ZyXEL Communications ZyXEL ZyWALL 35 - Manual (Page 305)

ZyWALL 35 User’s Guide
Chapter 16 Network Address Translation (NAT) 303
16.5.1 Default Server IP Address
In addition to the servers for specified services, NAT supports a default server IP address. A
default server receives packets from ports that are not specified in this screen.
16.5.2 Port Forwarding: Services and Port Numbers
The ZyWALL provides the additional safety of the DMZ ports for connecting your publicly
accessible servers. This makes the LAN more secure by physically separating it from your
public servers.
Use the Port Forwarding screen to forward incoming service requests to the server(s) on your
local network.
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.
16.5.3 Configuring Servers Behind 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 third (C in the example). You assign the LAN IP addresses and the ISP
assigns the WAN IP address. The NAT network appears as a single host on the Internet.
Note: If you do not assign a Default Server IP address, the
ZyWALL discards all packets received for ports that are not
specified here or in the remote management setup.
Table 101 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
SNMP (Simple Network Management Protocol) 161
SNMP trap 162
PPTP (Point-to-Point Tunneling Protocol) 1723