I recently upgraded a jail server from FreeBSD 8.2 to 8.4, and part of that process involved recompiling all of the applications. Along the way, nrpe on one jail stopped working. Nagios was reporting:
CHECK_NRPE: Socket timeout after 10 seconds.
Trying from the command line gave:
$ /usr/local/libexec/nagios/check_nrpe2 -H -H dbclone.example.org -c check_pgsql -t 1 CHECK_NRPE: Socket timeout after 1 seconds.
Other jails worked just fine:
$ /usr/local/libexec/nagios/check_nrpe2 -H building.unixathome.org -c check_pgsql -t 1 OK - database template1 (0 sec.)|time=0.000000s;2.000000;8.000000;0.000000
Same version of nrpe everywhere:
$ pkg_info | grep nrpe nrpe-2.13_2 Nagios Remote Plugin Executor
After a while, I found a similar issue, and decide to look at the config options for nrpe in the problem jail and compared it to to working jails.
It was SSL. This option was not checked in the problem jail:
[x] SSL Enable SSL support (disables plain-text server)
Once I checked it, ran portupgrade -f nrpe2, and restarted the daemon: service nrpe2 restart, all was well:
/usr/local/libexec/nagios/check_nrpe2 -H dbclone.unixathome.org -c check_pgsql -t 1 OK - database template1 (0 sec.)|time=0.000000s;2.000000;8.000000;0.000000