TMS zl Management and Configuration Guide ST.1.1.100226

4-4
Firewall
Overview
Overview
This chapter covers the configuration of the TMS zl Module firewall, including
these features:
■ “Named Objects” on page 4-9
■ “Firewall Access Policies” on page 4-22
■ “User Authentication” on page 4-47
■ “Application-Level Gateways (ALGs)” on page 4-87
■ “Attack Checking” on page 4-102
■ “Connection Timeouts” on page 4-112
■ “Resource Allocation” on page 4-115
■ “IP Reassembly” on page 4-126
It is best practice to configure named objects before you set up firewall access
policies. You can choose when and whether complete other tasks according
to the requirements of your system.
The section below provides general background information about firewalls
and an internal firewall, in particular.
General Firewall Concepts
This section provides background information on firewall concepts.
Need for an Internal Firewall
In the past, corporate networks were defined by clear, distinct boundaries,
and network administrators implemented security using an “us versus them”
mentality. Their job was to protect the inside, trusted network (us) against
would-be attackers on the outside (them).
To provide this protection, the first line of defense for any network has always
been a firewall—a collection of components configured to enforce a specific
access control policy between an internal (trusted) network and any other
(untrusted) network. Firewalls filter incoming and outgoing packets to ensure
that only authorized packets pass.