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Chapter 11 Network Address Translation (NAT)
VMG8825-B Series User’s Guide
181
11.9.4 NAT Application
The following figure illustrates a possible NAT application, where three inside LANs (logical LANs using IP
alias) behind the VMG can communicate with three distinct WAN networks.
Figure 97
NAT Application With IP Alias
Port Forwarding: Services and Port Numbers
The most often used port numbers are shown in the following table. Please refer to RFC 1700 for further
information about port numbers. Please also refer to the Supporting CD for more examples and details
on port forwarding and NAT.
Table 69 Services and Port Numbers
SERVICES
PORT NUMBER
ECHO
7
FTP (File Transfer Protocol)
21
SMTP (Simple Mail Transfer Protocol)
25
DNS (Domain Name System)
53
Finger
79
HTTP (Hyper Text Transfer protocol or WWW, Web)
80
POP3 (Post Office Protocol)
110
NNTP (Network News Transport Protocol)
119
DSL