[pups] Networking With 2.11 BSD and Begemot Emulator
Greg Lehey
grog at lemis.com
Thu Oct 5 13:03:25 AEST 2000
On Wednesday, 4 October 2000 at 8:24:07 -0700, Steven M. Schultz wrote:
> Hi -
>
>> From: Greg Lehey <grog at lemis.com>
>> No, that wasn't me. FreeBSD doesn't have a tap driver. Do you mean
>> Frank?
>
> Sure it does. The FreeBSD 4.1.1 release notes say so ;)
> Before that the 'if_tap.c' module was available (for some time)
> as a download that could be retrieved from the author's site.
I stand corrected:
> revision 1.1
> date: 2000/07/20 17:01:10; author: nsayer; state: Exp;
> Add the tap driver.
>
> The tap driver is used to present a virtual Ethernet interface to the
> system. Packets presented by the network stack to the interface are
> made available to a character device in /dev. With tap and the bridge
> code, you can make remote bridge configurations where both sides of
> the bridge are separated by userland daemons.
>
> This driver also has a special naming hack to allow it to serve a similar
> purpose to the vmware port.
>
> Submitted by: myevmenkin at att.com, vsilyaev at mindspring.com
Ah well, I still haven't used it.
>>> The missing piece I forgot earlier was on the hosting machine's
>>> side to publish an ARP entry for the simulated 11.
>>
>> I'm pretty sure we weren't using arp at all. tun is a point-to-point
>> interface.
>
> The reason for publishing an ARP entry on the hosting system is
> so that other systems on the LAN know how to get to the simulated
> 11 via the P11 hosting system. If the hosting system doesn't
> publish an ARP entry the gateway, etc won't know to send the packets
> to the machine running P11.
I did that with a static route entry.
>>> I'm not sure how ARP can be made to work thru the 'tun' device.
>>
>> I don't think it can. I think Harti used some magic there.
>
> I know it can't - I asked him about it :) That's when I first
> discovered that nothing was able to communicate with the simulated
> 11 - the 11 will not send anything unless it's able to get a
> response to its ARP request. On the hosting side it would be
> possible perhaps to use a "interface route" but 2.11 can not do that
> and will block waiting for an ARPREPLY.
As I say, it's not that simple. I used it without trouble for years.
Recently something broke, and I suspect it trashed my root file
system, and I haven't had time to go back and fix it. Since others
have the rest running, it's obviously nothing fundamental.
Greg
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