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GETNETENT(3) Library Functions Manual GETNETENT(3)

getnetent, getnetbyaddr, getnetbyname, setnetent, endnetentget network entry

#include <netdb.h>

struct netent *

struct netent *
getnetbyname(const char *name);

struct netent *
getnetbyaddr(in_addr_t net, int type);

setnetent(int stayopen);


The (), getnetbyname(), and getnetbyaddr() functions each return a pointer to an object with the following structure containing the broken-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:

The official name of the network.
A null-terminated list of alternate names for the network.
The type of the network number returned; currently only AF_INET.
The network number. Network numbers are returned in machine byte order.

The () function reads the next line of the file, opening the file if necessary.

The () 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 () function closes the file.

The () and () 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.


Null pointer (0) returned on EOF or error.

resolver(3), networks(5)

The getnetent(), getnetbyaddr(), getnetbyname(), setnetent(), and endnetent() functions appeared in 4.2BSD.

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 functions overwrite it. Only Internet network numbers are currently understood. Expecting network numbers to fit in no more than 32 bits is naive.

June 5, 2013 OpenBSD-5.9