Running OPNsense on an old PC is possible but consider performance and compatibility.
Running OPNsense on an old PC is possible but consider performance and compatibility.
It hurts when someone's backup rig they say "might just use as a router" is way ahead of what I have. Still, I believe using the machine as a Proxmox host could work well. You can add two port network cards and send them to a VM with PFSense/Opnsense or Sophos for filtering. Then link your WAN to one port and your LAN to another—super cool combo! Let me know if you try it, and I’ll help set it up.
This concept is promising, but if the person hasn’t worked much with networking or virtualization, combining them might be risky. It could accidentally disrupt your internet connection. I use PFSense in my lab for virtual setups, but I wouldn’t recommend it unless they’re already familiar with both areas. Learning them separately is usually safer before moving forward.
there are worries about power use being excessive, but the system will stay off when not in use. i predict this pc will run at around 10 to 20 watts, with most of the time it’s idle. because of internet activity, it stays idle about 95%. i’m using a del ll r210ii as a dedicated pfSense firewall. it comes with an e3-1270 processor, 16gb ram, and a 64gb samsung drive. under heavy load it can reach up to 130w, but never hits that because my gigabit connection drops to about 15% during downloads, and it only reaches roughly 35w with the ups. when idle it stays between 20 to 25w according to a power monitor i connected soon after setup. plus, it’s in my basement where it stays cool, so the fans never exceed their minimum idle speed.
Good luck with the setup! On FreeBSD Power Management isn’t very reliable. I compared an i5 4690 with pfSense versus OpenWRT and noticed the latter used much less power, dropping to around half as much. As mentioned before, you can only reduce power so much depending on the chipset. More PCIe lanes mean more integrated parts, which increases idle consumption. The chipset itself can draw up to 6 watts, while desktop RAM uses even more than laptop RAM. Also, more soldering onto the board versus using sockets lets manufacturers tighten tolerances. A board built for a 25W TDP with soldered SoC will idle much less than one designed for a socketed CPU with extra VRM overhead. I agree with your observations, but you’re comparing 35 watts to just 11 watts idle—my router reaches 25 watts when the WebUI loads. That low idle means you can run a cheap 12V UPS for longer and better efficiency than an inverter-based one, or even use PoE instead of a wall wart.