GETNETENT(3) BSD Library Functions Manual GETNETENT(3)NAME
getnetent, getnetbyaddr, getnetbyname, setnetent, endnetent — get network
entry
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <netdb.h>
struct netent *
getnetent();
struct netent *
getnetbyname(const char *name);
struct netent *
getnetbyaddr(uint32_t net, int type);
setnetent(int stayopen);
endnetent();
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 data base as described in
networks(5).
struct netent {
char *n_name; /* official name of net */
char **n_aliases; /* alias list */
int n_addrtype; /* net number type */
uint32_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 alternative 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 data base will not be closed after each call to
getnetbyname() or getnetbyaddr().
The endnetent() function closes the file.
The getnetbyname() function and getnetbyaddr() 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 ALSOnetworks(5), nsswitch.conf(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 prob‐
ably naive.
BSD May 8, 2004 BSD
