change password remote unix server using java

Question

I am looking for a way to fire passwd onto a remote unix server via a java code. I am using Jsch, I can successfully execute commands like find, zip, get. But when I pass 'passwd' command nothing happens. The motive is to create an application which can change the password of unix server in every 10 days.

This is the code I am trying to use (find command works fine)

JSch sftp=new JSch();
        Session session=sftp.getSession("Test", "150.236.9.75");
        session.setConfig("StrictHostKeyChecking", "no");
        session.setConfig("compression.s2c", "[email protected],zlib,none");
        session.setConfig("compression.c2s", "[email protected],zlib,none");
        session.setConfig("compression_level", "9");
        session.setPassword("Test@123");
        session.connect();

        if(session.isConnected())
        {
            String line="";
            System.out.println("connected");
            ChannelExec ch=(ChannelExec) session.openChannel("exec");
            String Command="passwd -s; Test@123; Pass@123; Pass@123";
            //String Command="find *";
            InputStream in = ch.getInputStream();
            ch.setCommand(Command);
            ch.connect();
            byte[] buffer = new byte[1024]; 
            int bytes;
            do {
                while (in.available() > 0) {
                    bytes = in.read(buffer, 0, 1024);
                    String file=new String(buffer, 0, bytes);
                    System.out.println(file);
                    line=line+file;
                }
            } while (!ch.isClosed());   
            ch.disconnect();
        }
        session.disconnect();

If I had to guess, the problem is that passwd asks for input after your run it and your program might not handle that correctly. Please post some relevant pieces of code so that we can see what you are doing right now. Are you able to interact with other commands that ask for user input or only those that send to STDOUT? — zero298
– zero298, Commented Jan 21, 2015 at 20:00
Get rid of the available() and while (!ch.isClosed()) tests. Neither of them does what you seem to think. The loop should be while ((bytes = in.read(buffer)) > 0) ... — user207421
– user207421, Commented Jan 21, 2015 at 20:20

Community · Accepted Answer · 2017-05-23 11:43:30Z

2

The passwd command requires interative input (i.e. read from stdin), see How to write in Java to stdin of ssh?

edited May 23, 2017 at 11:43

CommunityBot

11 silver badge

answered Jan 21, 2015 at 19:57

Alex

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Julián Martinez · Accepted Answer · 2018-06-19 15:36:13Z

0

For me running the next command without using Thread.sleep works:

echo -e \"new-password\nnew-password\" | passwd user-linux

edited Jun 19, 2018 at 15:36

answered Jun 14, 2018 at 21:51

Julián Martinez

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