HardenedBSD/etc/rc.firewall

#!/bin/sh -
# Copyright (c) 1996  Poul-Henning Kamp
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
#
# $FreeBSD$
#

#
# Setup system for firewall service.
#

# Suck in the configuration variables.
if [ -z "${source_rc_confs_defined}" ]; then
	if [ -r /etc/defaults/rc.conf ]; then
		. /etc/defaults/rc.conf
		source_rc_confs
	elif [ -r /etc/rc.conf ]; then
		. /etc/rc.conf
	fi
fi

############
# Define the firewall type in /etc/rc.conf.  Valid values are:
#   open     - will allow anyone in
#   client   - will try to protect just this machine
#   simple   - will try to protect a whole network
#   closed   - totally disables IP services except via lo0 interface
#   UNKNOWN  - disables the loading of firewall rules.
#   filename - will load the rules in the given filename (full path required)
#
# For ``client'' and ``simple'' the entries below should be customized
# appropriately.

############
#
# If you don't know enough about packet filtering, we suggest that you
# take time to read this book:
#
#	Building Internet Firewalls, 2nd Edition
#	Brent Chapman and Elizabeth Zwicky
#
#	O'Reilly & Associates, Inc
#	ISBN 1-56592-871-7
#	http://www.ora.com/
#	http://www.oreilly.com/catalog/fire2/
#
# For a more advanced treatment of Internet Security read:
#
#	Firewalls & Internet Security
#	Repelling the wily hacker
#	William R. Cheswick, Steven M. Bellowin
#
#	Addison-Wesley
#	ISBN 0-201-63357-4
#	http://www.awl.com/
#	http://www.awlonline.com/product/0%2C2627%2C0201633574%2C00.html
#

setup_loopback () {
	############
	# Only in rare cases do you want to change these rules
	#
	${fwcmd} add 100 pass all from any to any via lo0
	${fwcmd} add 200 deny all from any to 127.0.0.0/8
	${fwcmd} add 300 deny ip from 127.0.0.0/8 to any
}

if [ -n "${1}" ]; then
	firewall_type="${1}"
fi

############
# Set quiet mode if requested
#
case ${firewall_quiet} in
[Yy][Ee][Ss])
	fwcmd="/sbin/ipfw -q"
	;;
*)
	fwcmd="/sbin/ipfw"
	;;
esac

############
# Flush out the list before we begin.
#
${fwcmd} -f flush

############
# Network Address Translation.  All packets are passed to natd(8)
# before they encounter your remaining rules.  The firewall rules
# will then be run again on each packet after translation by natd
# starting at the rule number following the divert rule.
#
# For ``simple'' firewall type the divert rule should be put to a
# different place to not interfere with address-checking rules.
#
case ${firewall_type} in
[Oo][Pp][Ee][Nn]|[Cc][Ll][Ii][Ee][Nn][Tt])
	case ${natd_enable} in
	[Yy][Ee][Ss])
		if [ -n "${natd_interface}" ]; then
			${fwcmd} add 50 divert natd all from any to any via ${natd_interface}
		fi
		;;
	esac
esac

############
# If you just configured ipfw in the kernel as a tool to solve network
# problems or you just want to disallow some particular kinds of traffic
# then you will want to change the default policy to open.  You can also
# do this as your only action by setting the firewall_type to ``open''.
#
# ${fwcmd} add 65000 pass all from any to any


# Prototype setups.
#
case ${firewall_type} in
[Oo][Pp][Ee][Nn])
	setup_loopback
	${fwcmd} add 65000 pass all from any to any
	;;

[Cc][Ll][Ii][Ee][Nn][Tt])
	############
	# This is a prototype setup that will protect your system somewhat
	# against people from outside your own network.
	############

	# set these to your network and netmask and ip
	net="192.0.2.0"
	mask="255.255.255.0"
	ip="192.0.2.1"

	setup_loopback

	# Allow any traffic to or from my own net.
	${fwcmd} add pass all from ${ip} to ${net}:${mask}
	${fwcmd} add pass all from ${net}:${mask} to ${ip}

	# Allow TCP through if setup succeeded
	${fwcmd} add pass tcp from any to any established

	# Allow IP fragments to pass through
	${fwcmd} add pass all from any to any frag

	# Allow setup of incoming email
	${fwcmd} add pass tcp from any to ${ip} 25 setup

	# Allow setup of outgoing TCP connections only
	${fwcmd} add pass tcp from ${ip} to any setup

	# Disallow setup of all other TCP connections
	${fwcmd} add deny tcp from any to any setup

	# Allow DNS queries out in the world
	${fwcmd} add pass udp from ${ip} to any 53 keep-state

	# Allow NTP queries out in the world
	${fwcmd} add pass udp from ${ip} to any 123 keep-state

	# Everything else is denied by default, unless the
	# IPFIREWALL_DEFAULT_TO_ACCEPT option is set in your kernel
	# config file.
	;;

