Munin is a networked resource monitoring tool that can help analyze resource trends and provide operational data to answer a question like "what just happened to kill our performance?". It is designed to be very plug and play. A default installation provides a lot of graphs with very little work. Of particular interest to a VoIP server is how much bandwidth you consume.

Install munin with apt-get install munin, followed by editing the Nginx configuration template (don't forget to restart the server after the update) for the server on port 8080 to listen on either a private interface or localhost. DO NOT configure the web server to listen on your pubic IP as munin gives away a lot of operational details about the server.

Useful plugins for munin.

If you are looking for server side anonymity, these might be a bad idea since recording information about calls can be used as metadata.

SIP dialog tracking

Iñaki Baz Castillo <ibc [@t]> wrote a SIP dialog tracking plugin for Kamailio. All data is held only in memory. When the call ends, the record is automatically deleted from memory. It requires the Kamailio dialog module and corresponding changes to the configuration.

In the module configuration

loadmodule "" 

# ----- dialog tracking configuration ----

modparam("dialog", "dlg_flag", 4)

Add this to the top-level request_route block in kamailio.cfg and restart Kamailio

        if (is_method("INVITE"))
                t_reply("100", "Ringing");

At the top of /etc/kamailio/kamailio.cfg enable the SIP dialog blocks with

#!define WITH_DIALOG

Download the plugin it into your plugin directory, /etc/munin/plugins/ then add these lines to /etc/munin/plugin-conf.d/munin-node

user root

Make the plugin executable and restart munin

chmod 755 /etc/munin/plugins/<myplugin>
/etc/init.d/munin-node restart

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