Rules are organized sequentially in the order they are applied to each interface. This is the order in
which they will be evaluated by the PIX Firewall.
Organization of Access Lists
If you configure the PIX Firewall using PDM, the PIX Firewall will use access control lists (
ACL
s).
Access rules are grouped by the interface on which they are configured and enforced.
In the following table, assume that the PIX Firewall in use is configured with
ACL
s.
#
Action
Source
Name/Address
Destination
Name/Address
Interface
Service
Description
1
any
any
inside
ftp/tcp
2
any
any
inside
http/tcp
1
any
any
dmz
http/tcp
2
any
any
dmz
dns/udp
3
any
any
dmz
ftp/tcp
In the preceding example, the first two rules are in an
ACL
applied to the inside interface. These two
rules will be evaluated by the PIX Firewall in the order that they are numbered. Note that in all
ACLs, there is an implicit rule at the end of the ACL denying all other traffic received on the inside
interface from the network. The third, fourth, and fifth rules are in an
ACL
that is applied to the
interface named dmz. The numbering starts over because these rules are part of a new ACL and are
evaluated by the PIX Firewall separately from the ACL that is applied to the inside interface. There
is an implicit rule in all ACLs at the end of the ACL denying all other traffic received on the inside
interface from the network rule denying all other traffic.
This is irrelevant for users configuring a new PIX Firewall or with a PIX Firewall that uses the
access-list command for access control.
Organization of Rules in a PIX Firewall Configured with the
conduit Command.
In a PIX Firewall previously configured with
conduit
commands, the evaluation order that a PIX
Firewall will use corresponds to the order of the conduit commands in the PIX Firewall
configuration. The first rule is evaluated first, then the second, and so on.
This is irrelevant for users configuring a new PIX Firewall or with a PIX Firewall that uses the
access-list command for access control.
Organization of Rules in a PIX Firewall Configured with Outbound
Lists.
In a PIX Firewall configured with the
outbound
limitations on traffic, PDM will reorder
newly-created outbound lists using a "best match" algorithm. PDM may put an outbound rule
someplace other than where you specify. PDM will reorder the rules to display the same ordering
Summary of Contents for PIX 520 - PIX Firewall 520
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