Re: [User-mode-linux-user] Requirement for ethertap daemon.

[Lennert B. <bu...@gn...>]

On Tue, 22 Aug 2000, David Woodhouse wrote:

> >  I think you have never tested something like this. 
> 
> You're right. I was about to hack it up. Would you care to enlighten me 
> about what I'll discover, and save me the trouble? :)

Hehehe.. if you be so kind, I cannot refuse! :-)

[buytenh@mara buytenh]$ ls -al /dev/tap0
crw-rw-rw-    1 buytenh  admins    36,  16 Aug 16 18:32 /dev/tap0
[buytenh@mara buytenh]$ cat /dev/tap0
cat: /dev/tap0: Operation not permitted
[buytenh@mara buytenh]$ su
Password: 
[root@mara buytenh]# cat /dev/tap0
FET@
       s9^*
 !"#$%&'()*+,-./012345678PET@
                                s9 
 !"#$%&'()*+,-./01234567ET@
                                s9/
 !"#$%&'()*+,-./01234567ET@
                              s9?
 !"#$%&'()*+,-./01234567


While writing a TCP implementation in userland and wanting to use this
construction I encountered the same problem. Apparently it checks for some
POSIX capability on open. It shouldn't be too hard to dike it out though,
but that _will_ require modifications to each and every kernel you want to
run it on.

I've been looking at the present preferred way of communication (eth?
devices), but I'm not too happy about those.. the level of isolation
between virtual machines seems sub-optimal. I'm sure more thought will go
into this on my part.

For now I'm busy chasing a panic that won't reproduce when run under the
debugger... :-)



greetings,
Lennert