* New upstream release (closes: #474301). Important changes not previously

  backported to 4.7p1:
  - 4.9/4.9p1 (http://www.openssh.com/txt/release-4.9):
    + Added chroot(2) support for sshd(8), controlled by a new option
      "ChrootDirectory" (closes: #139047, LP: #24777).
    + Linked sftp-server(8) into sshd(8). The internal sftp server is used
      when the command "internal-sftp" is specified in a Subsystem or
      ForceCommand declaration. When used with ChrootDirectory, the
      internal sftp server requires no special configuration of files
      inside the chroot environment.
    + Added a protocol extension method "posix-rename@openssh.com" for
      sftp-server(8) to perform POSIX atomic rename() operations; sftp(1)
      prefers this if available (closes: #308561).
    + Removed the fixed limit of 100 file handles in sftp-server(8).
    + ssh(8) will now skip generation of SSH protocol 1 ephemeral server
      keys when in inetd mode and protocol 2 connections are negotiated.
      This speeds up protocol 2 connections to inetd-mode servers that
      also allow Protocol 1.
    + Accept the PermitRootLogin directive in a sshd_config(5) Match
      block. Allows for, e.g. permitting root only from the local network.
    + Reworked sftp(1) argument splitting and escaping to be more
      internally consistent (i.e. between sftp commands) and more
      consistent with sh(1). Please note that this will change the
      interpretation of some quoted strings, especially those with
      embedded backslash escape sequences.
    + Support "Banner=none" in sshd_config(5) to disable sending of a
      pre-login banner (e.g. in a Match block).
    + ssh(1) ProxyCommands are now executed with $SHELL rather than
      /bin/sh.
    + ssh(1)'s ConnectTimeout option is now applied to both the TCP
      connection and the SSH banner exchange (previously it just covered
      the TCP connection). This allows callers of ssh(1) to better detect
      and deal with stuck servers that accept a TCP connection but don't
      progress the protocol, and also makes ConnectTimeout useful for
      connections via a ProxyCommand.
    + scp(1) incorrectly reported "stalled" on slow copies (closes:
      #140828).
    + scp(1) date underflow for timestamps before epoch.
    + ssh(1) used the obsolete SIG DNS RRtype for host keys in DNS,
      instead of the current standard RRSIG.
    + Correctly drain ACKs when a sftp(1) upload write fails midway,
      avoids a fatal() exit from what should be a recoverable condition.
    + Fixed ssh-keygen(1) selective host key hashing (i.e. "ssh-keygen -HF
      hostname") to not include any IP address in the data to be hashed.
    + Make ssh(1) skip listening on the IPv6 wildcard address when a
      binding address of 0.0.0.0 is used against an old SSH server that
      does not support the RFC4254 syntax for wildcard bind addresses.
    + Enable IPV6_V6ONLY socket option on sshd(8) listen socket, as is
      already done for X11/TCP forwarding sockets (closes: #439661).
    + Fix FD leak that could hang a ssh(1) connection multiplexing master.
    + Make ssh(1) -q option documentation consistent with reality.
    + Fixed sshd(8) PAM support not calling pam_session_close(), or
      failing to call it with root privileges (closes: #372680).
    + Fix activation of OpenSSL engine support when requested in configure
      (LP: #119295).
  - 5.1/5.1p1 (http://www.openssh.com/txt/release-5.1):
    + Introduce experimental SSH Fingerprint ASCII Visualisation to ssh(1)
      and ssh-keygen(1). Visual fingerprint display is controlled by a new
      ssh_config(5) option "VisualHostKey". The intent is to render SSH
      host keys in a visual form that is amenable to easy recall and
      rejection of changed host keys.
    + sshd_config(5) now supports CIDR address/masklen matching in "Match
      address" blocks, with a fallback to classic wildcard matching.
    + sshd(8) now supports CIDR matching in ~/.ssh/authorized_keys
      from="..." restrictions, also with a fallback to classic wildcard
      matching.
