Nagios Plugin to Check the Status of PRI Lines in Asterisk

I have a number of Asterisk implementations that I keep an eye on that have multiple PRI connections. Knowing if and when they ever go down has the obvious benefits of alerting me to a problem in near real time. But besides that, it allows my customers and I to verify SLAs, track and log issues, etc.

To this end, I have written a Nagios plugin which queries Asterisk’s manager interface and executes the pri show spans CLI command (this is Asterisk 1.4 by the way). The script then parses the output to ascertain whether a PRI is up or not.

The actual code to connect to the manager interface and execute the query is simply:

if( ( $astsock = fsockopen( $host, $port, $errno, $errstr, $timeout ) ) === false )
    echo "Could not connect to Asterisk manager: $errstr";
    exit( STATUS_CRITICAL );

fputs( $astsock, "Action: Login\r\n");
fputs( $astsock, "UserName: $username\r\n");
fputs( $astsock, "Secret: $password\r\n\r\n"); 

fputs( $astsock, "Action: Command\r\n");
fputs( $astsock, "Command: pri show spans\r\n\r\n");

fputs( $astsock, "Action: Logoff\r\n\r\n");

while( !feof( $astsock ) )
    $asttext .= fread( $astsock, 8192 );

fclose( $astsock );

if( strpos( $asttext, "Authentication failed" ) !== false )
    echo "Asterisk manager authentication failed.";
    exit( STATUS_CRITICAL );

This plugin is hard coded to English and expects to find Provisioned, Up, Active for a good PRI. For example, the Asterisk implementations that support the pri show spans command that I have access to return one of:

  • PRI span 1/0: Provisioned, In Alarm, Down, Active
  • PRI span 3/0: Provisioned, Up, Active
  • PRI span 2/0: Up, Active

I’m actually running a slightly older version of Nagios at the moment, version 1.3. To integrate the plugin, first add the following command definition to an appropriate existing or new file under /etc/nagios-plugings/config/:

define command{
        command_name    check_asterisk_pri
        command_line    /usr/lib/nagios/plugins/check_asterisk_pri.php \\
             -H $HOSTADDRESS$ -U $ARG1$ -P $ARG2$ -w $ARG3$ \\
             -c $ARG4$ -n $ARG5$

where $ARG1$ is the Asterisk manager username and $ARG2$ is the password. $ARG3$ and $ARG4$ are the warning and critical thresholds respectively whereby if the number of available PRIs reaches one of these values, the appropriate error condition will be set. Lastly, $ARG5$ is the number of PRIs the plugin shouldexpect to find.

NB: the command_line line above is split for readability but it should all be on the one line.

Now create a test for a host in an appropriate file in /etc/nagios/config/:

define service{
        use                             core-service
        service_description             Asterisk PRIs
        check_command                   check_asterisk_pri!user!pass!2!1!4

Ensure that your Nagios server has permissions to access the Asterisk server via TCP on the Asterisk manager port (5038 by default). If on a public network, this should be done via stunnel or a VPN for security reasons.

Lastly, you’ll need a user with the appropriate permissions and host allow statements in your Asterisk configuration (/etc/asterisk/manager.conf):

secret = password
read = command
write = command

The next version may include support for BRI and Zap FXO ports also. I also plan on a Cacti plug in to show the channels on each PRI (up – on a call, down, etc). In any case, updates will be posted here.

The plug in can be download from:

UPDATED 20/03/2012: Aterisk 1.8.9 takes out the word “Provisioned” in “pri show spans”. Thanks to Shane O’Cain.

5 thoughts on “Nagios Plugin to Check the Status of PRI Lines in Asterisk”

  1. Thanks for publishing the script. I have found it useful. It works well with Nagios 2.9.

    For my setup, the Status Information reported by nagios showed “Content type: text/html” instead of useful results. I did change the top line of the script from “#! /usr/bin/php” to “#! /usr/bin/php -q” to suppress the header. Status Information in Nagios now shows “All 1 PRI(s) found are up and provisioned.”


  2. i keep getting a
    (Return code of 127 is out of bounds – plugin may be missing)

    define service{
    use generic-service
    host_name 20427
    service_description Asterisk PRI1
    check_command check_asterisk_pri!admin!pass!2!1!4

    define command{
    command_name check_asterisk_pri
    command_line $USER1$/check_asterisk_pri -H $HOSTADDRESS$ -U $ARG1$ -P $ARG2$ -w $ARG3$ -c $ARG4$ -n $ARG5$

    any ideas?

  3. Very helpful with one I was writing (non-Asterisk). Thanks for sharing.

    My problem was that I was doing a “return” instead of an “exit” so Nagios wasn’t seeing the status changes. I guess that would be obvious to a real programmer…I’m just a systems guy. 🙂

    Thanks again.

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