Lecture-3 ISO Model, Network Security, and Protocols

Lecture 3 51 firewalls firewalls are essential tools

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Unformatted text preview: rk traffic. A firewall is a network device used to filter traffic and is typically deployed between a private network and a link to the Internet, but it can be deployed between departments within an organization. Without firewalls, it would not be possible to restrict malicious traffic from Lecture-3 52 the Internet from entering into your Firewalls …cont. In addition to logging network traffic activity, firewalls should log several other events as well: Reboot of the firewall Proxies or dependencies that cannot or didn't start Proxies or other important services that have crashed or restarted Changes to the firewall configuration file A configuration or system error while the firewall is running Firewalls are only one part of an overall security solution. Lecture-3 53 Firewalls …cont. Static Packet-Filtering Firewall: A static packetfiltering firewall filters traffic by examining data from a message header. Application-Level Gateway Firewall: An applicationlevel gateway firewall is also called a proxy firewall. A proxy is a mechanism that copies packets from one network into another; the copy process also changes the source and destination address to protect the identity of the internal or private network. Circuit-Level Gateway Firewalls: Circuit-level gateway firewalls are used to establish communication circuit/session between trusted partners. Ø They operate at the Session layer (layer 5) of the OSI model. Lecture-3 54 Firewalls …cont. Stateful Inspection Firewalls: Stateful inspection firewalls evaluate the state or the context of network traffic. By examining source and destination addresses, application usage, source of origin, and the relationship between current packets and the previous packets of the same session, stateful inspection firewalls are able to grant a broader range of access for authorized users and activities and actively watch for and block unauthorized users and activities. Lecture-3 55 Firewalls …cont. Multihomed Firewalls: Some firewall systems have more than one inte...
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This note was uploaded on 01/21/2014 for the course IT 205 taught by Professor Kurts during the Winter '08 term at University of Phoenix.

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