407 lines
13 KiB
Bash
407 lines
13 KiB
Bash
#!/bin/sh -
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# Copyright (c) 1996 Poul-Henning Kamp
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# All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions
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# are met:
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# 1. Redistributions of source code must retain the above copyright
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# notice, this list of conditions and the following disclaimer.
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# 2. Redistributions in binary form must reproduce the above copyright
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# notice, this list of conditions and the following disclaimer in the
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# documentation and/or other materials provided with the distribution.
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#
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# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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# ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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# SUCH DAMAGE.
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#
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# $FreeBSD$
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#
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#
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# Setup system for ipfw(4) firewall service.
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#
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# Suck in the configuration variables.
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if [ -z "${source_rc_confs_defined}" ]; then
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if [ -r /etc/defaults/rc.conf ]; then
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. /etc/defaults/rc.conf
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source_rc_confs
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elif [ -r /etc/rc.conf ]; then
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. /etc/rc.conf
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fi
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fi
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############
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# Define the firewall type in /etc/rc.conf. Valid values are:
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# open - will allow anyone in
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# client - will try to protect just this machine
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# simple - will try to protect a whole network
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# closed - totally disables IP services except via lo0 interface
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# workstation - will try to protect just this machine using statefull
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# firewalling. See below for rc.conf variables used
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# UNKNOWN - disables the loading of firewall rules.
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# filename - will load the rules in the given filename (full path required)
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#
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# For ``client'' and ``simple'' the entries below should be customized
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# appropriately.
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############
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#
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# If you don't know enough about packet filtering, we suggest that you
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# take time to read this book:
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#
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# Building Internet Firewalls, 2nd Edition
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# Brent Chapman and Elizabeth Zwicky
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#
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# O'Reilly & Associates, Inc
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# ISBN 1-56592-871-7
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# http://www.ora.com/
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# http://www.oreilly.com/catalog/fire2/
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#
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# For a more advanced treatment of Internet Security read:
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#
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# Firewalls and Internet Security: Repelling the Wily Hacker, 2nd Edition
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# William R. Cheswick, Steven M. Bellowin, Aviel D. Rubin
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#
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# Addison-Wesley / Prentice Hall
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# ISBN 0-201-63466-X
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# http://www.pearsonhighered.com/
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# http://www.pearsonhighered.com/educator/academic/product/0,3110,020163466X,00.html
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#
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setup_loopback () {
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############
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# Only in rare cases do you want to change these rules
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#
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${fwcmd} add 100 pass all from any to any via lo0
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${fwcmd} add 200 deny all from any to 127.0.0.0/8
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${fwcmd} add 300 deny ip from 127.0.0.0/8 to any
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}
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if [ -n "${1}" ]; then
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firewall_type="${1}"
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fi
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############
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# Set quiet mode if requested
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#
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case ${firewall_quiet} in
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[Yy][Ee][Ss])
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fwcmd="/sbin/ipfw -q"
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;;
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*)
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fwcmd="/sbin/ipfw"
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;;
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esac
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############
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# Flush out the list before we begin.
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#
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${fwcmd} -f flush
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setup_loopback
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############
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# Network Address Translation. All packets are passed to natd(8)
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# before they encounter your remaining rules. The firewall rules
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# will then be run again on each packet after translation by natd
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# starting at the rule number following the divert rule.
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#
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# For ``simple'' firewall type the divert rule should be put to a
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# different place to not interfere with address-checking rules.
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#
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case ${firewall_type} in
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[Oo][Pp][Ee][Nn]|[Cc][Ll][Ii][Ee][Nn][Tt])
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case ${natd_enable} in
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[Yy][Ee][Ss])
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if [ -n "${natd_interface}" ]; then
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${fwcmd} add 50 divert natd ip4 from any to any via ${natd_interface}
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fi
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;;
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esac
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case ${firewall_nat_enable} in
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[Yy][Ee][Ss])
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if [ -n "${firewall_nat_interface}" ]; then
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if echo "${firewall_nat_interface}" | \
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grep -q -E '^[0-9]+(\.[0-9]+){0,3}$'; then
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firewall_nat_flags="ip ${firewall_nat_interface} ${firewall_nat_flags}"
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else
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firewall_nat_flags="if ${firewall_nat_interface} ${firewall_nat_flags}"
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fi
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${fwcmd} nat 123 config log ${firewall_nat_flags}
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${fwcmd} add 50 nat 123 ip4 from any to any via ${firewall_nat_interface}
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fi
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;;
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esac
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esac
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############
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# If you just configured ipfw in the kernel as a tool to solve network
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# problems or you just want to disallow some particular kinds of traffic
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# then you will want to change the default policy to open. You can also
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# do this as your only action by setting the firewall_type to ``open''.
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#
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# ${fwcmd} add 65000 pass all from any to any
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# Prototype setups.
