Research of Network Security and Firewalls Techniques Abstract: As the key facility that maintains the network security , firewalls take the purpose of establishing an obstacle between trust and trustless network, and put corresponding safety strategy into practice. In this paper , the computer network security and the techniques of firewalls were mainly discussed, the concept and classification of the firewalls were introduced. It also introduced three kind's of basic implement techniques of the firewalls: Packet filtering , Application Proxy and Monitor model in detail. Finally described the trend of development of the firewalls techniques in Internet briefly. Key words: network security, firewalls, Packet filtering, monitor 1. Introduction Now with the computer network and e-commerce used widely, network security has become an important problem that we must consider and resolve. More and more professions. enterprises and individuals surfer from the security problem in different degree. they are looking for the more reliable safety solution . In the defense system adopted by network security at present, the firewalls stand the very important position. As the key facility that maintains the network security. firewalls take the purpose of establishing an obstacle between trust and trustless network, and put corresponding safety strategy into practice. All the firewalls have the function to filter the IP address. This task checks the IP packet, makes the decision whether to release or to abandon it according to the source address and destination address of the IP. Shown in Fig.I, there is a firewall between two network sections, an UNIX computer is on one side of the firewall, and the other side is a PC...
