Com. Jcraft. Jsch. Jschexception: Auth Cancel
I'm Trying to Write an Ant Script to Retrieve an Url via Port Tunnelling. It Works Great When I Use a Password (The Names Xxxx'd out for Privacy): but It...
I'm trying to write an Ant script to retrieve an URL via port tunnelling.
It works great when I use a password (the names xxxx'd out for privacy):
<project default="main">
<target name="main">
<sshsession host="xxxx"
username="xxxx"
password="xxxx">
<LocalTunnel lport="1080" rhost="xxxx" rport="80"/>
<sequential>
<get src="" dest="/tmp/xxxx"/>
</sequential>
</sshsession>
</target>
</project>
But it doesn't work when I use a keyfile, like this:
<sshsession host="xxxx"
username="xxxx"
keyfile="/Users/xxxx/.ssh/id_dsa"
passphrase="xxxx">
<LocalTunnel lport="1080" rhost="xxxx" rport="80"/>
<sequential>
<get src="" dest="/tmp/xxxx"/>
</sequential>
</sshsession>
I get this exception:
/tmp/build.xml:8: com.jcraft.jsch.JSchException: Auth cancel
at com.jcraft.jsch.Session.connect(Session.java:451)
at com.jcraft.jsch.Session.connect(Session.java:150)
at org.apache.tools.ant.taskdefs.optional.ssh.SSHBase.openSession(SSHBase.java:223)
- I'm sure I'm using the correct keyfile (I've tried using the wrong name, which gives a legitimate FileNotFoundException).
- I can successfully ssh from the command line without being prompted for a password.
- I'm sure I'm using the correct passphrase for the keyfile.
What's the cause of this error and what can I do about it?
6 Answers
I debugged the code. This was failing because my private key was failing authentication; JSch silently fell back to password authentication, which was canceled, because I didn't specify a password.
JSch error handling sucks a lot. Retrace your steps, regenerate a (separate) private key file, use ssh -i to guarantee you're using the right file, and keep your fingers crossed.
To get the jsch connection to work, you must specify the paths to both the known_hosts file and to the file containing the private key. This is done using the setKnownHosts and addIdentity methods.
jsch.setKnownHosts("/path/to/.ssh/known_hosts");
jsch.addIdentity("/path/to/.ssh/id_rsa");
If the key has a passphrase, you can add it to the addIdentity argument list:
jsch.addIdentity("/path/to/.ssh/id_rsa", myPassPhrase);
I had the same issue while using sshexec task. I added passphrase attibute too and it worked fine. create a passphrase for your private key and add this as a attribute in your task. Also don't forget to convert your private key to open ssh format if you generated the key using puttygen on windows.
There is a brand new fork of Jsch out now. The exception handling is far more comprehensive. No more swallowing or defaulting. Head over to to check it out. If something doesn't work the way you expect, please raise it as an issue, or send a pull request as we are actively maintaining it. We are also looking to get it up on the maven central repos soon.
I had a similar Issue today. So i thought i will share my solution aswell. I got the same exception but the problem was in fact that i had a umlaut within my password. after choosing a new password without it everything worked fine.
For some reason, jsch use a quite different authentication method.
TLDL; Create a rsa-sha2-512 key (using a PEM format).
ssh-keygen -t rsa-sha2-512 -m PEM -T '' -f ~/.ssh/id_rsa-sha2-512
In cases where you cantt easily change key type:
recreate a rsa key (using a PEM format).
ssh-keygen -t rsa -m PEM -T '' -f ~/.ssh/id_rsaconfigure ssh server to accept this method.
sudo bash -c "echo 'PubkeyAcceptedAlgorithms +ssh-rsa' > /etc/ssh/sshd_config.d/ssh-rsa.conf"Restart sshd server.
sudo systemctl restart sshdnow, it works!
PS: JSCH supported types are: ssh-rsa, ssh-dss, ecdca-sha2-nistp256, ecdca-sha2-nistp384, ecdca-sha2-nistp521
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