Ik heb op http://www.linuxguruz.org echt hele mooie scripts gevonden voor een iptables firewall met masquerading. Het staan er trouwens nog veel meer.
Het probleem is alleen dat elke of iig veel messages op het screen worden gedisplayed. Dit is nou niet echt wat ik verwacht van een logging. Ik kan niet normaal werken want er komen telkens logging messages doorheen. Kan iemand mij vertellen wat er varnderd moet worden????
Dit is trouwens ook een heel geschikte voor een dynamisch IP-adress.
Hier onder staat het betreffende script.
Het is verder wel een aanrader. Zeker als mijn probleem is opgelost.
*************************************************************
#################################################################################
#
# 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 ppp0 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
#
#
########################################################################################
#!/bin/sh
# 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="eth0"
## Default internal interface (used, if INTIF isn't specified on command line)
DEFAULT_INTIF="eth1"
#----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="6665,6666,6667,6668,6669,7000"
# Webserver port
HTTPPORT="2080"
# FTPserver port
FTPPORT="2021"
# FTPdata port
FTPDATAPORT="2020"
# SSHserver
SSHPORT="22"
# TELNETserver
TELNETPORT="23"
# SWAT
SWATPORT="901"
#-----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"
#IP for forwarded HTTP-traffic
#HTTPIP="192.168.0.20"
#----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 -A 4 UG | awk '{ print $2}'`
echo Default GW: $EXTGW
#IP for forwarded HTTP-traffic
HTTPIP=$EXTIP
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'/'$INTMASK
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 2 > /proc/sys/net/ipv4/conf/all/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 0 > /proc/sys/net/ipv4/tcp_window_scaling
echo 0 > /proc/sys/net/ipv4/tcp_sack
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-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-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-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-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-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-prefix "fp=TCP:1 a=DROP "
$IPTABLES -A LDROP -p udp -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-prefix "fp=UDP:2 a=DROP "
$IPTABLES -A LDROP -p icmp -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-prefix "fp=ICMP:3 a=DROP "
$IPTABLES -A LDROP -f -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --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-prefix "fp=TCP:1 a=REJECT "
$IPTABLES -A LREJECT -p udp -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-prefix "fp=UDP:2 a=REJECT "
$IPTABLES -A LREJECT -p icmp -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-prefix "fp=ICMP:3 a=REJECT "
$IPTABLES -A LREJECT -f -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --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
#----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 $INTIF -s $INTLAN -j ACCEPT
#Kill anything from outside claiming to be from internal network (Address-Spoofing --> Should be already catched by rp_filter)
$IPTABLES -A INPUT -i $EXTIF -s $INTLAN -j LREJECT
##!!!!!!!!!!!!!!!!!!!!! Waarom niet -i $EXTIF
##Packets FROM EXTERNAL NET
##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):
##########
# ACCEPT #############
##########
# ftp-data
$IPTABLES -A INPUT -i $EXTIF -p tcp --dport $FTPDATAPORT -j TCPACCEPT
# ftp
$IPTABLES -A INPUT -i $EXTIF -p tcp --dport $FTPPORT -j TCPACCEPT
# ssh
$IPTABLES -A INPUT -i $EXTIF -p tcp --dport $SSHPORT -j TCPACCEPT
# http
$IPTABLES -A INPUT -i $EXTIF -p tcp --dport $HTTPPORT -j TCPACCEPT
# SWAT
$IPTABLES -A INPUT -i $EXTIF -p tcp --dport $SWATPORT -j TCPACCEPT
########
# DENY #############
########
#telnet
#$IPTABLES -A INPUT -i $EXTIF -p tcp --dport $TELNETPORT -j TCPACCEPT
# smtp
#$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 $EXTIF -p udp --dport 53 -j ACCEPT
# https
#$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 $INTIF -d $INTLAN -j ACCEPT
##Packets TO EXTERNAL NET
##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):
##########
# ACCEPT #############
##########
# ftp-data
$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport $FTPDATAPORT -j ACCEPT
# ftp
$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport $FTPPORT -j ACCEPT
