Journal IBitOBear's Journal: Firewall Script
#!/bin/bash -e
### BEGIN INIT INFO
# Provides: firewall
# Required-Start: networking
# Required-Stop: networking
# Default-Start: S
# Default-Stop: 0 6
# Short-Description: Secures interfaces.
### END INIT INFO
#################################################################################
#
# IPTABLES Firewall v 0.86
# by shadow999@firemail.de
#
# Small parts from http://members.optusnet.com.au/~technion/
# and some tutorials
#
# This script is intended to setup a masquerading firewall based on
# the IPTABLES (Net)filter-machanism of Linux 2.3.15+
# Syslogging matches fireparse for graphical output (see http://www.fireparse.com)
#
# Normally this script will work 'out-of-the-box', but you should adapt it to
# your own needs (At least you should set the correct default interfaces
# --> see Default-Interfaces section)
#
# Comments, suggestions, etc. are welcome
#
# Usage on your own risk ;)
#
# Syntax to invoke script: firewall (start|stop|restart|status) EXTIF INTIF
# Example: "firewall start eth1 eth0"
#
#################################################################################
#
# Version History:
#
# 0.86: Added a few comments
#
# 0.85: Various re-arrangements
# Added TCP-SYN-flood protection
# Added separate logging of pingfloods
# Added automatic detection of parameters on internal interface
# Made flooding-parameters variable
#
# 0.84: Added special ICMP-Filtering
#
# 0.83: Added ICMP-logging-chain
# Some minor changes
#
# 0.82: Reorganized parts of the script
# Added special user-chains
#
# 0.80: Altered logging strings to match fireparse
#
# 0.78: Added many comments
# Completed flushing of tables (missing -X)
#
# 0.75: Added automatic detection of IP-address, gateway, etc of external interface
#
# 0.7: Added new logging-chains
#
# 0.65: Added special sanity checks for TCP-Flags
# Silently filter out SMB-traffic
# Removed unclean-checks (according to some docs still unstable)
#
# 0.6: Major redesign of whole script, divided into chain-sections
#
# 0.5: Adopted parts of firewall-script from http://members.optusnet.com.au/~technion/
# Minor changes
#
#
########################################################################################
# This is the location of the iptables command
IPTABLES="/sbin/iptables"
case "$1" in
stop)
echo "Shutting down firewall..."
$IPTABLES -F
$IPTABLES -F -t mangle
$IPTABLES -F -t nat
$IPTABLES -X
$IPTABLES -X -t mangle
$IPTABLES -X -t nat
$IPTABLES -P INPUT ACCEPT
$IPTABLES -P OUTPUT ACCEPT
$IPTABLES -P FORWARD ACCEPT
echo "...done"
;;
status)
echo $"Table: filter"
$IPTABLES --list
echo $"Table: nat"
$IPTABLES -t nat --list
echo $"Table: mangle"
$IPTABLES -t mangle --list
;;
restart|reload)
$0 stop
$0 start
;;
start)
echo "Starting Firewall..."
echo ""
##--------------------------Begin Firewall---------------------------------##
#----Default-Interfaces-----#
## Default external interface (used, if EXTIF isn't specified on command line)
DEFAULT_EXTIF="eth1"
## Default internal interface (used, if INTIF isn't specified on command line)
DEFAULT_INTIF="eth0"
#----Special Variables-----#
# IP Mask for all IP addresses
UNIVERSE="0.0.0.0/0"
# Specification of the high unprivileged IP ports.
UNPRIVPORTS="1024:65535"
# Specification of X Window System (TCP) ports.
XWINPORTS="6000:6063"
# Ports for IRC-Connection-Tracking
IRCPORTS="6665,6666,6667,6668,1024,1025,1026,1027"
#-----Port-Forwarding Variables-----#
#For port-forwarding to an internal host, define a variable with the appropriate
#internal IP-Address here and take a look at the port-forwarding sections in the FORWARD +
#PREROUTING-chain:
#These are examples, uncomment to activate
#IP for forwarded Battlecom-traffic
#BATTLECOMIP="192.168.0.5"
#Bittorrent Computer
BITTORRENT=192.168.10.10
BITTPORT=57981
MONOTONE=192.168.10.10
MONOTONEPORT=4691
#Vonage
VONAGEIP=192.168.10.6
VONAGEPORTS=10000:20000
#Blizzard Downloader
BLIZZARD_DEST=192.168.10.95
BLIZZARD_PORTS=3724,6112,6881:6999
#BLIZZARD_PORTS=3724
#IP for forwarded HTTP-traffic
HTTPIP="192.168.10.250"
#----Flood Variables-----#
# Overall Limit for TCP-SYN-Flood detection
TCPSYNLIMIT="5/s"
# Burst Limit for TCP-SYN-Flood detection
TCPSYNLIMITBURST="10"
# Overall Limit for Loggging in Logging-Chains
LOGLIMIT="2/s"
# Burst Limit for Logging in Logging-Chains
LOGLIMITBURST="10"
# Overall Limit for Ping-Flood-Detection
PINGLIMIT="5/s"
# Burst Limit for Ping-Flood-Detection
PINGLIMITBURST="10"
#----Automatically determine infos about involved interfaces-----#
### External Interface:
## Get external interface from command-line
## If no interface is specified then set $DEFAULT_EXTIF as EXTIF
if [ "x$2" != "x" ]; then
EXTIF=$2
else
EXTIF=$DEFAULT_EXTIF
fi
echo External Interface: $EXTIF
## Determine external IP
EXTIP="`ifconfig $EXTIF | grep inet | cut -d : -f 2 | cut -d \ -f 1`"
if [ "$EXTIP" = '' ]; then
echo "Aborting: Unable to determine the IP-address of $EXTIF !"
exit 1
fi
echo External IP: $EXTIP
## Determine external gateway
EXTGW=`route -n | grep '0.0.0.0' | grep -A 4 UG | awk '{ print $2}'`
echo Default GW: $EXTGW
echo " --- "
### Internal Interface:
## Get internal interface from command-line
## If no interface is specified then set $DEFAULT_INTIF as INTIF
if [ "x$3" != "x" ]; then
INTIF=$3
else
INTIF=$DEFAULT_INTIF
fi
echo Internal Interface: $INTIF
## Determine internal IP
INTIP="`ifconfig $INTIF | grep inet | cut -d : -f 2 | cut -d \ -f 1`"
if [ "$INTIP" = '' ]; then
echo "Aborting: Unable to determine the IP-address of $INTIF !"
exit 1
fi
echo Internal IP: $INTIP
## Determine internal netmask
INTMASK="`ifconfig $INTIF | grep Mask | cut -d : -f 4`"
echo Internal Netmask: $INTMASK
## Determine network address of the internal network
INTLAN=$INTIP'/'23
echo Internal LAN: $INTLAN
echo ""
#----Load IPTABLES-modules-----#
#Insert modules- should be done automatically if needed
#If the IRC-modules are available, uncomment them below
echo "Loading IPTABLES modules"
dmesg -n 1 #Kill copyright display on module load
/sbin/modprobe ip_tables
/sbin/modprobe iptable_filter
/sbin/modprobe ip_conntrack
/sbin/modprobe ip_conntrack_ftp
/sbin/modprobe ip_nat_ftp
/sbin/modprobe ip_conntrack_irc ports=$IRCPORTS
/sbin/modprobe ip_nat_irc ports=$IRCPORTS
dmesg -n 6
echo " --- "
#----Clear/Reset all chains-----#
#Clear all IPTABLES-chains
#Flush everything, start from scratch
$IPTABLES -F
$IPTABLES -F -t mangle
$IPTABLES -F -t nat
$IPTABLES -X
$IPTABLES -X -t mangle
$IPTABLES -X -t nat
#Set default policies to DROP
$IPTABLES -P INPUT DROP
$IPTABLES -P OUTPUT DROP
$IPTABLES -P FORWARD DROP
#----Set network sysctl options-----#
echo "Setting sysctl options"
#Enable forwarding in kernel
echo 1 > /proc/sys/net/ipv4/ip_forward
#Disabling IP Spoofing attacks.
echo 1 > /proc/sys/net/ipv4/conf/all/rp_filter
echo 1 > /proc/sys/net/ipv4/conf/default/rp_filter
echo 1 > /proc/sys/net/ipv4/conf/${EXTIF}/rp_filter
#Don't respond to broadcast pings (Smurf-Amplifier-Protection)
echo "1" > /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts
#Block source routing
echo 0 > /proc/sys/net/ipv4/conf/all/accept_source_route
#Kill timestamps
echo 0 > /proc/sys/net/ipv4/tcp_timestamps
#Enable SYN Cookies
echo 1 > /proc/sys/net/ipv4/tcp_syncookies
#Kill redirects
echo 0 > /proc/sys/net/ipv4/conf/all/accept_redirects
#Enable bad error message protection
echo 1 > /proc/sys/net/ipv4/icmp_ignore_bogus_error_responses
#Log martians (packets with impossible addresses)
echo 1 > /proc/sys/net/ipv4/conf/all/log_martians
#Set out local port range
echo "32768 61000" > /proc/sys/net/ipv4/ip_local_port_range
#Reduce DoS'ing ability by reducing timeouts
echo 30 > /proc/sys/net/ipv4/tcp_fin_timeout
echo 2400 > /proc/sys/net/ipv4/tcp_keepalive_time
echo 1 > /proc/sys/net/ipv4/tcp_window_scaling
echo 1 > /proc/sys/net/ipv4/tcp_sack
echo 1 > /proc/sys/net/ipv4/tcp_timestamps
#Ignore icmp echo (ping) broadcast events
echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts
echo " --- "
echo "Creating user-chains"
#----Create logging chains-----#
##These are the logging-chains. They all have a certain limit of log-entries/sec to prevent log-flooding
##The syslog-entries will be fireparse-compatible (see http://www.fireparse.com)
#Invalid packets (not ESTABLISHED,RELATED or NEW)
$IPTABLES -N LINVALID
$IPTABLES -A LINVALID -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-level info --log-prefix "fp=INVALID:1 a=DROP "
$IPTABLES -A LINVALID -j DROP
#TCP-Packets with one ore more bad flags
$IPTABLES -N LBADFLAG
$IPTABLES -A LBADFLAG -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-level info --log-prefix "fp=BADFLAG:1 a=DROP "
$IPTABLES -A LBADFLAG -j DROP
#Logging of connection attempts on special ports (Trojan portscans, special services, etc.)
