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