I'm on a network where I don't own the router and I don't want to modify the network existing network by running a firewall over the entire network however I want to have a firewall protecting my server. How would I go about segmenting my network? I want to use a hardware firewall, probably in a pfSense box, I've been reading about subnets and VLANs, is there a way I could use these to split up my network into a separate many network that just my computer and server would be on?
pfsense will bridge. Seems to me the easiest route would be to isolate the two machines behind your pfsense box and bridge the outside interface with the inside. No reconfig of IP yet you have the separation you desire. You could even do some port forwarding if you wanted access to your server from the outside LAN.