    + Added an extended test mode (-T) to sshd(8) to request that it write
      its effective configuration to stdout and exit. Extended test mode
      also supports the specification of connection parameters (username,
      source address and hostname) to test the application of
      sshd_config(5) Match rules.
    + ssh(1) now prints the number of bytes transferred and the overall
      connection throughput for SSH protocol 2 sessions when in verbose
      mode (previously these statistics were displayed for protocol 1
      connections only).
    + sftp-server(8) now supports extension methods statvfs@openssh.com
      and fstatvfs@openssh.com that implement statvfs(2)-like operations.
    + sftp(1) now has a "df" command to the sftp client that uses the
      statvfs@openssh.com to produce a df(1)-like display of filesystem
      space and inode utilisation (requires statvfs@openssh.com support on
      the server).
    + Added a MaxSessions option to sshd_config(5) to allow control of the
      number of multiplexed sessions supported over a single TCP
      connection. This allows increasing the number of allowed sessions
      above the previous default of 10, disabling connection multiplexing
      (MaxSessions=1) or disallowing login/shell/subsystem sessions
      entirely (MaxSessions=0).
    + Added a no-more-sessions@openssh.com global request extension that
      is sent from ssh(1) to sshd(8) when the client knows that it will
      never request another session (i.e. when session multiplexing is
      disabled). This allows a server to disallow further session requests
      and terminate the session in cases where the client has been
      hijacked.
    + ssh-keygen(1) now supports the use of the -l option in combination
      with -F to search for a host in ~/.ssh/known_hosts and display its
      fingerprint.
    + ssh-keyscan(1) now defaults to "rsa" (protocol 2) keys, instead of
      "rsa1".
    + Added an AllowAgentForwarding option to sshd_config(8) to control
      whether authentication agent forwarding is permitted. Note that this
      is a loose control, as a client may install their own unofficial
      forwarder.
    + ssh(1) and sshd(8): avoid unnecessary malloc/copy/free when
      receiving network data, resulting in a ~10% speedup.
    + ssh(1) and sshd(8) will now try additional addresses when connecting
      to a port forward destination whose DNS name resolves to more than
      one address. The previous behaviour was to try the only first
      address and give up if that failed.
    + ssh(1) and sshd(8) now support signalling that channels are
      half-closed for writing, through a channel protocol extension
      notification "eow@openssh.com". This allows propagation of closed
      file descriptors, so that commands such as "ssh -2 localhost od
      /bin/ls | true" do not send unnecessary data over the wire.
    + sshd(8): increased the default size of ssh protocol 1 ephemeral keys
      from 768 to 1024 bits.
    + When ssh(1) has been requested to fork after authentication ("ssh
      -f") with ExitOnForwardFailure enabled, delay the fork until after
      replies for any -R forwards have been seen. Allows for robust
      detection of -R forward failure when using -f.
    + "Match group" blocks in sshd_config(5) now support negation of
      groups. E.g. "Match group staff,!guests".
    + sftp(1) and sftp-server(8) now allow chmod-like operations to set
      set[ug]id/sticky bits.
    + The MaxAuthTries option is now permitted in sshd_config(5) match
      blocks.
    + Multiplexed ssh(1) sessions now support a subset of the ~ escapes
      that are available to a primary connection.
    + ssh(1) connection multiplexing will now fall back to creating a new
      connection in most error cases (closes: #352830).
    + Make ssh(1) deal more gracefully with channel requests that fail.
      Previously it would optimistically assume that requests would always
      succeed, which could cause hangs if they did not (e.g. when the
      server runs out of file descriptors).
    + ssh(1) now reports multiplexing errors via the multiplex slave's
      stderr where possible (subject to LogLevel in the mux master).
    + Prevent sshd(8) from erroneously applying public key restrictions
      leaned from ~/.ssh/authorized_keys to other authentication methods
      when public key authentication subsequently fails (LP: #161047).
    + Fixed an UMAC alignment problem that manifested on Itanium
      platforms.

