freebsd-src/etc/rc.firewall

############
# Setup system for firewall service.
# $Id: rc.firewall,v 1.18 1998/04/18 10:27:05 brian Exp $

if [ -f /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 [ "x$1" != "x" ]; then
	firewall_type=$1
fi

############
# Set quiet mode if requested
if [ "x$firewall_quiet" = "xYES" ]; then
	fwcmd="/sbin/ipfw -q"
else
	fwcmd="/sbin/ipfw"
fi

############
# 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)).
if [ "X${natd_enable}" = X"YES" -a "X${natd_interface}" != X"" ]; then
        $fwcmd add divert natd all from any to any via ${natd_interface}
fi

############
# 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
# they 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.
if [ "${firewall_type}" = "open" -o "${firewall_type}" = "OPEN" ]; then

	$fwcmd add 65000 pass all from any to any

elif [ "${firewall_type}" = "client" ]; then

    ############
    # 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 as default.

elif [ "${firewall_type}" = "simple" ]; then

    ############
    # 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 as default.

elif [ "${firewall_type}" != "UNKNOWN" -a -r "${firewall_type}" ]; then
	$fwcmd ${firewall_type}
fi