Just wondering if it's possible to have virtual networking interfaces that are accessible through the host's interface and IP?
Then I'd like to assign a subdomain to it and have the host direct to the correct guest based on that.
there are two ways - you can either use libvirt's own iptables implementation, so the VMs are behind a NAT, or you can set up a bridge and use it instead. The bridge will ct as a virtual hub, into which the host and the VMs are plugged. in the first scenario, the VMs will be "behind" the host, since it will be acting as a router to the hosts' virtual network in the second, the VMs will be in the same network as the host (you can add VLANs in of course, to separate them)
You want a network bridge, then: