i want to redesign my network for security reasons. the company has some static IPs. we have 1web server,2 application server (AS). the AS is used by te staff to do their everyday tasks. we also have branch offices around the country and these branch users connect remotely via RDP to the AS and do their work. these servers are directly connect to the a D-Link switch on which the ISP internet is connected.then we have another D-Link switch which again the servers are connected to. I mean these servers have two NICs,one of these NIC is WAN and another as LAN. the LAN is for the local users and the WAN for the remote users.
Now I want to put a UTM between the ISP internet and the local network. the UTM i have selected is Zentyal(EBox). i have setup a machine for Zentyal. now my question is do i still need to have 2 D-Link switches on the local network or 1 D-Link will do. i mean how wil the remote users connect now since the UTM has been placed between the internet and local network.please help me as i am not an expert in networking.appreciate your help