1. FIREWALL

8. Packet filter - It looks at each packet entering or leaving the network and accepts or rejects it based on user-defined rules . Packet filtering is fairly effective and transparent to users, but it is difficult to configure. In addition, it is susceptible to IP spoofing . Packet Filtering Applications Presentations Sessions Transport DataLink Physical DataLink Physical Router Applications Presentations Sessions Transport DataLink Physical Network Network

9. Application gateway Application gateway (Proxy Server)- User uses TCP/IP applications, such as FTP and Telnet servers. This is very effective, but can impose a performance degradation. Applications Presentations Sessions Transport DataLink Physical Network DataLink Physical Applications Presentations Sessions Transport DataLink Physical Application Gateway Applications Presentations Sessions Transport Network Network Telnet HTTP FTP

15. SECURED Firewall Thank You…… Source – >CNS Text Book (William Stallings) > Wikipedia