[uml-user] Cant see DHCP-requests from a bridged UML

[Thomas P. <to...@gm...>]

Hello folks,

I want to configure an UML via DHCP, which is running on the host
system. I followed
http://usermodelinux.org/modules.php?name=News&file=article&sid=4 -
this are my experiences, because I had some problems:

I did this on the host:

$ brctl addbr br0
$ brctl stp br0 off
$ ifconfig eth0 0.0.0.0 promisc up
$ brctl addif br0 eth0
$ ifconfig br0 192.168.0.2 netmask 255.255.0.0 up

$ route add default gw 192.168.1.1
I do need need this, because my host is my gateway.

$ tunctl uid
$ ifconfig tap0 up
I use uml_net, so my tap-dev is already up and must not be
configured.

$ brctl addif br0 tap0

My box is started with "... eth0=tuntap,,,192.168.2.1 ...".


So, my box can reach the internet, and my host can reach my box.
Everything works fine. When I start tcpdump on the physical host
interface, which is part of the bridge, I see all the traffic, the
box generates and reaches. It is as intended, the box is really part
of the physical network. It sees ARP-Requests and so on...

The box itself has correct routing entries. The gateway is the IP of
the TAP-dev. I have encountered, that the IP does not matter...
Before starting dhclient I do a "ifconfig eth0 down".
But when I start "dhclient" on my box, I can't see the
DHCP-Requests. Then I get "SIOCSIFFLAGS: Protocol driver not
attached", what is this?
The box never gets an IP address from the DHCP server running on the
host. (box, tap, and host are on the same subnet, of course.)

So, where did I miss something? Is anyone outthere which is using
DHCP in UML? Can somone give me a hint?


TIA,
Tom