Good questions. Let's see if I can address both your concerns.
Win4Lin 3.0 provide a virtual network (VNET) which Windows accesses through a
virtual network card. That virtual network card has a pseudo MAC address so that
network packets generated in the Windows environment pass in to the virtual network
looking like real ethernet packets. Obviously, when those packets pass throught the
real network card of the Linux system, that pseudo MAC address is replaced by the
MAC address of the real NIC. As you correctly point out, if this were the way that
Win4Lin was expecting to support DHCP, this would be a real problem for most DHCP
servers.
So, here is how we handle this problem. The virtual network is able to recognize
DHCP request coming from a Win4Lin Windows session and modifies those request so
that, when they enter the real network, they appear to have been forwarded by a
DHCP/BOOTP relay. The DHCP request contains the pseudo MAC address of the Win4Lin
virtual NIC which is then wrapped in the ethernet packet of what appears to be a
DHCP relay. Since the DHCP server now sees the DHCP request as being forwarded by a
relay, it is happy to repond to the request. We have found this to be an acceptable
mode of operation for all DHCP implementations that we have tested against to date.
Wait, I hear you scream, what's this pseudo MAC address and how to you does it get
generated? How do you ensure that another Win4Lin user on the same network isn't
using the same pseudo MAC address and registering it with the same DHCP server?
Well, we believe that we have got that one covered. The pseudo MAC address is
derived from the IP address of the Linux host system and is generated in a way that
we believe has no realistic chance of being repeated in any network that shares a
DHCP server.
Now to answer your second question regarding your DSL line at home. This is not a
situation where the Win4Lin DHCP solution can be directly employed and so we would
recommend that you use the existing WinSock feature instead of the new VNET.
However, if you have a laptop machine that you need to move between home and the
office, Win4Lin 3.0 provides a command, win_network, that lets you toggle your
network configuration between WinSock and VNET. So, you can use VNET in the office
and then switch to WinSock when you go home (or vice-versa).
But this doesn't mean you can't use the Win4Lin virtual network feature in the home
environment. With a little bit of extra effort on the Linux side, you can set up
your Linux system to perform IP Masquerading and IP Forwarding (many Linux users do
this already to connect their "internal" home network to a DSL line). Then, the
Win4Lin session can be associated with a either a "dummy" NIC, or a second physical
NIC, that represents your "internal" network and you control whatever static or
dynamic IP address you want to provide. Alternatively, there are a number of cheap
DSL router/hubs on the market that can perform the IP Masquerading and Forwarding,
and will also act as a DHCP server for your home network.
Hope that helps,
Brian
[EMAIL PROTECTED] wrote:
> I've heard statements made of win4lin having a 'virtual' network card interface
> so it can get it's own IP address via DHCP.
>
> Now, I'll have my linux box on the network with an IP address-XXXA, win4lin
> will come up on the network and request a new address, but using the
> same ethernet mac address that my linux box is using. The
> DHCP servers here have the security on set to 'ANAL', will reject
> the request for a new IP address to the win4lin process because its using
> the same mac address that it already provided an address to.
>
> Under these circumstances, how am I to use win4lin 3.0?
>
> Or if you claim I should ask for an exemption, take the case of having a
> DSL line at home and you're allowed a single IP address via DHCP server
> from your ISP.
>
> Under those circumstances, how am I to use win4lin 3.0?
>
> J
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