sshd stops accepting connections

[Simon L. Nielsen]

Hello

Today I suddenly couldn't log in via ssh to a server I upgraded to
FreeBSD 5.3-RELEASE 4 days ago.  When I tried connect to port 22 using
telnet(1) the following just happend:

[simon at zaphod:~] telnet 192.168.3.2 22
Trying 192.168.3.2...
Connected to jet.nitro.dk.
Escape character is '^]'.
Connection closed by foreign host.

The servar had been running FreeBSD 5.2.1 for a while without
problems.  After logging in on the console and sending the sshd master
process a -HUP I could log in again (and I get the normal banner when
connecting to the port with telnet(1)).  I can't rally see in the log
what happened, but there is a lot of "stale" sshd's hanging around,
like:

root    46015  0,0  0,4  4928 2220  ??  I    Ons08pm   0:00,01 sshd: blah [pam] (sshd)
root    58286  0,0  0,4  4920 2236  ??  Is   Tor12pm   0:00,04 sshd: pascal [priv] (sshd)
sshd    58287  0,0  0,0     0    0  ??  Z    Tor12pm   0:00,03 <defunct>
root    58288  0,0  0,4  4928 2236  ??  I    Tor12pm   0:00,01 sshd: pascal [pam] (sshd)
root    58932  0,0  0,4  4920 2236  ??  Is   Tor01pm   0:00,05 sshd: ole_gudiksen [priv] (sshd)
sshd    58934  0,0  0,0     0    0  ??  Z    Tor01pm   0:00,06 <defunct>
root    58935  0,0  0,4  4928 2236  ??  I    Tor01pm   0:00,01 sshd: ole_gudiksen [pam] (sshd)

pstree show the connection between some of the processes like this:

 | |-+= 58286 root sshd: pascal [priv] (sshd)
 | | |--- 58287 sshd <defunct>
 | | \--- 58288 root sshd: pascal [pam] (sshd)

From all.log:

Nov 11 12:04:38 nfishbone sshd[58286]: fatal: Timeout before authentication for 82.211.207.191
Nov 11 13:02:34 nfishbone sshd[58932]: fatal: Timeout before authentication for 192.38.66.33

The only odd thing I could find in the logs with regard to ssh was a
few lines like:

Nov 11 22:35:49 nfishbone sshd[62378]: syslogin_perform_logout: logout() returned an error

I don't use any kind of "exotic" authentication on the system, only
standard unix password file and ssh-keys.

Does anybody have an idea of what's going on here, and if it's a ssh
bug or something silly I have done?

-- 
Simon L. Nielsen
FreeBSD Documentation Team
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