Access unix machine to read and save a file- from java code - Unix machine IP, userID, pwd given

[Archana Honnavalli]

Hi
I have a unix machine in my network
I have its IP - xxx.xxx.xxx.xxx
I have its userID and pwd - uid=uid - pwd=pwd

I need to access this machine from my java class.
I need to read a file from this machine.

PS: I do not want to map the machine on my drive and access it.

Please guide

[Archana Honnavalli]

Using this approach for the same
Here i am able to connect but telnet.login hangs and eventually "socket exception-connection abort" is shown

But same user id is working if i access unix system extenally

TelnetWrapper telnet = new TelnetWrapper();   
        try {   
            //Connect the socket and open the connection.   
            telnet.connect("xxx.xxx.xxx.xxx ", portNum;//pass arguments (ip, port)   
            System.out.println(telnet.getTerminalType());   
            System.out.println(telnet.getPrompt());   
            telnet.setPrompt("bash");   
            //Login into remote host.   
            telnet.login("uid", "pwd");//pass arguments (uid, pwd)   
            telnet.setPrompt("user@host");   
            telnet.waitfor("Terminal type?");   
            //Send a command to the remote host.   
            telnet.send("bash");   
            telnet.send("cd //location//");   
            System.out.println(telnet.send("ls -l"));   
            telnet.disconnect();   
        } catch (java.io.IOException e) {   
            e.printStackTrace();   
        }  

[Rob Spoor]

Is a telnet server actually running on the Unix machine? Most system administrators hate telnet because it's insecure, and therefore do not have it installed. They prefer SSH instead.

Also note that, at least as far as I know, telnet does not support file transfer. SSH does, through its SCP protocol.

[Archana Honnavalli]

Hi Rob Spoor,
I referred to your reply in the below link
http://www.coderanch.com/t/481758/sockets/java/Needs-connect-unix-box-JAVA

Similarly I am using SshWrapper class to connect.
This also uses jta26.jar.
Code mentioned below

SshWrapper ssh = new SshWrapper();
		try {
			ssh.connect("xxx.xxx.xxx.xxx", portNum);
			ssh.login("uid", "pwd");
			ssh.waitfor("$");
			ssh.send("cd //location//");
			System.out.println("PWD**********"+ssh.send("pwd"));
			System.out.println(ssh.send("ls -l"));
			ssh.disconnect();
		} catch (java.io.IOException e) {
			e.printStackTrace();
		}

I am able to connect to unix box
I am able to login also
But I am getting null at both the System.out.println lines.
Where am i going wrong?

[Archana Honnavalli]

From this link
http://javassh.org/download/source/de/mud/ssh/SshWrapper.html#read(byte[])
i understand that
Returns:
output of the command or null if no prompt is set

This i added
ssh.setPrompt("xxx@xxx");
after ssh.login command (after line 4)

Still i m getting present working directory as null in my console
and ls -l is not listing files the given location, but returning null in console.

Any idea?

[Rob Spoor]

What happens if you don't send the "cd //location//" command? Because then your example looks almost identical to the example on that page, except for the different waitfor symbol.

[Archana Honnavalli]

Tried with this.
Commented line 6 and line 8
Still getting null at line 7

Also eventually i need to access cd //location//
Because i need to access files in that directory.

SshWrapper ssh = new SshWrapper();   
        try {   
            ssh.connect("xxx.xxx.xxx.xxx", portNum);   
            ssh.login("uid", "pwd");   
            ssh.waitfor("Terminal type?");   
            //ssh.send("cd //location//");   
            System.out.println("PWD**********"+ssh.send("pwd"));   
            //System.out.println(ssh.send("ls -l"));   
            ssh.disconnect();   
        } catch (java.io.IOException e) {   
            e.printStackTrace();   
        } 

[Archana Honnavalli]

One more doubt after parsing line 4

 ssh.login("uid", "pwd");

console prints lot of information like addpayload2 1, packet len, ssh info.

This i dont see when i login from telnet window
That is cmd prompt
Give command- telnet IP
Telnet window opens and prompts for uid and pwd.
After this no such information is shown.

What is this?

P.S: New to unix

Thanks
Archana

[Eric Mission]

Archana, I've never used the SshWrapper class before so I can't comment on the error you are having but I am curious as to why you don't just use an SSH client. There are several freely available ones out there. I personally use PuTTy which has telnet, ssh and more.

I did some searching on this class and found a link to the SOURCE. I noticed that the class is using a basic socket to connect. As I mentioned before I'm not familiar with the API other than just reading the source but to me that generic socket connection may be your problem if it isn't taking permission into account. If the SshWrapper class does not account for permissions on the machine you are trying to access then that may explain why you are getting NULL when you send a command. In other words, the Unix machine may permit you to do a remote SSH connection but may forbid you from changing directories or running other commands.

I am guessing that you want to just issue a

more myfile

or a

cat myfile

to the server and you can't even change directories (remote access permission block?).


My recommendations: 1) I would try to create my own custom socket server/client application that would read the files or even transfer them locally for reading 2) use an SSH client.

Hope that helps.