File: //usr/share/doc/rp-pppoe-3.5/configs/firewall-standalone.ipchains
#!/bin/sh
#
# firewall-standalone This script sets up firewall rules for a standalone
# machine
#
# 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+
ANY=0.0.0.0/0
ipchains -P input ACCEPT
ipchains -P output ACCEPT
ipchains -P forward DENY
ipchains -F forward
ipchains -F input
ipchains -F output
# Deny TCP and UDP packets to privileged ports
ipchains -A input -l -i $EXTIF -d $ANY 0:1023 -p udp -j DENY
ipchains -A input -l -i $EXTIF -d $ANY 0:1023 -p tcp -j DENY
# Deny TCP connection attempts
ipchains -A input -l -i $EXTIF -p tcp -y -j DENY
# Deny ICMP echo-requests
ipchains -A input -l -i $EXTIF -s $ANY echo-request -p icmp -j DENY