misc/163843: Modified VersionAddendum field in sshd_config missing from SSH protocol string

S. Chen sp1024 at gmail.com
Thu Jan 5 23:00:30 UTC 2012


>Number:         163843
>Category:       misc
>Synopsis:       Modified VersionAddendum field in sshd_config missing from SSH protocol string
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Jan 05 23:00:29 UTC 2012
>Closed-Date:
>Last-Modified:
>Originator:     S. Chen
>Release:        9.0-RC3
>Organization:
>Environment:
FreeBSD host.domain.local 9.0-RC3 FreeBSD 9.0-RC3 #0: Sun Dec  4 08:56:36 UTC 2011     root at farrell.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  amd64

>Description:
In the SSH daemon's configuration file, sshd_config, a variable named "VersionAddendum" can be used to modify the additional version information appended to a typical SSH protocol version string.  However, when the variable is set, the value does not appear and yields a slightly malformed SSH protocol version string.

The full, default version string looks like the following.  Stock config used.

> echo | nc 127.0.0.1 22
SSH-2.0-OpenSSH_5.8p2_hpn13v11 FreeBSD-20110503


The version string when config is set to "VersionAddendum abc", follows.  Note the space between the SSH version and "_hpn13v11", and it's missing "abc".

> diff -u sshd_config.old sshd_config
-#VersionAddendum FreeBSD-20110503
+VersionAddendum abc

> echo | nc 127.0.0.1 22
SSH-2.0-OpenSSH_5.8p2 _hpn13v11

>How-To-Repeat:
1) Modify /etc/ssh/sshd_config, and change the "VersionAddendum" variable to something else (e.g. "abc").
2) Restart sshd (e.g. /etc/rc.d/sshd restart).
3) Retrieve the SSH version string from port 22 (e.g. "echo | nc 127.0.0.1 22).  Check for missing variable set in step 1.

>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted:


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