Proxy Firewall
Examines data and decides wheather requests chould be forwarded or refused
Stateful Inspection Firewall
Tracks state of every network communication channel and records it in a state table
Packet Filter Firewall
Blocks traffic to specific addresses, depending on type of application
Macro Virus
Exploits enhancements made to application programs
Retrovirus
Attacks or bypasses the antivirus software instaled on a computer
Stealth virus
Attempts to avoid detection by masking itself from applications
Companion virus
Attaches itself to legitimate programs and then creates program with different filename extension
Phage virus
Alters programs and databases