$IPTABLES -N LSPECIALPORT
$IPTABLES -A LSPECIALPORT -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-level info --log-prefix "fp=SPECIALPORT:1 a=DROP "
$IPTABLES -A LSPECIALPORT -j DROP
#Logging of possible TCP-SYN-Floods
$IPTABLES -N LSYNFLOOD
$IPTABLES -A LSYNFLOOD -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-level info --log-prefix "fp=SYNFLOOD:1 a=DROP "
$IPTABLES -A LSYNFLOOD -j DROP
#Logging of possible Ping-Floods
$IPTABLES -N LPINGFLOOD
$IPTABLES -A LPINGFLOOD -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-level info --log-prefix "fp=PINGFLOOD:1 a=DROP "
$IPTABLES -A LPINGFLOOD -j DROP
#All other dropped packets
$IPTABLES -N LDROP
$IPTABLES -A LDROP -p tcp -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-level info --log-prefix "fp=TCP:1 a=DROP "
$IPTABLES -A LDROP -p udp -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-level info --log-prefix "fp=UDP:2 a=DROP "
$IPTABLES -A LDROP -p icmp -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-level info --log-prefix "fp=ICMP:3 a=DROP "
$IPTABLES -A LDROP -f -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-level info --log-prefix "fp=FRAGMENT:4 a=DROP "
$IPTABLES -A LDROP -j DROP
#All other rejected packets
$IPTABLES -N LREJECT
$IPTABLES -A LREJECT -p tcp -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-level info --log-prefix "fp=TCP:1 a=REJECT "
$IPTABLES -A LREJECT -p udp -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-level info --log-prefix "fp=UDP:2 a=REJECT "
$IPTABLES -A LREJECT -p icmp -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-level info --log-prefix "fp=ICMP:3 a=REJECT "
$IPTABLES -A LREJECT -f -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-level info --log-prefix "fp=FRAGMENT:4 a=REJECT "
$IPTABLES -A LREJECT -p tcp -j REJECT --reject-with tcp-reset
$IPTABLES -A LREJECT -p udp -j REJECT --reject-with icmp-port-unreachable
$IPTABLES -A LREJECT -j REJECT
#----Create Accept-Chains-----#
#TCPACCEPT - Check for SYN-Floods before letting TCP-Packets in
$IPTABLES -N TCPACCEPT
$IPTABLES -A TCPACCEPT -p tcp --syn -m limit --limit $TCPSYNLIMIT --limit-burst $TCPSYNLIMITBURST -j ACCEPT
$IPTABLES -A TCPACCEPT -p tcp --syn -j LSYNFLOOD
$IPTABLES -A TCPACCEPT -p tcp ! --syn -j ACCEPT
#----Create special User-Chains-----#
#CHECKBADFLAG - Kill any Inbound/Outbound TCP-Packets with impossible flag-combinations (Some port-scanners use these, eg. nmap Xmas,Null,etc.-scan)
$IPTABLES -N CHECKBADFLAG
$IPTABLES -A CHECKBADFLAG -p tcp --tcp-flags ALL FIN,URG,PSH -j LBADFLAG
$IPTABLES -A CHECKBADFLAG -p tcp --tcp-flags ALL SYN,RST,ACK,FIN,URG -j LBADFLAG
$IPTABLES -A CHECKBADFLAG -p tcp --tcp-flags ALL ALL -j LBADFLAG
$IPTABLES -A CHECKBADFLAG -p tcp --tcp-flags ALL NONE -j LBADFLAG
$IPTABLES -A CHECKBADFLAG -p tcp --tcp-flags SYN,RST SYN,RST -j LBADFLAG
$IPTABLES -A CHECKBADFLAG -p tcp --tcp-flags SYN,FIN SYN,FIN -j LBADFLAG
#FILTERING FOR SPECIAL PORTS
#Inbound/Outbound SILENTDROPS/REJECTS (Things we don't want in our Logs)
#SMB-Traffic
$IPTABLES -N SMB
$IPTABLES -A SMB -p tcp --dport 137 -j DROP
$IPTABLES -A SMB -p tcp --dport 138 -j DROP
$IPTABLES -A SMB -p tcp --dport 139 -j DROP
$IPTABLES -A SMB -p tcp --dport 445 -j DROP
$IPTABLES -A SMB -p udp --dport 137 -j DROP
$IPTABLES -A SMB -p udp --dport 138 -j DROP
$IPTABLES -A SMB -p udp --dport 139 -j DROP
$IPTABLES -A SMB -p udp --dport 445 -j DROP
$IPTABLES -A SMB -p tcp --sport 137 -j DROP
$IPTABLES -A SMB -p tcp --sport 138 -j DROP
$IPTABLES -A SMB -p tcp --sport 139 -j DROP
$IPTABLES -A SMB -p tcp --sport 445 -j DROP
$IPTABLES -A SMB -p udp --sport 137 -j DROP
$IPTABLES -A SMB -p udp --sport 138 -j DROP
$IPTABLES -A SMB -p udp --sport 139 -j DROP
$IPTABLES -A SMB -p udp --sport 445 -j DROP
#Inbound Special Ports
$IPTABLES -N SPECIALPORTS
#Deepthroat Scan
$IPTABLES -A SPECIALPORTS -p tcp --dport 6670 -j LSPECIALPORT
#Subseven Scan
$IPTABLES -A SPECIALPORTS -p tcp --dport 1243 -j LSPECIALPORT
$IPTABLES -A SPECIALPORTS -p udp --dport 1243 -j LSPECIALPORT
$IPTABLES -A SPECIALPORTS -p tcp --dport 27374 -j LSPECIALPORT
$IPTABLES -A SPECIALPORTS -p udp --dport 27374 -j LSPECIALPORT
$IPTABLES -A SPECIALPORTS -p tcp --dport 6711:6713 -j LSPECIALPORT
#Netbus Scan
$IPTABLES -A SPECIALPORTS -p tcp --dport 12345:12346 -j LSPECIALPORT
$IPTABLES -A SPECIALPORTS -p tcp --dport 20034 -j LSPECIALPORT
#Back Orifice scan
$IPTABLES -A SPECIALPORTS -p udp --dport 31337:31338 -j LSPECIALPORT
#X-Win
$IPTABLES -A SPECIALPORTS -p tcp --dport $XWINPORTS -j LSPECIALPORT
#Hack'a'Tack 2000
$IPTABLES -A SPECIALPORTS -p udp --dport 28431 -j LSPECIALPORT
#ICMP/TRACEROUTE FILTERING
#Inbound ICMP/Traceroute
$IPTABLES -N ICMPINBOUND
#Ping Flood protection. Accept $PINGLIMIT echo-requests/sec, rest will be logged/dropped
$IPTABLES -A ICMPINBOUND -p icmp --icmp-type echo-request -m limit --limit $PINGLIMIT --limit-burst $PINGLIMITBURST -j ACCEPT
#
$IPTABLES -A ICMPINBOUND -p icmp --icmp-type echo-request -j LPINGFLOOD
#Block ICMP-Redirects (Should already be catched by sysctl-options, if enabled)
$IPTABLES -A ICMPINBOUND -p icmp --icmp-type redirect -j LDROP
#Block ICMP-Timestamp (Should already be catched by sysctl-options, if enabled)
$IPTABLES -A ICMPINBOUND -p icmp --icmp-type timestamp-request -j LDROP
$IPTABLES -A ICMPINBOUND -p icmp --icmp-type timestamp-reply -j LDROP
#Block ICMP-address-mask (can help to prevent OS-fingerprinting)
$IPTABLES -A ICMPINBOUND -p icmp --icmp-type address-mask-request -j LDROP
$IPTABLES -A ICMPINBOUND -p icmp --icmp-type address-mask-reply -j LDROP
#Allow all other ICMP in
$IPTABLES -A ICMPINBOUND -p icmp -j ACCEPT
#Outbound ICMP/Traceroute
$IPTABLES -N ICMPOUTBOUND
#Block ICMP-Redirects (Should already be catched by sysctl-options, if enabled)
$IPTABLES -A ICMPOUTBOUND -p icmp --icmp-type redirect -j LDROP
#Block ICMP-TTL-Expired
#MS Traceroute (MS uses ICMP instead of UDp for tracert)
$IPTABLES -A ICMPOUTBOUND -p icmp --icmp-type ttl-zero-during-transit -j LDROP
$IPTABLES -A ICMPOUTBOUND -p icmp --icmp-type ttl-zero-during-reassembly -j LDROP
#Block ICMP-Parameter-Problem
$IPTABLES -A ICMPOUTBOUND -p icmp --icmp-type parameter-problem -j LDROP
#Block ICMP-Timestamp (Should already be catched by sysctl-options, if enabled)
$IPTABLES -A ICMPOUTBOUND -p icmp --icmp-type timestamp-request -j LDROP
$IPTABLES -A ICMPOUTBOUND -p icmp --icmp-type timestamp-reply -j LDROP
#Block ICMP-address-mask (can help to prevent OS-fingerprinting)
$IPTABLES -A ICMPOUTBOUND -p icmp --icmp-type address-mask-request -j LDROP
$IPTABLES -A ICMPOUTBOUND -p icmp --icmp-type address-mask-reply -j LDROP
##Accept all other ICMP going out
$IPTABLES -A ICMPOUTBOUND -p icmp -j ACCEPT
########
# Throttle SSH connections by host
# to prevent brute force attacks
########
$IPTABLES --new-chain SSHTHROTTLE
$IPTABLES --flush SSHTHROTTLE
$IPTABLES --append SSHTHROTTLE --match recent --name ssh_throttle --seconds $(( 3600 * 18)) --update -j DROP
$IPTABLES --append SSHTHROTTLE --match limit --limit 3/hour -j RETURN
$IPTABLES --append SSHTHROTTLE --match recent --name ssh_throttle --set -j DROP
#----End User-Chains-----#
echo " --- "
#----Start Ruleset-----#
echo "Implementing firewall rules..."
