Blocking packets with iptables

[andreas93]

Hello i am trying to block a packet on my gameserver called banned_cdkey. But i cant get this command to work.
iptables -A INPUT -p udp -m string --algo bm --string "BANNED_CDKEY" --sport 20600 --dport 28960 -j DROP

Do i need to add a soruce ip of the computer or what am i doing wrong?

 

[Fitz Mutch]

... what am i doing wrong?

I think the packet is proably encrypted or you don't need the --sport parameter.

 

[andreas93]

No the packet is not encrypted because it works fine on a ubuntu machine. Im trying to do the same for windows but with the asus router as firewall.

 

[Fitz Mutch]

Is everything happening on your local network?

The INPUT chain is for packets destined for the router itself. The FORWARD chain is for packets passing through the router. Use -I instead of -A to put the rule on top.

iptables -I FORWARD -p udp -m string --algo bm --string "BANNED_CDKEY" --sport 20600 --dport 28960 -j DROP