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Restrictive Iptables Based Firewall for Webserver script
#!/bin/bash
# Restrictive Iptables Based Firewall for Webserver script
# Copyright (C) 2012 Cédric Walter - www.waltercedric.com
# Credits to all various authors
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
# Modify variable below and run the script to create, test,
# clear or persist the iptables rules
#
# Tested on Ubuntu Oneiric
# You are free to send me new rules, alter this script but keep this open for others
#
# Make rules persistent
# Add in /etc/network/interfaces
# iface eth0 inet dhcp
# pre-up iptables-restore < /etc/network/iptables
#
IPT="/sbin/iptables"
### Interfaces ###
PUB_IF="eth0" # public interface
LO_IF="lo" # loopback
SERVER_IP=$(ifconfig eth0 | grep 'inet addr:' | awk -F'inet addr:' '{ print $2}' | awk '{ print $1}')
########## Allow/block services #################################################
ALLOW_SSH="true"
ALLOW_HTTP="true"
ALLOW_FTP="false"
ALLOW_OUTGOING_NTP="true"
ALLOW_OUTGOING_SMTP="true"
ALLOW_INCOMING_ICMP="true"
USE_HARDENING_RULESET="true"
########## SSH #################################################
SSH_PORT=22
# This notes every NEW connection to port ${SSH_PORT} and adds it to the recent "list"
# If your IP is on the recent list, and you have ${SSH_LOGIN_ATTEMPT} or more entries on the list in the
# last ${SSH_LOGIN_ATTEMPT_TIMEFRAME} seconds, we drop your request.
SSH_LOGIN_ATTEMPT_PROTECTION="true"
SSH_LOGIN_ATTEMPT=4
SSH_LOGIN_ATTEMPT_TIMEFRAME_SECONDS=90
SSH_ALLOW_ONLY_IP="false"
SSH_ALLOW_ONLY_IP_LIST="122.xx.yy.zz/29"
#### FILES #####
BLOCKED_IP_TDB=/root/.fw/blocked.ip.txt
SPOOFIP=""
#SPOOFIP="127.0.0.0/8 192.168.0.0/16 172.16.0.0/12 10.0.0.0/8 169.254.0.0/16 0.0.0.0/8 240.0.0.0/4 255.255.255.255/32 168.254.0.0/16 224.0.0.0/4 240.0.0.0/5 248.0.0.0/5 192.0.2.0/24"
#BADIPS=$( [[ -f ${BLOCKED_IP_TDB} ]] && egrep -v "^#|^$" ${BLOCKED_IP_TDB})
###########################################################
### Dont change below this line ###
###########################################################
function clearAllIpTablesRules() {
echo "Clear all firewall rules";
#Default policy is DROP so first change the INPUT FORWARD and OUTPUT policy before the -F or you will be locked.
iptables -P INPUT ACCEPT
iptables -P FORWARD ACCEPT
iptables -P OUTPUT ACCEPT
iptables -F
iptables -X
iptables -t nat -F
iptables -t nat -X
iptables -t mangle -F
iptables -t mangle -X
}
function hardeningRules() {
if [ "${USE_HARDENING_RULESET}" == "true" ]; then
echo "Hardening: Drop sync"
$IPT -A INPUT -i ${PUB_IF} -p tcp ! --syn -m state --state NEW -j DROP
echo "Hardening: Drop Fragments"
$IPT -A INPUT -i ${PUB_IF} -f -j DROP
$IPT -A INPUT -i ${PUB_IF} -p tcp --tcp-flags ALL FIN,URG,PSH -j DROP
$IPT -A INPUT -i ${PUB_IF} -p tcp --tcp-flags ALL ALL -j DROP
echo "Hardening: Drop NULL packets"
$IPT -A INPUT -i ${PUB_IF} -p tcp --tcp-flags ALL NONE -m limit --limit 5/m --limit-burst 7 -j LOG --log-prefix " NULL Packets "
