Ssh connect using SSHJ from a Java 6 app

Thing you want to do

It is to make an SSH connection from a self-made application compiled with Java 6 to another machine using the SSHJ library. I used to try to do this using the JSch library, but this article As I wrote in 86c9e9efb5358601b25b), it doesn't work, so I'm trying to change it from the JSch library to the SSHJ library.

environment

access point

Ubuntu 16.04 LTS
OpenSSH 7.2p2

client

Windows 8.1 --Self-made application (developed with Java 6)
SSHJ

Sample code

I think that you can find many samples that perform password authentication when connecting with SSH, but it seems that there were few samples that perform key authentication (with passphrase), so I will write the sample code that succeeded in connecting as a memorandum. I will.

Simply connecting to SSH is not enough, so I tried to make the code download the file after connecting to SSH.

All-capital alphabets are the parts that need to be specified externally or defined in the code. Also, exception handling is a lot skipped.

`Sample.java`


        SSHClient ssh = new SSHClient();
        ssh.addHostKeyVerifier(new PromiscuousVerifier());
        try {
            ssh.connect(HOST, PORT);
            ssh.authPublickey(USER, ssh.loadKeys(PRIVATEKEYFILEPATH, PASSPHRASE));
            ssh.newSCPFileTransfer().download(SRCDIR, new FileSystemFile(DSTDIR));
            ssh.disconnect();
            ssh.close();
        } catch (UserAuthException e) {
            e.printStackTrace();
        } catch (TransportException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

Precautions for key authentication

The private key file that can be used with SSHJ seems to be a PEM format file.

I think that the private key file and public key file are created using the ssh-keygen command, but depending on the version of the ssh-keygen command used, the private key file in the following format is generated by default. .. If you use this private key file with the SSHJ library, authentication will fail.

To authenticate with the SSHJ library, use a private key file in the following format.

To generate a PEM-formatted private key file like the one above, specify -m PEM as an option for the ssh-keygen command.

-- that's all --