiplexing, the master process will
  change its process title to reflect the control path in use and
  when a ControlPersist-ed master is waiting to close; bz#1883 and
  bz#1911

• Other minor bugs fixed: 1849 1861 1862 1869 1875 1878 1879 1892
  1900 1905 1913

Portable OpenSSH Bugfixes:

• Fix a compilation error in the SELinux support code. bz#1851

• This release removes support for ssh-rand-helper. OpenSSH now
  obtains its random numbers directly from OpenSSL or from
  a PRNGd/EGD instance specified at configure time.

• sshd(8) now resets the SELinux process execution context before
  executing passwd for password changes; bz#1891

• Since gcc >= 4.x ignores all -Wno-options options, test only the
  corresponding -W-option when trying to determine whether it is
  accepted; bz#1901

• Add ECDSA key generation to the Cygwin ssh-{host,user}-config
  scripts.

• Updated .spec and init files for Linux; bz#1920

• Improved SELinux error messages in context change failures and
  suppress error messages when attempting to change from the
  "unconfined_t" type; bz#1924 bz#1919

• Fix build errors on platforms without dlopen(); bz#1929

pertinent adj. Approprié : qui se rapporte exactement à ce dont il est question.