freebsd-dev/etc/rc.firewall

############
# Setup system for firewall service.
# $FreeBSD$

# Suck in the configuration variables.
if [ -r /etc/defaults/rc.conf ]; then
	. /etc/defaults/rc.conf
elif [ -r /etc/rc.conf ]; then
	. /etc/rc.conf
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
#	Brent Chapman and Elizabeth Zwicky
#
#	O'Reilly & Associates, Inc
#	ISBN 1-56592-124-0
#	http://www.ora.com/
#
# 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 0-201-6337-4
#	http://www.awl.com/
#

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

############
# These rules are required for using natd.  All packets are passed to
# natd before they encounter your remaining rules.  The firewall rules
# will then be run again on each packet after translation by natd,
# minus any divert rules (see natd(8)).
#
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

############
# 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

############
# 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


# Prototype setups.
#
case ${firewall_type} in
[Oo][Pp][Ee][Nn])
	${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="192.168.4.0"
	mask="255.255.255.0"
	ip="192.168.4.17"

	# 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 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 any 53 to ${ip}
	${fwcmd} add pass udp from ${ip} to any 53

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

	# 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 named server 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="192.168.4.0"
	omask="255.255.255.0"
	oip="192.168.4.17"

	# set these to your inside interface network and netmask and ip
	iif="ed1"
	inet="192.168.3.0"
	imask="255.255.255.0"
	iip="192.168.3.17"

	# 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 192.168.0.0:255.255.0.0 to any via ${oif}
	${fwcmd} add deny all from any to 192.168.0.0:255.255.0.0 via ${oif}
	${fwcmd} add deny all from 172.16.0.0:255.240.0.0 to any via ${oif}
	${fwcmd} add deny all from any to 172.16.0.0:255.240.0.0 via ${oif}
	${fwcmd} add deny all from 10.0.0.0:255.0.0.0 to any via ${oif}
	${fwcmd} add deny all from any to 10.0.0.0:255.0.0.0 via ${oif}

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

	# 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

	# 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 any 53 to ${oip}
	${fwcmd} add pass udp from ${oip} to any 53

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

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

[Uu][Nn][Kk][Nn][Oo][Ww][Nn])
	;;
*)
	if [ -r "${firewall_type}" ]; then
		${fwcmd} ${firewall_type}
	fi
	;;
esac