GETNETENT(3) BSD Library Functions Manual GETNETENT(3)
NAME
getnetent, getnetbyaddr, getnetbyname, setnetent, endnetent - get network
entry
SYNOPSIS
#include <netdb.h>
struct netent *
getnetent(void);
struct netent *
getnetbyname(char *name);
struct netent *
getnetbyaddr(in_addr_t net, int type);
void
setnetent(int stayopen);
void
endnetent(void);
DESCRIPTION
The getnetent(), getnetbyname(), and getnetbyaddr() functions each return
a pointer to an object with the following structure containing the bro-
ken-out fields of a line in the network database, /etc/networks.
struct netent {
char *n_name; /* official name of net */
char **n_aliases; /* alias list */
int n_addrtype; /* net number type */
in_addr_t n_net; /* net number */
};
The members of this structure are:
n_name The official name of the network.
n_aliases A zero-terminated list of alternate names for the network.
n_addrtype The type of the network number returned; currently only
AF_INET.
n_net The network number. Network numbers are returned in machine
byte order.
The getnetent() function reads the next line of the file, opening the
file if necessary.
The setnetent() function opens and rewinds the file. If the stayopen
flag is non-zero, the net database will not be closed after each call to
getnetbyname() or getnetbyaddr().
The endnetent() function closes the file.
The getnetbyname() and getnetbyaddr() functions search the domain name
server if the system is configured to use one. If the search fails, or
no name server is configured, they sequentially search from the beginning
of the file until a matching net name or net address and type is found,
or until EOF is encountered. Network numbers are supplied in host order.
FILES
/etc/networks
DIAGNOSTICS
Null pointer (0) returned on EOF or error.
SEE ALSO
resolver(3), networks(5)
HISTORY
The getnetent(), getnetbyaddr(), getnetbyname(), setnetent(), and
endnetent() functions appeared in 4.2BSD.
BUGS
The data space used by these functions is static; if future use requires
the data, it should be copied before any subsequent calls to these func-
tions overwrite it. Only Internet network numbers are currently under-
stood. Expecting network numbers to fit in no more than 32 bits is
naive.
BSD March 13, 1997 BSD
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