Apache Karaf: no matching cipher found: client aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-gcm@openssh.com,aes256-gcm@openssh.com,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lysator.liu.se server

During a recent deployment of a custom Karaf distribution via the karaf-maven-plugin, I've experienced a very strange behaviour when deployed to FreeBSD rather than my developer Mac OS rig.

Connecting thru SSH failed, so the logging has been increased:

dfi:~ doma$ ssh karaf@optiplex1 -p 8100
no matching cipher found: client aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-gcm@openssh.com,aes256-gcm@openssh.com,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lysator.liu.se server 

Here's Karaf's exception logged:

16:24:03,890 INFO  8]-nio2-thread-1 125 shd.server.session.ServerSession Server session created from /192.168.0.21:64951
16:24:03,894 DEBUG 8]-nio2-thread-1 125 shd.server.session.ServerSession Client version string: SSH-2.0-OpenSSH_6.2
16:24:03,900 DEBUG 8]-nio2-thread-1 125 d.common.session.AbstractSession Send SSH_MSG_KEXINIT
16:24:03,901 DEBUG 8]-nio2-thread-1 125 d.common.session.AbstractSession Received SSH_MSG_KEXINIT
16:24:03,902 WARN  8]-nio2-thread-1 125 d.common.session.AbstractSession Exception caught
jjava.lang.IllegalStateException: Unable to negotiate key exchange for encryption algorithms (client to server) (client: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-gcm@openssh.com,aes256-gcm@openssh.com,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lys
ator.liu.se / server: )
        at org.apache.sshd.common.session.AbstractSession.negotiate(AbstractSession.java:1159)[125:org.apache.sshd.core:0.14.0]
        at org.apache.sshd.common.session.AbstractSession.doHandleMessage(AbstractSession.java:388)[125:org.apache.sshd.core:0.14.0]
        at org.apache.sshd.common.session.AbstractSession.handleMessage(AbstractSession.java:326)[125:org.apache.sshd.core:0.14.0]
        at org.apache.sshd.common.session.AbstractSession.decode(AbstractSession.java:780)[125:org.apache.sshd.core:0.14.0]
        at org.apache.sshd.common.session.AbstractSession.messageReceived(AbstractSession.java:308)[125:org.apache.sshd.core:0.14.0]
        at org.apache.sshd.common.AbstractSessionIoHandler.messageReceived(AbstractSessionIoHandler.java:54)
        at org.apache.sshd.common.io.nio2.Nio2Session$1.onCompleted(Nio2Session.java:184)
        at org.apache.sshd.common.io.nio2.Nio2Session$1.onCompleted(Nio2Session.java:170)
        at org.apache.sshd.common.io.nio2.Nio2CompletionHandler$1.run(Nio2CompletionHandler.java:32)
        at java.security.AccessController.doPrivileged(Native Method)[:1.8.0_60]
        at org.apache.sshd.common.io.nio2.Nio2CompletionHandler.completed(Nio2CompletionHandler.java:30)[125:org.apache.sshd.core:0.14.0]
        at sun.nio.ch.Invoker.invokeUnchecked(Invoker.java:126)[:1.8.0_60]
        at sun.nio.ch.Invoker.invokeDirect(Invoker.java:157)[:1.8.0_60]
        at sun.nio.ch.UnixAsynchronousSocketChannelImpl.implRead(UnixAsynchronousSocketChannelImpl.java:553)[:1.8.0_60]
        at sun.nio.ch.AsynchronousSocketChannelImpl.read(AsynchronousSocketChannelImpl.java:276)[:1.8.0_60]
        at sun.nio.ch.AsynchronousSocketChannelImpl.read(AsynchronousSocketChannelImpl.java:297)[:1.8.0_60]
        at java.nio.channels.AsynchronousSocketChannel.read(AsynchronousSocketChannel.java:420)[:1.8.0_60]
        at org.apache.sshd.common.io.nio2.Nio2Session.startReading(Nio2Session.java:170)[125:org.apache.sshd.core:0.14.0]
        at org.apache.sshd.common.io.nio2.Nio2Acceptor$AcceptCompletionHandler.onCompleted(Nio2Acceptor.java:135)[125:org.apache.sshd.core:0.14.0]
        at org.apache.sshd.common.io.nio2.Nio2Acceptor$AcceptCompletionHandler.onCompleted(Nio2Acceptor.java:120)[125:org.apache.sshd.core:0.14.0]
        at org.apache.sshd.common.io.nio2.Nio2CompletionHandler$1.run(Nio2CompletionHandler.java:32)
        at java.security.AccessController.doPrivileged(Native Method)[:1.8.0_60]
        at org.apache.sshd.common.io.nio2.Nio2CompletionHandler.completed(Nio2CompletionHandler.java:30)[125:org.apache.sshd.core:0.14.0]
        at sun.nio.ch.Invoker.invokeUnchecked(Invoker.java:126)[:1.8.0_60]
        at sun.nio.ch.Invoker$2.run(Invoker.java:218)[:1.8.0_60]
        at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(AsynchronousChannelGroupImpl.java:112)[:1.8.0_60]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)[:1.8.0_60]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)[:1.8.0_60]
        at java.lang.Thread.run(Thread.java:745)[:1.8.0_60]

After trying out all sort of tips read via google, finally realized: setting the JAVA_HOME fixes the issue. To solve for all users I added this line to /etc/profile:

export JAVA_HOME=/usr/local/openjdk7

You can also put the same line to $HOME/.profile to fix it only for one user.

Karaf is beautiful but this one was ugly. Well, my fault: starting Karaf actually complains about not setting JAVA_HOME (and that results may vary), but since I used it like that for quite a while, didn't expect this.