286cc6ca6a
draft-manning-dsua-01.txt.
Stop using public addresses as samples and use the recommended
192.0.2.0/24 netblock that has specifically been set aside for
documentation purposes.
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236 lines
6.7 KiB
Plaintext
236 lines
6.7 KiB
Plaintext
############
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# Setup system for firewall service.
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# $FreeBSD$
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# Suck in the configuration variables.
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if [ -r /etc/defaults/rc.conf ]; then
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. /etc/defaults/rc.conf
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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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############
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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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# 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
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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 1-56592-124-0
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# http://www.ora.com/
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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 0-201-6337-4
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# http://www.awl.com/
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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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############
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# These rules are required for using natd. All packets are passed to
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# natd 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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# minus any divert rules (see natd(8)).
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#
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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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############
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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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# ${fwcmd} add 65000 pass all from any to any
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############
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# Only in rare cases do you want to change these rules
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#
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${fwcmd} add 100 pass all from any to any via lo0
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${fwcmd} add 200 deny all from any to 127.0.0.0/8
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# If you're using 'options BRIDGE', uncomment the following line to pass ARP
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#${fwcmd} add 300 pass udp from 0.0.0.0 2054 to 0.0.0.0
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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 ${ip} 25 setup
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# Allow setup of outgoing TCP connections only
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${fwcmd} add pass tcp from ${ip} to any setup
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# Disallow setup of all other TCP connections
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${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 any 53 to ${ip}
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${fwcmd} add pass udp from ${ip} to any 53
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# Allow NTP queries out in the world
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${fwcmd} add pass udp from any 123 to ${ip}
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${fwcmd} add pass udp from ${ip} to any 123
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# Everything else is denied by default, unless the
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# IPFIREWALL_DEFAULT_TO_ACCEPT option is set in your kernel
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# config file.
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;;
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[Ss][Ii][Mm][Pp][Ll][Ee])
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############
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# This is a prototype setup for a simple firewall. Configure this
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# machine as a named server and ntp server, and point all the machines
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# on the inside at this machine for those services.
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############
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# set these to your outside interface network and netmask and ip
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oif="ed0"
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onet="192.0.2.0"
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omask="255.255.255.240"
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oip="192.0.2.1"
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# set these to your inside interface network and netmask and ip
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iif="ed1"
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inet="192.0.2.16"
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imask="255.255.255.240"
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iip="192.0.2.17"
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# Stop spoofing
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${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 10.0.0.0/8 to any via ${oif}
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${fwcmd} add deny all from any to 10.0.0.0/8 via ${oif}
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${fwcmd} add deny all from 172.16.0.0/12 to any 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 192.168.0.0/16 to any via ${oif}
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${fwcmd} add deny all from any to 192.168.0.0/16 via ${oif}
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# Stop draft-manning-dsua-01.txt nets on the outside interface
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${fwcmd} add deny all from 0.0.0.0/8 to any via ${oif}
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${fwcmd} add deny all from any to 0.0.0.0/8 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 any to 169.254.0.0/16 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 any to 192.0.2.0/24 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 any to 224.0.0.0/4 via ${oif}
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${fwcmd} add deny all from 240.0.0.0/4 to any via ${oif}
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${fwcmd} add deny all from any to 240.0.0.0/4 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 any 53 to ${oip}
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${fwcmd} add pass udp from ${oip} to any 53
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# Allow NTP queries out in the world
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${fwcmd} add pass udp from any 123 to ${oip}
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${fwcmd} add pass udp from ${oip} to any 123
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# Everything else is denied by default, unless the
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# IPFIREWALL_DEFAULT_TO_ACCEPT option is set in your kernel
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# config file.
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;;
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[Uu][Nn][Kk][Nn][Oo][Ww][Nn])
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;;
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*)
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if [ -r "${firewall_type}" ]; then
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${fwcmd} ${firewall_type}
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fi
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;;
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esac
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