Converting a peer-to-peer to a client-server configuration.
Current configuration: 4 computers connected peer to peer. Two computers are old xps's that support a legacy accounting program that is stored on an NAS and run locally. Two computer are Windows 7 that were purchased in anticipation of upgrading the accounting (legacy program will not work properly on anything after XP). The accounting side is on it's own segment over 100baseT wiring. No gateway. Each computer except one has a wireless connection to connect to the internet. One of the new computers is a higher end i7 that was going to be a workstation/server for running quickbooks and peachtree where the other win 7 would be the client.
Well, QB and PT are not strong enough to be the replacement accounting, so we are going with a larger system that requires windows server 2012
So working on new configuration. I am thinking i don't need the two segments anymore, but not looking forward to putting the accounting on same segment as rest of the office. So thinking of ways to segregate it. Can I just use the subnet mask to keep it separate? Doesn't seem that strong. So thinking maybe using one of the old computers and turning it into software firewall using IPCop or similar and have the wire from modem coming into it and then the other side is the accounting department. Other possibility and I have no idea if this is any doable, but maybe having the WinServer as the firewall by having modem wire coming into one nic on server and then another nic to connect to accounting and segment it that way.
So looking for input from the experts. Cost is definitely a factor in the decisions made.
Is IPCop the best of the free linux firewall to use? are the configurations above doable and what would be the best in your opinion.
The questions may change as feedback comes in.
Thanks in advance for your time and attention to this matter!