G.shdsl Router User Manual
Level 5: Application
Level 4: TCP
Level 3: IP
Level 2: Data Link
Level 1: Physical
Protocol
Source/Destination address
Source/destination port
IP options
connection status
192.168.0.5
172.16.3.4
UDP
SP=3264
SA=192.168.0.5
DP=1525
DA=172.16.3.4
Filter remember this
information
UDP
SP=1525
SA=172.16.3.4
DP=3264
DA=192.168.0.5
Matches outgoing so allows in
Nomatches so disallows in
UDP
SP=1525
SA=172.168.3.4
DP=2049
DA=192.168.0.5
Stateful Inspection
Internet
192.168.0.10
192.168.0.11
192.120.8.5
Firewall
Internal/Protected Network
External/Unprotected Network
NAT (Network Address Translation)
192.168.0.10
192.168.0.11
192.120.8.5
192.120.8.5
Internal IP
External IP
6