I am trying to SCP a file from my application to a server using j2ssh. The remote server is running TECTIA.
From the command line (Solaris machine where my app is deployed) the scp works fine using the key pair we exchanged.
From my application, j2ssh can not make a connection, throwing the exception:
Caused by: com.sshtools.j2ssh.transport.TransportProtocolException: The connection did not complete
The debug logs from j2ssh show the following:
com.sshtools.j2ssh.transport.TransportProtocolCommon.beginKeyExchange(Unknown Source) | Starting key exchange
com.sshtools.j2ssh.transport.TransportProtocolCommon.determineAlgorithm(Unknown Source) | Determine Algorithm
com.sshtools.j2ssh.transport.TransportProtocolCommon.determineAlgorithm(Unknown Source) | Client Algorithms: [diffie-hellman-group1-sha1]
com.sshtools.j2ssh.transport.TransportProtocolCommon.determineAlgorithm(Unknown Source) | Server Algorithms: [diffie-hellman-group14-sha1, diffie-hellman-group-exchange-sha1]
com.sshtools.j2ssh.transport.TransportProtocolCommon.sendMessage(Unknown Source) | Sending SSH_MSG_DISCONNECT
com.sshtools.j2ssh.transport.TransportProtocolCommon.run(Unknown Source) | The Transport Protocol has been stopped
From the above I can see above that there is no matching algorithm for the key exchange between my app and the server (debugging actually shows that the root of this problem is a AlgorithmNotAgreedException when no server and client algorithm match so I know this is the root cause).
How can I add new algorithms to j2ssh so it can find a match? The j2ssh documentation is pretty sparse.
You should have a sshtools.xml file in the j2ssh distribution. In that file you can add an additional ExtensionAlgorithm entry to map
diffie-hellman-group14-sha1 to
com.maverick.ssh.components.jce.DiffieHellmanGroup14Sha1
or to
com.maverick.ssh.components.standalone.DiffieHellmanGroup14Sha1