4-Port ADSL Router User Manual

Configuring IP Filters and Blocked Protocols
146
3.
Specify the [Protocol] = [TCP] and enable the [Store State]
setting.
4.
Select the [TCP Protocol], then specify a [Dest Port] = [80],
which is the well-known port number for web servers .
5.
Enable the rule by clicking the radio button at the top of the
page
.
6.
Click [Submit] to create the rule.
7.
On the [IP Filter Configuration] page, set the [Security Level:]
to the same level you chose for the rule, and set both the
[Private Default Action:] and the [Public Default Action:] to
[Accept].
8.
Click [Submit], and commit your changes. Figure 48
shows the
configuration for this rule. The specified computer
will not be
able to access the Web, but will be able to access FTP
Internet sites (and any others that use destination port
numbers other than 80).
Example 2
Blocking Telnet accesses to the ADSL Barricade:
1.
Add a new rule for packets incoming on the [ppp-0] interface.
2.
Specify that the packet must contain the TCP protocol, and
must be destined for port 23, the well-known port number
used for the Telnet protocol.
3.
[Enable] the rule by clicking the radio button at the top of the
page.