#################
## INPUT-Chain ## (everything that is addressed to the firewall itself)
#################
##GENERAL Filtering
# Kill INVALID packets (not ESTABLISHED, RELATED or NEW)
$IPTABLES -A INPUT -m state --state INVALID -j LINVALID
# Check TCP-Packets for Bad Flags
$IPTABLES -A INPUT -p tcp -j CHECKBADFLAG
##Packets FROM FIREWALL-BOX ITSELF
#Local IF
$IPTABLES -A INPUT -i lo -j ACCEPT
#
#Kill connections to the local interface from the outside world (--> Should be already catched by kernel/rp_filter)
$IPTABLES -A INPUT -d 127.0.0.0/8 -j LREJECT
##Packets FROM INTERNAL NET
##Allow unlimited traffic from internal network using legit addresses to firewall-box
##If protection from the internal interface is needed, alter it
$IPTABLES -A INPUT -i ! $EXTIF -s $INTLAN -j ACCEPT
#Allow Local DHCP Service Nonsense
$IPTABLES -I INPUT -i ! $EXTIF -p udp -s 0.0.0.0 -d 255.255.255.255 --sport 68 --dport 67 -j ACCEPT
#Kill anything from outside claiming to be from internal network (Address-Spoofing --> Should be already catched by rp_filter)
$IPTABLES -A INPUT -s $INTLAN -j LREJECT
##Packets FROM EXTERNAL NET
## DHCP Server on ISP's Site
$IPTABLES -I INPUT -i $EXTIF -p udp -s 0.0.0.0 -d 255.255.255.255 --sport 67 --dport 68 -j ACCEPT
if [ -f /var/lib/dhcp3/dhclient.${EXTIF}.leases ]; then
DHCPSID=$(grep dhcp-server-identifier /var/lib/dhcp3/dhclient.${EXTIF}.leases | tail --lines=1 | sed --expression='s;.* \([0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\).*;\1;')
echo $IPTABLES -I INPUT -i $EXTIF -p udp --sport 67 --dport 68 --source "$DHCPSID" -j ACCEPT
$IPTABLES -I INPUT -i $EXTIF -p udp --sport 67 --dport 68 --source "$DHCPSID" -j ACCEPT
fi
##ICMP & Traceroute filtering
#Filter ICMP
$IPTABLES -A INPUT -i $EXTIF -p icmp -j ICMPINBOUND
#Block UDP-Traceroute
$IPTABLES -A INPUT -p udp --dport 33434:33523 -j LDROP
##Silent Drops/Rejects (Things we don't want in our logs)
#Drop all SMB-Traffic
$IPTABLES -A INPUT -i $EXTIF -j SMB
#Silently reject Ident (Don't DROP ident, because of possible delays when establishing an outbound connection)
$IPTABLES -A INPUT -i $EXTIF -p tcp --dport 113 -j REJECT --reject-with tcp-reset
##Public services running ON FIREWALL-BOX (comment out to activate):
# ftp-data
#$IPTABLES -A INPUT -i $EXTIF -p tcp --dport 20 -j TCPACCEPT
# ftp
#$IPTABLES -A INPUT -i $EXTIF -p tcp --dport 21 -j TCPACCEPT
# ssh
$IPTABLES -A INPUT -i $EXTIF -p tcp --dport 22 -m state --state ESTABLISHED,RELATED -j TCPACCEPT
$IPTABLES -A INPUT -i $EXTIF -p tcp --dport 22 --syn -j SSHTHROTTLE
$IPTABLES -A INPUT -i $EXTIF -p tcp --dport 22 --match state --state NEW -j TCPACCEPT
#telnet
#$IPTABLES -A INPUT -i $EXTIF -p tcp --dport 23 -j TCPACCEPT
# smtp
#$IPTABLES -A INPUT -i $EXTIF -p tcp --dport 25 -j TCPACCEPT
# DNS
$IPTABLES -A INPUT -i $EXTIF -p tcp --dport 53 -j TCPACCEPT
$IPTABLES -A INPUT -i $EXTIF -p udp --dport 53 -j ACCEPT
# http
# $IPTABLES -A INPUT -i $EXTIF -p tcp --dport 80 -j TCPACCEPT
# https
#$IPTABLES -A INPUT -i $EXTIF -p tcp --dport 443 -j TCPACCEPT
# POP-3
#$IPTABLES -A INPUT -i $EXTIF -p tcp --dport 110 -j TCPACCEPT
##Separate logging of special portscans/connection attempts
$IPTABLES -A INPUT -i $EXTIF -j SPECIALPORTS
##Allow ESTABLISHED/RELATED connections in
$IPTABLES -A INPUT -i $EXTIF -m state --state ESTABLISHED -j ACCEPT
$IPTABLES -A INPUT -i $EXTIF -p tcp --dport $UNPRIVPORTS -m state --state RELATED -j TCPACCEPT
$IPTABLES -A INPUT -i $EXTIF -p udp --dport $UNPRIVPORTS -m state --state RELATED -j ACCEPT
##Catch all rule
$IPTABLES -A INPUT -j LDROP
##################
## Output-Chain ## (everything that comes directly from the Firewall-Box)
##################
##Packets TO FIREWALL-BOX ITSELF
#Local IF
$IPTABLES -A OUTPUT -o lo -j ACCEPT
##Packets TO INTERNAL NET
#Allow unlimited traffic to internal network using legit addresses
$IPTABLES -A OUTPUT -o ! $EXTIF -d $INTLAN -j ACCEPT
##Packets TO EXTERNAL NET
##NTP
$IPTABLES -A OUTPUT -o $EXTIF -p udp --sport ntp --dport ntp -j ACCEPT
##ICMP & Traceroute
$IPTABLES -A OUTPUT -o $EXTIF -p icmp -j ICMPOUTBOUND
##Silent Drops/Rejects (Things we don't want in our logs)
#SMB
$IPTABLES -A OUTPUT -o $EXTIF -j SMB
#Ident
$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport 113 -j REJECT --reject-with tcp-reset
##Public services running ON FIREWALL-BOX (comment out to activate):
# ftp-data
#$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport 20 -j ACCEPT
# ftp
#$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport 21 -j ACCEPT
# ssh
$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport 22 -m state --state ESTABLISHED,RELATED -j ACCEPT
$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport 8193 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
#telnet
#$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport 23 -m state --state ESTABLISHED -j ACCEPT
# smtp
#$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport 25 -m state --state ESTABLISHED -j ACCEPT
# DNS
$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport 53 -j ACCEPT
$IPTABLES -A OUTPUT -o $EXTIF -p udp --sport 53 -j ACCEPT
# http
#$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport 80 -m state --state ESTABLISHED -j ACCEPT
# https
#$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport 443 -m state --state ESTABLISHED -j ACCEPT
# POP-3
#$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport 110 -m state --state ESTABLISHED -j ACCEPT
# DHCP Server on ISP's Site
$IPTABLES -A OUTPUT -o $EXTIF -p udp --sport 68 --dport 67 --source 0.0.0.0 --destination 255.255.255.255 -j ACCEPT
if [ -f /etc/dhcpc/dhcpcd-${EXTIF}.info ]; then
DHCPSID=$(grep DHCPSID /etc/dhcpc/dhcpcd-${EXTIF}.info | awk -F= '{print $2}')
$IPTABLES -A OUTPUT -o $EXTIF -p udp --sport 68 --dport 67 --destination $DHCPSID -j ACCEPT
fi
# DHCP Server inside Firewall Box
$IPTABLES -A OUTPUT -o ! $EXTIF -p udp --sport 67 --dport 68 -j ACCEPT
##Accept all tcp/udp traffic on unprivileged ports going out
$IPTABLES -A OUTPUT -o $EXTIF -s $EXTIP -p tcp --sport $UNPRIVPORTS -j ACCEPT
$IPTABLES -A OUTPUT -o $EXTIF -s $EXTIP -p udp --sport $UNPRIVPORTS -j ACCEPT
##Catch all rule
$IPTABLES -A OUTPUT -j LDROP
####################
## FORWARD-Chain ## (everything that passes the firewall)
####################
##GENERAL Filtering
# optimal forwarding rates
$IPTABLES -A FORWARD -i ! $EXTIF -m state --state ESTABLISHED,RELATED -j ACCEPT
$IPTABLES -A FORWARD -i ! $EXTIF -o $EXTIF -m state --state NEW -j ACCEPT
#Kill invalid packets (not ESTABLISHED, RELATED or NEW)
$IPTABLES -A FORWARD -m state --state INVALID -j LINVALID
# Check TCP-Packets for Bad Flags
$IPTABLES -A FORWARD -p tcp -j CHECKBADFLAG
# Bad Broadcasting
$IPTABLES -A FORWARD -d 255.255.255.255 -j DROP
$IPTABLES -A FORWARD -d 192.168.10.0 -j DROP
$IPTABLES -A FORWARD -d 192.168.11.0 -j DROP
# Spoofing
$IPTABLES -A FORWARD -i $EXTIF -s 192.168.10.0/23 -j LDROP
##Silent Drops/Rejects (Things we don't want in our logs)
#SMB
$IPTABLES -A FORWARD -o $EXTIF -j SMB
$IPTABLES -A FORWARD -p tcp -m multiport --destination-ports 137,138,139,445 -j DROP
$IPTABLES -A FORWARD -p udp -m multiport --destination-ports 137,138,139,445 -j DROP
##Filtering FROM INTERNAL NET
##Special Drops/Rejects
# - To be done -
##Filter for some Trojans communicating to outside