# ssh
$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport $SSHPORT -m state --state ESTABLISHED -j ACCEPT
# http
$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport $HTTPPORT -m state --state ESTABLISHED -j ACCEPT
# SWAT
$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport $SWATPORT -m state --state ESTABLISHED -j ACCEPT
########
# DENY #############
########
#telnet
#$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport $TELNETPORT -m state --state ESTABLISHED -j ACCEPT
# smtp
#$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 $EXTIF -p udp --sport 53 -j ACCEPT
# https
#$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
##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
#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
##Filtering FROM INTERNAL NET
##Silent Drops/Rejects (Things we don't want in our logs)
#SMB
$IPTABLES -A FORWARD -o $EXTIF -j SMB
##Special Drops/Rejects
# - To be done -
##Filter for some Trojans communicating to outside
# - To be done -
##Port-Forwarding from Ports < 1024 [outbound] (--> Also see chain PREROUTING)
#HTTP-Forwarding
#$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 $INTIF -o $EXTIF -s $INTLAN -p tcp --sport $UNPRIVPORTS -j ACCEPT
$IPTABLES -A FORWARD -i $INTIF -o $EXTIF -s $INTLAN -p udp --sport $UNPRIVPORTS -j ACCEPT
$IPTABLES -A FORWARD -i $INTIF -o $EXTIF -s $INTLAN -p icmp -j ACCEPT
##Filtering FROM EXTERNAL NET
##Silent Drops/Rejects (Things we don't want in our logs)
#SMB
$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 $EXTIF -p icmp -m state --state RELATED -j ACCEPT
##Port-Forwarding [inbound] (--> Also see chain PREROUTING)
#HTTP-Forwarding
#$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
##Catch all rule/Deny every other forwarding
$IPTABLES -A FORWARD -j LDROP
################
## PREROUTING ##
################
##Port-Forwarding (--> Also see chain FORWARD)
##HTTP
$IPTABLES -A PREROUTING -t nat -i $EXTIF -p tcp -d $EXTIP --dport $HTTPPORT -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
###################
## POSTROUTING ##
###################
#Masquerade from Internal Net to External Net
$IPTABLES -A POSTROUTING -t nat -o $EXTIF -j MASQUERADE
#------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
Het probleem is alleen dat elke of iig veel messages op het screen worden gedisplayed. Dit is nou niet echt wat ik verwacht van een logging. Ik kan niet normaal werken want er komen telkens logging messages doorheen. Kan iemand mij vertellen wat er varnderd moet worden????
Dit is trouwens ook een heel geschikte voor een dynamisch IP-adress.
Hier onder staat het betreffende script.
Het is verder wel een aanrader. Zeker als mijn probleem is opgelost.
*************************************************************
#################################################################################
#
# 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 ppp0 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
#
#
########################################################################################
#!/bin/sh
# 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="eth0"
## Default internal interface (used, if INTIF isn't specified on command line)
DEFAULT_INTIF="eth1"
#----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="6665,6666,6667,6668,6669,7000"
# Webserver port
HTTPPORT="2080"
# FTPserver port
FTPPORT="2021"
# FTPdata port
FTPDATAPORT="2020"
# SSHserver
SSHPORT="22"
# TELNETserver
TELNETPORT="23"
# SWAT
SWATPORT="901"
#-----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"
#IP for forwarded HTTP-traffic
#HTTPIP="192.168.0.20"
#----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 -A 4 UG | awk '{ print $2}'`
echo Default GW: $EXTGW
#IP for forwarded HTTP-traffic
HTTPIP=$EXTIP
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'/'$INTMASK
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 2 > /proc/sys/net/ipv4/conf/all/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 0 > /proc/sys/net/ipv4/tcp_window_scaling
echo 0 > /proc/sys/net/ipv4/tcp_sack
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-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-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-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-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-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-prefix "fp=TCP:1 a=DROP "
