When it comes to Installing Untangle or getting untangle, you have both the choices. You can buy from Untangle. Or you can built your own hardware.
Hardware totally depends upon your network size and the application that you will be running on it. I have installed it for 50 Users in a PC with Atom Processor, 2GB RAM and 40GB HD. I never faced any issue.
I implemented this for one of my clients (Masaken Al Raha) for more than 10,000 users/devices. I installed it on HP Server with XEON 8 Core, 64GB RAM and 1TB HD.
If you study below table you will understand the calculation for Untangle Hardware Requirements easily.
Below Table has specs that will help you to understand the
Hardware Recommendations Table
|minimum spec||1 core||2 GB||10 GB||Platform only – no apps installed|
|1-50 devices||2 cores||4 GB||40 GB|
|51-150 devices||4 cores||8||80 GB|
|151-500 devices||4 or more cores||16||160 GB|
|501-1500 devices||4 or more cores||16||250 GB|
|1501-5000 devices||6 or more cores||32||500 GB|
Full Article on Untangle Firewall is available here