Digi TransPort, Руководство пользователя

Страница: 651 / 813

Firewall configuration
Digi TransPort User Guide 651
Firewall configuration
To configure firewall settings, go to Configuration > Security> Firewalls .
About firewalls
All Digi TransPort routers incorporate a comprehensive firewall facility. A firewall is a security
system that is used to restrict the type of traffic that the router will transmit or receive based on a
combination of IP address, service type, protocol type, port number and IP flags. Firewalls are
used to minimize the risk of unauthorized access to the local network resources by external users
or to restrict the range of external resources to which local users have access. A more detailed
description of how firewalls operate on Digi routers is given in “ Firewall scripts on page 655”.
Refer to this section before attempting to implement a firewall.
The rules governing the operation of the firewall are contained in a pseudo-file called
fw.txt . This
file can be created either by using the controls in the web page described below or by using a text
editor on a PC and then loading the resulting file onto the router using FTP or XMODEM. Digi
Routers are shipped with a default fw.txt file that can be used as the starting point for a custom
firewall configuration.
Firewall parameters
On the Configuration > Security> Firewalls page, firewall configuration done using settings in
the table described below. There are three other buttons that appear just below the table. Their
use will also be described.
Since a default file is supplied, when this page loads it will show the rules in the default
fw.txt file.
If fw.txt does not exist, a blank table will be shown.
Hits
The numbers that appear in this column of the table are the number of hits for the rule that
appears to the right.
#
This is non-editable and is simply the rule number.
Delete
Clicking this button deletes the rule that appears to its left.
Insert
These buttons are used to insert new lines. The insert buttons that appear alongside existing
rules insert new blank lines above the line on which they appear. The button at the bottom
creates a new blank line at the end of the table. (An empty table will only have the one button
at the bottom). To create a new rule, click the button at the point the new rule should appear
and a new text box should appear. Type the rule into the text box and once complete, click the
OK button. To abandon any changes click the Cancel button. Once the OK button has been
clicked the firewall task will validate the rule and if valid, will add it the table. If errors are
detected, a warning message will be displayed, at which point the rule may be edited or
deleted.