protocols - available protocols

The file contains information about the possible protocols. Each entry for a protocol consists of a line in the following format:

protocol_name  protocol_number  aliases  #comment

Example

ip         0       IP         # internet protocol, pseudo protocol number
icmp       1       ICMP       # internet control message protocol
ggp        3       GGP        # gateway-gateway protocol
tcp        6       TCP        # transmission control protocol
egp        8       EGP        # exterior gateway protocol
pup        12      PUP        # PARC universal packet protocol
udp        17      UDP        # user datagramm protocol
hmp        20      HMP        # host monitoring protocol
xns-idp    22      XNS-IDP    # Xerox NS IDP
rdp        27      RDP        # “reliable datagram” protocol

The file is to be considered as being static since the numbers are only assigned by the standards committees (OSI, IEEE and IANA).