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



On Tue, 2007-01-23 at 17:56 +0000, Jonathan Underwood wrote:
> Hi,
> 
> I'm having a spot of bother getting an ssh tunnel to work. Here's the situation:
> 
> I am trying to connect to machine C via a tunnel to machine B from
> machine A, with machine A being the local machine.
> 
> Machine C is behind a firewall, and so direct ssh from A to C isn't possible.
> 
> At the command line, once ssh'd into machine B from machine A, I can
> ssh from machine B to machine A.
> 
> So, on machine A (local machine) I run in one terminal (Terminal 1):
> 
> ssh  -R 8888:C:22 username B cat -
> 

My first guess was to suggest using
ssh -N -L 8888:C:22 username B

I believe -L 8888 forwards port 8888 on Machine A through ssh to machine
C, port 22.

I assume /etc/ssh/sshd_config, on Machine B, has not been changed from
the default of allowing TCP Forwarding (AllowTCPForwarding)

> which asks me for my password on machine B, which I duly enter.
> 
> Then, on machine A, in a second terminal (Terminal 2) I run
> 
> ssh -p 8888 localhost
> 
> On the terminal (Terminal 1) which is running the ssh tunnel I get this message:
> channel 2: open failed: administratively prohibited: open failed
> 
> And on Terminal 2 I get
> ssh_exchange_identification: Connection closed by remote host
> 
> Oddly, at no point have I been asked to enter login details for machine C.
> 
> I've ensured that port 22 is allowing incoming ssh connections on
> machine C. I've tried turning off SElinux on machine C. Machnine B is
> not under my control, so there's nothing much I can do there -- it is
> a SunOS machine and the ssh client does support the options for port
> forwarding (-L and -R).
> 
> Getting desperate - what am I doing wrong? :)
> 
> TIA
> Jonathan.
> 
-- 
Rick Sewill            tel:+1-218-287-1075 mailto:rsewill cableone net
1028 7th St. N.                               mailto:rsewill gmail com
Moorhead, MN 56560-1568      ymsgr:rsewill   sip:628497 fwd pulver com
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