# - To be done -
##Port-Forwarding from Ports < 1024 [outbound] (--> Also see chain PREROUTING)
#HTTP-Forwarding
#$IPTABLES -A FORWARD -o $EXTIF -s $HTTPIP -p tcp --sport 80 -j ACCEPT
##Allow all other forwarding (from Ports > 1024) from Internal Net to External Net
$IPTABLES -A FORWARD -i ! $EXTIF -o $EXTIF -s $INTLAN -p tcp --sport $UNPRIVPORTS -j ACCEPT
$IPTABLES -A FORWARD -i ! $EXTIF -o $EXTIF -s $INTLAN -p udp --sport $UNPRIVPORTS -j ACCEPT
$IPTABLES -A FORWARD -i ! $EXTIF -o $EXTIF -s $INTLAN -p icmp -j ACCEPT
##Allow non-external nets to talk to each other, q.v. wireless to wired "internal" networks
$IPTABLES -A FORWARD -i ! $EXTIF -o ! $EXTIF -s $INTLAN -p tcp -m multiport --destination-ports ssh,sunrpc,snmp,snmptrap,631,940,943,946,949 -j ACCEPT
$IPTABLES -A FORWARD -i ! $EXTIF -o ! $EXTIF -s $INTLAN -p udp -m multiport --destination-ports ssh,sunrpc,snmp,snmptrap,631,940,943,946,949 -j ACCEPT
$IPTABLES -A FORWARD -i ! $EXTIF -o ! $EXTIF -s $INTLAN -p tcp -m multiport --destination-ports $UNPRIVPORTS -j ACCEPT
$IPTABLES -A FORWARD -i ! $EXTIF -o ! $EXTIF -s $INTLAN -p udp -m multiport --destination-ports $UNPRIVPORTS -j ACCEPT
##Filtering FROM EXTERNAL NET
##Silent Drops/Rejects (Things we don't want in our logs)
#SMB Handled Above
#$IPTABLES -A FORWARD -i $EXTIF -j SMB
##Allow replies coming in
$IPTABLES -A FORWARD -i $EXTIF -m state --state ESTABLISHED -j ACCEPT
$IPTABLES -A FORWARD -i $EXTIF -p tcp --dport $UNPRIVPORTS -m state --state RELATED -j TCPACCEPT
$IPTABLES -A FORWARD -i $EXTIF -p udp --dport $UNPRIVPORTS -m state --state RELATED -j ACCEPT
$IPTABLES -A FORWARD -i $EXTIF -p icmp -m state --state RELATED -j ACCEPT
$IPTABLES -A FORWARD -i $EXTIF -m state --state RELATED -j ACCEPT
##Port-Forwarding [inbound] (--> Also see chain PREROUTING)
#HTTP-Forwarding
$IPTABLES -A FORWARD -i $EXTIF -p tcp -d $HTTPIP --dport 80 -j ACCEPT
#Battlecom-Forwarding
#$IPTABLES -A FORWARD -p tcp --dport 2300:2400 -i $EXTIF -d $BATTLECOMIP -j ACCEPT
#$IPTABLES -A FORWARD -p udp --dport 2300:2400 -i $EXTIF -d $BATTLECOMIP -j ACCEPT
#$IPTABLES -A FORWARD -p tcp --dport 47624 -i $EXTIF -d $BATTLECOMIP -j ACCEPT
$IPTABLES -A FORWARD -p tcp --dport $BITTPORT -i $EXTIF -d $BITTORRENT -j ACCEPT
$IPTABLES -A FORWARD -p udp --dport $BITTPORT -i $EXTIF -d $BITTORRENT -j ACCEPT
$IPTABLES -A FORWARD -p tcp --dport $MONOTONEPORT -i $EXTIF -d $MONOTONE -j ACCEPT
$IPTABLES -A FORWARD -p udp --dport $VONAGEPORTS -i $EXTIF -d $VONAGEIP -j ACCEPT
$IPTABLES -A FORWARD -p tcp --match multiport --destination-ports $BLIZZARD_PORTS -i $EXTIF -d $BLIZZARD_DEST -j ACCEPT
$IPTABLES -A FORWARD -i $EXTIF -d $BLIZZARD_DEST -p tcp --match multiport --destination-ports $BLIZZARD_PORTS --match state --state NEW -j ACCEPT
##Catch all rule/Deny every other forwarding
$IPTABLES -A FORWARD -j LDROP
################
## PREROUTING ##
################
##Port-Forwarding (--> Also see chain FORWARD)
##NTP
$IPTABLES -A PREROUTING -t nat -i ! $EXTIF -p udp --destination-port ntp -j REDIRECT
##HTTP
$IPTABLES -A PREROUTING -t nat -i $EXTIF -p tcp -d $EXTIP --dport 80 -j DNAT --to $HTTPIP
##Battlecom
#$IPTABLES -t nat -A PREROUTING -d $EXTIP -p tcp --destination-port 2300:2400 -i $EXTIF -j DNAT --to $BATTLECOMIP
#$IPTABLES -t nat -A PREROUTING -d $EXTIP -p udp --destination-port 2300:2400 -i $EXTIF -j DNAT --to $BATTLECOMIP
#$IPTABLES -t nat -A PREROUTING -d $EXTIP -p tcp --destination-port 47624 -i $EXTIF -j DNAT --to $BATTLECOMIP:47624
$IPTABLES -t nat -A PREROUTING -d $EXTIP -p tcp --destination-port $BITTPORT -i $EXTIF -j DNAT --to $BITTORRENT:$BITTPORT
$IPTABLES -t nat -A PREROUTING -d $EXTIP -p udp --destination-port $BITTPORT -i $EXTIF -j DNAT --to $BITTORRENT:$BITTPORT
##Monotone
$IPTABLES -t nat -A PREROUTING -d $EXTIP -p tcp --destination-port $MONOTONEPORT -i $EXTIF -j DNAT --to $MONOTONE:$MONOTONEPORT
##Vonage
$IPTABLES -t nat -A PREROUTING -d $EXTIP -p udp --destination-port $VONAGEPORTS -i $EXTIF -j DNAT --to $VONAGEIP
##Blizzard
$IPTABLES -t nat -A PREROUTING --destination $EXTIP --in-interface $EXTIF -p tcp --tcp-flags SYN,ACK,FIN,RST SYN --match multiport --destination-ports $BLIZZARD_PORTS -j DNAT --to $BLIZZARD_DEST
###################
## POSTROUTING ##
###################
#Masquerade from Internal Net to External Net
$IPTABLES -A POSTROUTING -t nat --out-interface $EXTIF -j SNAT --to-source $EXTIP
# Initial Shape Classifier
# gIive "overhead" packets highest priority
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp -j CLASSIFY --set-class 1:60
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --tcp-flags ALL ACK -m length --length 40:68 -m state --state ESTABLISHED,RELATED -j CLASSIFY --set-class 1:10
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --syn -m length --length 40:68 -j CLASSIFY --set-class 1:10
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --tcp-flags ALL SYN,ACK -m length --length 40:68 -j CLASSIFY --set-class 1:10
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --tcp-flags ALL ACK -m length --length 40:100 -j CLASSIFY --set-class 1:10
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --tcp-flags ALL RST -j CLASSIFY --set-class 1:10
#$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --tcp-flags ALL ACK,RST -j CLASSIFY --set-class 1:10
#$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --tcp-flags ALL ACK,FIN -j CLASSIFY --set-class 1:10
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --tcp-flags ALL FIN -j CLASSIFY --set-class 1:10
# interactive SSH traffic and UDP gaming
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p udp -j CLASSIFY --set-class 1:20
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF --source $VONAGEIP -p udp -j RETURN
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p udp -j CLASSIFY --set-class 1:30
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --sport ssh -m length --length 40:100 -j CLASSIFY --set-class 1:20
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --dport ssh -m length --length 40:100 -j CLASSIFY --set-class 1:20
# interactive mail or web traffic
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp -m multiport --dport http,pop2,pop3,imap,https,imaps -j CLASSIFY --set-class 1:30
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp -m multiport --sport http,pop2,pop3,imap,https,imaps -j CLASSIFY --set-class 1:30
# dns lookups
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --dport domain -j CLASSIFY --set-class 1:30
# ICMP
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p icmp -m length --length 28:1500 -m limit --limit 2/s --limit-burst 5 -j CLASSIFY --set-class 1:40
# bulk traffic
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --sport ssh -m length --length 101: -j CLASSIFY --set-class 1:50
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --dport ssh -m length --length 101: -j CLASSIFY --set-class 1:50
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --sport 25 -j CLASSIFY --set-class 1:50
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --dport 6667 -j CLASSIFY --set-class 1:50
ip6tables -P FORWARD DROP
#------End Ruleset------#
echo "...done"
echo ""
echo "--> IPTABLES firewall loaded/activated <--"
##--------------------------------End Firewall---------------------------------##
;;
*)
echo "Usage: firewall (start|stop|restart|status) EXTIF INTIF"
