i like to use jsch to open a sftp connection to download some files.

String SFTPPRIVATEKEY = "/folder/privatekeyfile.ppk";
String SFTPUSER = "user";
String SFTPPASS = "";
String SFTPHOST = "server.tld";
String SFTPPORT = "22";
int usePrivateKey = 1;

public boolean connect() {
        boolean isConnected = false;
        try {
            JSch jsch = new JSch();
            
            if (usePrivateKey) {
                jsch.addIdentity(SFTPPRIVATEKEY);
            }
            
            session = jsch.getSession(SFTPUSER,SFTPHOST,SFTPPORT);
            if (!usePrivateKey) {
                session.setPassword(SFTPPASS);
            }
            
            java.util.Properties config = new java.util.Properties();
            config.put("StrictHostKeyChecking", "no"); 
            session.setConfig(config);
            session.connect();
            if (session.isConnected() == true) {
                log.println("Connection to Session server is successfully");
            }
            channel = session.openChannel("sftp");
            channel.connect();
            channelSftp = (ChannelSftp)channel;
            isConnected = true;
        } catch (JSchException e) {
            log.println("SFTPClient Connect ERROR: " e.getMessage());
            e.printStackTrace();
            
        }
        return isConnected;
    }

If i run my code i get:

com.jcraft.jsch.JSchException: USERAUTH fail

I tried to connect using sftp on the shell on the same client where my java code runs. I run

sftp -i privatekeyfile.ppk [email protected]

It prompts for a passphrase for the privatekeyfile. I entered the passphrase and the connection works great.

But jsch did not connect. I found no option to set the passphrase in jsch. Maybe this is the problem?

Can some of you help?

Thanks

CodePudding user response：

There's JSch.addIdentity overload that takes the passphrase:

public void addIdentity(String prvkey, String passphrase)

Obligatory warning: Do not use StrictHostKeyChecking=no to blindly accept all host keys. That is a security flaw. You lose a protection against MITM attacks. For the correct (and secure) approach, see: How to resolve Java UnknownHostKey, while using JSch SFTP library?