Putting a Virtual Machine Between the Users and the Gateway

Question

Hello fellow superusers,

I was thinking of installing Pepperspot (which is the dual stack IPv6/IPv4 version of Chillispot, which is essentially an appliance that authenticates people with a captive portal and does some accounting) on a virtual machine to act as a network access controller for a 100 Mb/s gateway. What I'm installing on this virtual appliance is really quite irrelevant. What I would like to know from you folks is what are the hardware requirements for a server to be able to pass 100 Mb/s through a virtual machine? pfSense recommends at least a Pentium 3 and a lot of RAM for 100 Mb/s connection, but how much slowdown should I expect because of virtualization? Should I not be trying this through a virtual machine? Has anyone run a large amount of bandwidth through a virtual machine before?

I've left out my motivation for doing this for the sake of brevity, but let me know if this would help answer my question.

P.S. I apologize if this is in the wrong Stack Exchange, I though it would be most appropriate to post here (instead of Server Fault) because it was related to hardware and did not involve any complex networking.

Answer 1

You can do this through a virtual machine. While I don't have any direct experience with your exact use-case, I've set up several environments with pfsense on a vm. I definitely echo their advice to have a good amount of ram.

It depends on how much traffic you have on the connection, but there are a couple things you can do:

• Get a processor that has virtualization extensions (Intel VT and AMD-V). The processors that have those extensions enable the vm to run at near-native hardware speeds.
• Get network cards that allow TCP offloading. This will save the processor some work, but really probably won't be necessary depending on what else you're running on the computer (other vm's)

edit: I also found this mailing list entry at m0n0wall: http://m0n0.ch/wall/list/showmsg.php?id=291/75 . The person asking gives some pretty detailed stats on how chillispot runs in his vm and it's worth noting that he's using a host system with very meager specs.