exit 1
esac
exit 0
### BEGIN INIT INFO
# Provides: firewall
# Required-Start: networking
# Required-Stop: networking
# Default-Start: S
# Default-Stop: 0 6
# Short-Description: Secures interfaces.
### END INIT INFO
#################################################################################
#
# IPTABLES Firewall v 0.86
# by shadow999@firemail.de
#
# Small parts from http://members.optusnet.com.au/~technion/
# and some tutorials
#
# This script is intended to setup a masquerading firewall based on
# the IPTABLES (Net)filter-machanism of Linux 2.3.15+
# Syslogging matches fireparse for graphical output (see http://www.fireparse.com)
#
# Normally this script will work 'out-of-the-box', but you should adapt it to
# your own needs (At least you should set the correct default interfaces
# --> see Default-Interfaces section)
#
# Comments, suggestions, etc. are welcome
#
# Usage on your own risk
#
# Syntax to invoke script: firewall (start|stop|restart|status) EXTIF INTIF
# Example: "firewall start eth1 eth0"
#
#################################################################################
#
# Version History:
#
# 0.86: Added a few comments
#
# 0.85: Various re-arrangements
# Added TCP-SYN-flood protection
# Added separate logging of pingfloods
# Added automatic detection of parameters on internal interface
# Made flooding-parameters variable
#
# 0.84: Added special ICMP-Filtering
#
# 0.83: Added ICMP-logging-chain
# Some minor changes
#
# 0.82: Reorganized parts of the script
# Added special user-chains
#
# 0.80: Altered logging strings to match fireparse
#
# 0.78: Added many comments
# Completed flushing of tables (missing -X)
#
# 0.75: Added automatic detection of IP-address, gateway, etc of external interface
#
# 0.7: Added new logging-chains
#
# 0.65: Added special sanity checks for TCP-Flags
# Silently filter out SMB-traffic
# Removed unclean-checks (according to some docs still unstable)
#
# 0.6: Major redesign of whole script, divided into chain-sections
#
# 0.5: Adopted parts of firewall-script from http://members.optusnet.com.au/~technion/
# Minor changes
#
#
########################################################################################
# This is the location of the iptables command
IPTABLES="/sbin/iptables"
case "$1" in
stop)
echo "Shutting down firewall..."
$IPTABLES -F
$IPTABLES -F -t mangle
$IPTABLES -F -t nat
$IPTABLES -X
$IPTABLES -X -t mangle
$IPTABLES -X -t nat
$IPTABLES -P INPUT ACCEPT
$IPTABLES -P OUTPUT ACCEPT
$IPTABLES -P FORWARD ACCEPT
echo "...done"
status)
echo $"Table: filter"
$IPTABLES --list
echo $"Table: nat"
$IPTABLES -t nat --list
echo $"Table: mangle"
$IPTABLES -t mangle --list
restart|reload)
$0 stop
$0 start
start)
echo "Starting Firewall..."
echo ""
##--------------------------Begin Firewall---------------------------------##
#----Default-Interfaces-----#
## Default external interface (used, if EXTIF isn't specified on command line)
DEFAULT_EXTIF="eth1"
## Default internal interface (used, if INTIF isn't specified on command line)
DEFAULT_INTIF="eth0"
#----Special Variables-----#
# IP Mask for all IP addresses
UNIVERSE="0.0.0.0/0"
# Specification of the high unprivileged IP ports.
UNPRIVPORTS="1024:65535"
# Specification of X Window System (TCP) ports.
XWINPORTS="6000:6063"
# Ports for IRC-Connection-Tracking
IRCPORTS="6665,6666,6667,6668,1024,1025,1026,1027"
#-----Port-Forwarding Variables-----#
#For port-forwarding to an internal host, define a variable with the appropriate
#internal IP-Address here and take a look at the port-forwarding sections in the FORWARD +
#PREROUTING-chain:
#These are examples, uncomment to activate
#IP for forwarded Battlecom-traffic
#BATTLECOMIP="192.168.0.5"
#Bittorrent Computer
BITTORRENT=192.168.10.10
BITTPORT=57981
MONOTONE=192.168.10.10
MONOTONEPORT=4691
#Vonage
VONAGEIP=192.168.10.6
VONAGEPORTS=10000:20000
#Blizzard Downloader
BLIZZARD_DEST=192.168.10.95
BLIZZARD_PORTS=3724,6112,6881:6999
#BLIZZARD_PORTS=3724
#IP for forwarded HTTP-traffic
HTTPIP="192.168.10.250"
#----Flood Variables-----#
# Overall Limit for TCP-SYN-Flood detection
TCPSYNLIMIT="5/s"
# Burst Limit for TCP-SYN-Flood detection
TCPSYNLIMITBURST="10"
# Overall Limit for Loggging in Logging-Chains
LOGLIMIT="2/s"
# Burst Limit for Logging in Logging-Chains
LOGLIMITBURST="10"
# Overall Limit for Ping-Flood-Detection
PINGLIMIT="5/s"
# Burst Limit for Ping-Flood-Detection
PINGLIMITBURST="10"
#----Automatically determine infos about involved interfaces-----#
### External Interface:
## Get external interface from command-line
## If no interface is specified then set $DEFAULT_EXTIF as EXTIF
if [ "x$2" != "x" ]; then
EXTIF=$2
else
EXTIF=$DEFAULT_EXTIF
fi
echo External Interface: $EXTIF
## Determine external IP
EXTIP="`ifconfig $EXTIF | grep inet | cut -d : -f 2 | cut -d \ -f 1`"
if [ "$EXTIP" = '' ]; then
echo "Aborting: Unable to determine the IP-address of $EXTIF !"
exit 1
fi
echo External IP: $EXTIP
## Determine external gateway
EXTGW=`route -n | grep '0.0.0.0' | grep -A 4 UG | awk '{ print $2}'`
echo Default GW: $EXTGW
echo " --- "
### Internal Interface:
## Get internal interface from command-line
## If no interface is specified then set $DEFAULT_INTIF as INTIF
if [ "x$3" != "x" ]; then
INTIF=$3
else
INTIF=$DEFAULT_INTIF
fi
echo Internal Interface: $INTIF
## Determine internal IP
INTIP="`ifconfig $INTIF | grep inet | cut -d : -f 2 | cut -d \ -f 1`"
if [ "$INTIP" = '' ]; then
echo "Aborting: Unable to determine the IP-address of $INTIF !"
exit 1
fi
echo Internal IP: $INTIP
## Determine internal netmask
INTMASK="`ifconfig $INTIF | grep Mask | cut -d : -f 4`"
echo Internal Netmask: $INTMASK
## Determine network address of the internal network
INTLAN=$INTIP'/'23
echo Internal LAN: $INTLAN
echo ""
#----Load IPTABLES-modules-----#
#Insert modules- should be done automatically if needed
#If the IRC-modules are available, uncomment them below
echo "Loading IPTABLES modules"
dmesg -n 1 #Kill copyright display on module load
/sbin/modprobe ip_tables
/sbin/modprobe iptable_filter
/sbin/modprobe ip_conntrack
/sbin/modprobe ip_conntrack_ftp
/sbin/modprobe ip_nat_ftp
/sbin/modprobe ip_conntrack_irc ports=$IRCPORTS
/sbin/modprobe ip_nat_irc ports=$IRCPORTS
dmesg -n 6
echo " --- "
#----Clear/Reset all chains-----#
#Clear all IPTABLES-chains
#Flush everything, start from scratch
$IPTABLES -F
$IPTABLES -F -t mangle
$IPTABLES -F -t nat
$IPTABLES -X
$IPTABLES -X -t mangle
$IPTABLES -X -t nat
#Set default policies to DROP
$IPTABLES -P INPUT DROP
$IPTABLES -P OUTPUT DROP
$IPTABLES -P FORWARD DROP
#----Set network sysctl options-----#
echo "Setting sysctl options"
#Enable forwarding in kernel
echo 1 >
#Disabling IP Spoofing attacks.
echo 1 >
echo 1 >
echo 1 >
#Don't respond to broadcast pings (Smurf-Amplifier-Protection)
echo "1" >
#Block source routing
echo 0 >
#Kill timestamps
echo 0 >
#Enable SYN Cookies
echo 1 >
#Kill redirects
echo 0 >
#Enable bad error message protection
echo 1 >
#Log martians (packets with impossible addresses)
echo 1 >
#Set out local port range
echo "32768 61000" >
#Reduce DoS'ing ability by reducing timeouts
echo 30 >
echo 2400 >
echo 1 >
echo 1 >
echo 1 >
#Ignore icmp echo (ping) broadcast events
echo 1 >
echo " --- "
echo "Creating user-chains"
#----Create logging chains-----#
##These are the logging-chains. They all have a certain limit of log-entries/sec to prevent log-flooding
##The syslog-entries will be fireparse-compatible (see http://www.fireparse.com)
#Invalid packets (not ESTABLISHED,RELATED or NEW)
$IPTABLES -N LINVALID
$IPTABLES -A LINVALID -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-level info --log-prefix "fp=INVALID:1 a=DROP "
$IPTABLES -A LINVALID -j DROP
#TCP-Packets with one ore more bad flags
$IPTABLES -N LBADFLAG
$IPTABLES -A LBADFLAG -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-level info --log-prefix "fp=BADFLAG:1 a=DROP "
$IPTABLES -A LBADFLAG -j DROP
#Logging of connection attempts on special ports (Trojan portscans, special services, etc.)
