'\" t .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) .\" .\" SPDX-License-Identifier: Linux-man-pages-copyleft .\" .\" References consulted: .\" Linux libc source code .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) .\" 386BSD man pages .\" Modified Sat Jul 24 21:48:06 1993 by Rik Faith (faith@cs.unc.edu) .TH getnetent 3 2024-05-02 "Linux man-pages 6.9.1" .SH NAME getnetent, getnetbyname, getnetbyaddr, setnetent, endnetent \- get network entry .SH LIBRARY Standard C library .RI ( libc ", " \-lc ) .SH SYNOPSIS .nf .B #include .P .B struct netent *getnetent(void); .P .BI "struct netent *getnetbyname(const char *" name ); .BI "struct netent *getnetbyaddr(uint32_t " net ", int " type ); .P .BI "void setnetent(int " stayopen ); .B void endnetent(void); .fi .SH DESCRIPTION The .BR getnetent () function reads the next entry from the networks database and returns a .I netent structure containing the broken-out fields from the entry. A connection is opened to the database if necessary. .P The .BR getnetbyname () function returns a .I netent structure for the entry from the database that matches the network .IR name . .P The .BR getnetbyaddr () function returns a .I netent structure for the entry from the database that matches the network number .I net of type .IR type . The .I net argument must be in host byte order. .P The .BR setnetent () function opens a connection to the database, and sets the next entry to the first entry. If .I stayopen is nonzero, then the connection to the database will not be closed between calls to one of the .BR getnet* () functions. .P The .BR endnetent () function closes the connection to the database. .P The .I netent structure is defined in .I as follows: .P .in +4n .EX 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 */ } .EE .in .P The members of the .I netent structure are: .TP .I n_name The official name of the network. .TP .I n_aliases A NULL-terminated list of alternative names for the network. .TP .I n_addrtype The type of the network number; always .BR AF_INET . .TP .I n_net The network number in host byte order. .SH RETURN VALUE The .BR getnetent (), .BR getnetbyname (), and .BR getnetbyaddr () functions return a pointer to a statically allocated .I netent structure, or a null pointer if an error occurs or the end of the file is reached. .SH FILES .TP .I /etc/networks networks database file .SH ATTRIBUTES For an explanation of the terms used in this section, see .BR attributes (7). .TS allbox; lb lb lbx l l l. Interface Attribute Value T{ .na .nh .BR getnetent () T} Thread safety T{ .na .nh MT-Unsafe race:netent race:netentbuf env locale T} T{ .na .nh .BR getnetbyname () T} Thread safety T{ .na .nh MT-Unsafe race:netbyname env locale T} T{ .na .nh .BR getnetbyaddr () T} Thread safety T{ .na .nh MT-Unsafe race:netbyaddr locale T} T{ .na .nh .BR setnetent (), .BR endnetent () T} Thread safety T{ .na .nh MT-Unsafe race:netent env locale T} .TE .P In the above table, .I netent in .I race:netent signifies that if any of the functions .BR setnetent (), .BR getnetent (), or .BR endnetent () are used in parallel in different threads of a program, then data races could occur. .SH STANDARDS POSIX.1-2008. .SH HISTORY POSIX.1-2001, 4.3BSD. .P Before glibc 2.2, the .I net argument of .BR getnetbyaddr () was of type .IR long . .SH SEE ALSO .BR getnetent_r (3), .BR getprotoent (3), .BR getservent (3) .\" .BR networks (5) .br RFC\ 1101