Hi, Been lurking and reading docs for a bit now. I am getting to the point with the ruleset for the gateway box that I am no longer sure that I am not missing something. If folks would review the script for clueful-ness it would be greatly appreciated. (If it turns out I have a clue I would feel more qualified to comment on other's problems. :-) Otherwise, I am happy to acquire some.) The most helpful iptables doc was Iptables Tutorial by Oskar Andreasson. Thanks to this list I tossed the old-style IP alias set up for the ip tool and the Linux Advanced Routing & Traffic Control HOWTO. I have used bits and pieces from here and there thus I am worried about the script's coherence. I would love to hear about a better way of allowing remote access to the winblows box. cheers, ken /* iptables */ #! /bin/bash # Delete and flush old tables and rulesets iptables -F iptables -X iptables -Z iptables -t nat -F iptables -t mangle -F # define policy iptables -P INPUT DROP iptables -P OUTPUT DROP iptables -P FORWARD DROP # enable loopback traffic iptables -A INPUT -i lo -j ACCEPT iptables -A OUTPUT -o lo -j ACCEPT # enable DNAT for win2k iptables -t nat -A PREROUTING -p tcp -d <public ip> \ -j DNAT --to <private ip> # create user defined chains iptables -N win2k iptables -N traffic iptables -N stopout iptables -N ftp # create/define win2k chain iptables -A win2k -p tcp ! --syn -m state --state NEW -j LOG \ --log-prefix "**NEW not syn: " iptables -A win2k -p tcp ! --syn -m state --state NEW -j DROP # remote host needs access to internal server iptables -A win2k -p tcp -s <remote ip/32> -j ACCEPT iptables -A win2k -p tcp --dport 80 -j ACCEPT iptables -A win2k -p tcp -j traffic iptables -A win2k -p all -j LOG -m limit --limit 1/s \ --log-prefix "** End 'o chain " iptables -A win2k -p all -j DROP # authorized lan traffic iptables -A traffic -m state --state ESTABLISHED,RELATED \ -j ACCEPT iptables -A traffic -m state --state NEW -i ! eth1 -j ACCEPT iptables -A traffic -j LOG -m limit --limit 1/s \ --log-level info --log-prefix "**PACKET_DROP** " iptables -A traffic -j DROP iptables -A INPUT -j traffic iptables -A OUTPUT -j traffic iptables -A FORWARD -p tcp -d <private ip> -j win2k iptables -A FORWARD -j traffic # block braindead outbound traffic iptables -A FORWARD -p udp --dport 137:138 -j stopout iptables -A FORWARD -p tcp --dport 139 -j stopout iptables -A FORWARD -p udp --dport 145 -j stopout iptables -A FORWARD -p udp --dport 10008 -j stopout # lion iptables -A FORWARD -p udp --dport 65535 -j stopout # ramen # define stopout chain iptables -A stopout -m limit --limit 1/s -j LOG \ --log-level info --log-prefix "**WTF?** " iptables -A stopout -j DROP # set up IP forwarding and snat iptables -A FORWARD -i eth1 -o eth0 -m state \ --state ESTABLISHED,RELATED -j ACCEPT iptables -A FORWARD -i eth0 -o eth1 -j ACCEPT iptables -A FORWARD -j LOG -m limit --limit 1/s \ --log-level info --log-prefix "**FORWARD_DROP** " iptables -A FORWARD -j DROP iptables -t nat -A POSTROUTING -o eth1 \ -j SNAT --to <public ip> # connection tracking ftp # allow outbound iptables -A ftp -i eth0 -p tcp --sport 21 -m state \ --state ESTABLISHED -j ACCEPT iptables -A ftp -o eth1 -p tcp --dport 21 -m state \ --state NEW,ESTABLISHED -j ACCEPT # passive ftp iptables -A ftp -i eth0 -p tcp --sport 1024:65535 --dport 1024:65535 \ -m state --state ESTABLISHED -j ACCEPT iptables -A ftp -o eth1 -p tcp --sport 1024:65535 --dport 1024:65535 \ -m state --state ESTABLISHED,RELATED -j ACCEPT echo 1 > /proc/sys/net/ipv4/ip_forward /* end iptables */
