Bad iptables argument

Question

I'm trying to defend Portmap using IPtables. For this I should deny receiving packages from all IPs but 192.168.0.0/24 on TCP and UDP.

For doing this I've written such IPtables rules:

iptables -A INPUT -p tcp -s! 192.168.0.0/24  --dport 111 -j DROP
iptables -A INPUT -p udp -s! 192.168.0.0/24  --dport 111 -j DROP

But I got such error:

Bad argument `192.168.0.0/24'
Try `iptables -h' or 'iptables --help' for more information.

How can I edit rules to get correct ones?

Solution

Syntax is wrong. You have to make a rule like:

iptables -A INPUT -p tcp ! -s 192.168.0.0/24  --dport 111 -j DROP

Exclamation mark needs to be prefixed, when you are trying to make oposite match.