TCP and UDP,ICMP and IPSEC PROTOCOLS

TCP and UDP

TCP and UDP are used by applications. An application server typically listens at a fixed TCP or UDP port, while application clients typically use any of a wide range of ports—and as with other aspects of firewall rulesets, deny by default policies should be used for incoming TCP and UDP traffic.

Less stringent policies are generally used for outgoing TCP and UDP traffic because most organizations permit their users [..]

Firewall – VPN Environments

Firewall environments are made up of firewall devices and associated systems and applications designed to work together. For example, one site may use a firewall environment composed of a boundary router, a main firewall, and intrusion detection systems connected to the protected network and the network between the router and main firewall.

The latest trend in firewall offerings is to add cryptographic services for firewall to firewall encryption. The encrypted traffic[..]