$IPT -A INPUT -i ${PUB_IF} -p tcp --tcp-flags ALL NONE -j DROP
$IPT -A INPUT -i ${PUB_IF} -p tcp --tcp-flags SYN,RST SYN,RST -j DROP
echo "Hardening: Drop XMAS"
$IPT -A INPUT -i ${PUB_IF} -p tcp --tcp-flags SYN,FIN SYN,FIN -m limit --limit 5/m --limit-burst 7 -j LOG --log-prefix " XMAS Packets "
$IPT -A INPUT -i ${PUB_IF} -p tcp --tcp-flags SYN,FIN SYN,FIN -j DROP
echo "Hardening: Drop FIN packet scans"
$IPT -A INPUT -i ${PUB_IF} -p tcp --tcp-flags FIN,ACK FIN -m limit --limit 5/m --limit-burst 7 -j LOG --log-prefix " Fin Packets Scan "
$IPT -A INPUT -i ${PUB_IF} -p tcp --tcp-flags FIN,ACK FIN -j DROP
$IPT -A INPUT -i ${PUB_IF} -p tcp --tcp-flags ALL SYN,RST,ACK,FIN,URG -j DROP
echo "Hardening: Log and get rid of broadcast / multicast and invalid"
$IPT -A INPUT -i ${PUB_IF} -m pkttype --pkt-type broadcast -j LOG --log-prefix " Broadcast "
$IPT -A INPUT -i ${PUB_IF} -m pkttype --pkt-type broadcast -j DROP
$IPT -A INPUT -i ${PUB_IF} -m pkttype --pkt-type multicast -j LOG --log-prefix " Multicast "
$IPT -A INPUT -i ${PUB_IF} -m pkttype --pkt-type multicast -j DROP
$IPT -A INPUT -i ${PUB_IF} -m state --state INVALID -j LOG --log-prefix " Invalid "
$IPT -A INPUT -i ${PUB_IF} -m state --state INVALID -j DROP
fi
}
function logAndBlockSpoofedIPRules() {
$IPT -N spooflist
for ipblock in $SPOOFIP
do
$IPT -A spooflist -i ${PUB_IF} -s $ipblock -j LOG --log-prefix " SPOOF List Block "
$IPT -A spooflist -i ${PUB_IF} -s $ipblock -j DROP
done
$IPT -I INPUT -j spooflist
$IPT -I OUTPUT -j spooflist
$IPT -I FORWARD -j spooflist
}
function sshRules() {
if [ "${ALLOW_SSH}" == "true" ]; then
echo "Allow SSH";
if [ "${SSH_ALLOW_ONLY_IP}" == "true" ]; then
# Allow ssh only from selected public ips
for ip in ${SSH_ALLOW_ONLY_IP_LIST}
do
$IPT -A INPUT -i ${PUB_IF} -s ${ip} -p tcp -d ${SERVER_IP} --destination-port 22 -j ACCEPT
$IPT -A OUTPUT -o ${PUB_IF} -d ${ip} -p tcp -s ${SERVER_IP} --sport 22 -j ACCEPT
done
else
# allow for all
$IPT -A INPUT -i ${PUB_IF} -p tcp -d ${SERVER_IP} --destination-port ${SSH_PORT} -j ACCEPT
$IPT -A OUTPUT -o ${PUB_IF} -p tcp -s ${SERVER_IP} --sport ${SSH_PORT} -j ACCEPT
fi
if [ "${SSH_LOGIN_ATTEMPT_PROTECTION}" == "true" ]; then
$IPT -I INPUT -p tcp --dport ${SSH_PORT} -i eth0 -m state --state NEW -m recent --set
$IPT -I INPUT -p tcp --dport ${SSH_PORT} -i eth0 -m state --state NEW -m recent --update --seconds ${SSH_LOGIN_ATTEMPT_TIMEFRAME_SECONDS} --hitcount ${SSH_LOGIN_ATTEMPT} -j DROP
fi
fi
}
function icmpRules() {
if [ "${ALLOW_INCOMING_ICMP}" == "true" ]; then
echo "Allow incoming ICMP";
$IPT -A INPUT -i ${PUB_IF} -p icmp --icmp-type 8 -s 0/0 -m state --state NEW,ESTABLISHED,RELATED -m limit --limit 30/sec -j ACCEPT
$IPT -A OUTPUT -o ${PUB_IF} -p icmp --icmp-type 0 -d 0/0 -m state --state ESTABLISHED,RELATED -j ACCEPT
fi
}
function httpRules() {
if [ "${ALLOW_HTTP}" == "true" ]; then
echo "Allow HTTP";
$IPT -A INPUT -i ${PUB_IF} -p tcp --dport 80 -m state --state NEW,ESTABLISHED -j ACCEPT
#Allow outgoing (ESTABLISHED only) HTTP connection response (for the corrresponding incoming SSH connection request).
