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[FreeBSD/FreeBSD.git] / 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
#   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
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