Iptables quick guide

http://www.linode.com/wiki/index.php/Netfilter_IPTables_Mini_Howto

Changing the default policy in iptables

iptables -P INPUT DROP

allow outbound rsync and insert rule at the top of the chain

iptables -I OUTPUT -p tcp -d 1.1.1.1 --dport 873 -j ACCEPT

allow muliple ports example

list of ports

iptables -A tableName -p tcp  --match multiport --dports port1,port2,port3 -j ACCEPT

example

iptables -A INPUT -p tcp --match multiport --dports 22,80,443 -j ACCEPT

port range

iptables -A tableName -p tcp --dports start_port:end_port -j ACCEPT

example

iptables -I OUTPUT -p tcp -d 1.1.1.1 --dport 1024:65535 -j ACCEPT

IP range example

 iptables -A INPUT -p tcp --dport 22 -m iprange --src-range 192.168.1.100-192.168.1.200 -j ACCEPT  

NAT

show nat rules

iptables -L -t nat

hide nat behind and interface

iptables -t nat -A POSTROUTING -o tun0 -s 192.168.1.0/24 -j MASQUERADE

destination NAT

iptables -t nat -A PREROUTING -d 1.1.1.10 -j DNAT --to-destination 192.168.1.228

saving rules for reload on reboot

on fedora 17

iptables-save > /etc/sysconfig/iptables