网络安全与防火墙 英文文献翻译

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 client. While the PC client asks a telnet request for the UNIX computer, the client procedure of telnet in the PC produces a TCP packet and passes the packet to the local protocol stack to prepare to send. The protocol stack fills it in one IP packet. then, sends it to UNIX computer through the path defined by the TCP/IP stack of PC. The IP packet can't reach the UNIX computer until it passes the firewall between the PC and the UNIX computer.

Fig. I Ip Address Filtering

The application firewall is a very efficient means of network security on Internet,it is installed between the trust and trustless network, can isolate the connection between the trust and trustless network, and doesn't hamper people's access to the trustless network at the same time. It can isolate the connection between the risk area (namely there may be a certain risk on Internet) and the safe area (LAN), and doesn't hamper people's access to the risk area at the same time. Firewall can monitor the traffic flowing in and out from the network to finish the task seemingly impossible;it only allows the safe and checked information to enter into, and meanwhile resists on the data that may bring about the threat to enterprise. As the fault and defect of the security problem become