--- /dev/null
+# ===========================================================================
+# http://www.gnu.org/software/autoconf-archive/ax_lib_socket_nsl.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+# AX_LIB_SOCKET_NSL
+#
+# DESCRIPTION
+#
+# This macro figures out what libraries are required on this platform to
+# link sockets programs.
+#
+# The common cases are not to need any extra libraries, or to need
+# -lsocket and -lnsl. We need to avoid linking with libnsl unless we need
+# it, though, since on some OSes where it isn't necessary it will totally
+# break networking. Unisys also includes gethostbyname() in libsocket but
+# needs libnsl for socket().
+#
+# LICENSE
+#
+# Copyright (c) 2008 Russ Allbery <rra@stanford.edu>
+# Copyright (c) 2008 Stepan Kasal <kasal@ucw.cz>
+# Copyright (c) 2008 Warren Young <warren@etr-usa.com>
+#
+# Copying and distribution of this file, with or without modification, are
+# permitted in any medium without royalty provided the copyright notice
+# and this notice are preserved. This file is offered as-is, without any
+# warranty.
+
+#serial 6
+
+AU_ALIAS([LIB_SOCKET_NSL], [AX_LIB_SOCKET_NSL])
+AC_DEFUN([AX_LIB_SOCKET_NSL],
+[
+ AC_SEARCH_LIBS([gethostbyname], [nsl])
+ AC_SEARCH_LIBS([socket], [socket], [], [
+ AC_CHECK_LIB([socket], [socket], [LIBS="-lsocket -lnsl $LIBS"],
+ [], [-lnsl])])
+])