ZyXEL Communications P-870HW-51a v2 User Manual

Chapter 8 Network Address Translation (NAT)

P-870HW-51a v2 User’s Guide

The following table describes the fields in this screen. 

The following section contains additional technical information about the ZyXEL 
Device features described in this chapter.

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.

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 third (C in the example). You assign the LAN IP 

Table 30   NAT - DMZ Host

Default Server

Enter the IP address of the default server which receives packets from 
ports that are not specified in the 

 screen. 

Note: If you do not assign a Default Server, the ZyXEL Device 

discards all packets received for ports that are not specified 
in the NAT Port Forwarding screen.

Save

Click Save to save your changes back to the ZyXEL Device.

Table 31   Services and Port Numbers

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

SNMP (Simple Network Management Protocol)

161

SNMP trap

162

PPTP (Point-to-Point Tunneling Protocol)

1723