Kamailio with DNSSEC

The dnssec module in Kamailio was added during the development of v4.1.0 (expected to be released later in 2013). Therefore this tutorial presents how to add DNSSEC module in the default configuration file of Kamailio, following GIT installation guidelines.

In short, this tutorial focuses on:

  • install Kamailio development version from GIT repository on Ubuntu 12.04 32b
  • enable user authentication and persistent location service using MySQL server
  • add DNSSEC support to configuration file

Note: the DNSSEC module is several days old at the time of writing initial version of this tutorial. For any assistance, email to sr-users (at) lists.kamailio.org -- it is a public mailing list that requires subscription, see more details at:

Note: Ubuntu 12.04 was chosen because dnssec tools devel library are provided for this distribution, making the installation of the required dependencies much easier. There are packages for other Linux distribution (e.g., Fedora), most of the steps provided in this tutorial being valid (the rest have to updated for the specifics of the distribution, e.g., how to install packages, create system users or init.d scripts).

About DNSSEC

For reading more about DNSSEC, head to:

Many related resources, including the required libraries for Kamailio's DNSSEC module, are available at:

DNSSEC Tools Installation

The dnssec-tools package should be available on recent Debian/Ubuntu, to install it us:

apt-get install dnssec-tools

DNSSEC Tools Devel Libraries Installation

You need DNSSEC tools devel libraries to compile Kamailio's DNSSEC module. You can download the libraries from:

The files are:

    dns-validator_2.0-1_i386.deb
    libval-threads_2.0-1_i386.deb
    libval-threads-dev_2.0-1_i386.deb
    libsres_2.0-1_i386.deb
    libsres-dev_2.0-1_i386.deb

Once you download the deb files, install them with dpkg -i ...

Kamailio Installation

Here is a quick guide to install Kamailio development version from GIT repository. If you look for a more detailed tutorial, check:

Prerequisites

Install the packages needed to build Kamailio:

    apt-get install make autoconf gcc flex bison git-core
    apt-get install libmysqlclient-dev libssl-dev

Fetch Sources from GIT Repository

First of all, you have to create a directory on the file system where the sources will be stored.

      mkdir -p /usr/local/src/kamailio-devel
      cd /usr/local/src/kamailio-devel

Download the sources from GIT using the following commands.

      git clone --depth 1 git://git.sip-router.org/sip-router kamailio
      cd kamailio

Compile and Install

Run next set of commands:

      cd /usr/local/src/kamailio-devel/kamailio
      make cfg include_modules="db_mysql dnssec"
      make all
      make install

Installation Details

The binaries and executable scripts were installed in:

      /usr/local/sbin

These are:

  • kamailio - Kamailio SIP server
  • kamdbctl - script to create and manage the databases
  • kamctl - script to manage and control Kamailio SIP server
  • kamcmd - CLI - command line tool to interface with Kamailio SIP server

To be able to use the binaries from command line, make sure that /usr/local/sbin is set in PATH environment variable. You can check that with echo $PATH. If not and you are using bash, open /root/.bash_profile and at the end add:

      PATH=$PATH:/usr/local/sbin
      export PATH

Kamailio modules are installed in:

      /usr/local/lib/kamailio/modules/

Note: On 64 bit systems, /usr/local/lib64 may be used.

The documentation and readme files are installed in:

      /usr/local/share/doc/kamailio/

The man pages are installed in:

      /usr/local/share/man/man5/
      /usr/local/share/man/man8/

The configuration file was installed in:

      /usr/local/etc/kamailio/kamailio.cfg

Kamctl Setup

kamctl is command line tool useful to control Kamailio. It can add or remove SIP user profiles.

Edit /usr/local/etc/kamailio/kamctlrc, locate DBENGINE variable and set it to MYSQL:

    DBENGINE=MYSQL

Also, you can set SIP_DOMAIN to you server hostname or IP address.

You can change other values in kamctlrc file, at least it is recommended to change the default passwords for the users to be created to connect to database.

Database Setup

Once you are done updating kamctlrc file, run the script to create the database used by Kamailio:

      /usr/local/sbin/kamdbctl create

You can call this script without any parameter to get some help for the usage. You will be asked for the domain name Kamailio is going to serve (e.g., mysipserver.com) and the password of the 'root' MySQL user. The script will create a database named 'kamailio' containing the tables required by Kamailio. You can change the default settings in the kamctlrc file mentioned above.

The script will add two users in MySQL:

  • kamailio - (with default password kamailiorw) - user which has full access rights to kamailio database

  • kamailioro - (with default password kamailioro) - user which has read-only access rights to kamailio database

Do change the passwords for these two users to something different that the default values that come with sources.

Adding SIP Users

Kamctl can be used for adding users, for example adding user test with password testpasswd:

    kamctl add test testpasswd

Init.d Script

The init.d script can be used to start/stop the Kamailio server in a nicer way. A sample of init.d script for Kamailio is provided at:

      /usr/local/src/kamailio-devel/kamailio/pkg/kamailio/deb/debian/kamailio.init

The default file for init.d script is provided at:

      /usr/local/src/kamailio-devel/kamailio/pkg/kamailio/debian/kamailio.default

Run next command to deploy the init.d scripts:

      make install-initd-debian

It will create also user and group kamailio, plus runtime directory /var/run/kamailio.

Now Kamailio can be started or stopped with:

      /etc/init.d/kamailio start
      /etc/init.d/kamailio stop

Update Kamailio Config File

Next step is to enable user authentication, persistent location service and add dnssec module. You have to edit the configuration file.

      /usr/local/etc/kamailio/kamailio.cfg

Follow the instruction in the comments to enable usage of MySQL. Basically you have to add several lines at the top of config file (but after the first line), like:

    #!define WITH_MYSQL
    #!define WITH_AUTH
    #!define WITH_USRLOCDB

If you changed the password for the 'kamailio' user of MySQL, you have to update the value for DBURL define.

Add DNSSEC Module

The README of DNSSEC module is available at:

You have to load dnssec module in kamailio.cfg:

    loadmodule "dnssec.so"

Add the above line somewhere before the first line starting with modparam.

The module does not require any parameter, you are ready to use the configuration file now.

Start Kamailio with:

    /etc/init.d/kamailio start

DNS Server DNSSEC Enabled

This tutorial does not include yet (left for future updates) how to setup a DNSSEC-enabled DNS server, there are many useful resources on the web. Among them:

Testing

One way to test is to setup two instances of Kamailio, one serving domainA.com and the second domainB.com.

Then alice@domainA.com can call bob@domainB.com. Kamailio instance serving domainA.com will do DNS lookup do discover the IP address of domainB.com

One easy way to test is to use a Open DNS resolver that provides Recursive DNSSEC capabilities. One of those is 8.8.8.8 ( Google Open DNS). As per the FAQ, DNSSEC support is enabled (https://developers.google.com/speed/public-dns/faq#dnssec)

Edit /etc/resolv.conf and modify your nameserver definition to have:

nameserver 8.8.8.8

Launch Kamailio with DNSSEC module enabled and try to send a SIP package to the domain www.dnssec-failed.org. DNS resolving for this domain should fail, as it is a test domain which provides an incorrect signature. Kamailio should report: "0(70805) INFO: dnssec [dnssec_func.c:145]: invalid domain www.dnssec-failed.org reason VAL_UNTRUSTED_ANSWER"

Remarks

  • setup of a DNS server with DNSSEC support is left for future updates of this tutorial
  • the DNSSEC module overwrites the API in the core for doing DNS queries, therefore is nothing else required to do apart of loading the module
  • Kamailio will do a DNS query each time it has to forward a SIP request based on hostname