MCSE : Security Specialist
Identify the purpose and benefits of using a firewall/proxy.
Firewall
A
firewall is used to prevent unauthorized access to or from a
network. They are frequently used to prevent unauthorized users from
accessing private networks connected to the Internet, especially
intranets. All messages entering or leaving the intranet pass
through the firewall, which examines each message and blocks those
that do not meet the specified security criteria.
Firewall techniques:
-
Packet filter looks at each packet entering or leaving the
network and accepts or rejects it based on user-defined rules.
-
Application gateway applies security mechanisms to specific
applications, such as FTP and Telnet servers.
-
Circuit-level gateway applies security mechanisms when a TCP or
UDP connection is established. Once the connection has been
made, packets can flow between the hosts without further
checking.
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