#!/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 ipfw(4) 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
# workstation - will try to protect just this machine using statefull
# firewalling. See below for rc.conf variables used
# 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
setup_loopback
############
# 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 ip4 from any to any via ${natd_interface}
fi
;;
esac
case ${firewall_nat_enable} in
[Yy][Ee][Ss])
if [ -n "${firewall_nat_interface}" ]; then
${fwcmd} nat 123 config if ${firewall_nat_interface} log
${fwcmd} add 50 nat 123 ip4 from any to any via ${firewall_nat_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])
${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"
# 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 me 25 setup
# Allow setup of outgoing TCP connections only
${fwcmd} add pass tcp from me 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 me to any 53 keep-state
# Allow NTP queries out in the world
${fwcmd} add pass udp from me 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"
# 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.
;;
[Ww][Oo][Rr][Kk][Ss][Tt][Aa][Tt][Ii][Oo][Nn])
# Configuration:
# firewall_myservices: List of TCP ports on which this host
# offers services.
# firewall_allowservices: List of IPs which has access to
# $firewall_myservices.
# firewall_trusted: List of IPs which has full access
# to this host. Be very carefull
# when setting this. This option can
# seriously degrade the level of
# protection provided by the firewall.
# firewall_logdeny: Boolean (YES/NO) specifying if the
# default denied packets should be
# logged (in /var/log/security).
# firewall_nologports: List of TCP/UDP ports for which
# denied incomming packets are not
# logged.
# Allow packets for which a state has been built.
${fwcmd} add check-state
# For services permitted below.
${fwcmd} add pass tcp from me to any established
# Allow any connection out, adding state for each.
${fwcmd} add pass tcp from me to any setup keep-state
${fwcmd} add pass udp from me to any keep-state
${fwcmd} add pass icmp from me to any keep-state
# Allow DHCP.
${fwcmd} add pass udp from 0.0.0.0 68 to 255.255.255.255 67 out
${fwcmd} add pass udp from any 67 to me 68 in
${fwcmd} add pass udp from any 67 to 255.255.255.255 68 in
# Some servers will ping the IP while trying to decide if it's
# still in use.
${fwcmd} add pass icmp from any to any icmptype 8
# Allow "mandatory" ICMP in.
${fwcmd} add pass icmp from any to any icmptype 3,4,11
# Add permits for this workstations published services below
# Only IPs and nets in firewall_allowservices is allowed in.
# If you really wish to let anyone use services on your
# workstation, then set "firewall_allowservices='any'" in /etc/rc.conf
#
# Note: We don't use keep-state as that would allow DoS of
# our statetable.
# You can add 'keep-state' to the lines for slightly
# better performance if you fell that DoS of your
# workstation won't be a problem.
#
for i in ${firewall_allowservices} ; do
for j in ${firewall_myservices} ; do
${fwcmd} add pass tcp from $i to me $j
done
done
# Allow all connections from trusted IPs.
# Playing with the content of firewall_trusted could seriously
# degrade the level of protection provided by the firewall.
for i in ${firewall_trusted} ; do
${fwcmd} add pass ip from $i to me
done
${fwcmd} add 65000 count ip from any to any
# Drop packets to ports where we don't want logging
for i in ${firewall_nologports} ; do
${fwcmd} add deny { tcp or udp } from any to any $i in
done
# Broadcasts and muticasts
${fwcmd} add deny ip from any to 255.255.255.255
${fwcmd} add deny ip from any to 224.0.0.0/24 in # XXX
# Noise from routers
${fwcmd} add deny udp from any to any 520 in
# Noise from webbrowsing.
# The statefull filter is a bit agressive, and will cause some
# connection teardowns to be logged.
${fwcmd} add deny tcp from any 80,443 to any 1024-65535 in
# Deny and (if wanted) log the rest unconditionally.
log=""
if [ ${firewall_logdeny:-x} = "YES" -o ${firewall_logdeny:-x} = "yes" ] ; then
log="log logamount 500" # The default of 100 is too low.
sysctl net.inet.ip.fw.verbose=1 >/dev/null
fi
${fwcmd} add deny $log ip from any to any
;;
[Cc][Ll][Oo][Ss][Ee][Dd])
${fwcmd} add 65000 deny ip from any to any
;;
[Uu][Nn][Kk][Nn][Oo][Ww][Nn])
;;
*)
if [ -r "${firewall_type}" ]; then
${fwcmd} ${firewall_flags} ${firewall_type}
fi
;;
esac
