What you need to know about symmetric NAT

This article continues on from where Types of NAT left off. A symmetric NAT applies restrictions exactly the same way as a port restricted cone NAT but handles the NAT translation differently. All types of NAT discussed so far don’t change the source port when NATing connections. For example when a client accesses the Internet using IP 192.168.0.1 and source port 56723 NAT changes the source IP to say 56.35.67.35 but keeps the port number the same; this is known as port preservation.