#30 Documentation: tutorial, issue regarding /dev/net/tun

[Fermín Galán]

Peter Faller's report:

It looks to me that the ownership and permissions of the /dev/net/tun device is reset on each boot:

peter@earth:~$ ls -l /dev/net/tun
crw------- 1 root root 10, 200 2006-05-22 16:25 /dev/net/tun peter@earth:~$ id vnuml
uid=1000(vnuml) gid=501(vnuml) groups=501(vnuml),123(uml-net)

This is on Ubuntu 6.06.1, and I did the installation using apt.

Regards
Peter Faller

On Tue, 2006-11-21 at 14:00 +0100, Fermin Galan Marquez wrote:
> Dear Peter,
>
> > Just one thing I found that you may want to add to the tutorial: it
> > is necessary to do a 'chmod 666 /dev/net/tun' as root to get the
> > Net3 and Mgmt_Net to work in tutorial_user[12].xml examples.
>
> Looking in detail your suggestion, actually the requirement is that
> 'vnuml' user has rw permissions on the device (of course 666 is a way
> of giving permission to everyone :).
>
> In fact, this is tool in the tutorial
> (http://jungla.dit.upm.es/~vnuml/doc/current/tutorial/index.html):
>
> "As part of the VNUML install process, a non-privileged user vnuml
> was created (check it now with 'id vnuml'). This user is a member of
> the uml-net group, which owns the /dev/net/tun cloning device. It will
> own the uml_switch process that will be started for the Net3 network,
> so that this process won't need to be run by root."
>
> For example, in my Debian system:
>
> tornado:~# ls -l /dev/net/tun
> crw-rw---- 1 root uml-net 10, 200 2005-09-09 11:12 /dev/net/tun
> tornado:~# id vnuml
> uid=1001(vnuml) gid=1001(vnuml) grupos=1001(vnuml),104(uml-net)
>
> If you has needed explicetly use 'chmod 666 /dev/net/tun' maybe there
> is a bug in the VNUML installation procedure. In order to debug it,
> could you please tell as the following information regarding your enviroment:
>
> - Your distribution name and version
> - How did you install VNUML: wheter from .tar.gz or APT.
> - The output of the following commands:
>
> ls -l /dev/net/tun
> id vnuml