ff2f6fe80f
With the second (and last) part of my previous Summer of Code work, we get: -ipfw's in kernel nat -redirect_* and LSNAT support General information about nat syntax and some examples are available in the ipfw (8) man page. The redirect and LSNAT syntax are identical to natd, so please refer to natd (8) man page. To enable in kernel nat in rc.conf, two options were added: o firewall_nat_enable: equivalent to natd_enable o firewall_nat_interface: equivalent to natd_interface Remember to set net.inet.ip.fw.one_pass to 0, if you want the packet to continue being checked by the firewall ruleset after being (de)aliased. NOTA BENE: due to some problems with libalias architecture, in kernel nat won't work with TSO enabled nic, thus you have to disable TSO via ifconfig (ifconfig foo0 -tso). Approved by: glebius (mentor)
402 lines
13 KiB
Bash
402 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 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 & Internet Security
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# Repelling the wily hacker
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# William R. Cheswick, Steven M. Bellowin
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#
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# Addison-Wesley
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# ISBN 0-201-63357-4
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# http://www.awl.com/
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# http://www.awlonline.com/product/0%2C2627%2C0201633574%2C00.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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${fwcmd} nat 123 config if ${firewall_nat_interface} log
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${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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ip="192.0.2.1"
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# Allow any traffic to or from my own net.
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${fwcmd} add pass all from ${ip} to ${net}:${mask}
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${fwcmd} add pass all from ${net}:${mask} to ${ip}
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# Allow TCP through if setup succeeded
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${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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oip="192.0.2.1"
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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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iip="192.0.2.17"
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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 ${oip} 25 setup
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# Allow access to our DNS
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${fwcmd} add pass tcp from any to ${oip} 53 setup
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${fwcmd} add pass udp from any to ${oip} 53
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${fwcmd} add pass udp from ${oip} 53 to any
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# Allow access to our WWW
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${fwcmd} add pass tcp from any to ${oip} 80 setup
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# Reject&Log all setup of incoming connections from the outside
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${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 ${oip} to any 53 keep-state
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# Allow NTP queries out in the world
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${fwcmd} add pass udp from ${oip} 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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