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Announce: OpenSSH 4.2 released

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Damien Miller

Sep 1, 2005, 10:58:57 AM9/1/05
OpenSSH 4.2 has just been released. It will be available from the
mirrors listed at shortly.

OpenSSH is a 100% complete SSH protocol version 1.3, 1.5 and 2.0
implementation and includes sftp client and server support.

We would like to thank the OpenSSH community for their continued
support of the project, especially those who contributed source,
reported bugs, tested snapshots and purchased T-shirts or posters.

T-shirt, poster and CD sales directly support the project. Pictures
and more information can be found at: and

For international orders use
and for European orders, use

Changes since OpenSSH 4.1:

- SECURITY: Fix a bug introduced in OpenSSH 4.0 that caused
GatewayPorts to be incorrectly activated for dynamic ("-D") port
forwardings when no listen address was explicitly specified.

- SECURITY: sshd in OpenSSH versions prior to 4.2 allow GSSAPI
credentials to be delegated to users who log in with methods
other than GSSAPI authentication (e.g. public key) when the
client requests it. This behaviour has been changed in OpenSSH
4.2 to only delegate credentials to users who authenticate
using the GSSAPI method. This eliminates the risk of credentials
being inadvertently exposed to an untrusted user/host (though
users should not activate GSSAPIDelegateCredentials to begin
with when the remote user or host is untrusted)

- Added a new compression method that delays the start of zlib
compression until the user has been authenticated successfully.
The new method ("Compression delayed") is on by default in the
server. This eliminates the risk of any zlib vulnerability
leading to a compromise of the server from unauthenticated users.

NB. Older OpenSSH (<3.5) versions have a bug that will cause them
to refuse to connect to any server that does not offer compression
when the client has compression requested. Since the new "delayed"
server mode isn't supported by these older clients, they will
refuse to connect to a new server unless compression is disabled
(on the client end) or the original compression method is enabled
on the server ("Compression yes" in sshd_config)

- Another round of proactive changes for signed vs unsigned integer
bugs has been completed, including changing the atomicio() API to
encourage safer programming. This work is ongoing.

- Added support for the improved arcfour cipher modes from
draft-harris-ssh-arcfour-fixes-02. The improves the cipher's
resistance to a number of attacks by discarding early keystream

- Increase the default size of new RSA/DSA keys generated by
ssh-keygen from 1024 to 2048 bits.

- Many bugfixes and improvements to connection multiplexing,

- Added ControlMaster=auto/autoask options to support opportunistic
multiplexing (see the ssh_config(5) manpage for details).

- The client will now gracefully fallback to starting a new TCP
connection if it cannot connect to a specified multiplexing
control socket

- Added %h (target hostname), %p (target port) and %r (remote
username) expansion sequences to ControlPath. Also allow
ControlPath=none to disable connection multiplexing.

- Implemented support for X11 and agent forwarding over multiplexed
connections. Because of protocol limitations, the slave
connections inherit the master's DISPLAY and SSH_AUTH_SOCK rather
than distinctly forwarding their own.

- Portable OpenSSH: Added support for long passwords (> 8-char) on
UnixWare 7.

- The following bugs from were closed:

#471 - Misleading error message if /dev/tty perms wrong
#623 - Don't use $HOME in manpages
#829 - Don't allocate a tty if -n option is set
#1025 - Correctly handle disabled special character in ttymodes
#1033 - Fix compile-time warnings
#1046 - AIX 5.3 Garbage on Login
#1054 - Don't terminate connection on getpeername() failure
#1076 - GSSAPIDelegateCredentials issue mentioned above

- Lots of other improvements and fixes. Please refer to the ChangeLog
for details

Thanks to everyone who has contributed patches, problem or test reports.


- SHA1 (openssh-4.2.tar.gz) = d2bd777986a30e446268ceeb24cddbf2edf51b21
- SHA1 (openssh-4.2p1.tar.gz) = 5e7231cfa8ec673ea856ce291b78fac8b380eb78

Reporting Bugs:

- please read

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

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