We currently have a LAN connected to the internet through a Cisco Router running NAT. One of our servers, basically the main one, is running Exchange as well as File and Print Services.
We have NO firewall and need one desparately. Because our ISP has an MX record for our server it is wide open on the internet.
We are interested in getting a firewall, any recommendations? Good time to get a proxy server/firewall at this time?
The only thing coming inside would need to be email from the outside, how would we set this up on the firewall? Just open a certain port? Which one?