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Java remote SSH

Posted on 2012-04-01
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Last Modified: 2012-04-02
Hi, experts,

I need to execute Linux commands on a remote server (actually, EC2 machines) from my Java code. I found two libraries, sshj and jsch. Both are extensively used, but neither is extensively documented.

This is an example of using private/public key, but oh, so hard! http://stackoverflow.com/questions/3686710/sshj-example-of-private-public-key-authentication

Any help or explanation anywhere?

Thanks.
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Question by:kerzner
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Expert Comment

by:for_yan
ID: 37794350
I think this is an example of how to execute remote command from Java

http://www.jcraft.com/jsch/examples/Exec.java

using JSch:

http://www.jcraft.com/jsch/
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by:kerzner
ID: 37794369
Actually, this example is shorter, https://github.com/shikhar/sshj/blob/master/src/main/java/examples/Exec.java, which pushes me to use sshj, but even so - what does each call mean? And how do I make it use public/private keys?

Thank you,
Mark
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Expert Comment

by:for_yan
ID: 37794373
shorter is not always the simpler
I just used the example in the link which I posted and executed command ps on my linux host from winodws.
I didn't do anything with public/private key
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by:kerzner
ID: 37794376
Well, I have to use the keys - that's the only way to connect to EC2 machines. There are not username/passwords there. But you might be right, longer code, if it works, who cares. I might need to understand it, that's the problem :)
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for_yan earned 500 total points
ID: 37794386
Yes, if so, then you need to understand that, but I'm sure it is doable.
At least with user/password it works
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Expert Comment

by:for_yan
ID: 37794388
there are many examples here - hopefully you can find something suitablefor your situation:
http://www.jcraft.com/jsch/examples/
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Author Comment

by:kerzner
ID: 37794391
Perhaps yes. I will try this one, http://www.jcraft.com/jsch/examples/UserAuthPubKey.java, and report the results
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by:for_yan
ID: 37794398
Sure, makes sense
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Expert Comment

by:Sharon Seth
ID: 37794893
Another thought - if you don't want the authentication process to happen from code , you can always manually configure passwordless ssh b/w the two machines
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Author Comment

by:kerzner
ID: 37795959
Thanks, that's a good idea, but in my case I start and stop EC2 machines, and I also must allow login from Windows, so the pure java solution is preferable.
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Expert Comment

by:garypfirstech
ID: 37797732
I'm not sure exactly what you're trying to do.  If you're just trying to start and stop EC2 machines from a java program running on your desktop, you should use Amazon's Java SDK.  The Javadoc is at http://docs.amazonwebservices.com/AWSJavaSDK/latest/javadoc/index.html.
Instructions are at http://docs.amazonwebservices.com/AWSSdkDocsJava/latest/DeveloperGuide/welcome.html?r=1075.

To start or stop an EC2 instance, use class AmazonEC2Client method startInstances.  You pass the constructor for AmazonEC2Client your access key and secret key credentials in an AWSCredentials object and the SDK handles everything.

If this is not what you're trying to do, please ignore the post.  Otherwise, if you have additional questions, please post.

Thanks,
Gary
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Expert Comment

by:garypfirstech
ID: 37797780
PS Use AmazonEC2Client.runInstances (instead of startInstances) for instances not backed by EBS.

Gary
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Author Comment

by:kerzner
ID: 37797833
Gary,

I already start and stop instances with Typica. Now I need to set the Hadoop cluster and run my jobs there.

Thank you
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Expert Comment

by:garypfirstech
ID: 37797910
So, why not switch to the supported Amazon Java SDK for this and use AmazonElasticMapReduceClient.runJobFlow?

Gary
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Author Comment

by:kerzner
ID: 37797925
Because I am building my own AMI and running hadoop jobs on them. I need to many Linux utilities and other open source software that installing all these on each cluster machine on startup is not feasible. Here the project, http://freeeed.org/
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