My linux box uses a nonstandard port for ssh. Nagios' check_ssh (of course) keeps marking the process as critical since it can't connect on that port. The object file localhost.cfg allows for parameters to be passed to check_ssh.

The documentation uses the example of:

for ...

/usr/local/nagios/libexec/check_ping -H -w 100.0,90% -c 200.0,60%


define service{
    host_name       linuxbox
    service_description PING
    check_command   check_ping!200.0,80%!400.0,40%

However, it doesn't describe in which order to pass parameters. In my localhost.cfg I have tried:




...where xxx22 is the actual port. But it doesn't identify that as the port.

Looking at the check_ssh man page doesn't seem to indicate in what order to place these switches...

The check_ssh Plugin

    check_ssh v2.2.1.git (nagios-plugins 2.2.1)
    Copyright (c) 1999 Remi Paulmier <remi@sinfomic.fr>
    Copyright (c) 2000-2014 Nagios Plugin Development Team

    Try to connect to an SSH server at specified server and port

    check_ssh  [-4|-6] [-t <timeout>] [-r <remote version>] [-p <port>] <host>

     -h, --help
        Print detailed help screen
     -V, --version
        Print version information
        Read options from an ini file. See
        for usage and examples.
     -H, --hostname=ADDRESS
        Host name, IP Address, or unix socket (must be an absolute path)
     -p, --port=INTEGER
        Port number (default: 22)
     -4, --use-ipv4
        Use IPv4 connection
     -6, --use-ipv6
        Use IPv6 connection
     -t, --timeout=INTEGER:<timeout state>
        Seconds before connection times out (default: 10)
        Optional ":<timeout state>" can be a state integer (0,1,2,3) or a state STRING
     -r, --remote-version=STRING
        Alert if string doesn't match expected server version (ex: OpenSSH_3.9p1)
     -P, --remote-protocol=STRING
        Alert if protocol doesn't match expected protocol version (ex: 2.0)
     -v, --verbose
        Show details for command-line debugging (Nagios may truncate output)

    Send email to help@nagios-plugins.org if you have questions regarding use
    of this software. To submit patches or suggest improvements, send email to

You can define a command and use that command for your service.

define command{
  command_name check_ssh_2222
  command_line /usr/lib/nagios/plugins/check_ssh -p 2222 $ARG1

And then for your service:

check_command   check_ssh_2222
  • Thanks for the post. I tried that as well, but ran into a different issue. Maybe you could look there and get credit for the answer if you have ideas. Thx. https://unix.stackexchange.com/questions/457409/nagios-failing-restart-with-new-service-directove-in-localhost-cfg – BurningKrome Jul 20 '18 at 10:15

My /etc/nagios/objects/commands.cfg states

define command{
    command_name    check_ping
    command_line    $USER1$/check_ping -H $HOSTADDRESS$ -w $ARG1$ -c $ARG2$ -p 5

which defines the arguments in between the exclamation marks as in the documentation example you gave. It also tells us that

define command{
        command_name    check_ssh
        command_line    $USER1$/check_ssh $ARG1$ $HOSTADDRESS$

I think that your entry should be


since there is no predefined argument to specify the port, like --port=$ARG1$ in the definition, but only a generic place holder.

Edit: I think the localhost should not be part of the check_ssh!... line, since nagios will substitute $HOSTADDRESS$ for the appropriate hosts ip/name.

  • Thanks for that. I put in ` check_ssh!--host=localhost!--port=xxx22` and nagios will start with service nagios restart. But it still reports the starts (via web interface) as "unknown". – BurningKrome Jul 20 '18 at 9:59
  • P.s. at the command line ./check_ssh --host localhost --port xxx22 responds with ./check_ssh --host localhost --port 32122 SSH OK - OpenSSH_6.7p1 Debian-5+deb8u4 (protocol 2.0) | time=0.007549s;;;0.000000;10.000000 ... so it appears the check_ssh parameters themselves are OK...? – BurningKrome Jul 20 '18 at 10:19

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