IPMI is useful for administration, but is not that usable from outside a gateway. Yet we could map out the ports for connecting to IPMI.[1]

Port Protocol Usage
623 UDP IPMI Commandline Tool
5900 TCP VNC Control
5901 TCP VNC Video
5120 TCP Virtual CD
5123 TCP Virtual Floppy
6666 UDP Serial-over-LAN

Mapping the ports are anyway easier than a VPN.

  1. Post image by U. Vezzani, Share Alike 3.0. ↩︎