PF firewall script

https://bash.cyberciti.biz/firewall/linux-iptables-firewall-shell-script-for-standalone-server/

1. !/bin/bash
2. A Linux Shell Script with common rules for IPTABLES Firewall.
3. By default this script only open port 80, 22, 53 (input)
4. All outgoing traffic is allowed (default - output)
5. -------------------------------------------------------------------------
6. Copyright (c) 2004 nixCraft project <http://cyberciti.biz/fb/>
7. This script is licensed under GNU GPL version 2.0 or above
8. -------------------------------------------------------------------------
9. This script is part of nixCraft shell script collection (NSSC)
10. Visit http://bash.cyberciti.biz/ for more information.
11. -------------------------------------------------------------------------

IPT="/sbin/iptables" SPAMLIST="blockedip" SPAMDROPMSG="BLOCKED IP DROP"

echo "Starting IPv4 Wall..." $IPT -F $IPT -X $IPT -t nat -F $IPT -t nat -X $IPT -t mangle -F $IPT -t mangle -X modprobe ip_conntrack

[ -f /root/scripts/blocked.ips.txt ] && BADIPS=$(egrep -v -E "^#|^$" /root/scripts/blocked.ips.txt)

PUB_IF="eth0"

1. unlimited

$IPT -A INPUT -i lo -j ACCEPT $IPT -A OUTPUT -o lo -j ACCEPT

1. DROP all incomming traffic

$IPT -P INPUT DROP $IPT -P OUTPUT DROP $IPT -P FORWARD DROP

if [ -f /root/scripts/blocked.ips.txt ]; then

1. create a new iptables list

$IPT -N $SPAMLIST

for ipblock in $BADIPS do

  $IPT -A $SPAMLIST -s $ipblock -j LOG --log-prefix "$SPAMDROPMSG"
  $IPT -A $SPAMLIST -s $ipblock -j DROP

done

$IPT -I INPUT -j $SPAMLIST $IPT -I OUTPUT -j $SPAMLIST $IPT -I FORWARD -j $SPAMLIST fi

1. Block sync

$IPT -A INPUT -i ${PUB_IF} -p tcp ! --syn -m state --state NEW -m limit --limit 5/m --limit-burst 7 -j LOG --log-level 4 --log-prefix "Drop Sync" $IPT -A INPUT -i ${PUB_IF} -p tcp ! --syn -m state --state NEW -j DROP

1. Block Fragments

$IPT -A INPUT -i ${PUB_IF} -f -m limit --limit 5/m --limit-burst 7 -j LOG --log-level 4 --log-prefix "Fragments Packets" $IPT -A INPUT -i ${PUB_IF} -f -j DROP

1. Block bad stuff

$IPT -A INPUT -i ${PUB_IF} -p tcp --tcp-flags ALL FIN,URG,PSH -j DROP $IPT -A INPUT -i ${PUB_IF} -p tcp --tcp-flags ALL ALL -j DROP

$IPT -A INPUT -i ${PUB_IF} -p tcp --tcp-flags ALL NONE -m limit --limit 5/m --limit-burst 7 -j LOG --log-level 4 --log-prefix "NULL Packets" $IPT -A INPUT -i ${PUB_IF} -p tcp --tcp-flags ALL NONE -j DROP # NULL packets

$IPT -A INPUT -i ${PUB_IF} -p tcp --tcp-flags SYN,RST SYN,RST -j DROP

$IPT -A INPUT -i ${PUB_IF} -p tcp --tcp-flags SYN,FIN SYN,FIN -m limit --limit 5/m --limit-burst 7 -j LOG --log-level 4 --log-prefix "XMAS Packets" $IPT -A INPUT -i ${PUB_IF} -p tcp --tcp-flags SYN,FIN SYN,FIN -j DROP #XMAS

$IPT -A INPUT -i ${PUB_IF} -p tcp --tcp-flags FIN,ACK FIN -m limit --limit 5/m --limit-burst 7 -j LOG --log-level 4 --log-prefix "Fin Packets Scan" $IPT -A INPUT -i ${PUB_IF} -p tcp --tcp-flags FIN,ACK FIN -j DROP # FIN packet scans

$IPT -A INPUT -i ${PUB_IF} -p tcp --tcp-flags ALL SYN,RST,ACK,FIN,URG -j DROP

1. Allow full outgoing connection but no incomming stuff

$IPT -A INPUT -i eth0 -m state --state ESTABLISHED,RELATED -j ACCEPT $IPT -A OUTPUT -o eth0 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT

1. Allow ssh

$IPT -A INPUT -p tcp --destination-port 22 -j ACCEPT

1. allow incomming ICMP ping pong stuff

$IPT -A INPUT -p icmp --icmp-type 8 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT $IPT -A OUTPUT -p icmp --icmp-type 0 -m state --state ESTABLISHED,RELATED -j ACCEPT

1. Allow port 53 tcp/udp (DNS Server)

$IPT -A INPUT -p udp --dport 53 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT $IPT -A OUTPUT -p udp --sport 53 -m state --state ESTABLISHED,RELATED -j ACCEPT

$IPT -A INPUT -p tcp --destination-port 53 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT $IPT -A OUTPUT -p tcp --sport 53 -m state --state ESTABLISHED,RELATED -j ACCEPT

1. Open port 80

$IPT -A INPUT -p tcp --destination-port 80 -j ACCEPT

1. 1. 1. 1. 1. Add your rules below ######

1. 1. 1. 1. 1. END your rules ############

1. Do not log smb/windows sharing packets - too much logging

$IPT -A INPUT -p tcp -i eth0 --dport 137:139 -j REJECT $IPT -A INPUT -p udp -i eth0 --dport 137:139 -j REJECT

1. log everything else and drop

$IPT -A INPUT -j LOG $IPT -A FORWARD -j LOG $IPT -A INPUT -j DROP

exit 0