Mike Fedyk - Routing, VMware & Wireless

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May 27th, 2007

09:42 pm

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Routing, VMware & Wireless
I spent today hacking with my friend Charles Wyble in addition to returning and borrowing some books. :)

We setup a Linux router in a VMware guest. His machine now has five ethernet ports (one built-in and four in a multi-port card), but the tulip driver in Ubuntu Dapper Server has a weird probing quirk. The ports that physically are ordered 1, 2, 3, 4 were detected as eth4, eth1, eth2, eth3. No problem. Just reorder the network interface names in /etc/iftab and we're set.

Next we configured the vmware networking so that each vmnet is associated with the correspondingly named ethX number. So eth1 -> vmnet1, etc. Then we added a "host only" interface, but it took over vmnet1 and that was fun debugging. "Why am I not seeing my public IP address on this interface?!"

After getting packets flowing, installed shorewall and setup a dmz. A cursory look at this setup shows that there is a price to pay in resource usage. What would take 2-7% cpu usage (a torrent of FC5 at 600Kbyte/s) to do on the the host system takes about 25% processor usage within the VM guest on an AMD Athlon XP 2200+. The security and flexibility of this setup is unquestionable, but it is good to know the cost.

Also Charles had a problem with Windows in a VMware guest on his Ubuntu Feisty 64bit laptop not being able to get out to the network. It turned out not being a windows problem, but a ndiswrapper problem with his bcm43xx chipset wireless card. Plugging in a wired ethernet connection worked around the problem and getting a Ralink mini-PCI card will be a more permanent solution.

I guess it was a windows problem, since a windows NDIS driver caused the problem. Heh.

Tags: linux, ralink, shorewall, vmware

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