CODEWITHSUNDEEP
javajenkinsssh
Alex Chudinov
Alex Chudinov

Reputation: 724

Connecting jenkins agent: Malformed SSH byte string

I encontered this problem when was trying to connect jenkins agent trough the ssh. I've passed all the steps as described here: https://acloudguru.com/blog/engineering/adding-a-jenkins-agent-node, except one - instead yum install java-1.8.0-openjdk I've used apt install default-jre, which in the end has gave me openjdk 11.0.13 2021-10-19. After the all trying launch the agent I am getting error:

java.io.IOException: Malformed SSH byte string.
    at com.trilead.ssh2.packets.TypesReader.readByteString(TypesReader.java:132)
    at com.trilead.ssh2.packets.TypesReader.readMPINT(TypesReader.java:117)
    at com.trilead.ssh2.signature.RSAKeyAlgorithm.decodePublicKey(RSAKeyAlgorithm.java:113)
    at com.trilead.ssh2.signature.RSAKeyAlgorithm.decodePublicKey(RSAKeyAlgorithm.java:28)
    at com.trilead.ssh2.KnownHosts.addHostkey(KnownHosts.java:108)
    at com.trilead.ssh2.KnownHosts.initialize(KnownHosts.java:410)
    at com.trilead.ssh2.KnownHosts.initialize(KnownHosts.java:438)
    at com.trilead.ssh2.KnownHosts.<init>(KnownHosts.java:87)
    at hudson.plugins.sshslaves.verifiers.KnownHostsFileKeyVerificationStrategy.getPreferredKeyAlgorithms(KnownHostsFileKeyVerificationStrategy.java:108)
    at hudson.plugins.sshslaves.SSHLauncher$1.call(SSHLauncher.java:425)
    at hudson.plugins.sshslaves.SSHLauncher$1.call(SSHLauncher.java:421)
    at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
    at java.base/java.lang.Thread.run(Thread.java:829)
[01/04/22 15:30:12] Launch failed - cleaning up connection
[01/04/22 15:30:12] [SSH] Connection closed.

Please, help me to understand, what happens and how can it be resolved. I am newbuy with jenkins and not familiar with java. Googling of this problem did not supply some sensible result to me. Thank you.

Upvotes: 0

Views: 553

Answers (1)

Mesut
Mesut

Reputation: 56

This is most likely due to incorrect content of the KnownHosts file. Therefore, make sure that the KnownHosts file is correct with the content of id_rsa.pub(public file), if it is incorrect, you will need to add it after Host name or IP address. Such as;

HOSTNAME ssh-rsa AAAAB3NzaC1yc...

Upvotes: 2

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