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Modifying Port Settings
This chapter describes how to modify the Port ID numbers
associated with the Hurricane 9200/S’s Web, FTP, and Telnet
servers.
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The header information in an IP data packet specifies a destination
port number. Routers use the port number along with the IP
addresses to forward the packet to its intended recipient.
For example, all IP data packets that the ADSL/Ethernet router
receives from the Internet specify the same IP address (your public
IP address) as the destination. However, depending on the port
number contained in a data packets, the ADSL/Ethernet router may
pass the packet on to its embedded Web or Telnet servers, or to
another computer on the network.
The Internet community has developed a list of common server
types such as HTTP, Telnet, e-mail, and many others, and has
defined port numbers that can be assigned each. This is not a
mandatory scheme, but is useful in promoting communication
between separately administered LANs.
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In some cases, you may want to assign non-standard port numbers
to the HTTP and Telnet servers that are embedded on the
Hurricane 9200/S. The following scenario is one example in which
changing the HTTP port number may be necessary:
You have an externally visible Web server on your LAN,
with a NAT rule (RDR flavor) that redirects incoming
HTTP packets to that Web server. When incoming
packets contain a destination IP address of your public IP
address (which is assigned to the ADSL/Ethernet router’s
WAN interface) and the standard Web server port number
of 80, the NAT rule recognizes the port number and
redirects the packets to your Web server’s local IP
address.
Assume in this scenario that you also want to enable
external access to the Hurricane 9200/S’s Configuration
Manager, so that your ISP can log in and manager your
system, for example. Accessing Configuration Manager
requires accessing the Hurricane 9200/S’s own Web
server (also called its HTTP server). In this case, you
would want to use the Port Settings feature to assign a
non-standard port number to the Hurricane 9200/S’s
HTTP server. Without a non-standard port number, the
NAT rule would redirect your ISP’s log in attempt to your
