Monitoring SSH tunnel

[mindas]

Hi,

I am trying to set up a monitor of SSH tunnel I have created. Basically the remote end of this tunnel has an endless loop with

echo "pong" | nc -l 13307

whereas I do "nc localhost 13307" on the other end of the tunnel to see if the tunnel is still functioning. This all works, but I want to hook this to Zabbix.

So I have following in my zabbix_agentd.conf on the monitored machine:

...
UserParameter=tunping,nc 127.0.0.1 13307
UserParameter=ping,echo 1
...

If I run "nc 127.0.0.1 13307" on the monitored machine, I get "pong".
But if I do the same from Zabbix server, I get the following:

user@zabbix:$ zabbix_get -s monitored_machine -k tunping
ZBX_NOTSUPPORTED
user@zabbix:$ zabbix_get -s monitored_machine -k ping
1

Is there any reason why tunping fails bug ping works? I am using 1.8.1 version of Zabbix, as it comes by default with Ubuntu lucid.

Excerpt from /var/log/zabbix-agent/zabbix_agentd.log:
22268:20101229:235836.631 Processing request.
22268:20101229:235836.632 Requested [tunping]
22268:20101229:235836.635 Before
22268:20101229:235836.635 Sending back [ZBX_NOTSUPPORTED]

Is there any other way to ask zabbix agent to telnet to a port on localhost and retrieve whatever comes back?

[dima_dm]

Is there any other way to ask zabbix agent to telnet to a port on localhost and retrieve whatever comes back?

Write script that return single line as output.
Example:
Write Perl script with module Net::Telnet

[mindas]

Write script that return single line as output.
Example:
Write Perl script with module Net::Telnet

The thing is, I already have a custom script that does what I need (using netcat), but for some strange reason Zabbix does not pick it up. So I don't really mind how this problem is solved - either with getting it to work using custom script, or using some standard Zabbix functionality, I just want to get things done!

[dima_dm]

Run script from zabbix user
nc 127.0.0.1 13307
and show output of a script

[mindas]

Ghm...

root@zabbix #: nc localhost 13307
pong
root@zabbix:# su -c "nc localhost 13307" zabbix
root@zabbix:#

Researching further I found that zabbix user has shell set to /bin/false (it comes like this as a default in Ubuntu). Changing it to /bin/bash fixed the issue locally (su -c ... command works now), but remote zabbix_get still returns ZBX_NOTSUPPORTED. Zabbix agent logs do not contain any more information than before.

Огpомное спасибо Dima for your help.

[dima_dm]

May by problem in SELinux policy?
Use
sudo -u zabbix nc localhost 13307
for testing purpose

[mindas]

Both this and su'ing to zabbix user and executing the command by hand works, it's just Zabbix agent that is not picking it up. I will investigate further to see if there is anything else I can think of. Thanks again.

[dima_dm]

Do you restart zabbix_agentd then you change zabbix_agentd.conf file?
restart zabbix_agentd and try again.

[mindas]

Yes I did - I restarted the daemon after every change (should have mentioned this, sorry!)

[dima_dm]

Yes I did - I restarted the daemon after every change (should have mentioned this, sorry!)

Write full path for nc script
UserParameter=tunping,/path/nc 127.0.0.1 13307

[mindas]

Tried that as well - same result

[dima_dm]

Tried that as well - same result

You can add debug code in script ns, and log in file /tmp/ns.debug each action in script.
You can use Telnet checks from zabbix server
http://www.zabbix.com/documentation/...l/config/items -> 19.11. Telnet checks

[mindas]

I have solved this differently by apt-get installing netpipes.

For some strange reason

UserParameter=tunping,/bin/nc 127.0.0.1 13307

doesn't work from Zabbix, but the following does:

UserParameter=tunping2,/usr/bin/hose 127.0.0.1 13307 --in cat

Must be something to do with combination of Zabbix/Netcat.
Hopefully this will be useful for somebody.

Thanks again Дима for your help!