xymon ssh scan

[McGraw, Robert P]

Any ideas on how to solve the following problem.


hamilton is shown as ssh ok, status unchanged
for a week, but you can't ssh in:

% ssh -v hamilton
OpenSSH_4.3p2, OpenSSL 0.9.8e-fips-rhel5 01 Jul 2008
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Connecting to hamilton [128.210.3.42] port 22.
debug1: Connection established.
debug1: identity file /homes/jflack/.ssh/identity type -1
debug1: identity file /homes/jflack/.ssh/id_rsa type -1
debug1: identity file /homes/jflack/.ssh/id_dsa type -1
debug1: loaded 3 keys
debug1: Remote protocol version 1.99, remote software version OpenSSH_3.9p1
debug1: match: OpenSSH_3.9p1 pat OpenSSH_3.*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_4.3
debug1: SSH2_MSG_KEXINIT sent
Read from socket failed: Connection reset by peer

Apparently something goes wrong in the server just at the start
of key exchange. The xymon ssh test reports the remote protocol
and software versions, so it must converse at least that far, but
I guess it doesn't go on through the key exchange.

The ssh server going wrong that way seems to be a familiar failure
mode for our linux boxes, so it would be nice to have a test for it
in xymon. An ssh identity that's allowed to run some single very
restricted command would work. Actually ssh-keyscan does the trick
too, and doesn't require any logging in or permission on the host.
The only trick is ssh-keyscan exits with status 0 whether it
succeeded or not, so it would have to be used in a script that
actually parses its output to see if it worked.

Dustin's script that does ssh-keyscan for updating the keys list
could be a useful starting point.

_____________________________________________________________________
Robert P. McGraw, Jr.
Manager, Computer System                    EMAIL: rmcgraw at purdue.edu
Purdue University                            ROOM: MATH-807
Department of Mathematics                   PHONE: (765) 494-6055
150 N. University Street                      
West Lafayette, IN 47907-2067