NAT, also known as Network Address Translation, was the solution found to solve the shortage of IP addresses forecast in mid 90s. The solution consisted of using a small range of IP addresses (in most cases a single IP addresses) on the outside port of the firewall and a range of reserved addresses (non-registered addresses defined in RFC1918) on the inside port of the firewall.
Unfortunately, NAT breaks SIP communication. In this chapter, we will explain some ways to solve the NAT traversal challenge.
By the end of this chapter you will be able to:
Explain why NAT breaks SIP communication
Describe the different NAT types and their implications
Describe the main mechanisms available for NAT traversal
Implement a NAT traversal mechanism called TURN
Install and configure the MediaProxy server and its related modules
NAT is usually implemented on routers and firewalls. The NAT router maps the internal address to an external address keeping an address mapping table. Sometimes...