$IPTABLES -A LDROP -p udp -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-prefix "fp=UDP:2 a=DROP "
$IPTABLES -A LDROP -p icmp -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-prefix "fp=ICMP:3 a=DROP "
$IPTABLES -A LDROP -f -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --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-prefix "fp=TCP:1 a=REJECT "
$IPTABLES -A LREJECT -p udp -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-prefix "fp=UDP:2 a=REJECT "
$IPTABLES -A LREJECT -p icmp -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --log-prefix "fp=ICMP:3 a=REJECT "
$IPTABLES -A LREJECT -f -m limit --limit $LOGLIMIT --limit-burst $LOGLIMITBURST -j LOG --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
#----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 $INTIF -s $INTLAN -j ACCEPT
#Kill anything from outside claiming to be from internal network (Address-Spoofing --> Should be already catched by rp_filter)
$IPTABLES -A INPUT -i $EXTIF -s $INTLAN -j LREJECT
##!!!!!!!!!!!!!!!!!!!!! Waarom niet -i $EXTIF
##Packets FROM EXTERNAL NET
##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):
##########
# ACCEPT #############
##########
# ftp-data
$IPTABLES -A INPUT -i $EXTIF -p tcp --dport $FTPDATAPORT -j TCPACCEPT
# ftp
$IPTABLES -A INPUT -i $EXTIF -p tcp --dport $FTPPORT -j TCPACCEPT
# ssh
$IPTABLES -A INPUT -i $EXTIF -p tcp --dport $SSHPORT -j TCPACCEPT
# http
$IPTABLES -A INPUT -i $EXTIF -p tcp --dport $HTTPPORT -j TCPACCEPT
# SWAT
$IPTABLES -A INPUT -i $EXTIF -p tcp --dport $SWATPORT -j TCPACCEPT
########
# DENY #############
########
#telnet
#$IPTABLES -A INPUT -i $EXTIF -p tcp --dport $TELNETPORT -j TCPACCEPT
# smtp
#$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 $EXTIF -p udp --dport 53 -j ACCEPT
# https
#$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 $INTIF -d $INTLAN -j ACCEPT
##Packets TO EXTERNAL NET
##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):
##########
# ACCEPT #############
##########
# ftp-data
$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport $FTPDATAPORT -j ACCEPT
# ftp
$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport $FTPPORT -j ACCEPT
# ssh
$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport $SSHPORT -m state --state ESTABLISHED -j ACCEPT
# http
$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport $HTTPPORT -m state --state ESTABLISHED -j ACCEPT
# SWAT
$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport $SWATPORT -m state --state ESTABLISHED -j ACCEPT
########
# DENY #############
########
#telnet
#$IPTABLES -A OUTPUT -o $EXTIF -p tcp --sport $TELNETPORT -m state --state ESTABLISHED -j ACCEPT
# smtp
#$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 $EXTIF -p udp --sport 53 -j ACCEPT
# https
#$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
##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
#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
##Filtering FROM INTERNAL NET
##Silent Drops/Rejects (Things we don't want in our logs)
#SMB
$IPTABLES -A FORWARD -o $EXTIF -j SMB
##Special Drops/Rejects
# - To be done -
##Filter for some Trojans communicating to outside
# - To be done -
##Port-Forwarding from Ports < 1024 [outbound] (--> Also see chain PREROUTING)
#HTTP-Forwarding
#$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 $INTIF -o $EXTIF -s $INTLAN -p tcp --sport $UNPRIVPORTS -j ACCEPT
$IPTABLES -A FORWARD -i $INTIF -o $EXTIF -s $INTLAN -p udp --sport $UNPRIVPORTS -j ACCEPT
$IPTABLES -A FORWARD -i $INTIF -o $EXTIF -s $INTLAN -p icmp -j ACCEPT
##Filtering FROM EXTERNAL NET
##Silent Drops/Rejects (Things we don't want in our logs)
#SMB
$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 $EXTIF -p icmp -m state --state RELATED -j ACCEPT
##Port-Forwarding [inbound] (--> Also see chain PREROUTING)
#HTTP-Forwarding
#$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
##Catch all rule/Deny every other forwarding
$IPTABLES -A FORWARD -j LDROP
################
## PREROUTING ##
################
##Port-Forwarding (--> Also see chain FORWARD)
##HTTP
$IPTABLES -A PREROUTING -t nat -i $EXTIF -p tcp -d $EXTIP --dport $HTTPPORT -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
###################
## POSTROUTING ##
###################
#Masquerade from Internal Net to External Net
$IPTABLES -A POSTROUTING -t nat -o $EXTIF -j MASQUERADE
#------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
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