Firewall ports to open so secure duo works correctly?

[gbesner1]

Hello !

I am new to the solution. I need to secure 4 servers, those servers have no access to the internet whatsoever. I need the solution to work, what is the bare minimum I need to open on my firewall so the solution works correctly ? the servers are allowed to talk only to the internet for this solution to work only.

Thank you

Guillaume

[twalker1]

In this scenario we have a protected card data environment with a couple servers in it. It doesn’t use any O365 services. We just use DUO for MFA to login to the server. The firewall in front of this CDE is completely locked down. If I don’t whitelist the 40.126.0.0/19 subnet, then the DUO Security screen never comes up to send me the push. It just times out.