[Ss][Ii][Mm][Pp][Ll][Ee])
	############
	# This is a prototype setup for a simple firewall.  Configure this
	# machine as a DNS and NTP server, and point all the machines
	# on the inside at this machine for those services.
	############

	# set these to your outside interface network and netmask and ip
	oif="ed0"
	onet="192.0.2.0"
	omask="255.255.255.240"
	oip="192.0.2.1"

	# set these to your inside interface network and netmask and ip
	iif="ed1"
	inet="192.0.2.16"
	imask="255.255.255.240"
	iip="192.0.2.17"

	setup_loopback

	# Stop spoofing
	${fwcmd} add deny all from ${inet}:${imask} to any in via ${oif}
	${fwcmd} add deny all from ${onet}:${omask} to any in via ${iif}

	# Stop RFC1918 nets on the outside interface
	${fwcmd} add deny all from any to 10.0.0.0/8 via ${oif}
	${fwcmd} add deny all from any to 172.16.0.0/12 via ${oif}
	${fwcmd} add deny all from any to 192.168.0.0/16 via ${oif}

	# Stop draft-manning-dsua-03.txt (1 May 2000) nets (includes RESERVED-1,
	# DHCP auto-configuration, NET-TEST, MULTICAST (class D), and class E)
	# on the outside interface
	${fwcmd} add deny all from any to 0.0.0.0/8 via ${oif}
	${fwcmd} add deny all from any to 169.254.0.0/16 via ${oif}
	${fwcmd} add deny all from any to 192.0.2.0/24 via ${oif}
	${fwcmd} add deny all from any to 224.0.0.0/4 via ${oif}
	${fwcmd} add deny all from any to 240.0.0.0/4 via ${oif}

	# Network Address Translation.  This rule is placed here deliberately
	# so that it does not interfere with the surrounding address-checking
	# rules.  If for example one of your internal LAN machines had its IP
	# address set to 192.0.2.1 then an incoming packet for it after being
	# translated by natd(8) would match the `deny' rule above.  Similarly
	# an outgoing packet originated from it before being translated would
	# match the `deny' rule below.
	case ${natd_enable} in
	[Yy][Ee][Ss])
		if [ -n "${natd_interface}" ]; then
			${fwcmd} add divert natd all from any to any via ${natd_interface}
		fi
		;;
	esac

	# Stop RFC1918 nets on the outside interface
	${fwcmd} add deny all from 10.0.0.0/8 to any via ${oif}
	${fwcmd} add deny all from 172.16.0.0/12 to any via ${oif}
	${fwcmd} add deny all from 192.168.0.0/16 to any via ${oif}

	# Stop draft-manning-dsua-03.txt (1 May 2000) nets (includes RESERVED-1,
	# DHCP auto-configuration, NET-TEST, MULTICAST (class D), and class E)
	# on the outside interface
	${fwcmd} add deny all from 0.0.0.0/8 to any via ${oif}
	${fwcmd} add deny all from 169.254.0.0/16 to any via ${oif}
	${fwcmd} add deny all from 192.0.2.0/24 to any via ${oif}
	${fwcmd} add deny all from 224.0.0.0/4 to any via ${oif}
	${fwcmd} add deny all from 240.0.0.0/4 to any via ${oif}

	# Allow TCP through if setup succeeded
	${fwcmd} add pass tcp from any to any established

	# Allow IP fragments to pass through
	${fwcmd} add pass all from any to any frag

	# Allow setup of incoming email
	${fwcmd} add pass tcp from any to ${oip} 25 setup

	# Allow access to our DNS
	${fwcmd} add pass tcp from any to ${oip} 53 setup
	${fwcmd} add pass udp from any to ${oip} 53
	${fwcmd} add pass udp from ${oip} 53 to any

	# Allow access to our WWW
	${fwcmd} add pass tcp from any to ${oip} 80 setup

	# Reject&Log all setup of incoming connections from the outside
	${fwcmd} add deny log tcp from any to any in via ${oif} setup

	# Allow setup of any other TCP connection
	${fwcmd} add pass tcp from any to any setup

	# Allow DNS queries out in the world
	${fwcmd} add pass udp from ${oip} to any 53 keep-state

	# Allow NTP queries out in the world
	${fwcmd} add pass udp from ${oip} to any 123 keep-state

	# Everything else is denied by default, unless the
	# IPFIREWALL_DEFAULT_TO_ACCEPT option is set in your kernel
	# config file.
	;;

[Cc][Ll][Oo][Ss][Ee][Dd])
	setup_loopback
	;;
[Uu][Nn][Kk][Nn][Oo][Ww][Nn])
	;;
*)
	if [ -r "${firewall_type}" ]; then
		${fwcmd} ${firewall_flags} ${firewall_type}
	fi
	;;
esac