Subject: Re: Bridge problems, possibly due to proxy arp on Parallels Desktop

[David Evans]

[ posted to freebsd-net at freebsd.org 2010-10-28 ]

I believe I have now found the answer to my problem.

The rule is simple: You cannot bridge a Desktop virtual NIC.  The
reason for this, I believe so far, is that Parallels have only implemented
a simplified version of bridging on their bridged networking scheme. If you
try to use more than one MAC address per NIC, it get confused and fails
in mysterious ways: ping only works when another ping is running; ARP
replies go to the wrong NIC; ping does not work for certain combinations
of hosts. Obviously, what Parallels have implemented is perfectly adequate
for 99.9999% of users; it's only people like me who insist on testing
everything to destruction.

I have now built a VPN on top of the existing network without using any
bridging to a Desktop virtual NIC. On one VM I am running FreeBSD with 3
VPN servers bridged together. On another VM I am running a FreeBSD client.
Another FreeBSD client runs on a PC.  A third client runs on OS X. It is
all working just like I expected. Of course you would not normally run
3 servers on one machine but would combine them into one, but I'm only
testing.
 
It is certainly very useful to be able to run all this on virtual machines.
There is no way I could have tested this out on my available hardware. It has
been an interesting learning experience.