Add "dual dhclient" script, which can be specified as dhclient_program in

rc.conf in order to launch the base system dhclient for IPv4 and the ISC
dhcp client for IPv6.

I'm not sure if this will be useful to anyone else, but adding this trivial
port will simplify the configuration of IPv6 on Amazon EC2 instances.  I
hope this port becomes redundant in the future due to the base system
gaining support for IPv6 DHCP.

net/Makefile

@@ -119,6 +119,7 @@
     SUBDIR += dshell
     SUBDIR += dtcp
     SUBDIR += dtcpclient
+    SUBDIR += dual-dhclient
     SUBDIR += e169-stats
     SUBDIR += easysoap
     SUBDIR += echoping

net/dual-dhclient/Makefile

@@ -0,0 +1,25 @@
+# $FreeBSD$
+
+PORTNAME=	dual-dhclient
+PORTVERSION=	1.0
+CATEGORIES=	net
+MASTER_SITES=	# none
+DISTFILES=	# none
+EXTRACT_ONLY=	# none
+
+MAINTAINER=	cperciva@FreeBSD.org
+COMMENT=	Spawns dhclients for a dual-stack network
+
+LICENSE=	PD
+
+RUN_DEPENDS=	${LOCALBASE}/sbin/dhclient:net/isc-dhcp43-client
+
+NO_WRKSUBDIR=	yes
+NO_BUILD=	yes
+
+PLIST_FILES=	sbin/dual-dhclient
+
+do-install:
+	${INSTALL_SCRIPT} ${FILESDIR}/dual-dhclient ${STAGEDIR}${PREFIX}/sbin
+
+.include <bsd.port.mk>

net/dual-dhclient/files/dual-dhclient

@@ -0,0 +1,8 @@
+#!/bin/sh
+
+# $FreeBSD$
+
+# Public domain
+
+/sbin/dhclient "$@"
+/usr/local/sbin/dhclient -6 -nw -cf /dev/null "$@"

net/dual-dhclient/pkg-descr

@@ -0,0 +1,3 @@
+This port provides a script which spawns both /sbin/dhclient and
+/usr/local/sbin/dhclient -6; this simplifies the configuration needed to
+run DHCP on both protocols of a dual-stack network.

net/dual-dhclient/pkg-message

@@ -0,0 +1,4 @@
+To enable dual-stack DHCP, set
+  dhclient_program="/usr/local/sbin/dual-dhclient"
+in /etc/rc.conf (and make sure the appropriate ifconfig_* lines include
+DHCP or SYNCDHCP).