The NAT router maintains a translation table:
| Inside Local | Inside Global | Outside Global | |192.168.1.100:54321|203.0.113.5:40001|93.184.216.34:80| |192.168.1.101:54322|203.0.113.5:40002|93.184.216.34:80|
Table entries include:
- Protocol (TCP/UDP)
- Internal IP and port
- External IP and port
- Destination IP and port
- Timeout timestamp
Entry lifecycle:
- Created when outbound connection starts
- Updated with each packet to reset timeout
- Deleted after inactivity timeout (often seconds for TCP)