$IPT -A OUTPUT -o ${PUB_IF} -p tcp --sport 80 -m state --state ESTABLISHED -j ACCEPT
#$IPT -A INPUT -i eth2 -p tcp --dport 80 -j ACCEPT
#$IPT -A INPUT -i eth2 -p tcp --dport 443 -j ACCEPT
#$IPT -A INPUT -i ${PUB_IF} -p tcp -s 0/0 --sport 1024:65535 --dport 80 -m state --state NEW,ESTABLISHED -j ACCEPT
#$IPT -A OUTPUT -o ${PUB_IF} -p tcp --sport 80 -d 0/0 --dport 1024:65535 -m state --state ESTABLISHED -j ACCEPT
fi
}
function ntpRules() {
if [ "${ALLOW_OUTGOING_NTP}" == "true" ]; then
echo "Allow outgoing NTP";
$IPT -A OUTPUT -o ${PUB_IF} -p udp --dport 123 -m state --state NEW,ESTABLISHED -j ACCEPT
$IPT -A INPUT -i ${PUB_IF} -p udp --sport 123 -m state --state ESTABLISHED -j ACCEPT
fi
}
function smtpRules() {
if [ "${ALLOW_OUTGOING_SMTP}" == "true" ]; then
echo "Allow outgoing SMTP";
$IPT -A OUTPUT -o ${PUB_IF} -p tcp --dport 25 -m state --state NEW,ESTABLISHED -j ACCEPT
$IPT -A INPUT -i ${PUB_IF} -p tcp --sport 25 -m state --state ESTABLISHED -j ACCEPT
fi
}
function ftpRules() {
if [ "${ALLOW_FTP}" == "true" ]; then
echo "Allow FTP";
$IPT -A INPUT -p tcp --dport ftp -i eth0 -j ACCEPT
$IPT -A INPUT -p udp --dport ftp -i eth0 -j ACCEPT
$IPT -A INPUT -p tcp --dport ftp-data -i eth0 -j ACCEPT
$IPT -A INPUT -p udp --dport ftp-data -i eth0 -j ACCEPT
fi
}
function dropAndCloseEverythingRules() {
echo "Drop And Close Everything";
$IPT -P INPUT DROP
$IPT -P OUTPUT DROP
$IPT -P FORWARD DROP
}
function dropAndLogEverythingElseRules() {
$IPT -A INPUT -m limit --limit 5/m --limit-burst 7 -j LOG --log-prefix " DEFAULT DROP "
$IPT -A INPUT -j DROP
}
function unlimiteLoopbackRules() {
$IPT -A INPUT -i ${LO_IF} -j ACCEPT
$IPT -A OUTPUT -o ${LO_IF} -j ACCEPT
}
function createIptablesRules() {
echo "Setting $(hostname) Firewall...";
dropAndCloseEverythingRules
unlimiteLoopbackRules
hardeningRules
logAndBlockSpoofedIPRules
sshRules
httpRules
icmpRules
ntpRules
smtpRules
ftpRules
dropAndLogEverythingElseRules
}
echo " Firewall script by www.waltercedric.com"
echo " Credits to all various authors - GNU/GPL 3.0 Script"
echo " Choose one of the following options:"
echo
echo "[N]ew firewall rules"
echo "[C]lear all firewall rules"
echo "[T]est firewall rules"
echo "[S]ave firewall rules to /etc/network/iptables"
echo "[E]xit"
echo
read choice
case "$choice" in
"N" | "n" )
clearAllIpTablesRules
createIptablesRules
;;
"C" | "c" )
clearAllIpTablesRules
;;
"T" | "t" )
clearAllIpTablesRules
createIptablesRules
iptables-apply
;;
"S" | "s" )
clearAllIpTablesRules
createIptablesRules
iptables-save > /etc/network/iptables
;;
* )
exit 0
;;
esac
@Niemi

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Niemi commented Jul 10, 2014

Hi,
maybe is good for modern iptables to change:
s/-m state --state/-m conntrack --ctstate/g

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