User's Manual

SR804N Cable Modem User Manual
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Figure 21 Port Filtering configuration
This page is used to prevent PCs from sending outgoing TCP/UDP traffic to the WAN
on specific IP port numbers.
By specifying a starting and ending port range, you may determine what TCP/UDP
traffic is allowed out to the WAN on a per-port basis. Note the specified port ranges
are blocked for ALL PCs and this setting is not IP address or MAC address specific.
For instance, if you would like to block all PCs on the private LAN from accessing
HTTP sites (or “web surfing”), you would set the “Start Port” to 80, the “End Port” to
80, the “Protocol” to TCP, check the “Enabled” box, and click Apply.
5.3.5 Forwarding
Choose Advanced > Forwarding to display the following page.
Figure 22 Forwarding
This allows for incoming requests on specific port numbers to reach web servers, FTP
servers, mail servers, etc. so they can be accessible from the public internet. A table
of commonly used port numbers is also provided.
Forwarding allows you to run a publicly accessible server on the LAN by specifying
the mapping of TCP/UDP ports to a local PC
To specify a mapping, you must enter the range of port numbers that should be
forwarded locally, and the IP address to which traffic to those ports should be sent. If
only a single port specification is desired, enter the same port number in the “start”
and “end” locations for that IP address. A table of commonly used Port numbers is
supplied on the page for convenience.