Rules against Spoofing on a external interface like eth0

[Ertan Gönülal]

Hi,
how i can write a Rule to protect against spoofing?

I want to write a rule like this in IP-Tables:

-A INPUT -s 192.168.1.0/255.255.255.0 -i eth0 -j DROP

The eth0 interface has for example a IP 195.30.40.1

internet - eth0 ----| Firewall |----eth1(192.68.1.0/24) 


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