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#
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case ${firewall_type} in
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[Oo][Pp][Ee][Nn])
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${fwcmd} add 65000 pass all from any to any
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;;
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[Cc][Ll][Ii][Ee][Nn][Tt])
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############
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# This is a prototype setup that will protect your system somewhat
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# against people from outside your own network.
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############
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# set these to your network and netmask and ip
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net="192.0.2.0"
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mask="255.255.255.0"
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# Allow limited broadcast traffic from my own net.
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${fwcmd} add pass all from ${net}:${mask} to 255.255.255.255
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# Allow any traffic to or from my own net.
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${fwcmd} add pass all from me to ${net}:${mask}
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${fwcmd} add pass all from ${net}:${mask} to me
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# Allow TCP through if setup succeeded
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${fwcmd} add pass tcp from any to any established
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# Allow IP fragments to pass through
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${fwcmd} add pass all from any to any frag
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# Allow setup of incoming email
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${fwcmd} add pass tcp from any to me 25 setup
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# Allow setup of outgoing TCP connections only
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${fwcmd} add pass tcp from me to any setup
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# Disallow setup of all other TCP connections
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${fwcmd} add deny tcp from any to any setup
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# Allow DNS queries out in the world
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${fwcmd} add pass udp from me to any 53 keep-state
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# Allow NTP queries out in the world
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${fwcmd} add pass udp from me to any 123 keep-state
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# Everything else is denied by default, unless the
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# IPFIREWALL_DEFAULT_TO_ACCEPT option is set in your kernel
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# config file.
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;;
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[Ss][Ii][Mm][Pp][Ll][Ee])
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############
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# This is a prototype setup for a simple firewall. Configure this
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# machine as a DNS and NTP server, and point all the machines
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# on the inside at this machine for those services.
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############
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# set these to your outside interface network and netmask and ip
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oif="ed0"
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onet="192.0.2.0"
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omask="255.255.255.240"
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# set these to your inside interface network and netmask and ip
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iif="ed1"
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inet="192.0.2.16"
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imask="255.255.255.240"
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# Stop spoofing
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${fwcmd} add deny all from ${inet}:${imask} to any in via ${oif}
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${fwcmd} add deny all from ${onet}:${omask} to any in via ${iif}
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# Stop RFC1918 nets on the outside interface
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${fwcmd} add deny all from any to 10.0.0.0/8 via ${oif}
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${fwcmd} add deny all from any to 172.16.0.0/12 via ${oif}
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${fwcmd} add deny all from any to 192.168.0.0/16 via ${oif}
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# Stop draft-manning-dsua-03.txt (1 May 2000) nets (includes RESERVED-1,
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# DHCP auto-configuration, NET-TEST, MULTICAST (class D), and class E)
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# on the outside interface
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${fwcmd} add deny all from any to 0.0.0.0/8 via ${oif}
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${fwcmd} add deny all from any to 169.254.0.0/16 via ${oif}
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${fwcmd} add deny all from any to 192.0.2.0/24 via ${oif}
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${fwcmd} add deny all from any to 224.0.0.0/4 via ${oif}
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${fwcmd} add deny all from any to 240.0.0.0/4 via ${oif}
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# Network Address Translation. This rule is placed here deliberately
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# so that it does not interfere with the surrounding address-checking
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# rules. If for example one of your internal LAN machines had its IP
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# address set to 192.0.2.1 then an incoming packet for it after being
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# translated by natd(8) would match the `deny' rule above. Similarly
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# an outgoing packet originated from it before being translated would
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# match the `deny' rule below.
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case ${natd_enable} in
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[Yy][Ee][Ss])
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if [ -n "${natd_interface}" ]; then
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${fwcmd} add divert natd all from any to any via ${natd_interface}
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fi
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;;
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esac
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# Stop RFC1918 nets on the outside interface
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${fwcmd} add deny all from 10.0.0.0/8 to any via ${oif}
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${fwcmd} add deny all from 172.16.0.0/12 to any via ${oif}
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${fwcmd} add deny all from 192.168.0.0/16 to any via ${oif}
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# Stop draft-manning-dsua-03.txt (1 May 2000) nets (includes RESERVED-1,
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# DHCP auto-configuration, NET-TEST, MULTICAST (class D), and class E)
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# on the outside interface
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${fwcmd} add deny all from 0.0.0.0/8 to any via ${oif}
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${fwcmd} add deny all from 169.254.0.0/16 to any via ${oif}
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${fwcmd} add deny all from 192.0.2.0/24 to any via ${oif}
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${fwcmd} add deny all from 224.0.0.0/4 to any via ${oif}
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${fwcmd} add deny all from 240.0.0.0/4 to any via ${oif}
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# Allow TCP through if setup succeeded
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${fwcmd} add pass tcp from any to any established
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# Allow IP fragments to pass through
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${fwcmd} add pass all from any to any frag
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# Allow setup of incoming email
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${fwcmd} add pass tcp from any to me 25 setup
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# Allow access to our DNS
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${fwcmd} add pass tcp from any to me 53 setup
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${fwcmd} add pass udp from any to me 53
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${fwcmd} add pass udp from me 53 to any
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# Allow access to our WWW
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${fwcmd} add pass tcp from any to me 80 setup
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# Reject&Log all setup of incoming connections from the outside
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${fwcmd} add deny log tcp from any to any in via ${oif} setup
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# Allow setup of any other TCP connection
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${fwcmd} add pass tcp from any to any setup
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# Allow DNS queries out in the world
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${fwcmd} add pass udp from me to any 53 keep-state
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# Allow NTP queries out in the world
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${fwcmd} add pass udp from me to any 123 keep-state
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# Everything else is denied by default, unless the
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# IPFIREWALL_DEFAULT_TO_ACCEPT option is set in your kernel
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# config file.
