networks(4)
NAME
networks - network name database
SYNOPSIS
/etc/inet/networks
/etc/networks
DESCRIPTION
The networks file is a local source of information regarding
the networks which comprise the Internet. The networks file
can be used in conjunction with, or instead of, other net-
works sources, including the NIS maps networks.byname and
networks.byaddr and the NIS+ table networks. Programs use
the getnetbyname(3SOCKET) routines to access this informa-
tion.
The network file has a single line for each network, with
the following information:
official-network-name network-number aliases
Items are separated by any number of SPACE or TAB charac-
ters. A `#' indicates the beginning of a comment. Characters
up to the end of the line are not interpreted by routines
which search the file. This file is normally created from
the official network database maintained at the Network
Information Control Center (NIC), though local changes may
be required to bring it up to date regarding unofficial
aliases and/or unknown networks.
Network numbers may be specified in the conventional dot
(`.') notation using the inet_network routine from the
Internet address manipulation library, inet(7P). Network
names may contain any printable character other than a field
delimiter, NEWLINE, or comment character.
SEE ALSO
getnetbyaddr(3SOCKET), getnetbyname(3SOCKET), inet(3SOCKET),
nsswitch.conf(4), inet(7P)
NOTES
The official SVR4 name of the networks file is
/etc/inet/networks. The symbolic link /etc/networks exists
for BSD compatibility.
The network number in networks database is the host address
shifted to the right by the number of 0 bits in the address
mask. For example, for the address 24.132.47.86 that has a
mask of fffffe00, its network number is 803351. This is
obtained when the address is shifted right by 9 bits. The
address maps to 12.66.23. The trailing 0 bits should not be
specified. The network number here is different from that
described in netmasks(4). For this example, the entry in
netmasks would be 24.132.46.0fffffe00.
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