kamailio-course

This repo is linked to the Udemy Course "Learn SIP Through Kamailio"[https://www.udemy.com/course/learn-sip-through-kamailio/?referralCode=1091DEB811F7C7329839].

Important

If you choose to work only from the main branch, and not start with course/01-basic-config, then you will need to run the initial_setup.sh script. This script MUST be called from the directory that it resides in.

git clone https://github.com/keithcroxford/kamailio-course.git
cd kamailio-course
chmod +x initial_setup.sh
./init_setup.sh

Branch Definitions

• course/01-basic-config = Setting up the inital structure
• course/02-first-refactor = Performing a refactor to start to separate concerns.
• course/03-general-reqs = Building out the General Requirements
• course/04-rtpengine = Setting up RTPEngine to allow Media
• course/05-cdrs = Call Detail Record Configuration
• course/06-tls = Setting up TLS
• course/07-topo = Setting up the topology hiding functionality
• course/08-registrar = Building a basic SIP Registrar
• course/09-removing-codecs = Removing codecs from the SDP as a
• course/10-secfilter = Demonstrates how traffic can be blocked with Secfilter, Pike and Htable
• course/11-dispatcher = Load balancing inbound traffic to multiple core B2BUAs
• course/12-srtp = Shows to to convert RTP -> SRTP and vice versa
• course/13-enum = Demonstrates how outbound calls can be routed with ENUM

Business Requirements

When building a SIP Proxy, it's important to understand the business requirements. This ensures that you build the right functionality, without overengineering. For this course, we will use the following requirements.

General

• The service must be able to differentiate between requests from the Public Side, and the “Core” side.
• Packets are not permitted to travel from the Public Internet to the core without going through the Proxy/SBC.
• All packets that can be seen by external parties must not present the private IPs found within the core.
• The service must respond to external SIP options with a 200 OK (assuming the IP is permitted)
• The service must create call detail records and store them in a database.
• CDRS will contain the time of the call attempt, duration, source #, destination #, remote IP, call ID,
• CDRs will begin counting the duration once the call is connected.
• The service must work with SIP using UDP (port 5060) and TLS (port 5061). TCP on port 5060 must not be permitted.
• The service must offer support for encrypted media (SRTP)

Inbound

• The service must have the ability to block IPs if they are potentially malicious
• The service must have the ability to accept registrations from external devices.
• All codecs other that G.711U and G.711A must be removed from INVITE before making it to the core services
• The service must have the ability to distribute inbound calls to multiple core servers using round robin distribution.

Outbound

• Outbound requests must use ENUM.
• If multiple records exist AND a request fails, the proxy must try to send the call to the next endpoint in the list within an acceptable time frame.
• If TLS is used, offer SRTP by default.