RE: intermittent key exchange failures about sshj

[gelmayan]

In fact I'm working on a project for an IAAS offer of cloud computing. And It's all about the provisionning of the netscreen ISG 1000 series firewall of JUNIPER.

[shikhar]

Can you describe how to reproduce this?

[gelmayan]

First of all thank you for replying to my issue. It's really a tough one.
In fact It's simple, you just develop a junit test for example to a host, in able to open , and close, several connexion via a loop.
Here is an the whole code of my testing junit:

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Date;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import net.schmizz.sshj.SSHClient;
import net.schmizz.sshj.connection.channel.direct.Session;
import net.schmizz.sshj.connection.channel.direct.Session.Shell;

import org.apache.log4j.Logger;
import org.junit.Ignore;

import com.orange.fcr.exception.TimeOutException;
@Ignore
public class TestSSH2 {

    private static Logger logger = Logger.getLogger(TestSSH2.class);

    String TIMEOUT_ERROR_MESSAGE = "TimeOut: unable to have a response from the device";

    private long send(OutputStream out, String commande) throws IOException {
        long count = 0L;
        count = commande.getBytes().length;
        out.write(commande.getBytes(), 0, commande.getBytes().length);

        out.flush();
        return count;
    }

    public SSHClient sshClient;


    @SuppressWarnings("static-access")
    public String receive(InputStream in, int bufSize, int sshTimeOut) throws IOException,
            InterruptedException, TimeOutException {

        long deadline = 0;
        if (sshTimeOut >= 0){
            deadline = new Date().getTime() + sshTimeOut;
        }
        int read = 0;
        StringBuilder resultat = new StringBuilder();

        Pattern p = Pattern.compile("^*([a-zA-Z0-9()]+)->\\s*$");
        Matcher m;
        int count = 0;//nomber of bytes to read
        //waiting for the first bytes to read
        while ((count=in.available()) < 0) {
            if ((deadline != 0) && new Date().getTime() > deadline) {
                throw new TimeOutException(TIMEOUT_ERROR_MESSAGE);
            }
            try {
                Thread.currentThread().sleep(100);
            }catch (InterruptedException ignored) {
                /* ignore */
            }
        }
        //begin reading the bytes
        while(((count =in.available()) >= 0)){
            byte[] buf = new byte[bufSize];
            if(count > 0){
                read = in.read(buf);
            }
            else{
                read = 0;
            }
            if (read > 0) {
                String res = new String(buf, 0, read);
                resultat.append(res);
            }

            m = p.matcher(resultat);
            //Go out when I find a first read
            if (m.find()) {
                break;
            }//deadline passed: timeout exception finishing to read the message
            else if ((deadline != 0) && (new Date().getTime() > deadline)) {
                throw new TimeOutException(TIMEOUT_ERROR_MESSAGE);
            }
        }
        return resultat.toString();
    }




    public void connect() throws IOException{
        this.sshClient = new SSHClient();
        sshClient.addHostKeyVerifier("c5:c6:59:24:b6:9c:62:31:29:6a:c1:c4:a5:fa:ea:05");
        sshClient.connect("10.1.31.43", 22);
        sshClient.authPassword("dihadmin", "dihadmin");
    }

    public static void main(String... args) throws Exception {


        TestSSH2 testSSH2 = new TestSSH2();
        for(int i = 0; i < 300; i++){
            testSSH2.connect();

            try {

                Session session = testSSH2.sshClient.startSession();
                Shell shell1 = null;

                try {
                    logger.error("begin loop n°:"+i);
                    session.allocateDefaultPTY();

                    shell1 = session.startShell();

                    String resultat1;

                    String resultat2;

                    String resultat3;
                    logger.error("loop n°:"+i + " preambule receive:");
                    testSSH2.receive(shell1.getInputStream(),
                            shell1.getLocalMaxPacketSize(),2000);

                    logger.error("loop n°:"+i + " send n°1");
                    testSSH2.send(shell1.getOutputStream(), "get console\n");

                    logger.error("loop n°:"+i + "receive n°1");
                    resultat1 = testSSH2.receive(shell1.getInputStream(),
                            shell1.getLocalMaxPacketSize(),2000);

                    logger.error("loop n°:"+i + " send n°2");
                    testSSH2.send(shell1.getOutputStream(), "get vrouter\n");

                    logger.error("loop n°:"+i + " receive n°2");
                    resultat2 = testSSH2.receive(shell1.getInputStream(),
                            shell1.getLocalMaxPacketSize(),2000);

                    logger.error("loop n°:"+i + " send n°3");
                    testSSH2.send(shell1.getOutputStream(), "get config\n");

                    logger.error("loop n°:"+i + " receive n°3");
                    resultat3 = testSSH2.receive(shell1.getInputStream(),
                            shell1.getLocalMaxPacketSize(),3000);

                    logger.error("loop n°:"+i + " send n°4");
                    testSSH2.send(shell1.getOutputStream(), "exit\n");

                    logger.error("response for cmd1:"+resultat1);
                    logger.error("response for cmd2:"+resultat2);
                    logger.error("response for cmd3:"+resultat3);

                } finally {
                    shell1.close();
                    session.close();
                }

            } finally {
                testSSH2.sshClient.disconnect();
            }
        }
    }
}

As you can see in this code, I'm in a loop for, I'm creating for each iteration, a new sshClient base on the API of sshj.
I disconnect from it at the end.
I have no errors for about 100 connexions, and then it stops. I'm not able to connect to the device.
Anyway, it is quite random the issue, It happens specially when you try to make connexions one after the other.

Any help can be welcomed. Don't hesitate if you nedd more information!!!

[shikhar]

What SSH server is this? I can't reproduce on my end, using OpenSSH sshd 5.6. Complete debug-level logs would be very helpful.