IP protocol number

Q0001

IP protocol number is 1-byte field in IP protocol header. This value specifies the higher-level protocol contained in the packet data field. The table "Assignments for an IP Packet Protocol Field" lists some of the values that have been assigned to specific protocols or organizations. Note that this list is subject to change. The Internet Assigned Numbers Authority (IANA) is the keeper of the protocol assignments. Official lists are published in the "Assigned Numbers" RFC 1700.

Assignments for an IP Packet Protocol Field
Value Protocol
1 ICMP
2 IGMP
3 GGP
6 TCP
8 EGP
17 UDP
47 GRE
50 ESP
51 AH
89 OSPF
115 L2TP