NAT from one computer to another

[alexm3]

Good afternoon! 

I am a networking rookie currently working with a Fortigate 80F, and am trying to understand how NAT works. I have two computers connected to the router with static IP addresses of 192.168.1.1 (PC1) and 192.168.1.101 (PC2). I am looking to set something basic up in which I can ping a virtual IP address (let's say 192.168.50.1) on PC1, and this will translate to PC2's IP address and get a reply back from PC2. I set up a Virtual IP to do this on PC1, and still have all interfaces on the hardware switch. I didn't get any response from the ping. I also added an IPv4 policy to allow traffic from the internal switch through that pings the VIP, but this also didn't work. Am I missing something here? I'm confused as to why this isn't working. I would really appreciate any insights anyone can provide!

[alexm3]

Thanks for your response! Which subnet mask would need to be expanded in this case? The subnet of the internal3 and internal4 ports, or the subnet mask of the PCs themselves? Sorry for such novice questions, I am very new to networking. I really appreciate your help!

[rwpatterson]

If your subnet is 255.255.255.0 (24 bit), then the first three octets of all devices in the subnet have to match.

192.168.1.x, 192.168.2.x, etc. 

(192.168.2.0/24 and 192.168.3.0/24 respectively)

A device on internal3 would need to have 192.168.2.x, and internal4 would need to have 192.168.4.x. Default gateways would be the Fortigate IP address for each interface.

Please look into a rudimentary online networking tutorial. It will help you loads going forward if you plan on pursuing this as a career.