SSH connection using JAVA using ch.ethz.ssh2.Connection

Question

I'am trying to connect to a remote server over ssh2 using the lib ch.ethz.ssh2.Connection

connexion = new Connection(host);
connexion.connect();
boolean isOK = connexion.authenticateWithPassword(login, pass);

But I get an IOException in connexion.connect(); with this error message:

Connection closed (Signature sent by remote is wrong!)

I tried to connect to the same server using Putty, I get a message that tells me that the fingerprint is not what it expected, but if I click yes to confirm I can connect.

I read in Java Doc that I can ignore the verification of the key, but it's not recomended (http://www.ganymed.ethz.ch/ssh2/javadoc/ch/ethz/ssh2/Connection.html#connect%28ch.ethz.ssh2.ServerHostKeyVerifier,%20int,%20int%29).

What I'am looking for, is a way to change something in the server so I can connect correctely. I don't want to change the Java code.

Thanks,

Otmane MALIH

Aaron Digulla · Accepted Answer · 2012-09-11 11:37:27Z

1

The remote fingerprint is cached somewhere on your computer. You need to do two things:

Find out why the remote fingerprint has changed. It's unlikely but possible that someone did tamper with your connection or the remote server.
Flush the cache. Check the documentation of your SSH framework how to do that. Next time you connect, the remote fingerprint will be cached anew.

answered Sep 11, 2012 at 11:37

Aaron Digulla

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2 Comments

Otmane MALIH Over a year ago

Well, I did delete the key in the known_hosts, and I tried to connect again from Java code, but without succes, and no key was added to the known_hosts. Then I tried to connect using Putty, a new entry was added to the file known_hosts, but even after that, I can't connect from java code!

Aaron Digulla Over a year ago

ch.ethz.ssh2 probably stores this in a different place. RTFM.

Otmane MALIH · Accepted Answer · 2012-09-14 14:00:14Z

0

Well it turns out that it's due to bug in the version of ganymed I used.

I changed it from 001 to 209 and now everything works fine.

Thank you Aaron Digulla for your answers.

answered Sep 14, 2012 at 14:00

Otmane MALIH

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