[ILUG] Help, Please! User Mode Linux on Debian - ethertap problem
cmcclean at ait.ie
Tue Oct 12 10:02:05 IST 2004
I teach Linux System Administration here at Athlone IT. I use a project-based
apporach. For the last four years what I've done is assemble a collection of
old-ish hardware (PI and IIs), allow the students to install Linux on them,
put them on the network and then guide the class through installation,
configuration and maintenance of inter/networking services.
This year I've had relibility problems with the old hardware, so I'm trying to
set up a number of virtual Linux boxes using User Mode Linux. However, I'm
running into a blank when it comes to doing the network configuration, and it
seems to be down to the ethertap.
Here's what I've done:
1) Installed Debian (woody) on host
2) apt-get install user-mode-linux
3) bunzip2 Debian-3.0r2.ext2.bz2
4) Run UML with
linux con0=fd:0,fd:1 con=pts con1=tty:/dev/tty8 eth0=ethertap,tap0,mac
However, when I try to configure networking on the UML with ifconfig, I get
SIOCSIFFLAGS: Invalid argument
and in the host output I get
etap_tramp : uml_net failed
etap_tramp failed - errno = 22
I noticed that the tap devices are not created on the (Debian) host by
default, so I installed diald (the only place where I could find them).
I think the problem could be that ethertap is not included in the host kernel
- I tried recompiling the kernel but at not stage did I get the ETHERTAP
option, and in any case the kernel compile failed with errors.
I've been trying to set this up for almost a week, with no success. I've tried
switching to Libranet (following the IBM tutorial at
but the same problem occurs. I also tried installing Fedora on the host, but
the User Mode Linux RPMs are 2 years out of date and buggy according to UML
sourceforge. I've also made extensive use of Google for the last week, but
still no progress.
Can anyone offer a suggestion on how to proceed? I have never encountered the
tap devices before.
Help me Obi Wan, you're my only hope!!!
Thanks in advance,
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