Ubuntu/Debian as internet gateway
I have a project that I would like to do. I would like to add a server to my network that would act as a gateway that would have anti-virus/anti spam features.
Just to tell you what I am looking for let me explain that I already have a main router that I am not willing to replace. I would like to have my connection look like: Internet -> main router -> THIS project -> switch -> clients.
I would also like to make this gateway a mandatory gateway (two nics)
My network is 192.168.1.0 on 255.255.255.0
My only problem is that I don't know where to begin. What I would like to find is a program that could inspect packets for information that is harmful, and how to implement it on a software/hardware level.
Let me know if I am wasting time, or if this can't be done. Thank you.