ICMP In Internet Applications, And Security Issues

The paper introduce the usage and importance of the ICMP protocol in the TCP/IP protocol stack. It is designed for meeting the needs of working well of network devices in the non-link network system,It provides the mechanism for Routers(Hosts) to send back error messages. The methods used by The ICMP Protocol are now the problem of Protocol security and network security.When introducing it's basic usage such as ECHO Request and ECHO Reply,a detailed report on how to determine the Host state whether it is safely has been made. After sending out the normal or man-made ICMP Packet to a target network (host,router and network OS),We can wait to receive the reply or other information and analyse the result according to principle which were made by RFC and discovered in the paper.Accompanied with other protocol in the TCP/IP,the paper want to introduce the idea,method and technique about security checking to our network,host and so on. In the process of mastering the ICMP protocol even the TCP/IP protocol,the paper bring forward the countermeasure and recommendation on the subject.