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;;
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[Ww][Oo][Rr][Kk][Ss][Tt][Aa][Tt][Ii][Oo][Nn])
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# Configuration:
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# firewall_myservices: List of TCP ports on which this host
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# offers services.
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# firewall_allowservices: List of IPs which has access to
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# $firewall_myservices.
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# firewall_trusted: List of IPs which has full access
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# to this host. Be very carefull
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# when setting this. This option can
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# seriously degrade the level of
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# protection provided by the firewall.
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# firewall_logdeny: Boolean (YES/NO) specifying if the
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# default denied packets should be
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# logged (in /var/log/security).
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# firewall_nologports: List of TCP/UDP ports for which
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# denied incomming packets are not
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# logged.
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# Allow packets for which a state has been built.
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${fwcmd} add check-state
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# For services permitted below.
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${fwcmd} add pass tcp from me to any established
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# Allow any connection out, adding state for each.
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${fwcmd} add pass tcp from me to any setup keep-state
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${fwcmd} add pass udp from me to any keep-state
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${fwcmd} add pass icmp from me to any keep-state
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# Allow DHCP.
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${fwcmd} add pass udp from 0.0.0.0 68 to 255.255.255.255 67 out
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${fwcmd} add pass udp from any 67 to me 68 in
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${fwcmd} add pass udp from any 67 to 255.255.255.255 68 in
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# Some servers will ping the IP while trying to decide if it's
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# still in use.
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${fwcmd} add pass icmp from any to any icmptype 8
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# Allow "mandatory" ICMP in.
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${fwcmd} add pass icmp from any to any icmptype 3,4,11
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# Add permits for this workstations published services below
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# Only IPs and nets in firewall_allowservices is allowed in.
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# If you really wish to let anyone use services on your
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# workstation, then set "firewall_allowservices='any'" in /etc/rc.conf
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#
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# Note: We don't use keep-state as that would allow DoS of
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# our statetable.
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# You can add 'keep-state' to the lines for slightly
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# better performance if you fell that DoS of your
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# workstation won't be a problem.
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#
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for i in ${firewall_allowservices} ; do
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for j in ${firewall_myservices} ; do
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${fwcmd} add pass tcp from $i to me $j
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done
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done
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# Allow all connections from trusted IPs.
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# Playing with the content of firewall_trusted could seriously
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# degrade the level of protection provided by the firewall.
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for i in ${firewall_trusted} ; do
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${fwcmd} add pass ip from $i to me
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done
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${fwcmd} add 65000 count ip from any to any
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# Drop packets to ports where we don't want logging
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for i in ${firewall_nologports} ; do
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${fwcmd} add deny { tcp or udp } from any to any $i in
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done
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# Broadcasts and muticasts
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${fwcmd} add deny ip from any to 255.255.255.255
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${fwcmd} add deny ip from any to 224.0.0.0/24 in # XXX
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# Noise from routers
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${fwcmd} add deny udp from any to any 520 in
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# Noise from webbrowsing.
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# The statefull filter is a bit agressive, and will cause some
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# connection teardowns to be logged.
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${fwcmd} add deny tcp from any 80,443 to any 1024-65535 in
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# Deny and (if wanted) log the rest unconditionally.
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log=""
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if [ ${firewall_logdeny:-x} = "YES" -o ${firewall_logdeny:-x} = "yes" ] ; then
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log="log logamount 500" # The default of 100 is too low.
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sysctl net.inet.ip.fw.verbose=1 >/dev/null
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fi
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${fwcmd} add deny $log ip from any to any
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;;
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[Cc][Ll][Oo][Ss][Ee][Dd])
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${fwcmd} add 65000 deny ip from any to any
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;;
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[Uu][Nn][Kk][Nn][Oo][Ww][Nn])
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;;
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*)
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if [ -r "${firewall_type}" ]; then
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${fwcmd} ${firewall_flags} ${firewall_type}
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fi
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;;
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esac
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