archboot/etc/ppp/firewall-masq
Alexander Baldeck 2a150b1dca Initial revision
2007-02-22 22:46:50 +00:00

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#!/bin/sh
#
# firewall-masq This script sets up firewall rules for a machine
# acting as a masquerading gateway
#
# Copyright (C) 2000 Roaring Penguin Software Inc. This software may
# be distributed under the terms of the GNU General Public License, version
# 2 or any later version.
# LIC: GPL
# Interface to Internet
EXTIF=ppp+
# NAT-Tables are different, so we can use ACCEPT everywhere (?)
iptables -t nat -P PREROUTING ACCEPT
iptables -t nat -P OUTPUT ACCEPT
iptables -t nat -P POSTROUTING ACCEPT
# Flush the NAT-Table
iptables -t nat -F
iptables -t filter -P INPUT DROP
iptables -t filter -F
# Allow incoming SSH
#iptables -t filter -A INPUT -i $EXTIF -p tcp --dport 22 -j ACCEPT
# Log & Deny the rest of the privileged ports
iptables -t filter -A INPUT -i $EXTIF -p tcp --dport 0:1023 -j LOG
iptables -t filter -A INPUT -i $EXTIF -p udp --dport 0:1023 -j LOG
iptables -t filter -A INPUT -i $EXTIF -p tcp --dport 0:1023 -j DROP
iptables -t filter -A INPUT -i $EXTIF -p udp --dport 0:1023 -j DROP
# Log & Deny NFS
iptables -t filter -A INPUT -i $EXTIF -p udp --dport 2049 -j LOG
iptables -t filter -A INPUT -i $EXTIF -p tcp --dport 2049 -j LOG
iptables -t filter -A INPUT -i $EXTIF -p udp --dport 2049 -j DROP
iptables -t filter -A INPUT -i $EXTIF -p tcp --dport 2049 -j DROP
# Log & Deny X11
iptables -t filter -A INPUT -i $EXTIF -p tcp --dport 6000:6063 -j LOG
iptables -t filter -A INPUT -i $EXTIF -p tcp --dport 6000:6063 -j DROP
# Log & Deny XFS
iptables -t filter -A INPUT -i $EXTIF -p tcp --dport 7100 -j LOG
iptables -t filter -A INPUT -i $EXTIF -p tcp --dport 7100 -j DROP
# Deny TCP connection attempts
iptables -t filter -A INPUT -i $EXTIF -p tcp --syn -j LOG
iptables -t filter -A INPUT -i $EXTIF -p tcp --syn -j DROP
# Deny ICMP echo-requests
iptables -t filter -A INPUT -i $EXTIF -p icmp --icmp-type echo-request -j DROP
# Do masquerading
iptables -t nat -A POSTROUTING -o $EXTIF -j MASQUERADE
# Enable forwarding
echo 1 > /proc/sys/net/ipv4/ip_forward
# no IP spoofing
if [ -e /proc/sys/net/ipv4/conf/all/rp_filter ] ; then
for i in /proc/sys/net/ipv4/conf/*/rp_filter; do
echo 1 > $i
done
fi
# Disable Source Routed Packets
for i in /proc/sys/net/ipv4/conf/*/accept_source_route; do
echo 0 > $i
done