$IPTABLES -N LSPECIALPORT
$IPTABLES -A LSPECIALPORT -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-level info --log-prefix "fp=SPECIALPORT:1 a=DROP "
$IPTABLES -A LSPECIALPORT -j DROP
#Logging of possible TCP-SYN-Floods
$IPTABLES -N LSYNFLOOD
$IPTABLES -A LSYNFLOOD -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-level info --log-prefix "fp=SYNFLOOD:1 a=DROP "
$IPTABLES -A LSYNFLOOD -j DROP
#Logging of possible Ping-Floods
$IPTABLES -N LPINGFLOOD
$IPTABLES -A LPINGFLOOD -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-level info --log-prefix "fp=PINGFLOOD:1 a=DROP "
$IPTABLES -A LPINGFLOOD -j DROP
#All other dropped packets
$IPTABLES -N LDROP
$IPTABLES -A LDROP -p tcp -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-level info --log-prefix "fp=TCP:1 a=DROP "
$IPTABLES -A LDROP -p udp -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-level info --log-prefix "fp=UDP:2 a=DROP "
$IPTABLES -A LDROP -p icmp -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-level info --log-prefix "fp=ICMP:3 a=DROP "
$IPTABLES -A LDROP -f -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-level info --log-prefix "fp=FRAGMENT:4 a=DROP "
$IPTABLES -A LDROP -j DROP
#All other rejected packets
$IPTABLES -N LREJECT
$IPTABLES -A LREJECT -p tcp -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-level info --log-prefix "fp=TCP:1 a=REJECT "
$IPTABLES -A LREJECT -p udp -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-level info --log-prefix "fp=UDP:2 a=REJECT "
$IPTABLES -A LREJECT -p icmp -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-level info --log-prefix "fp=ICMP:3 a=REJECT "
$IPTABLES -A LREJECT -f -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-level info --log-prefix "fp=FRAGMENT:4 a=REJECT "
$IPTABLES -A LREJECT -p tcp -j REJECT --reject-with tcp-reset
$IPTABLES -A LREJECT -p udp -j REJECT --reject-with icmp-port-unreachable
$IPTABLES -A LREJECT -j REJECT
#----Create Accept-Chains-----#
#TCPACCEPT - Check for SYN-Floods before letting TCP-Packets in
$IPTABLES -N TCPACCEPT
$IPTABLES -A TCPACCEPT -p tcp --syn -m limit --limit $TCPSYNLIMIT --limit-burst $TCPSYNLIMITBURST -j ACCEPT
$IPTABLES -A TCPACCEPT -p tcp --syn -j LSYNFLOOD
$IPTABLES -A TCPACCEPT -p tcp ! --syn -j ACCEPT
#----Create special User-Chains-----#
#CHECKBADFLAG - Kill any Inbound/Outbound TCP-Packets with impossible flag-combinations (Some port-scanners use these, eg. nmap Xmas,Null,etc.-scan)
$IPTABLES -N CHECKBADFLAG
$IPTABLES -A CHECKBADFLAG -p tcp --tcp-flags ALL FIN,URG,PSH -j LBADFLAG
$IPTABLES -A CHECKBADFLAG -p tcp --tcp-flags ALL SYN,RST,ACK,FIN,URG -j LBADFLAG
$IPTABLES -A CHECKBADFLAG -p tcp --tcp-flags ALL ALL -j LBADFLAG
$IPTABLES -A CHECKBADFLAG -p tcp --tcp-flags ALL NONE -j LBADFLAG
$IPTABLES -A CHECKBADFLAG -p tcp --tcp-flags SYN,RST SYN,RST -j LBADFLAG
$IPTABLES -A CHECKBADFLAG -p tcp --tcp-flags SYN,FIN SYN,FIN -j LBADFLAG
#FILTERING FOR SPECIAL PORTS
#Inbound/Outbound SILENTDROPS/REJECTS (Things we don't want in our Logs)
#SMB-Traffic
$IPTABLES -N SMB
$IPTABLES -A SMB -p tcp --dport 137 -j DROP
$IPTABLES -A SMB -p tcp --dport 138 -j DROP
$IPTABLES -A SMB -p tcp --dport 139 -j DROP
$IPTABLES -A SMB -p tcp --dport 445 -j DROP
$IPTABLES -A SMB -p udp --dport 137 -j DROP
$IPTABLES -A SMB -p udp --dport 138 -j DROP
$IPTABLES -A SMB -p udp --dport 139 -j DROP
$IPTABLES -A SMB -p udp --dport 445 -j DROP
$IPTABLES -A SMB -p tcp --sport 137 -j DROP
$IPTABLES -A SMB -p tcp --sport 138 -j DROP
$IPTABLES -A SMB -p tcp --sport 139 -j DROP
$IPTABLES -A SMB -p tcp --sport 445 -j DROP
$IPTABLES -A SMB -p udp --sport 137 -j DROP
$IPTABLES -A SMB -p udp --sport 138 -j DROP
$IPTABLES -A SMB -p udp --sport 139 -j DROP
$IPTABLES -A SMB -p udp --sport 445 -j DROP
#Inbound Special Ports
$IPTABLES -N SPECIALPORTS
#Deepthroat Scan
$IPTABLES -A SPECIALPORTS -p tcp --dport 6670 -j LSPECIALPORT
#Subseven Scan
$IPTABLES -A SPECIALPORTS -p tcp --dport 1243 -j LSPECIALPORT
$IPTABLES -A SPECIALPORTS -p udp --dport 1243 -j LSPECIALPORT
$IPTABLES -A SPECIALPORTS -p tcp --dport 27374 -j LSPECIALPORT
$IPTABLES -A SPECIALPORTS -p udp --dport 27374 -j LSPECIALPORT
$IPTABLES -A SPECIALPORTS -p tcp --dport 6711:6713 -j LSPECIALPORT
#Netbus Scan
$IPTABLES -A SPECIALPORTS -p tcp --dport 12345:12346 -j LSPECIALPORT
$IPTABLES -A SPECIALPORTS -p tcp --dport 20034 -j LSPECIALPORT
#Back Orifice scan
$IPTABLES -A SPECIALPORTS -p udp --dport 31337:31338 -j LSPECIALPORT
#X-Win
$IPTABLES -A SPECIALPORTS -p tcp --dport $XWINPORTS -j LSPECIALPORT
#Hack'a'Tack 2000
$IPTABLES -A SPECIALPORTS -p udp --dport 28431 -j LSPECIALPORT
#ICMP/TRACEROUTE FILTERING
#Inbound ICMP/Traceroute
$IPTABLES -N ICMPINBOUND
#Ping Flood protection. Accept $PINGLIMIT echo-requests/sec, rest will be logged/dropped
$IPTABLES -A ICMPINBOUND -p icmp --icmp-type echo-request -m limit --limit $PINGLIMIT --limit-burst $PINGLIMITBURST -j ACCEPT
#
$IPTABLES -A ICMPINBOUND -p icmp --icmp-type echo-request -j LPINGFLOOD
#Block ICMP-Redirects (Should already be catched by sysctl-options, if enabled)
$IPTABLES -A ICMPINBOUND -p icmp --icmp-type redirect -j LDROP
#Block ICMP-Timestamp (Should already be catched by sysctl-options, if enabled)
$IPTABLES -A ICMPINBOUND -p icmp --icmp-type timestamp-request -j LDROP
$IPTABLES -A ICMPINBOUND -p icmp --icmp-type timestamp-reply -j LDROP
#Block ICMP-address-mask (can help to prevent OS-fingerprinting)
$IPTABLES -A ICMPINBOUND -p icmp --icmp-type address-mask-request -j LDROP
$IPTABLES -A ICMPINBOUND -p icmp --icmp-type address-mask-reply -j LDROP
#Allow all other ICMP in
$IPTABLES -A ICMPINBOUND -p icmp -j ACCEPT
#Outbound ICMP/Traceroute
$IPTABLES -N ICMPOUTBOUND
#Block ICMP-Redirects (Should already be catched by sysctl-options, if enabled)
$IPTABLES -A ICMPOUTBOUND -p icmp --icmp-type redirect -j LDROP
#Block ICMP-TTL-Expired
#MS Traceroute (MS uses ICMP instead of UDp for tracert)
$IPTABLES -A ICMPOUTBOUND -p icmp --icmp-type ttl-zero-during-transit -j LDROP
$IPTABLES -A ICMPOUTBOUND -p icmp --icmp-type ttl-zero-during-reassembly -j LDROP
#Block ICMP-Parameter-Problem
$IPTABLES -A ICMPOUTBOUND -p icmp --icmp-type parameter-problem -j LDROP
#Block ICMP-Timestamp (Should already be catched by sysctl-options, if enabled)
$IPTABLES -A ICMPOUTBOUND -p icmp --icmp-type timestamp-request -j LDROP
$IPTABLES -A ICMPOUTBOUND -p icmp --icmp-type timestamp-reply -j LDROP
#Block ICMP-address-mask (can help to prevent OS-fingerprinting)
$IPTABLES -A ICMPOUTBOUND -p icmp --icmp-type address-mask-request -j LDROP
$IPTABLES -A ICMPOUTBOUND -p icmp --icmp-type address-mask-reply -j LDROP
##Accept all other ICMP going out
$IPTABLES -A ICMPOUTBOUND -p icmp -j ACCEPT
########
# Throttle SSH connections by host
# to prevent brute force attacks
########
$IPTABLES --new-chain SSHTHROTTLE
$IPTABLES --flush SSHTHROTTLE
$IPTABLES --append SSHTHROTTLE --match recent --name ssh_throttle --seconds $(( 3600 * 18)) --update -j DROP
$IPTABLES --append SSHTHROTTLE --match limit --limit 3/hour -j RETURN
$IPTABLES --append SSHTHROTTLE --match recent --name ssh_throttle --set -j DROP
#----End User-Chains-----#
echo " --- "
#----Start Ruleset-----#
echo "Implementing firewall rules..."
