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ZyWALL 10/50 Internet Security Gateway
Filter Configuration 18-15
Step 4. Enter a descriptive name or comment in the Edit Comments field and press [ENTER].
Step 5. Press [ENTER] at the message [Press ENTER to confirm] to open Menu 21.1.3 - Filter
Rules Summary.
Step 6. Enter 1 to configure the first filter rule (the only filter rule of this set). Make the entries in this
menu as shown in the following figure.
Figure 18-11 Example Filter — Menu 21.1.3.1
Menu 21.1.3.1 - TCP/IP Filter Rule
Filter #: 3,1
Filter Type= TCP/IP Filter Rule
Active= Yes
IP Protocol= 6 IP Source Route= No
Destination: IP Addr= 0.0.0.0
IP Mask= 0.0.0.0
Port #= 23
Port # Comp= Equal
Source: IP Addr= 0.0.0.0
IP Mask= 0.0.0.0
Port #= 0
Port # Comp= None
TCP Estab= No
More= No Log= None
Action Matched= Drop
Action Not Matched= Forward
Press ENTER to Confirm or ESC to Cancel:
Press S
p
ace Bar to To
gg
le.
Press [SPACE BAR] to choose this filter rule
type. The first filter rule type determines all
subsequent filter types within a set.
Select Yes to make the rule active.
6 is the TCP protocol.
Select Equal here as you are looking for packets
going to port 23 only.
There are no more rules to check.
Select Forward here so that the packet will be
forwarded if its destination is not
the telnet port.
The port number for the telnet service (TCP protocol)
is 23. See RFC 1060 for port numbers of well-known
services.
Select Drop here so that the packet will
be dropped if its destination is the telnet
port.