Jenkins slave node is offline : Authentication failed

Question

My jenkins slave node is offline. The log is as follows:

[06/11/15 09:02:52] [SSH] Opening SSH connection to <ip>.
ERROR: Server rejected the 1 private key(s) for jenkins (credentialId:d7a17c00-1300-4cf3-8cf5-810b3297ebc6/method:publickey)
[06/11/15 09:02:52] [SSH] Authentication failed.
hudson.AbortException: Authentication failed.
    at hudson.plugins.sshslaves.SSHLauncher.openConnection(SSHLauncher.java:1178)
    at hudson.plugins.sshslaves.SSHLauncher$2.call(SSHLauncher.java:701)
    at hudson.plugins.sshslaves.SSHLauncher$2.call(SSHLauncher.java:696)
    at java.util.concurrent.FutureTask.run(FutureTask.java:262)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:745)
[06/11/15 09:02:52] Launch failed - cleaning up connection
[06/11/15 09:02:52] [SSH] Connection closed.

I have verified below:

Authorized_keys file at /var/lib/jenkins-slave/.ssh has correct public key of master.
Authorized_keys file at /var/lib/jenkins/.ssh has correct public key of master.
Master has its private and public key files at /var/lib/jenkins/.ssh folder and also at ~/.ssh folder.

I also tried "ssh -i .ssh/id_rsa -l jenkins ” from master machine but it is asking for password. Looks like it is not identifying slave machine.

There is known_hosts file in .ssh folder of both master and slave machine. What data goes in there?

How to resolve the issue?

To save you the headaches of SSH autentication, why don't you just input the username and password of the slave UNIX server? — jinggoy
I could resolve the issue. there was permission issue with my .ssh folder. It had to be read write execute for the owner alone and read for others n group. — nishat

Trond Trond · Accepted Answer · 2016-09-16T16:03:36

I have just been gone through this pain recently.

What I found out is that you have to make sure the .ssh directory has 700 permissions, and that jenkins has read and the id_rsa.pub should have 644 (not 755 as previously recommended, that would make the file executable, which shouldn't be required).

Also I found that if you have a Windows based slave in there you have to make sure you create your keys without a passphrase.

Jenkins slave node is offline : Authentication failed

1 Answers