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#!/bin/bash
 
#
#   easy-to-edit iptables init script for Arch
#           2010 by Alexander Koch
#
 
 
# TCP services: ssh
SERVICES_TCP=( 22 )
# UDP services:
SERVICES_UDP=( )
 
. /etc/rc.conf
. /etc/rc.d/functions
 
if [ -e "/etc/conf.d/iptables" ]; then
    . /etc/conf.d/iptables
fi
if [ -z "$IPTABLES" ]; then
    IPTABLES="/usr/sbin/iptables"
fi
if ! [ -x "$IPTABLES" ]; then
    echo "unable to execute iptables binary: $IPTABLES"
    exit 1
fi
 
function reset_tables() {
    ERR=0
    $IPTABLES -F || ERR=1
    $IPTABLES -X || ERR=1
    $IPTABLES -P INPUT ACCEPT || ERR=1
    $IPTABLES -P OUTPUT ACCEPT || ERR=1
    if [ $IPTABLES_FORWARD -eq 1 ]; then
        $IPTABLES -P FORWARD ACCEPT || ERR=1
        echo 1 >/proc/sys/net/ipv4/ip_forward || ERR=1
    else
        $IPTABLES -P FORWARD DROP || ERR=1
        echo 0 >/proc/sys/net/ipv4/ip_forward || ERR=1
    fi
 
    return $ERR
}
 
function setup_tables() {
    ERR=0
 
    # setup prevention chain against common attacks
    $IPTABLES -N preventions || ERR=1
    $IPTABLES -A preventions -f -j DROP || ERR=1                           # frags
    $IPTABLES -A preventions -p tcp --tcp-flags ALL ALL -j DROP || ERR=1   # XMAS
    $IPTABLES -A preventions -p tcp --tcp-flags ALL NONE -j DROP || ERR=1  # null
 
    # setup services chain
    $IPTABLES -N services || ERR=1
    for PORT in ${SERVICES_TCP[@]}; do
        $IPTABLES -A services -p tcp --dport $PORT -j ACCEPT || ERR=1
    done
    for PORT in ${SERVICES_UDP[@]}; do
        $IPTABLES -A services -p udp --dport $PORT -j ACCEPT || ERR=1
    done
 
    # allow incoming ping requests
    iptables -A services -p icmp --icmp-type echo-request -j ACCEPT || ERR=1
 
    # setup main chains
    $IPTABLES -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT || ERR=1
    $IPTABLES -A INPUT -i lo -j ACCEPT || ERR=1
    $IPTABLES -A INPUT -j preventions || ERR=1
    $IPTABLES -A INPUT -m state --state NEW -j services || ERR=1
    $IPTABLES -A INPUT -p tcp -j REJECT --reject-with tcp-reset || ERR=1
    $IPTABLES -A INPUT -p udp -j REJECT --reject-with icmp-port-unreachable || ERR=1
    $IPTABLES -P INPUT DROP || ERR=1
 
    return $ERR
}
 
case "$1" in
    start)
        stat_busy "Loading IP Tables"
        reset_tables
        if ! setup_tables; then
            stat_fail
            exit 1
        else
            add_daemon miptables
            stat_done
        fi
        ;;
    stop)
        stat_busy "Flushing IP Tables"
        if reset_tables; then
            rm_daemon miptables
            stat_done
        else
            stat_fail
            exit 1
        fi
        ;;
    restart)
        if ! ck_daemon miptables; then
            rm_daemon miptables
        fi
        $0 start
        exit $?
        ;;
    *)
        echo "usage: $0 {start|stop|restart}"
        ;;
esac
 
exit 0