How to Setup Kamailio with TLS and RTPProxy

Setting up Kamailio with TLS and RTPProxy can be a bit complex, but I’ll guide you through the process step by step. Here’s an outline of what you need to do:

1. Setup and Prerequisites

Ensure you have the following components installed:

• A machine with Linux (Ubuntu/Debian preferred).
• Kamailio SIP server.
• RTPProxy for media relaying.
• TLS certificates (self-signed or CA-signed).

2. Kamailio Installation

1. Update your system and install dependencies:bashCopy codesudo apt update && sudo apt upgrade -y sudo apt install build-essential curl net-tools sudo apt install libssl-dev libmariadb-dev libmariadb3
2. Add the Kamailio repository:bashCopy codesudo sh -c "echo 'deb http://deb.kamailio.org/kamailio55 bionic main' > /etc/apt/sources.list.d/kamailio.list" wget -O- http://deb.kamailio.org/kamailiodebkey.gpg | sudo apt-key add - sudo apt update
3. Install Kamailio:bashCopy code
4. sudo apt install kamailio kamailio-mysql-modules kamailio-tls-modules
5. Enable MySQL support:
6. Edit /etc/kamailio/kamctlrc and set the DBENGINE to MYSQL:bashCopy codeDBENGINE=MYSQL
7. Create the database:bashCopy code
8. sudo kamdbctl create

3. Configure TLS in Kamailio

1. Generate TLS Certificates (self-signed or from a trusted CA):bashCopy codeopenssl genrsa -out /etc/kamailio/kamailio.key 2048 openssl req -new -key /etc/kamailio/kamailio.key -out /etc/kamailio/kamailio.csr openssl x509 -req -days 365 -in /etc/kamailio/kamailio.csr -signkey /etc/kamailio/kamailio.key -out /etc/kamailio/kamailio.crt
2. Configure Kamailio for TLS by editing the main configuration file /etc/kamailio/kamailio.cfg:
   • Set the listening port for TLS.bashCopy codelisten=tls:your-ip:5061
   • Load the TLS module:bashCopy codeloadmodule "tls.so"
   • Configure the TLS settings:bashCopy codemodparam("tls", "config", "/etc/kamailio/tls.cfg")
3. Create TLS Configuration File (/etc/kamailio/tls.cfg):bashCopy code[server:default] method = TLSv1.2 verify_certificate = no require_certificate = no private_key = /etc/kamailio/kamailio.key certificate = /etc/kamailio/kamailio.crt
4. Restart Kamailio:bashCopy codesudo systemctl restart kamailio

4. Install and Configure RTPProxy

1. Install RTPProxy:bashCopy codesudo apt install rtpproxy
2. Run RTPProxy with the following command:bashCopy codertpproxy -F -l your-ip -s udp:127.0.0.1:7722 -u rtpproxy -p /var/run/rtpproxy/rtpproxy.pid Explanation:
   • -F: Forks the process to run in the background.
   • -l: Specifies the external IP address.
   • -s: The socket address for communication between Kamailio and RTPProxy.
   • -u: The user that runs RTPProxy.
   • -p: Specifies the PID file.
3. Configure Kamailio to use RTPProxy:
   • Load the RTPProxy module in the Kamailio configuration file (/etc/kamailio/kamailio.cfg):bashCopy codeloadmodule "rtpproxy.so" modparam("rtpproxy", "rtpproxy_sock", "udp:127.0.0.1:7722")
   • Use the RTPProxy functions in the routing logic. For example, in the route block of kamailio.cfg:bashCopy codeif (is_method("INVITE")) { if (rtpproxy_offer()) { xlog("L_INFO", "RTPProxy offer succeeded\n"); } } if (is_method("ACK")) { rtpproxy_answer(); } if (is_method("BYE") || is_method("CANCEL")) { rtpproxy_stop(); }
4. Restart Kamailio to apply the changes:bashCopy codesudo systemctl restart kamailio

5. Testing the Setup

1. Verify Kamailio is listening on the required ports:bashCopy codenetstat -ntlp | grep kamailio You should see Kamailio listening on port 5061 for TLS.
2. Verify RTPProxy is running:bashCopy codeps aux | grep rtpproxy
3. Use a SIP client that supports TLS and send an INVITE request. The call flow should use TLS for signaling and RTPProxy to relay media.

6. Troubleshooting

• Kamailio logs: Check /var/log/syslog or run kamailio in debug mode.
• RTPProxy logs: Logs are usually found in /var/log/rtpproxy.log.

This setup provides a basic configuration for Kamailio using TLS for secure signaling and RTPProxy for media handling. For more advanced features, such as authentication or NAT traversal, you may need additional configuration tweaks.