Download An Administrators Guide to Networking

APPENDIX O. FIREWALL AND NAT
addr=$2
else
read -p "Type the mac address: " addr
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fi
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echo $addr >> /etc/allowed_macs
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iptables -A FORWARD -i eth1 -m mac --mac-source $addr
-s $lan -j ACCEPT
;;
remove_mac)
if [ $# = 2 ]; then
addr=$2
else
read -p "Type the mac address: " addr
fi
←-
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cat /etc/allowed_macs | grep -i -x -v $addr > /etc/ ←allowed_macs
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iptables -D FORWARD -i eth1 -m mac --mac-source $addr
-s $lan -j ACCEPT
;;
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*)
echo "Usage: /etc/init.d/ipt_setup (start|stop|restart ←|status|add_mac [MAC]|remove_mac [MAC])"
exit 1
;;
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←-
esac
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exit 0
Listing O.1: Script to Setup Firewall and NAT on Hubert
The general script used to setup a basic firewall on the rest of the servers
is listed in Listing O.2.
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#! /bin/bash
# /etc/init.d/ipt_setup
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hubert=172.16.0.1
fry=172.16.0.2
hermes=172.16.0.3
zoidberg=172.16.0.4
bender=172.16.0.5
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