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Cyclades-PR4000
Chapter 14 - Filters and Rules
Steps necessary to activate filtering on the exterior router in the example:
1 There are two interfaces with two directions each. Filtering on link 1 requires the creation of two rule lists,
called exterior_in and exterior_out. Create them using the menu CONFIG =>RULES LIST =>IP
=>ADD RULE LIST and the following parameters:
Rule List Type = Filter
Default Scope = Deny
Linked Rule List Name = None
2 Create the rules for each rule list in the order in which they should be evaluated. The order is important and
mis-ordering the rules can cause unexpected results. This is done in the menu CONFIG =>RULES LIST
=>IP =>CONFIGURE RULES. The parameters for rules 0 and 1 in the example are shown in Figure 12.4.
3 Link the rule lists to the respective interface parameters in the menu CONFIG =>INTERFACE =>
<INTERFACE>
=>NETWORK PROTOCOL =>INCOMING/ OUTGOING RULE LIST NAME. exterior_in should be set as the
incoming rule list name and exterior_out should be set as the outgoing rule list name.
Exterior_in, rule 0, allows a remote computer to connect to the bastion host using the TCP protocol on its
SMTP port. Exterior_out, rule 0, allows the Bastion Server to RESPOND to the connection started by the
remote computer. To send e-mail
out
, two more rules would be needed. If all the router needs to do is receive e-
mail, the configuration is done. If not, other “holes” must be created in the deny ball.