1 files changed, 52 insertions, 6 deletions

diff --git a/ssh.1 b/ssh.1
index 8b5c46c74..1229201da 100644
--- a/ssh.1
+++ b/ssh.1
@@ -34,8 +34,8 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.\" $OpenBSD: ssh.1,v 1.270 2007/06/12 13:43:55 jmc Exp $
-.Dd $Mdocdate: June 12 2007 $
+.\" $OpenBSD: ssh.1,v 1.277 2008/07/02 13:47:39 djm Exp $
+.Dd $Mdocdate: July 2 2008 $
 .Dt SSH 1
 .Os
 .Sh NAME
@@ -290,6 +290,15 @@ This implies
 The recommended way to start X11 programs at a remote site is with
 something like
 .Ic ssh -f host xterm .
+.Pp
+If the
+.Cm ExitOnForwardFailure
+configuration option is set to
+.Dq yes ,
+then a client started with
+.Fl f
+will wait for all remote port forwards to be successfully established
+before placing itself in the background.
 .It Fl g
 Allows remote hosts to connect to local forwarded ports.
 .It Fl I Ar smartcard_device
@@ -498,6 +507,7 @@ For full details of the options listed below, and their possible values, see
 .It User
 .It UserKnownHostsFile
 .It VerifyHostKeyDNS
+.It VisualHostKey
 .It XAuthLocation
 .El
 .It Fl p Ar port
@@ -506,7 +516,7 @@ This can be specified on a
 per-host basis in the configuration file.
 .It Fl q
 Quiet mode.
-Causes all warning and diagnostic messages to be suppressed.
+Causes most warning and diagnostic messages to be suppressed.
 Only fatal errors are displayed.
 If a second
 .Fl q
@@ -1035,9 +1045,31 @@ Fingerprints can be determined using
 .Pp
 .Dl $ ssh-keygen -l -f /etc/ssh/ssh_host_rsa_key
 .Pp
-If the fingerprint is already known,
-it can be matched and verified,
-and the key can be accepted.
+If the fingerprint is already known, it can be matched
+and the key can be accepted or rejected.
+Because of the difficulty of comparing host keys
+just by looking at hex strings,
+there is also support to compare host keys visually,
+using
+.Em random art .
+By setting the
+.Cm VisualHostKey
+option to
+.Dq yes ,
+a small ASCII graphic gets displayed on every login to a server, no matter
+if the session itself is interactive or not.
+By learning the pattern a known server produces, a user can easily
+find out that the host key has changed when a completely different pattern
+is displayed.
+Because these patterns are not unambiguous however, a pattern that looks
+similar to the pattern remembered only gives a good probability that the
+host key is the same, not guaranteed proof.
+.Pp
+To get a listing of the fingerprints along with their random art for
+all known hosts, the following command line can be used:
+.Pp
+.Dl $ ssh-keygen -lv -f ~/.ssh/known_hosts
+.Pp
 If the fingerprint is unknown,
 an alternative method of verification is available:
 SSH fingerprints verified by DNS.
@@ -1253,6 +1285,13 @@ This file is used in exactly the same way as
 but allows host-based authentication without permitting login with
 rlogin/rsh.
 .Pp
+.It ~/.ssh/
+This directory is the default location for all user-specific configuration
+and authentication information.
+There is no general requirement to keep the entire contents of this directory
+secret, but the recommended permissions are read/write/execute for the user,
+and not accessible by others.
+.Pp
 .It ~/.ssh/authorized_keys
 Lists the public keys (RSA/DSA) that can be used for logging in as this user.
 The format of this file is described in the
@@ -1438,6 +1477,13 @@ manual page for more information.
 .%T "The Secure Shell (SSH) Public Key File Format"
 .%D 2006
 .Re
+.Rs
+.%T "Hash Visualization: a New Technique to improve Real-World Security"
+.%A A. Perrig
+.%A D. Song
+.%D 1999
+.%O "International Workshop on Cryptographic Techniques and E-Commerce (CrypTEC '99)"
+.Re
 .Sh AUTHORS
 OpenSSH is a derivative of the original and free
 ssh 1.2.12 release by Tatu Ylonen.