Assigned Internet Protocol Numbers

http://technet.microsoft.com/en-us/library/cc959827.aspx

http://www.iana.org/assignments/protocol-numbers/protocol-numbers.xml

Protocol Numbers

In an IP header, the Protocol field identifies the service in the next higher level in the protocol stack to which data is passed. Table C.4 shows these commonly used IP protocol numbers. Protocol numbers are used to configure firewalls, routers and proxies.

Table C.4 Common Protocol Numbers

Service	Protocol Number
Internet Control Message Protocol (ICMP)	1
Transmission Control Protocol (TCP)	6
User Datagram Protocol (UDP)	17
General Routing Encapsulation (PPTP data over GRE)	47
Authentication Header (AH) IPSec	51
Encapsulation Security Payload (ESP) IPSec	50
Exterior Gateway Protocol (EGP)	8
Gateway-Gateway Protocol (GGP)	3
Host Monitoring Protocol (HMP)	20
Internet Group Management Protocol (IGMP)	88
MIT Remote Virtual Disk (RVD)	66
OSPF Open Shortest Path First	89
PARC Universal Packet Protocol (PUP)	12
Reliable Datagram Protocol (RDP)	27
Reservation Protocol (RSVP) QoS	46