Is is possible to apply an AV analysis on DNAT rules?

IPS is possible. AV not. AV is based on common Proxy technologies like WAF / Reverse Proxy. 

Most likely DNAT Traffic is encrypted - so you cannot scan them anyways. 

Hello LuCar Toni,

Thanks for the reply.

I'm still a little bit confused.

For example, I'm using DNAT rules to publish internal servers for different services, let's say a specific server use HTTP. That traffic is not encrypted, right? 

How I can protect my internal servers?

If I use a WAF rule instead for those server does the firewall scan the traffic?

BR.