Secure FTPJAVA StyleBY RICH HELTON

(SUN CERTIFIED (SC) JAVA PROGRAMMER, SC JAVA DEVELOPER, SC ENTERPRISE ARCHITECT)

January 2010

Secure Java FTP(Java Style)

JFtp– Java Network Browser

The program can be found at http://j-ftp.sourceforge.net/ The source code can be found at

http://sourceforge.net/projects/j-ftp/files/.

Benefits of JFtp

Can run the Java code from the browser through “Web Start”.

Can download the JAR file and run it locally.Cross Platform. Runs easily on Mac OSX, Linux,

Windows, etc.Runs multiple protocols, SFTP, SMB, NFS, HTTP, and

various transfer protocols.Open Source so the code can be used to execute batch

jobs.Free to use.

To Launch or Download

JFtp can be run directly from the browser or downloaded.

To Launch

Clicking on “Launch via Java Web Start” will launch the JFtp from the browser.

Java must be able to run from the local Browser. If so a Security Warning will pop up:

To Launch

After clicking the “Run” button. JFtp Starts:

To Launch

Clicking on File->Connect to SFTP Server…..SFTP Configuration Starts:

Matching

When configuring SFTP, the ports, encryption, and authentication must match the server configuration for handshaking.

The source for the dialog box can be found at http://kickjava.com/src/net/sf/jftp/gui/hostchooser/SftpHostChooser.java.htm

Testing

One method to test locally is to pull down OpenSSH on a test machine.

OpenSSH can be found at http://www.openssh.com/ .Using OpenSSH, users and groups can be created using: C:\Program Files\OpenSSH\bin>mkpasswd -l -u RichH >> ..\etc\passwd

C:\Program Files\OpenSSH\bin>mkgroup -l >> ..\etc\group

Starting open SSH is done with:

Verify it is started:

Testing

Let’s connect through SFTP:

If Successful, the log window will tell you:

Testing SSH

Let’s connect SSH through Tools->SSH Shell…:

If Successful, the SSH Shell will appear:

JAR File

Instead of running from the “Web Start”, a JAR file can be used to run it using the “java –jar jtp.jar” command.

If Java is configured correctly, the JFtp will run in a Java Console that works like the “Web Start” version.

Some information about the GUI may be displayed:

Compiling Java

Compiling at the JFtp Code

The source code can be found at http://sourceforge.net/projects/j-ftp/files/.

Unzip the source, cd to j-ftp and ensure that the build.xml file is present:

Build.xml is the build file, similar to a “make” file for “C”, that Apache Ant will use to build and deploy the files.

ANT

Ant is a Java library and command-line tool. Ant's mission is to drive processes described in build files as targets and extension points dependent upon each other. The main known usage of Ant is the build of Java applications.

It can be found http://ant.apache.org/

Building

After installing Ant, run it in the build.xml directory:

Running

The build will create a jtfp.jar file in the builds/jars directory.

This file can be run with the “java –jar jftp.jar” command.

Editing JFTP

Looking at the JFtp Code

The review Java Code, I usually use Jedit, because it is a simpler editor, found at http://www.jedit.org/ .

Eclipse is also one of the most Java Editor, found at http://www.eclipse.org/ . More information can be found at http://en.wikipedia.org/wiki/Eclipse_ide .

These editors are Open Source with any plugins for coding.

The main file will be found at “src\java\net\sf\jftp\JFtp.java”.

Notice that the “package” name is “net.sf.jftp” which will define where the file has to live as well, as will as where the files will be placed in the JAR.

Looking at the JFtp Code

Jedit on JFtp.java:

Looking at the JFtp Code

To get UML diagrams of the code, ArgoUML can be used to parse the code to display the diagrams.

ArgoUML is an Open Source UML Modeler found at http://argouml.tigris.org/ .

UML

The Unified Modeling Language (UML) is used to visualize the software and how it works in a standardized blueprint. An example Use case:

ArgoUML

Javadocs

Javadocs is a document generating tool that is part of Java that generates HTML files describing the Java code. Referenced from http://en.wikipedia.org/wiki/Javadocs .

This is a way to self document the code. Inserting macros and comments in the code will create an HTML browse able view of the code:

Free Samples, as always

JFtp provides free sample code if you don’t want to use the GUI.

Under the doc directory, FTPDownload.java provides a download examples, and FTPUpload.java provides a upload example.

The “Web Start” code can also be found in this directory in the code “jftp.jnlp”

Information on the Java Network Launching Protocol can be found at http://en.wikipedia.org/wiki/.jnlp .

Compiling FtpDownload

Make sure that the jftp.jar is in the classpath and compile the FtpDownload.java.

JFtp Libraries

JFtp makes use of 2 different Java Libraries

JFtp uses a library for Jcraft’s “jsch” library, which is their Java Secure Shell, when the “Use JSch instead of j2ssh” is selected:

JSch

The JSch package is found at http://www.jcraft.com/jsch/Otherwise the standard j2ssh library is used found at

http://sourceforge.net/projects/sshtools/ .Both libraries support the Secure Copy Protocol (SCP) for

copying files through SSH.JFtp creates wrappers in its net.sf.jtp.net.wrappers for use

of such classes as SftpConnection, NfsConnection, HttpTransfer, Sftp2Connection, etc. that does the connection, downloading, uploading, change directory, remove directory and other work.

JSch

The JSch package is found at http://www.jcraft.com/jsch/Otherwise the standard j2ssh library is used found at

http://sourceforge.net/projects/sshtools/ .Both libraries support the Secure Copy Protocol (SCP) for

copying files through SSH.JFtp creates wrappers in its net.sf.jtp.net.wrappers for use

of such classes as SftpConnection, NfsConnection, HttpTransfer, Sftp2Connection, etc. that does the connection, downloading, uploading, change directory, remove directory and other work.

Sftp2Connection Class

One of the wrapper classes that uses the Jsch library is the Sftp2Connection class.

This class has functionality for login, setLocalPath, upload, download, and more.

Sftp2Connection upload snippet

public static void main(String[] args) {

String username = "RichH";

String password = ”password";

Sftp2Connection conn = new Sftp2Connection("localhost", ""+22, null);

conn.login(username,password);

System.out.println("PWD:" +conn.getPWD());

System.out.println("Local Path:"+conn.getLocalPath());

conn.setLocalPath("/jars");

System.out.println("Local Path:"+conn.getLocalPath());

conn.upload("jftp.jar");

conn.disconnect();

}

Sftp2Connection Upload snippet

The code snippet will create a secure connection for the Sftp2Connection class.

Then the login( ) function will authenticate using the username and password.

The Local directory will be the root directory as well as the remote directory, so the local directory is changed to “C:\jars”.

This directory contains “C:\jars\jftp.jar” that is uploaded with the upload ( ) function.

If there is any error along the way, an exception will happen pointing at the stack where the error code appeared.

Sftp2Connection Upload snippet

Running through JFtp manually, you can observe if the file is uploaded:

Conclusion

There are many Open Source Solutions

Users are no longer dependent on the survival of the software vendor.

Users can continue to develop and change the core of the acquired software.

Users can benefit from successful developments by others who have used or developed the software.

Open standards, such as XML are used for data exchange. The standards are open and not proprietary.