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man pages section 5: File Formats

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Updated: Thursday, June 13, 2019
 
 

protocols(5)

Name

protocols - protocol name database

Synopsis

/etc/inet/protocols
/etc/protocols

Description

The protocols file is a local source of information regarding the known protocols used in the Internet. The protocols file can be used in conjunction with or instead of other protocols sources, including the NIS maps ``protocols.byname'' and “protocols.bynumber”. Programs use the getprotobyname(3C) routine to access this information.

The protocols file has one line for each protocol. The line has the following format:

official-protocol-name protocol-number aliases

Items are separated by any number of blanks and/or TAB characters. A `#' indicates the beginning of a comment; characters up to the end of the line are not interpreted by routines which search the file. Protocol names may contain any printable character other than a field delimiter, NEWLINE, or comment character.

Examples

Example 1 A Sample Database

The following is a sample database:

#
# Internet (IP) protocols
#
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 datagram protocol

#
# Internet (IPv6) extension headers
#
hopopt      0   HOPOPT      # Hop-by-hop options for IPv6
ipv6        41  IPv6        # IPv6 in IP encapsulation
ipv6-route  43  IPv6-Route  # Routing header for IPv6
ipv6-frag   44  IPv6-Frag   # Fragment header for IPv6
esp         50  ESP         # Encap Security Payload for IPv6
ah          51  AH          # Authentication Header for IPv6
ipv6-icmp   58  IPv6-ICMP   # IPv6 internet control message protocol
ipv6-nonxt  59  IPv6-NoNxt  # No next header extension header for IPv6
ipv6-opts   60  IPv6-Opts   # Destination Options for IPv6

Files

/etc/nsswitch.conf

configuration file for name-service switch

See Also

getprotobyname(3C), nsswitch.conf(5)

Notes

/etc/inet/protocols is the official SVR4 name of the protocols file. The symbolic link /etc/protocols exists for BSD compatibility.