ICMP TYPE NUMBERS (last updated 2001 August 27) The Internet Control Message Protocol (ICMP) has many messages that are identified by a "type" field. Type Name Reference ---- ------------------------- --------- 0 Echo Reply [RFC792] 1 Unassigned [JBP] 2 Unassigned [JBP] 3 Destination Unreachable [RFC792] 4 Source Quench [RFC792] 5 Redirect [RFC792] 6 Alternate Host Address [JBP] 7 Unassigned [JBP] 8 Echo [RFC792] 9 Router Advertisement [RFC1256] 10 Router Solicitation [RFC1256] 11 Time Exceeded [RFC792] 12 Parameter Problem [RFC792] 13 Timestamp [RFC792] 14 Timestamp Reply [RFC792] 15 Information Request [RFC792] 16 Information Reply [RFC792] 17 Address Mask Request [RFC950] 18 Address Mask Reply [RFC950] 19 Reserved (for Security) [Solo] 20-29 Reserved (for Robustness Experiment) [ZSu] 30 Traceroute [RFC1393] 31 Datagram Conversion Error [RFC1475] 32 Mobile Host Redirect [David Johnson] 33 IPv6 Where-Are-You [Bill Simpson] 34 IPv6 I-Am-Here [Bill Simpson] 35 Mobile Registration Request [Bill Simpson] 36 Mobile Registration Reply [Bill Simpson] 37 Domain Name Request [Simpson] 38 Domain Name Reply [Simpson] 39 SKIP [Markson] 40 Photuris [RFC2521] 41-255 Reserved [JBP] Many of these ICMP types have a "code" field. Here we list the types again with their assigned code fields. Type Name Reference ---- ------------------------- --------- 0 Echo Reply [RFC792] Codes 0 No Code 1 Unassigned [JBP] 2 Unassigned [JBP] 3 Destination Unreachable [RFC792] Codes 0 Net Unreachable 1 Host Unreachable 2 Protocol Unreachable 3 Port Unreachable 4 Fragmentation Needed and Don't Fragment was Set 5 Source Route Failed 6 Destination Network Unknown 7 Destination Host Unknown 8 Source Host Isolated 9 Communication with Destination Network is Administratively Prohibited 10 Communication with Destination Host is Administratively Prohibited 11 Destination Network Unreachable for Type of Service 12 Destination Host Unreachable for Type of Service 13 Communication Administratively Prohibited [RFC1812] 14 Host Precedence Violation [RFC1812] 15 Precedence cutoff in effect [RFC1812] 4 Source Quench [RFC792] Codes 0 No Code 5 Redirect [RFC792] Codes 0 Redirect Datagram for the Network (or subnet) 1 Redirect Datagram for the Host 2 Redirect Datagram for the Type of Service and Network 3 Redirect Datagram for the Type of Service and Host 6 Alternate Host Address [JBP] Codes 0 Alternate Address for Host 7 Unassigned [JBP] 8 Echo [RFC792] Codes 0 No Code 9 Router Advertisement [RFC1256] Codes 0 Normal router advertisement 16 Does not route common traffic [RFC2002] 10 Router Selection [RFC1256] Codes 0 No Code 11 Time Exceeded [RFC792] Codes 0 Time to Live exceeded in Transit 1 Fragment Reassembly Time Exceeded 12 Parameter Problem [RFC792] Codes 0 Pointer indicates the error 1 Missing a Required Option [RFC1108] 2 Bad Length 13 Timestamp [RFC792] Codes 0 No Code 14 Timestamp Reply [RFC792] Codes 0 No Code 15 Information Request [RFC792] Codes 0 No Code 16 Information Reply [RFC792] Codes 0 No Code 17 Address Mask Request [RFC950] Codes 0 No Code 18 Address Mask Reply [RFC950] Codes 0 No Code 19 Reserved (for Security) [Solo] 20-29 Reserved (for Robustness Experiment) [ZSu] 30 Traceroute [RFC1393] 31 Datagram Conversion Error [RFC1475] 32 Mobile Host Redirect [David Johnson] 33 IPv6 Where-Are-You [Bill Simpson] 34 IPv6 I-Am-Here [Bill Simpson] 35 Mobile Registration Request [Bill Simpson] 36 Mobile Registration Reply [Bill Simpson] 39 SKIP [Markson] 40 Photuris [RFC2521] Codes 0 = Bad SPI 1 = Authentication Failed 2 = Decompression Failed 3 = Decryption Failed 4 = Need Authentication 5 = Need Authorization REFERENCES ---------- [RFC792] Postel, J., "Internet Control Message Protocol", STD 5, RFC 792, USC/Information Sciences Institute, September 1981. [RFC950] Mogul, J., and J. Postel, "Internet Standard Subnetting Procedure", STD 5, RFC 950, Stanford, USC/Information Sciences Institute, August 1985. [RFC1108] Kent, S., "U.S. Department of Defense Security Options for the Internet Protocol", RFC 1108, November 1991. [RFC1256] Deering, S., Editor, "ICMP Router Discovery Messages", RFC 1256, Xerox PARC, September 1991. [RFC1393] Malkin, G., "Traceroute Using an IP Option", RFC 1393, Xylogics, Inc., January 1993. [RFC1475] Ullmann, R., "TP/IX: The Next Internet", RFC 1475, Process Software Corporation, June 1993. [RFC1812] Baker, F., "Requirements for IP Version 4 Routers", RFC 1812, Cisco Systems, June 1995. [RFC2002] C. Perkins, Editor, "IP Mobility Support", RFC 2002, October 1996. [RFC2521] P. Karn and W. Simpson, "ICMP Security Failures Messages", RFC 2521, March 1999. PEOPLE ------ [JBP] Jon Postel, , September 1995. [David Johnson] [Markson] Tom Markson, , September 1995. [Simpson] Bill Simpson, , October 1995. [Solo] [ZSu] Zaw-Sing Su []