ENDNETENT(3P) POSIX Programmer's Manual ENDNETENT(3P)PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the corresponding
Linux manual page for details of Linux behavior), or the interface may
not be implemented on Linux.
endnetent, getnetbyaddr, getnetbyname, getnetent, setnetent — network
struct netent *getnetbyaddr(uint32_t net, int type);
struct netent *getnetbyname(const char *name);
struct netent *getnetent(void);
void setnetent(int stayopen);
These functions shall retrieve information about networks. This infor‐
mation is considered to be stored in a database that can be accessed
sequentially or randomly. The implementation of this database is
The setnetent() function shall open and rewind the database. If the
stayopen argument is non-zero, the connection to the net database shall
not be closed after each call to getnetent() (either directly, or indi‐
rectly through one of the other getnet*() functions), and the implemen‐
tation may maintain an open file descriptor to the database.
The getnetent() function shall read the next entry of the database,
opening and closing a connection to the database as necessary.
The getnetbyaddr() function shall search the database from the begin‐
ning, and find the first entry for which the address family specified
by type matches the n_addrtype member and the network number net
matches the n_net member, opening and closing a connection to the data‐
base as necessary. The net argument shall be the network number in
host byte order.
The getnetbyname() function shall search the database from the begin‐
ning and find the first entry for which the network name specified by
name matches the n_name member, opening and closing a connection to the
database as necessary.
The getnetbyaddr(), getnetbyname(), and getnetent() functions shall
each return a pointer to a netent structure, the members of which shall
contain the fields of an entry in the network database.
The endnetent() function shall close the database, releasing any open
These functions need not be thread-safe.
Upon successful completion, getnetbyaddr(), getnetbyname(), and getne‐
tent() shall return a pointer to a netent structure if the requested
entry was found, and a null pointer if the end of the database was
reached or the requested entry was not found. Otherwise, a null
pointer shall be returned.
The application shall not modify the structure to which the return
value points, nor any storage areas pointed to by pointers within the
structure. The returned pointer, and pointers within the structure,
might be invalidated or the structure or the storage areas might be
overwritten by a subsequent call to getnetbyaddr(), getnetbyname(), or
No errors are defined.
The following sections are informative.
The Base Definitions volume of POSIX.1‐2008, <netdb.h>
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
cal and Electronics Engineers, Inc and The Open Group. (This is
POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the source
files to man page format. To report such errors, see https://www.ker‐
IEEE/The Open Group 2013 ENDNETENT(3P)