#################
## INPUT-Chain ## (everything that is addressed to the firewall itself)
#################
##GENERAL Filtering
# Kill INVALID packets (not ESTABLISHED, RELATED or NEW)
$IPTABLES -A INPUT -m state --state INVALID -j LINVALID
# Check TCP-Packets for Bad Flags
$IPTABLES -A INPUT -p tcp -j CHECKBADFLAG
##Packets FROM FIREWALL-BOX ITSELF
#Local IF
$IPTABLES -A INPUT -i lo -j ACCEPT
#
#Kill connections to the local interface from the outside world (--> Should be already catched by kernel/rp_filter)
$IPTABLES -A INPUT -d 127.0.0.0/8 -j LREJECT
##Packets FROM INTERNAL NET
##Allow unlimited traffic from internal network using legit addresses to firewall-box
##If protection from the internal interface is needed, alter it
$IPTABLES -A INPUT -i ! $EXTIF -s $INTLAN -j ACCEPT
#Allow Local DHCP Service Nonsense
$IPTABLES -I INPUT -i ! $EXTIF -p udp -s 0.0.0.0 -d 255.255.255.255 --sport 68 --dport 67 -j ACCEPT
#Kill anything from outside claiming to be from internal network (Address-Spoofing --> Should be already catched by rp_filter)
$IPTABLES -A INPUT -s $INTLAN -j LREJECT
##Packets FROM EXTERNAL NET
## DHCP Server on ISP's Site
$IPTABLES -I INPUT -i $EXTIF -p udp -s 0.0.0.0 -d 255.255.255.255 --sport 67 --dport 68 -j ACCEPT
if [ -f
DHCPSID=$(grep dhcp-server-identifier
echo $IPTABLES -I INPUT -i $EXTIF -p udp --sport 67 --dport 68 --source "$DHCPSID" -j ACCEPT
$IPTABLES -I INPUT -i $EXTIF -p udp --sport 67 --dport 68 --source "$DHCPSID" -j ACCEPT
fi
##ICMP & Traceroute filtering
#Filter ICMP
$IPTABLES -A INPUT -i $EXTIF -p icmp -j ICMPINBOUND
#Block UDP-Traceroute
$IPTABLES -A INPUT -p udp --dport 33434:33523 -j LDROP
##Silent Drops/Rejects (Things we don't want in our logs)
#Drop all SMB-Traffic
$IPTABLES -A INPUT -i $EXTIF -j SMB
#Silently reject Ident (Don't DROP ident, because of possible delays when establishing an outbound connection)
$IPTABLES -A INPUT -i $EXTIF -p tcp --dport 113 -j REJECT --reject-with tcp-reset
##Public services running ON FIREWALL-BOX (comment out to activate):
# ftp-data
#$IPTABLES -A INPUT -i $EXTIF -p tcp --dport 20 -j TCPACCEPT
# ftp
#$IPTABLES -A INPUT -i $EXTIF -p tcp --dport 21 -j TCPACCEPT
# ssh
$IPTABLES -A INPUT -i $EXTIF -p tcp --dport 22 -m state --state ESTABLISHED,RELATED -j TCPACCEPT
$IPTABLES -A INPUT -i $EXTIF -p tcp --dport 22 --syn -j SSHTHROTTLE
$IPTABLES -A INPUT -i $EXTIF -p tcp --dport 22 --match state --state NEW -j TCPACCEPT
#telnet
#$IPTABLES -A INPUT -i $EXTIF -p tcp --dport 23 -j TCPACCEPT
# smtp
#$IPTABLES -A INPUT -i $EXTIF -p tcp --dport 25 -j TCPACCEPT
# DNS
$IPTABLES -A INPUT -i $EXTIF -p tcp --dport 53 -j TCPACCEPT
$IPTABLES -A INPUT -i $EXTIF -p udp --dport 53 -j ACCEPT
# http
# $IPTABLES -A INPUT -i $EXTIF -p tcp --dport 80 -j TCPACCEPT
# https
#$IPTABLES -A INPUT -i $EXTIF -p tcp --dport 443 -j TCPACCEPT
# POP-3
#$IPTABLES -A INPUT -i $EXTIF -p tcp --dport 110 -j TCPACCEPT
##Separate logging of special portscans/connection attempts
$IPTABLES -A INPUT -i $EXTIF -j SPECIALPORTS
##Allow ESTABLISHED/RELATED connections in
$IPTABLES -A INPUT -i $EXTIF -m state --state ESTABLISHED -j ACCEPT
$IPTABLES -A INPUT -i $EXTIF -p tcp --dport $UNPRIVPORTS -m state --state RELATED -j TCPACCEPT
$IPTABLES -A INPUT -i $EXTIF -p udp --dport $UNPRIVPORTS -m state --state RELATED -j ACCEPT
##Catch all rule
$IPTABLES -A INPUT -j LDROP
##################
## Output-Chain ## (everything that comes directly from the Firewall-Box)
##################
##Packets TO FIREWALL-BOX ITSELF
#Local IF
$IPTABLES -A OUTPUT -o lo -j ACCEPT
##Packets TO INTERNAL NET
#Allow unlimited traffic to internal network using legit addresses
$IPTABLES -A OUTPUT -o ! $EXTIF -d $INTLAN -j ACCEPT
##Packets TO EXTERNAL NET
##NTP
$IPTABLES -A OUTPUT -o $EXTIF -p udp --sport ntp --dport ntp -j ACCEPT
##ICMP & Traceroute
$IPTABLES -A OUTPUT -o $EXTIF -p icmp -j ICMPOUTBOUND
##Silent Drops/Rejects (Things we don't want in our logs)
#SMB
$IPTABLES -A OUTPUT -o $EXTIF -j SMB
#Ident
$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport 113 -j REJECT --reject-with tcp-reset
##Public services running ON FIREWALL-BOX (comment out to activate):
# ftp-data
#$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport 20 -j ACCEPT
# ftp
#$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport 21 -j ACCEPT
# ssh
$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport 22 -m state --state ESTABLISHED,RELATED -j ACCEPT
$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport 8193 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
#telnet
#$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport 23 -m state --state ESTABLISHED -j ACCEPT
# smtp
#$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport 25 -m state --state ESTABLISHED -j ACCEPT
# DNS
$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport 53 -j ACCEPT
$IPTABLES -A OUTPUT -o $EXTIF -p udp --sport 53 -j ACCEPT
# http
#$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport 80 -m state --state ESTABLISHED -j ACCEPT
# https
#$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport 443 -m state --state ESTABLISHED -j ACCEPT
# POP-3
#$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport 110 -m state --state ESTABLISHED -j ACCEPT
# DHCP Server on ISP's Site
$IPTABLES -A OUTPUT -o $EXTIF -p udp --sport 68 --dport 67 --source 0.0.0.0 --destination 255.255.255.255 -j ACCEPT
if [ -f
DHCPSID=$(grep DHCPSID
$IPTABLES -A OUTPUT -o $EXTIF -p udp --sport 68 --dport 67 --destination $DHCPSID -j ACCEPT
fi
# DHCP Server inside Firewall Box
$IPTABLES -A OUTPUT -o ! $EXTIF -p udp --sport 67 --dport 68 -j ACCEPT
##Accept all tcp/udp traffic on unprivileged ports going out
$IPTABLES -A OUTPUT -o $EXTIF -s $EXTIP -p tcp --sport $UNPRIVPORTS -j ACCEPT
$IPTABLES -A OUTPUT -o $EXTIF -s $EXTIP -p udp --sport $UNPRIVPORTS -j ACCEPT
##Catch all rule
$IPTABLES -A OUTPUT -j LDROP
####################
## FORWARD-Chain ## (everything that passes the firewall)
####################
##GENERAL Filtering
# optimal forwarding rates
$IPTABLES -A FORWARD -i ! $EXTIF -m state --state ESTABLISHED,RELATED -j ACCEPT
$IPTABLES -A FORWARD -i ! $EXTIF -o $EXTIF -m state --state NEW -j ACCEPT
#Kill invalid packets (not ESTABLISHED, RELATED or NEW)
$IPTABLES -A FORWARD -m state --state INVALID -j LINVALID
# Check TCP-Packets for Bad Flags
$IPTABLES -A FORWARD -p tcp -j CHECKBADFLAG
# Bad Broadcasting
$IPTABLES -A FORWARD -d 255.255.255.255 -j DROP
$IPTABLES -A FORWARD -d 192.168.10.0 -j DROP
$IPTABLES -A FORWARD -d 192.168.11.0 -j DROP
# Spoofing
$IPTABLES -A FORWARD -i $EXTIF -s 192.168.10.0/23 -j LDROP
##Silent Drops/Rejects (Things we don't want in our logs)
#SMB
$IPTABLES -A FORWARD -o $EXTIF -j SMB
$IPTABLES -A FORWARD -p tcp -m multiport --destination-ports 137,138,139,445 -j DROP
$IPTABLES -A FORWARD -p udp -m multiport --destination-ports 137,138,139,445 -j DROP
##Filtering FROM INTERNAL NET
##Special Drops/Rejects
# - To be done -
##Filter for some Trojans communicating to outside
# - To be done -
##Port-Forwarding from Ports < 1024 [outbound] (--> Also see chain PREROUTING)
#HTTP-Forwarding
#$IPTABLES -A FORWARD -o $EXTIF -s $HTTPIP -p tcp --sport 80 -j ACCEPT
