Re: Firewall administering tool

[Andrew Hesford <ajh3@cec.wustl.edu>]

I use the Vim Firewall Generator" (TM). Using iptables and linux 2.4.0, I just type the rules by hand. Here are the rules I use:

iptables -N block
iptables -A block -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A block -m state --state NEW -i ! eth0 -j ACCEPT
iptables -A block -p tcp --dport 22 -j ACCEPT
iptables -A block -p udp --dport 22 -j ACCEPT
iptables -A block -j DROP

iptables -A INPUT -j block
iptables -A FORWARD -j block

iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 22 -j DNAT --to 192.1
68.1.5
iptables -t nat -A PREROUTING -i eth0 -p udp --dport 22 -j DNAT --to 192.1
68.1.5
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

This masquerades my cable modem for any PC on 192.168.1.0/24, denies all incoming connections unless related to or established by an inside machine, and forwards SSH connections to an interior machine.
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