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#!/bin/bash
#%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%#
# IPTables port whitelisting-/blacklisting [Thomas Lange <tl@nerdmind.de>] #
#%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%#
# #
# This script configures your firewall with whitelisting or blacklisting rules #
# and is compatible with IPv4 and IPv6. If you do not have IPv6 just uncomment #
# all lines which containing a "${IPTABLES_V6}". If you want to add additional #
# rules then you can do that at the end of the script. This makes sense if you #
# want allow or disallow internal network traffic from gateway or something. #
# #
#%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%#
#===============================================================================
# Set whitelisting or blacklisting mode
#===============================================================================
MODE='WHITELISTING' # This can only be "WHITELISTING" or "BLACKLISTING"
#===============================================================================
# Whitelisting matching rules: <protocol>:<port>
#===============================================================================
WHITELISTING=(
# SSH
'tcp:22'
# DNS
'tcp:53'
'udp:53'
# HTTP
'tcp:80'
'tcp:443'
)
#===============================================================================
# Blacklisting matching rules: <protocol>:<port>
#===============================================================================
BLACKLISTING=()
#===============================================================================
# Define IPTables commands for IPv4 and IPv6
#===============================================================================
IPTABLES_V4=`which iptables`
IPTABLES_V6=`which ip6tables`
#===============================================================================
# Wrapper function for IPTables with IPv4 and IPv6
#===============================================================================
IPTABLES() {
${IPTABLES_V4} $@ # Executes the given arguments with IPTables for IPv4
${IPTABLES_V6} $@ # Executes the given arguments with IPTables for IPv6
}
#===============================================================================
# Set whitelisting and blacklisting chain names
#===============================================================================
WHITELIST_CHAIN='WHITELIST'
BLACKLIST_CHAIN='BLACKLIST'
#===============================================================================
# INPUT policy reset and flush
#===============================================================================
IPTABLES --policy INPUT ACCEPT
IPTABLES --flush INPUT
#===============================================================================
# Ping requests over ICMP and ICMPv6 protocol are always accepted
#===============================================================================
${IPTABLES_V4} --append INPUT --protocol icmp --jump ACCEPT
${IPTABLES_V6} --append INPUT --protocol icmpv6 --jump ACCEPT
#===============================================================================
# Local loopback connections are also always accepted
#===============================================================================
IPTABLES --append INPUT -i lo --jump ACCEPT
#===============================================================================
# Accept all (already) related and established connections
#===============================================================================
IPTABLES --append INPUT --match state --state RELATED,ESTABLISHED --jump ACCEPT
#===============================================================================
# Flush whitelisting and blacklisting chains if exists
#===============================================================================
IPTABLES --flush "${WHITELIST_CHAIN}" &> /dev/null
IPTABLES --flush "${BLACKLIST_CHAIN}" &> /dev/null
#===============================================================================
# Delete references to whitelisting and blacklisting chains if exists
#===============================================================================
IPTABLES --delete INPUT --jump "${WHITELIST_CHAIN}" &> /dev/null
IPTABLES --delete INPUT --jump "${BLACKLIST_CHAIN}" &> /dev/null
#===============================================================================
# Delete whitelisting and blacklisting chains if exists
#===============================================================================
IPTABLES --delete-chain "${WHITELIST_CHAIN}" &> /dev/null
IPTABLES --delete-chain "${BLACKLIST_CHAIN}" &> /dev/null
#===============================================================================
# Create new whitelisting-/blacklisting chain
#===============================================================================
if [ ${MODE} == 'WHITELISTING' ]; then IPTABLES --new-chain "${WHITELIST_CHAIN}"; fi
if [ ${MODE} == 'BLACKLISTING' ]; then IPTABLES --new-chain "${BLACKLIST_CHAIN}"; fi
#===============================================================================
# Create reference to the whitelisting-/blacklisting chain
#===============================================================================
if [ ${MODE} == 'WHITELISTING' ]; then IPTABLES --table filter --append INPUT --jump "${WHITELIST_CHAIN}"; fi
if [ ${MODE} == 'BLACKLISTING' ]; then IPTABLES --table filter --append INPUT --jump "${BLACKLIST_CHAIN}"; fi
#===============================================================================
# Create IPTables matching rules for whitelisting
#===============================================================================
if [ ${MODE} == 'WHITELISTING' ]; then
for rule in "${WHITELISTING[@]}"; do
IPTABLES --append "${WHITELIST_CHAIN}" --protocol "${rule%%:*}" --destination-port "${rule##*:}" --jump ACCEPT
done
IPTABLES --policy INPUT DROP
fi
#===============================================================================
# Create IPTables matching rules for blacklisting
#===============================================================================
if [ ${MODE} == 'BLACKLISTING' ]; then
for rule in "${BLACKLISTING[@]}"; do
IPTABLES --append "${BLACKLIST_CHAIN}" --protocol "${rule%%:*}" --destination-port "${rule##*:}" --jump REJECT
done
IPTABLES --policy INPUT ACCEPT
fi
#===============================================================================
# ADDITIONAL RULES
#===============================================================================
${IPTABLES_V4} --append INPUT --source 192.168.1.0/24 --jump ACCEPT
${IPTABLES_V6} --append INPUT --source fe80::/64 --jump ACCEPT
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