ZyXEL Communications VMG3925-B10A User Manual page 171

Figure 90 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 68 Services and Port Numbers
SERVICES
ECHO
FTP (File Transfer Protocol)
SMTP (Simple Mail Transfer Protocol)
DNS (Domain Name System)
Finger
HTTP (Hyper Text Transfer protocol or WWW, Web)
POP3 (Post Office Protocol)
NNTP (Network News Transport Protocol)
SNMP (Simple Network Management Protocol)
SNMP trap
PPTP (Point-to-Point Tunneling Protocol)
Port Forwarding Example
Let's say you want to assign ports 21-25 to one FTP, Telnet and SMTP server (A in the example),
port 80 to another (B in the example) and assign a default server IP address of 192.168.1.35 to a
Chapter 11 Network Address Translation (NAT)
VMG3925-B10A User's Guide
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PORT NUMBER
7
21
25
53
79
80
110
119
161
162
1723