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The ICMP header starts after the IPv4 header and is identified by its protocol number, 1. [6] All ICMP packets have an eight-byte header and variable-sized data section. The first four bytes of the header have fixed format, while the last four bytes depend on the type and code of the ICMP packet.
The Echo Protocol is a service in the Internet Protocol Suite defined in 1983 in RFC 862 by Jon Postel. It was originally proposed as a way to test and measure an IP network. A host may connect to a server that supports the Echo Protocol using the Transmission Control Protocol (TCP) or the User Datagram Protocol (UDP) on the well-known port ...
Pinging involves sending an ICMP echo request to the target host and waiting for an ICMP echo reply. The program reports errors, packet loss , and a statistical summary of the results, typically including the minimum, maximum, the mean round-trip times, and standard deviation of the mean.
Sequence Number Reset 139 ICMP Node Information Query 0 The Data field contains an IPv6 address which is the Subject of this Query. 1 The Data field contains a name which is the Subject of this Query, or is empty, as in the case of a NOOP. 2 The Data field contains an IPv4 address which is the Subject of this Query. 140 ICMP Node Information ...
Protocol Number Keyword Protocol References/RFC; 0x00 0 HOPOPT IPv6 Hop-by-Hop Option: RFC 8200: 0x01 1 ICMP Internet Control Message Protocol: RFC 792: 0x02 2 IGMP Internet Group Management Protocol: RFC 1112: 0x03 3 GGP Gateway-to-Gateway Protocol: RFC 823: 0x04 4 IP-in-IP IP in IP (encapsulation) RFC 2003: 0x05 5 ST Internet Stream Protocol ...
Cisco's implementation of traceroute also uses a sequence of UDP datagrams, each with incrementing TTL values, to an invalid port number at the remote host; by default, UDP port 33434 is used. An extended version of this command (known as the extended traceroute command) can change the destination port number used by the UDP probe messages. [13]
IP address of the immediate next-hop (not the BGP nexthop) along the route to the destination; Source & destination IP masks (prefix lengths in the CIDR notation) For ICMP flows, the Source Port is zero, and the Destination Port number field codes ICMP message Type and Code (port = ICMP-Type * 256 + ICMP-Code) [citation needed].
The client performs all communication using ICMP echo request packets, while the proxy uses echo reply packets. In theory, it is possible to have the proxy use echo request packets (which makes implementation much easier), but these packets are not necessarily forwarded to the client, as the client could be behind a translated address . This ...