Permitting Or Denying Traffic With Access Lists; Applying Nat; Protecting From Ip Fragments; Using Aaa For Through Traffic - Cisco 7604 Configuration Manual

Security Policy Overview
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Permitting or Denying Traffic with Access Lists

You can apply an access list to allow traffic through an interface. For transparent firewall mode, you can
also apply an EtherType access list to allow non-IP traffic.

Applying NAT

Some of the benefits of NAT include the following:
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Protecting from IP Fragments

The FWSM provides IP fragment protection. This feature performs full reassembly of all ICMP error
messages and virtual reassembly of the remaining IP fragments that are routed through the FWSM.
Fragments that fail the security check are dropped and logged. Virtual reassembly cannot be disabled.

Using AAA for Through Traffic

You can require authentication and/or authorization for certain types of traffic, for example, for HTTP.
The FWSM also sends accounting information to a RADIUS or TACACS+ server.

Applying Internet Filtering

Although you can use access lists to prevent outbound access to specific websites or FTP servers,
configuring and managing web usage this way is not practical because of the size and dynamic nature of
the Internet. We recommend that you use the FWSM in conjunction with a separate server running one
of the following Internet filtering products:
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Catalyst 6500 Series Switch and Cisco 7600 Series Router Firewall Services Module Configuration Guide using ASDM
1-4
Using AAA for Through Traffic, page 1-4
Applying Internet Filtering, page 1-4
Applying Application Inspection, page 1-5
Applying Connection Limits, page 1-5
You can use private addresses on your inside networks. Private addresses are not routable on the
Internet.
NAT hides the local addresses from other networks, so attackers cannot learn the real address of a
host.
NAT can resolve IP routing problems by supporting overlapping IP addresses.
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Chapter 1 Introduction to the Firewall Services Module
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