IPTables Example Config

#flush tables
/usr/sbin/iptables -F

# DUMP
/usr/sbin/iptables -N DUMP > /dev/null
/usr/sbin/iptables -F DUMP
/usr/sbin/iptables -A DUMP -p tcp -j LOG
/usr/sbin/iptables -A DUMP -p udp -j LOG
/usr/sbin/iptables -A DUMP -p tcp -j REJECT --reject-with tcp-reset
/usr/sbin/iptables -A DUMP -p udp -j REJECT --reject-with icmp-port-unreachable
/usr/sbin/iptables -A DUMP -j DROP

# Stateful table
/sbin/iptables -N STATEFUL > /dev/null
/sbin/iptables -F STATEFUL
/sbin/iptables -I STATEFUL -m state --state ESTABLISHED,RELATED -j ACCEPT
/sbin/iptables -A STATEFUL -m state --state NEW -i ! eth0 -j ACCEPT
/sbin/iptables -A STATEFUL -j DUMP

# loopback rules
/sbin/iptables -A INPUT -i lo -j ACCEPT
/sbin/iptables -A OUTPUT -o lo -j ACCEPT

# drop reserved addresses incoming (these are reserved addresses
# but may change soon
/sbin/iptables -A INPUT -i eth0 -s 0.0.0.0/8 -j DUMP
/sbin/iptables -A INPUT -i eth0 -s 1.0.0.0/8 -j DUMP
/sbin/iptables -A INPUT -i eth0 -s 2.0.0.0/8 -j DUMP
/sbin/iptables -A INPUT -i eth0 -s 5.0.0.0/8 -j DUMP
/sbin/iptables -A INPUT -i eth0 -s 7.0.0.0/8 -j DUMP
/sbin/iptables -A INPUT -i eth0 -s 10.0.0.0/8 -j DUMP
/sbin/iptables -A INPUT -i eth0 -s 23.0.0.0/8 -j DUMP
/sbin/iptables -A INPUT -i eth0 -s 27.0.0.0/8 -j DUMP
/sbin/iptables -A INPUT -i eth0 -s 31.0.0.0/8 -j DUMP
/sbin/iptables -A INPUT -i eth0 -s 36.0.0.0/8 -j DUMP
/sbin/iptables -A INPUT -i eth0 -s 39.0.0.0/8 -j DUMP
/sbin/iptables -A INPUT -i eth0 -s 41.0.0.0/8 -j DUMP
/sbin/iptables -A INPUT -i eth0 -s 42.0.0.0/8 -j DUMP
/sbin/iptables -A INPUT -i eth0 -s 58.0.0.0/8 -j DUMP
/sbin/iptables -A INPUT -i eth0 -s 59.0.0.0/8 -j DUMP
/sbin/iptables -A INPUT -i eth0 -s 60.0.0.0/8 -j DUMP
/sbin/iptables -A INPUT -i eth0 -s 127.0.0.0/8 -j DUMP
/sbin/iptables -A INPUT -i eth0 -s 169.254.0.0/16 -j DUMP
/sbin/iptables -A INPUT -i eth0 -s 172.16.0.0/12 -j DUMP
/sbin/iptables -A INPUT -i eth0 -s 192.168.0.0/16 -j DUMP
/sbin/iptables -A INPUT -i eth0 -s 197.0.0.0/8 -j DUMP
/sbin/iptables -A INPUT -i eth0 -s 224.0.0.0/3 -j DUMP
/sbin/iptables -A INPUT -i eth0 -s 240.0.0.0/8 -j DUMP

#set iptables to allow everything from my work network
/usr/sbin/iptables -A INPUT -i eth1 -p all -s 160.86.0.0/16 -j ACCEPT
/usr/sbin/iptables -A INPUT -i eth1 -p all -j DROP

# allow certain inbound ICMP types (ping, traceroute..)
/sbin/iptables -A INPUT -i eth0 -p icmp --icmp-type destination-unreachable -j ACCEPT
/sbin/iptables -A INPUT -i eth0 -p icmp --icmp-type time-exceeded -j ACCEPT
/sbin/iptables -A INPUT -i eth0 -p icmp --icmp-type echo-reply -j ACCEPT
/sbin/iptables -A INPUT -i eth0 -p icmp --icmp-type echo-request -j ACCEPT

# Drop all packets to port 111 except those from localhost
/usr/sbin/iptables -A INPUT -s !127.0.0.0/8 -p tcp --dport 111 -j DROP

# kill off identd quick 
/sbin/iptables -A INPUT -p tcp -i eth0 --dport 113 -j REJECT --reject-with tcp-reset

# sfs
/sbin/iptables -A INPUT -p tcp -i eth0 --dport 4  -j ACCEPT
# ftp
/sbin/iptables -A INPUT -p tcp -i eth0 --dport 21 -j ACCEPT
/sbin/iptables -A INPUT -p udp -i eth0 --dport 21 -j ACCEPT
# ssh
/sbin/iptables -A INPUT -p tcp -i eth0 --dport 22 -j ACCEPT
/sbin/iptables -A INPUT -p udp -i eth0 --dport 22 -j ACCEPT
# www
/sbin/iptables -A INPUT -p tcp -i eth0 --dport 80 -j ACCEPT
/sbin/iptables -A INPUT -p udp -i eth0 --dport 80 -j ACCEPT
# https
/sbin/iptables -A INPUT -p tcp -i eth0 --dport 443 -j ACCEPT
/sbin/iptables -A INPUT -p udp -i eth0 --dport 443 -j ACCEPT

# Don't log route packets coming from routers - too much logging
/sbin/iptables -A INPUT -p udp -i eth0 --dport 520 -j REJECT

# Don't log smb/windows sharing packets - too much logging
/sbin/iptables -A INPUT -p tcp -i eth0 --dport 137:139 -j REJECT
/sbin/iptables -A INPUT -p udp -i eth0 --dport 137:139 -j REJECT