##Allow all other forwarding (from Ports > 1024) from Internal Net to External Net
$IPTABLES -A FORWARD -i ! $EXTIF -o $EXTIF -s $INTLAN -p tcp --sport $UNPRIVPORTS -j ACCEPT
$IPTABLES -A FORWARD -i ! $EXTIF -o $EXTIF -s $INTLAN -p udp --sport $UNPRIVPORTS -j ACCEPT
$IPTABLES -A FORWARD -i ! $EXTIF -o $EXTIF -s $INTLAN -p icmp -j ACCEPT
##Allow non-external nets to talk to each other, q.v. wireless to wired "internal" networks
$IPTABLES -A FORWARD -i ! $EXTIF -o ! $EXTIF -s $INTLAN -p tcp -m multiport --destination-ports ssh,sunrpc,snmp,snmptrap,631,940,943,946,949 -j ACCEPT
$IPTABLES -A FORWARD -i ! $EXTIF -o ! $EXTIF -s $INTLAN -p udp -m multiport --destination-ports ssh,sunrpc,snmp,snmptrap,631,940,943,946,949 -j ACCEPT
$IPTABLES -A FORWARD -i ! $EXTIF -o ! $EXTIF -s $INTLAN -p tcp -m multiport --destination-ports $UNPRIVPORTS -j ACCEPT
$IPTABLES -A FORWARD -i ! $EXTIF -o ! $EXTIF -s $INTLAN -p udp -m multiport --destination-ports $UNPRIVPORTS -j ACCEPT
##Filtering FROM EXTERNAL NET
##Silent Drops/Rejects (Things we don't want in our logs)
#SMB Handled Above
#$IPTABLES -A FORWARD -i $EXTIF -j SMB
##Allow replies coming in
$IPTABLES -A FORWARD -i $EXTIF -m state --state ESTABLISHED -j ACCEPT
$IPTABLES -A FORWARD -i $EXTIF -p tcp --dport $UNPRIVPORTS -m state --state RELATED -j TCPACCEPT
$IPTABLES -A FORWARD -i $EXTIF -p udp --dport $UNPRIVPORTS -m state --state RELATED -j ACCEPT
$IPTABLES -A FORWARD -i $EXTIF -p icmp -m state --state RELATED -j ACCEPT
$IPTABLES -A FORWARD -i $EXTIF -m state --state RELATED -j ACCEPT
##Port-Forwarding [inbound] (--> Also see chain PREROUTING)
#HTTP-Forwarding
$IPTABLES -A FORWARD -i $EXTIF -p tcp -d $HTTPIP --dport 80 -j ACCEPT
#Battlecom-Forwarding
#$IPTABLES -A FORWARD -p tcp --dport 2300:2400 -i $EXTIF -d $BATTLECOMIP -j ACCEPT
#$IPTABLES -A FORWARD -p udp --dport 2300:2400 -i $EXTIF -d $BATTLECOMIP -j ACCEPT
#$IPTABLES -A FORWARD -p tcp --dport 47624 -i $EXTIF -d $BATTLECOMIP -j ACCEPT
$IPTABLES -A FORWARD -p tcp --dport $BITTPORT -i $EXTIF -d $BITTORRENT -j ACCEPT
$IPTABLES -A FORWARD -p udp --dport $BITTPORT -i $EXTIF -d $BITTORRENT -j ACCEPT
$IPTABLES -A FORWARD -p tcp --dport $MONOTONEPORT -i $EXTIF -d $MONOTONE -j ACCEPT
$IPTABLES -A FORWARD -p udp --dport $VONAGEPORTS -i $EXTIF -d $VONAGEIP -j ACCEPT
$IPTABLES -A FORWARD -p tcp --match multiport --destination-ports $BLIZZARD_PORTS -i $EXTIF -d $BLIZZARD_DEST -j ACCEPT
$IPTABLES -A FORWARD -i $EXTIF -d $BLIZZARD_DEST -p tcp --match multiport --destination-ports $BLIZZARD_PORTS --match state --state NEW -j ACCEPT
##Catch all rule/Deny every other forwarding
$IPTABLES -A FORWARD -j LDROP
################
## PREROUTING ##
################
##Port-Forwarding (--> Also see chain FORWARD)
##NTP
$IPTABLES -A PREROUTING -t nat -i ! $EXTIF -p udp --destination-port ntp -j REDIRECT
##HTTP
$IPTABLES -A PREROUTING -t nat -i $EXTIF -p tcp -d $EXTIP --dport 80 -j DNAT --to $HTTPIP
##Battlecom
#$IPTABLES -t nat -A PREROUTING -d $EXTIP -p tcp --destination-port 2300:2400 -i $EXTIF -j DNAT --to $BATTLECOMIP
#$IPTABLES -t nat -A PREROUTING -d $EXTIP -p udp --destination-port 2300:2400 -i $EXTIF -j DNAT --to $BATTLECOMIP
#$IPTABLES -t nat -A PREROUTING -d $EXTIP -p tcp --destination-port 47624 -i $EXTIF -j DNAT --to $BATTLECOMIP:47624
$IPTABLES -t nat -A PREROUTING -d $EXTIP -p tcp --destination-port $BITTPORT -i $EXTIF -j DNAT --to $BITTORRENT:$BITTPORT
$IPTABLES -t nat -A PREROUTING -d $EXTIP -p udp --destination-port $BITTPORT -i $EXTIF -j DNAT --to $BITTORRENT:$BITTPORT
##Monotone
$IPTABLES -t nat -A PREROUTING -d $EXTIP -p tcp --destination-port $MONOTONEPORT -i $EXTIF -j DNAT --to $MONOTONE:$MONOTONEPORT
##Vonage
$IPTABLES -t nat -A PREROUTING -d $EXTIP -p udp --destination-port $VONAGEPORTS -i $EXTIF -j DNAT --to $VONAGEIP
##Blizzard
$IPTABLES -t nat -A PREROUTING --destination $EXTIP --in-interface $EXTIF -p tcp --tcp-flags SYN,ACK,FIN,RST SYN --match multiport --destination-ports $BLIZZARD_PORTS -j DNAT --to $BLIZZARD_DEST
###################
## POSTROUTING ##
###################
#Masquerade from Internal Net to External Net
$IPTABLES -A POSTROUTING -t nat --out-interface $EXTIF -j SNAT --to-source $EXTIP
# Initial Shape Classifier
# gIive "overhead" packets highest priority
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp -j CLASSIFY --set-class 1:60
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --tcp-flags ALL ACK -m length --length 40:68 -m state --state ESTABLISHED,RELATED -j CLASSIFY --set-class 1:10
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --syn -m length --length 40:68 -j CLASSIFY --set-class 1:10
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --tcp-flags ALL SYN,ACK -m length --length 40:68 -j CLASSIFY --set-class 1:10
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --tcp-flags ALL ACK -m length --length 40:100 -j CLASSIFY --set-class 1:10
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --tcp-flags ALL RST -j CLASSIFY --set-class 1:10
#$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --tcp-flags ALL ACK,RST -j CLASSIFY --set-class 1:10
#$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --tcp-flags ALL ACK,FIN -j CLASSIFY --set-class 1:10
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --tcp-flags ALL FIN -j CLASSIFY --set-class 1:10
# interactive SSH traffic and UDP gaming
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p udp -j CLASSIFY --set-class 1:20
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF --source $VONAGEIP -p udp -j RETURN
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p udp -j CLASSIFY --set-class 1:30
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --sport ssh -m length --length 40:100 -j CLASSIFY --set-class 1:20
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --dport ssh -m length --length 40:100 -j CLASSIFY --set-class 1:20
# interactive mail or web traffic
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp -m multiport --dport http,pop2,pop3,imap,https,imaps -j CLASSIFY --set-class 1:30
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp -m multiport --sport http,pop2,pop3,imap,https,imaps -j CLASSIFY --set-class 1:30
# dns lookups
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --dport domain -j CLASSIFY --set-class 1:30
# ICMP
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p icmp -m length --length 28:1500 -m limit --limit 2/s --limit-burst 5 -j CLASSIFY --set-class 1:40
# bulk traffic
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --sport ssh -m length --length 101: -j CLASSIFY --set-class 1:50
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --dport ssh -m length --length 101: -j CLASSIFY --set-class 1:50
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --sport 25 -j CLASSIFY --set-class 1:50
$IPTABLES -t mangle -A POSTROUTING -o $EXTIF -p tcp --dport 6667 -j CLASSIFY --set-class 1:50
ip6tables -P FORWARD DROP
#------End Ruleset------#
echo "...done"
echo ""
echo "--> IPTABLES firewall loaded/activated <--"
##--------------------------------End Firewall---------------------------------##
;;
*)
echo "Usage: firewall (start|stop|restart|status) EXTIF INTIF"
exit 1
esac
exit 0
Firewall Script More Login
Firewall Script
Slashdot Top Deals