getnetent, getnetbyname, getnetbyaddr, setnetent, endnetent - get network entry
Standard C library (libc, -lc)
#include <netdb.h>
struct netent *getnetent(void);
struct netent *getnetbyname(const char *name);
struct netent *getnetbyaddr(uint32_t net, int type);
void setnetent(int stayopen);
void endnetent(void);
The getnetent() function reads the next entry from
the networks database and returns a netent structure containing
the broken-out fields from the entry. A connection is opened to the
database if necessary.
The getnetbyname() function returns a
netent structure for the entry from the database that matches
the network name.
The getnetbyaddr() function returns a
netent structure for the entry from the database that matches
the network number net of type type. The net
argument must be in host byte order.
The setnetent() function opens a connection to the
database, and sets the next entry to the first entry. If
stayopen is nonzero, then the connection to the database will
not be closed between calls to one of the getnet*()
functions.
The endnetent() function closes the connection to the database.
The netent structure is defined in <netdb.h>
as follows:
struct netent {
char *n_name; /* official network name */
char **n_aliases; /* alias list */
int n_addrtype; /* net address type */
uint32_t n_net; /* network number */
}
The members of the netent structure are:
n_nameThe official name of the network.
n_aliasesA NULL-terminated list of alternative names for the network.
n_addrtypeThe type of the network number; always AF_INET.
n_netThe network number in host byte order.
The getnetent(), getnetbyname(),
and getnetbyaddr() functions return a pointer to a
statically allocated netent structure, or a null pointer if an
error occurs or the end of the file is reached.
/etc/networksnetworks database file
For an explanation of the terms used in this section, see attributes(7).
| Interface | Attribute | Value |
| Thread safety | MT-Unsafe race:netent race:netentbuf env locale |
|
| Thread safety | MT-Unsafe race:netbyname env locale |
|
| Thread safety | MT-Unsafe race:netbyaddr locale |
|
| Thread safety | MT-Unsafe race:netent env locale |
In the above table, netent in race:netent signifies
that if any of the functions setnetent(),
getnetent(), or endnetent() are used
in parallel in different threads of a program, then data races could
occur.
POSIX.1-2008.
POSIX.1-2001, 4.3BSD.
Before glibc 2.2, the net argument of
getnetbyaddr() was of type long.
getnetent_r(3), getprotoent(3),
getservent(3)
RFC 1101