A Survey on Internet Protocol Filtering Mechanisms

Mechanism that decides which types of IP datagrams will be processed normally and which will be discarded is called IP filtering. Discarding datagrams means that the datagram is completely ignored and deleted, as if it had never been received. There are many criteria to determine which datagrams are to be filtered. IP filtering is a network layer facility which doesn't understand anything about the application using the network connection. It only knows about the connections themselves. if we want to deny users access to internal network on the default telnet port, but rely on IP filtering alone, it is not possible to stop them from using the telnet program with a port that allow to pass through firewall. By using proxy servers for each service, it is possible to solve this problem. The proxy servers can prevent abuses. If firewall supports a World Wide Web proxy, telnet connection will always be answered by the proxy and will allow only http requests to pass. A large number of proxy-server programs are there. Some are free software and many others are commercial products. Here we present a survey on IP filtering mechanisms.