12.0

Table 14-2
Firewall rule parameters (continued)
DescriptionParameter
The applications that trigger the rule.
When an application is the only trigger in an allow traffic rule, the
firewall allows the application to perform any network operation. The
application is the significant value, not the network operation that the
application performs.
For example, suppose you allow Internet Explorer, and define no other
triggers. Computer users can access the remote sites that use HTTP,
HTTPS, FTP, Gopher, and any other protocol that the Web browser
supports. You can define additional triggers to describe the network
protocols and hosts with which communication is allowed.
Application
The hosts that trigger the rule.
You can define the host relationship as follows:
■ Local and remote hosts
This relationship is commonly used in host-based firewalls. It is
independent of the traffic direction.
The local host is the local client computer. The remote host is the
computer that communicates with the client computer.
If the client communicates with a Web server, the remote host is the
Web server and the local host is the client. The local host is the same
for inbound traffic and outbound traffic.
■ Source and destination hosts
This relationship is commonly used in network-based firewalls. It is
dependent on the traffic direction.
The source host is the computer that sends the packet. The source
host is the remote computer for inbound traffic. The source host is
the local computer for outbound traffic.
The destination host is the computer that receives the packet. The
destination host is the local computer for inbound traffic. The
destination host is the remote computer for outbound traffic.
If the client communicates with a Web server, and the traffic is
inbound, the source host is the Web server and the destination host
is the client. For outbound traffic, the source host is the client and
the destination host is the Web server.
Host
131Managing firewall protection
How the firewall works