Re: ssh tunneling and "channel 2: open failed: administratively prohibited: open failed"

["Jonathan Underwood" <jonathan underwood gmail com>]

Hi Rick,

On 23/01/07, Rick Sewill <rsewill cableone net> wrote:

> When you ssh from machine A to machine B,
> can you ssh from machine B to machine C?

Yes, I can.

> It may not provide much information, but my next instinct would be to
> turn on verbose mode, "man ssh"
> ssh -v -v -v -p 8888 localhost

ssh -vvv -p 8888 localhost
OpenSSH_4.3p2, OpenSSL 0.9.8b 04 May 2006
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug2: ssh_connect: needpriv 0
debug1: Connecting to localhost [::1] port 8888.
debug1: Connection established.
debug1: identity file /home/jgu/.ssh/identity type -1
debug1: identity file /home/jgu/.ssh/id_rsa type -1
debug1: identity file /home/jgu/.ssh/id_dsa type -1
ssh_exchange_identification: Connection closed by remote host

and, also, if I start up the tunnel with -vvv, I get this each time I
try to connect to port 8888 on the local host:

debug1: Connection to port 8888 forwarding to withnail.phys.ucl.ac.uk
port 22 requested.
debug2: fd 9 setting TCP_NODELAY
debug2: fd 9 setting O_NONBLOCK
debug3: fd 9 is O_NONBLOCK
debug1: channel 3: new [direct-tcpip]
channel 3: open failed: administratively prohibited: open failed
debug1: channel 3: free: direct-tcpip: listening port 8888 for
withnail.phys.ucl.ac.uk port 22, connect from ::1 port 36180,
nchannels 4
debug3: channel 3: status: The following connections are open:
 #2 client-session (t4 r0 i0/0 o0/0 fd 6/7 cfd -1)
 #3 direct-tcpip: listening port 8888 for withnail.phys.ucl.ac.uk
port 22, connect from ::1 port 36180 (t3 r-1 i0/0 o0/0 fd 9/9 cfd -1)

debug3: channel 3: close_fds r 9 w 9 e -1 c -1
debug1: Connection to port 8888 forwarding to withnail.phys.ucl.ac.uk
port 22 requested.
debug2: fd 9 setting TCP_NODELAY
debug2: fd 9 setting O_NONBLOCK
debug3: fd 9 is O_NONBLOCK
debug1: channel 3: new [direct-tcpip]
channel 3: open failed: administratively prohibited: open failed
debug1: channel 3: free: direct-tcpip: listening port 8888 for
withnail.phys.ucl.ac.uk port 22, connect from ::1 port 36181,
nchannels 4
debug3: channel 3: status: The following connections are open:
 #2 client-session (t4 r0 i0/0 o0/0 fd 6/7 cfd -1)
 #3 direct-tcpip: listening port 8888 for withnail.phys.ucl.ac.uk
port 22, connect from ::1 port 36181 (t3 r-1 i0/0 o0/0 fd 9/9 cfd -1)

debug3: channel 3: close_fds r 9 w 9 e -1 c -1

Does that shed any light ?
J.