tun channel FDs changed to -1?

[Fergal Meath]

Hi,

I have sshd (OpenSSH_5.8p1) running on uCLinux (Linux version 2.6.19-uc1)
Interactive sessions are working okay.
Tunnel device seems to be set up but is not passing any traffic to other
end.
Debug output shows that tun channel 0 file descriptors are changed from 8/8
to -1/-1.
Does anyone know how or what could be causing this?

Client command is…
ssh –w0:0 root at 192.168.1.100 ifconfig tun0 10.0.0.1 pointopoint 10.0.0.2
netmask 255.255.255.255

My sshd debug output is shown below.

Any help or tips would be appreciated,
Regards,

Fergal

---------- SSHD DEBUG OUTPUT
----------------------------------------------------
Jan  1 01:50:09 (none) auth.info sshd[2344]: Accepted password for root
from 192.168.1.200 port 55408 ssh2
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug1: Entering interactive
session for SSH2.
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug2: fd 6 setting
O_NONBLOCK
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug2: fd 7 setting
O_NONBLOCK
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug1:
server_init_dispatch_20
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug1:
server_input_channel_open: ctype tun at openssh.com rchan 0 win 2097152 max
32768
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug1: sys_tun_open: tun0
mode 1 fd 8
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug2: fd 8 setting
O_NONBLOCK
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug3: fd 8 is O_NONBLOCK
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug1: channel 0: new [tun]
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug1:
server_input_channel_open: confirm tun at openssh.com
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug1:
server_input_channel_open: ctype session rchan 2 win 2097152 max 32768
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug1: input_session_request
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug1: channel 1: new
[server-session]
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug2: session_new: allocate
(allocated 0 max 10)
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug3: session_unused:
session id 0 unused
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug1: session_new: session 0
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug1: session_open: channel
1
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug1: session_open: session
0: link with channel 1
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug1:
server_input_channel_open: confirm session
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug1:
server_input_channel_req: channel 1 request env reply 0
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug1: session_by_channel:
session 0 channel 1
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug1:
session_input_channel_req: session 0 req env
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug2: Ignoring env request
LANG: disallowed name
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug1:
server_input_channel_req: channel 1 request exec reply 1
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug1: session_by_channel:
session 0 channel 1
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug1:
session_input_channel_req: session 0 req exec
Jan  1 01:50:09 (none) auth.debug sshd[2415]: debug1: permanently_set_uid:
0/0
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug2: fd 4 setting
TCP_NODELAY
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug3: packet_set_tos: set
IP_TOS 0x08
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug2: fd 11 setting
O_NONBLOCK
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug2: fd 10 setting
O_NONBLOCK
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug2: fd 13 setting
O_NONBLOCK
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug2: channel 1: rcvd eof
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug2: channel 1: output
open -> drain
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug2: channel 1: obuf empty
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug2: channel 1: close_write
Jan  1 01:50:09 (none) auth.debug sshd[2344]: debug2: channel 1: output
drain -> closed
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug1: Received SIGCHLD.
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug1: session_by_pid: pid
2415
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug1: session_exit_message:
session 0 channel 1 pid 2415
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug2: channel 1: request
exit-status confirm 0
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug1: session_exit_message:
release channel 1
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug2: channel 1: read<=0
rfd 11 len 0
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug2: channel 1: read failed
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug2: channel 1: close_read
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug2: channel 1: input open
-> drain
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug2: channel 1: read 0
from efd 13
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug2: channel 1: closing
read-efd 13
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug2: channel 1: ibuf empty
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug2: channel 1: send eof
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug2: channel 1: input
drain -> closed
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug2: channel 1: send close
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug2: notify_done: reading
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug3: channel 1: will not
send data after close
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug2: channel 1: rcvd close
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug3: channel 1: will not
send data after close
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug2: channel 1: is dead
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug2: channel 1: gc: notify
user
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug1: session_by_channel:
session 0 channel 1
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug1:
session_close_by_channel: channel 1 child 0
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug1: session_close:
session 0 pid 0
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug3: session_unused:
session id 0 unused
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug2: channel 1: gc: user
detached
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug2: channel 1: is dead
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug2: channel 1: garbage
collecting
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug1: channel 1: free:
server-session, nchannels 2
Jan  1 01:50:10 (none) auth.debug sshd[2344]: debug3: channel 1: status:
The following connections are open:\r\n  #0 tun (t4 r0 i0/0 o0/0 fd -1/-1
cc -1)\r\n  #1 server-session (t4 r2 i3/0 o3/0 fd -1/-1 cc -1)\r\n