TunTap seems to make UML hang hard if a IP addres is omitted from the
command line. It looks like it's because uml_net dumps core when you
ifconfig up an interface within UML.
----- Original Message -----
From: "Martin Volf" <martin.volf@...>
Sent: Friday, September 14, 2001 10:08 PM
Subject: Re: [uml-user] problems with uml TUN/TAP on early host 2.4 kernels
> > Darn... I seem to have spoken too soon - although ping works, running a
> > tcp application to connect from the host (e.g. ssh, ftp) to the uml box
> > times
> > out, whereas going from the uml box to the host works. Strangely,
> > http serving works, although when you connect on port 80, netstat does
> > not report a session in the establish state (just SYN_RECV). I had
> > originally treated this as a routing problem, but if I just change
> > to ethertap in the uml kernel startup, tcp apps work normally.
> > Has anyone else seen this? When I look at tcpdump output on tap0 and
> I experienced the same thing with TUN/TAP transport, i.e. it does not
> if uml_net is compiled with original RedHat 7.1 /usr/include/linux (the
> error message). But with /usr/include/linux matching my kernel version
> (2.4.9-ac10) it works in both directions (tested only telnet, ssh and
> > the ack from the host to the syn response from the uml box never appears
> > eth0, so the uml side of the tcp session never reaches an establish
> > I can
> > post these if folks are interested. I have seen this problem on both a
> > 300 MHz PII and an 2-way 800 MHz PIII so don't think its timing related.
> > In addition to having good luck with 2.4.9 previously, I've used 2.4.7
> > today
> > and that TUN/TAP kernel module works with 2.4.9-5um.
> > -Tim
> > Lostcabin Brewery
> > Oakland, CA
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