Figure 18-22 Snmp; Table 15-3 Services And Port Numbers - ZyXEL Communications ZyWALL 5 User Manual

You may enter a single port number or a range of port numbers to be forwarded, and the local IP
address of the desired server. The port number identifies a service; for example, web service is on port
80 and FTP on port 21. In some cases, such as for unknown services or where one server can support
more than one service (for example both FTP and web service), it might be better to specify a range of
port numbers. You can allocate a server IP address that corresponds to a port or a range of ports.
Many residential broadband ISP accounts do not allow you to run any server processes (such as a Web
or FTP server) from your location. Your ISP may periodically check for servers and may suspend your
account if it discovers any active services at your location. If you are unsure, refer to your ISP.
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.
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.
15.3.1 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 SUA Server page 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 SUA/NAT.
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)
15.3.2 Configuring Servers Behind SUA (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
NAT

Table 15-3 Services and Port Numbers

SERVICES
ZyWALL 5 Internet Security Appliance
PORT NUMBER
7
21
25
53
79
80
110
119
161
162
1723
15-5