F-SECURE LINUX SECURITY Manual page 54

54 | F-Secure Linux Security | Using the Product
• Responder port: the port on the computer where the connection ends.
Whether the port on the computer is an initiator port or responder port depends on the direction
of the traffic:
• If the firewall service is for outbound traffic, the initiator port is the port on your own computer.
The responder port is then the port on a remote computer.
• If the firewall service is for inbound traffic, the initiator port is the port on a remote computer.
The responder port is then the port on your own computer.
The responder ports are typically mentioned in the software documentation. The initiator port
can usually be any port higher than 1023. However, for some games you may also have to
define specific initiator ports. In this case, they are also mentioned in the software documentation.
If you create a new firewall rule, you have several predefined services that you can add to the
rule. You can also create and add your own services if the service that you need is not on the
services list.
Creating Firewall Services and Rules
You can create new firewall services and rules if you want to allow traffic that is blocked or if you
want to block specific net traffic. When you create or edit firewall rules, you should allow only
the needed services and deny all the rest to minimize security risks.
To use the Firewall Wizard, go to
instructions and finish the wizard.
Follow these instructions to create a new service and rule in the advaced user interface:
1. Create a new service.
a) Select the Network Services
b) Define a unique name for the service in the
c) Enter a descriptive comment in the
services.
d) Select a protocol number for the service from the
If your service does not use ICMP, TCP or UDP protocol, select Numeric and type the
protocol number in the field reserved for it.
e) If your service uses the TCP or UDP protocol, define
f) If your service uses TCP or UDP protocols, define
g) Click Add as a new service
h) Click Save.
The new service is saved to the service list.
2. Create a new rule for the service.
I want to... and click Create a firewall
in the Advanced mode
Service Name
Description field to distinguish this service from other
Protocol
Responder Ports
to add the service to the Network services list.
rule, follow the onscreen
menu.
field.
drop-down list.
Initiator Ports the service covers.
the service covers.