Random null pointer exception

[pksilen]

I experience a null pointer exception randomly. I.e. it does not happen all the time and not in all environments

14:55:15  Caused by: java.lang.NullPointerException
14:55:15    at java.base/java.lang.Class.forName0(Native Method)
14:55:15    at java.base/java.lang.Class.forName(Class.java:375)
14:55:15    at com.jcraft.jsch.Session.receive_kexinit(Session.java:601)

I am using the latest version of JSCH and Java 17.
This started to happen after I added following lines of code:

JSch.setConfig("kex", "curve25519-sha256,curve25519-sha256@libssh.org,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512");
JSch.setConfig("cipher.s2c", "aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com");
JSch.setConfig("cipher.c2s", "aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com");
JSch.setConfig("mac.s2c", "hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com");
JSch.setConfig("mac.c2s", "hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com");
JSch.setConfig("server_host_key", "ssh-ed25519,rsa-sha2-512,rsa-sha2-256");
JSch.setConfig("PubkeyAcceptedAlgorithms", "ssh-ed25519,rsa-sha2-512,rsa-sha2-256");

[norrisjeremy]

Hi @pksilen,

What is the exact version of JSch for which you received this NPE?
Contrary to what you stated, this could not have occurred with the latest version (0.2.17) because line 601 of Session.java is a blank line.

Thanks,
Jeremy

[norrisjeremy]

Hi @pksilen,

What is the exact version of JSch for which you received this NPE? Contrary to what you stated, this could not have occurred with the latest version (0.2.17) because line 601 of Session.java is a blank line.

Thanks, Jeremy

Btw, I believe that you are in fact using a very old version of JSch that does not actually support the following algorithms:

JSch.setConfig("kex", "curve25519-sha256,curve25519-sha256@libssh.org,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512");

[pksilen]

Hi,
Thanks for the feedback. I noticed that there is also another version (0.1.55) of JSCH in my classpath. It is probably coming as a transitive dependency from another library. I need to fix that. I will close this ticket.