Hi,
first, a disclaimer: I don't really need the proprietary Microsoft
Windows environment for my work. It happens that, for interoperability's
sake, I sometimes install free (libre) software on this proprietary
environment on customer systems. It's always quite painful, has strange
implications, and is always quite difficult to debug. But well, some
people apparently still need it.
After that, the issue I saw, which I currently cannot understand:
I installed the libre software OpenVPN including the TAP driver on
the proprietary Microsoft Windows environment. I did set up a
encrypted tunnel between two machines on the same Ethernet subnet
(this is probably important).
Testing pings and telnet on the remote tunnel address (e.g.
192.168.1.2) and capturing data with the libre software Ethereal on the
real Ethernet interface did show me that the flow of data was
correctly routed through the tunnel.
However, accessing \\192.168.1.2\c$ did go through the Ethernet
interface, and *not the tunnel*, and strangely half-using the private
addresses!
I wonder if there is some NetBEUI/NetBIOS/whatever interaction which
kind-of `resolves' the private IP address as a host name. Thus
probably as long as noone replies NetBEUI/NetBIOS it should work ...
but could be exploitable, isn't it ?
The obvious solution could be to completely disable this resolution,
or maybe use a real DNS name for the private addresses of the tunnel.
After all NetBEUI/NetBIOS predates the standard IP networking support
in the proprietary Microsoft Windows environment and could be considered
obsolete today (if using a WINS server or DNS resolution). But it is
still activated by default.
Looking at the routing tables through NETSTAT.EXE is ... well ...
strange. No interface, strange routes, it's a bit difficult to really
understand how routing works on this proprietary plateform.
Has someone also experienced this, or was it some strange local pecularity ?
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