Firewall Is A Barrier To Network Security

A firewall (as a blocking point, control point) can greatly improve the security of an internal network and reduce risks by filtering insecure services. Since only carefully selected application protocols can pass through the firewall, the network environment becomes more secure. For example, the firewall can prohibit the well-known insecure NFS protocol from entering and exiting the protected network, so that it is impossible for external attackers to use these weak protocols to attack the internal network. The firewall can also protect the network from routing-based attacks, such as source routing attacks in IP options and redirection paths in ICMP redirects. The firewall should be able to reject all the above types of attack packets and notify the firewall administrator.