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WimaxTech 08-17-2012 04:51 PM

SSH through SSH
I have inherited a test station at work that runs bash script. I am new to linux but have managed to get most of the software to work with this exception:

I am having a problem with the following line:

ssh -q -o "ConnectTimeout 10" root@$OSR_PC "sshpass -p default ssh -q -o \"ConnectTimeout 10\" root@$OSR_IP \"export lm_ctrl_channel_bw=$CHNL_BW; export lm_ctrl_dl_freq=$DL_CF; export lm_ctrl_afs=0; configdb -S lm_ctrl; reboot; exit\""

The test setup is as follows:

OBR_PC is linked to OSR_PC (address
The OSR_PC is linked to OSR_IP(address:

The software is to send the commands to the OSR_IP through the OSR_PC from the OBR_PC but I cannot get a link with this line and nether can my IT tech.
He wants to create an entire new configuration.
I can ssh into the OSR_PC and then ssh onto the OSR_IP.

Can I make the above script work without rewriting the entire program which is quite extensive?

Thanx in advance


suicidaleggroll 08-17-2012 04:58 PM

Where is it failing?

I don't know about that command, but I can run

[user@comp1 ~]$ ssh comp2 "ssh comp3 ls"
and it successfully makes it through the chain and spits out the contents of comp3.

WimaxTech 08-17-2012 05:10 PM

It appears fo fail after "sshpass -p default ssh -q -o \"ConnectTimeout 10\" root@$OSR_IP \"
There's a lot going on with this script that I do not know yet.

zQUEz 08-17-2012 07:13 PM

If I were in your shoes, for the sake of testing where the failure is, I would take out the variables that reference known IP's, I would also setup ~/.ssh/config files on each machine that you are ssh'ing into to pre configure the "connecttimeout" options, and if possible I would even configure a passwordless ssh key for root@$OSR_IP to get rid of the "sshpass" command (BTW I had never heard of that till your post). That should leave you with a very minimalist command. Assuming that all works, you could back out of those changes to find the one that breaks.

Tinkster 08-17-2012 08:22 PM


Originally Posted by WimaxTech (Post 4757105)
It appears fo fail after "sshpass -p default ssh -q -o \"ConnectTimeout 10\" root@$OSR_IP \"
There's a lot going on with this script that I do not know yet.

If you are a tester you should be aware of the fact that debug info
is crucial. Can you please tell us 'how" it fails, what output are
you getting?


WimaxTech 08-18-2012 12:48 PM

The software is setting frequency and bandwidth parameters on two systems to establish communication between the two.
The OBR unit, controlled from OBR_PC, is not a problem and works fine.
The software control of the OSR_IP does not report any error. The program continues to run but the parameters on OSR_IP are not changed. This results in a "Test Failure".
Entering the command line in Terminal,

ssh -q -o "ConnectTimeout 10" root@$OSR_PC "sshpass -p default ssh -q -o \"ConnectTimeout 10\" root@$OSR_IP"

I am unable to reach the command prompt of OSR_IP.
I have tried symplfing the line to : ssh root@$OSR_PC "sshpass -p default ssh root@$OSR_IP"
The return shows that the OSR_IP address has been added but nothing more happens.
I have been searching for a reason for this. As I have said earlier, I can ssh into OSR_PC and then ssh into OSR_IP and from what I know so far – this should work.
Is there a Good reference document that would help my understanding of using ssh in this manner?

Tinkster 08-19-2012 04:51 PM

Well ... I'd start hunting for sshpass; I've not come across that command in
over 15 years of using Linux. What does it do, where does it live?


chrism01 08-19-2012 05:48 PM

sshpass is not recommended for the reasons stated on the man page
I would indeed go with post#4; simplify the code (at least for debugging the issue) and use ssh auth-keys instead of sshpass.

WimaxTech 08-19-2012 07:23 PM

sshpass is a utility designed for running ssh using the mode referred to as "keyboard-interactive" password authentication, but in non-interactive mode.

Security is a non-issue as the entire system on which it's run is closed and there can be no outside connections.

chrism01 08-19-2012 07:42 PM

I know what its used for; I read the page :)
Nonetheless, simplification would be better.

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