dmesg is as follows.

Linux version (benwing@quiche) (gcc version 3.3.5 (Debian 1:3.3.5-8ubuntu2.1)) #6 Tue Sep 19 18:22:48 CDT 2006
On node 0 totalpages: 8192
  DMA zone: 8192 pages, LIFO batch:1
Built 1 zonelists
Kernel command line: ubd0=./root_fs eth0=tuntap,benwingtap con0=fd:0,fd:1 root=/dev/ubda
PID hash table entries: 256 (order: 8, 1024 bytes)
Dentry cache hash table entries: 4096 (order: 2, 16384 bytes)
Inode-cache hash table entries: 2048 (order: 1, 8192 bytes)
Memory: 29968k available
Calibrating delay loop... 4639.94 BogoMIPS (lpj=23199744)
Mount-cache hash table entries: 512
Checking for host processor cmov support...Yes
Checking for host processor xmm support...No
Checking that host ptys support output SIGIO...Yes
Checking that host ptys support SIGIO on close...No, enabling workaround
Using 2.6 host AIO
NET: Registered protocol family 16
NET: Registered protocol family 2
IP route cache hash table entries: 256 (order: -2, 1024 bytes)
TCP established hash table entries: 1024 (order: 0, 4096 bytes)
TCP bind hash table entries: 512 (order: -1, 2048 bytes)
TCP: Hash tables configured (established 1024 bind 512)
TCP reno registered
Checking host MADV_REMOVE support...MADV_REMOVE failed, err = -22
Can't release memory to the host - memory hotplug won't be supported
mconsole (version 2) initialized on /home/benwing/.uml/MkqlXU/mconsole
Netdevice 0 : TUN/TAP backend -
Host TLS support detected
Detected host type: i386
VFS: Disk quotas dquot_6.5.1
Dquot-cache hash table entries: 1024 (order 0, 4096 bytes)
Initializing Cryptographic API
io scheduler noop registered
io scheduler anticipatory registered (default)
io scheduler deadline registered
io scheduler cfq registered
SLIP: version 0.8.4-NET3.019-NEWTTY (dynamic channels, max=256).
TCP bic registered
Initialized stdio console driver
Console initialized on /dev/tty0
Initializing software serial port version 1
 ubda: unknown partition table
EXT2-fs warning (device ubda): ext2_fill_super: mounting ext3 filesystem as ext2
VFS: Mounted root (ext2 filesystem) readonly.
line_ioctl: tty0: ioctl KDSIGACCEPT called
NET: Registered protocol family 1
line_ioctl: tty0: unknown ioctl: 0x541e
line_ioctl: tty0: unknown ioctl: 0x5603
Failed to open /dev/net/tun, err = 13
Failed to open /dev/net/tun, err = 13
line_ioctl: tty0: unknown ioctl: 0x541e
line_ioctl: tty0: unknown ioctl: 0x5603
Failed to open /dev/net/tun, err = 13
Failed to open /dev/net/tun, err = 13

i'm not sure why it can't open /dev/net/tun and whether this is guest or host.

in the guest:

root@ubuntu:~# ls -l /dev/net/tun
crw-------  1 root root 10, 200 Sep 19 23:29 /dev/net/tun

in the host:

quiche:/home/benwing/ut/os-fall-2006/hw0/foo/linux- 2084% ls -l /dev/net/tun
crw-rw----  1 root uml-net 10, 200 2006-08-24 09:17 /dev/net/tun

On 9/19/06, Jeff Dike <> wrote:
On Tue, Sep 19, 2006 at 06:03:08PM -0500, Ben Wing wrote:
> i used the ubuntu root fs on, followed all your directions
> and i get
> root@ubuntu :~# ifup eth0
> SIOCSIFFLAGS: Permission denied
> SIOCSIFFLAGS: Permission denied
> Failed to bring up eth0.
> root@ubuntu:~#

What does dmesg say?