Using *.ppk to connect SSH (Run command line) over Java

Question

I'm writing java swing app. I need my app connect to server CentOS 5.5, using username + *.ppk file (I don't have password). Then, my app execute some command line on this server.

Is this possible ? What library is best for it ?

Answer 1

There is a number of libraries that support what you're trying to achieve in different ways. Connecting to an SSH server via Java is no big thing anymore these days.

Those are some libraries that you might consider:

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Ganymede

• http://www.cleondris.ch/opensource/ssh2/

Ganymede was made by some students at the ETH Zurich and works quite well. I personally use it in a project that runs on a very old machine using Java 1.3. It doesn't require anything besides a JRE. It is, however, not very active anymore. There is that company that seems to support it (Cleondris), but I wouldn't know how reliable they are. Doesn't matter much though since it's open source anyways. If you need to run your app on old java versions or need to know, that your app runs withou the Java Cryptography Extension (JCE), you could chose this.

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JSch

• http://sourceforge.net/projects/jsch/

JSch too is a mature piece of software and just works. If you've ever used ant to do SSH/SCP related tasks, you probably know it already. It's always a bother since you have to provide it to ant manually :-) The project is well maintained, as it seems and widely used. I used it in a lot of modern UI/Batch applications and was/am always happy with it. It does use JCE though and I did once experience problems with that (on an older JRE, but still). If you plan to distribute your software to clients unknown to you, this might be a problem. JCE needs stuff installed / configured inside the JRE installation itself. Probably works 99% of the time, but still...

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SSHTools

• http://sshtools.sourceforge.net/

Never used this one but heard good things. May be worth a try.

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Converting ppk to OpenSSH format using Java

As this is obviously possible, it's only a matter of implementing it. Fortunately for you, there are actually multiple implementations around. It might even be implemented in one of the suggested SSH libraries, but I didn't check.

A quick google search revealed two choices to me:

trilead-putty-extension

• https://github.com/kohsuke/trilead-putty-extension

Seems to me like a very nice choice. Even though it's an extension to Trilead SSH library (which, it seems, isn't available anymore), it's not a lot of code and could easily be integrated into an existing project. There is one class that does the work and can convert a ppk key into a openssh one. String to string, so no surprises there. Should really be a piece of cake.

I don't know what happend to Trilead. The company doesn't mention it anymore on their website, but it certrainly existed at some point (http://techtavern.wordpress.com/2008/11/13/about-trilead-ssh-open-source-project/).

By the way: The guy who wrote it is the one who also wrote Jenkins/Hudson. http://kohsuke.org/

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"ChillKat" Java Library

• http://www.example-code.com/java/ssh_ppk_to_pem.aspn

Well... this just as an alternative. Doesn't seem worth the effort and overhead to download a "multi-purpose" library just for that. You could maybe extract the relevant parts or let yourself be inspired by it. Maybe the trilead extension doesn't work and you have to pick this one, but I wouldn't consider it first choice.

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You can of course always convert the .ppk file manually, as explained here: http://www.lmolnar.com/geek/how-to-convert-puttys-private-key-ppk-into-opensshs-private-key-format-in-linux/

And other places, I guess. There is the graphical tool puttygen too, which is included in putty-installer or downloadable standalone via the putty website (http://www.chiark.greenend.org.uk/~sgtatham/putty/).

Would you like to know more?

Check this: http://linuxmafia.com/ssh/java.html or write a comment.

Answer 2

If converting the .ppk to a less proprietary format (ie .pub rsa or dsa) is an option, then give a try toputtygen (usage: "puttygen keyfile.ppk -o id_rsa -O private-openssh") from the putty-tools package.
Then use SSHTools , a java API for SSH (and more)

Answer 3

One of options is to use SSHBlackbox package of our SecureBlackbox product. It supports loading of Putty keys and full scope of SSH-related functionality (SFTP requires SFTPBlackbox package). SecureBlackbox comes with extensive samples and support.

Answer 4

当前的 JSch 版本不支持 *.ppk 文件，但 JSch 可以通过 Putty 的 Pageant 使用jsch-agent-proxy来使用这些文件。

Answer 5

1. Install and open puttygen
2. Click on "Load an existing private key file"
3. Click on menu item "Conversions" -> "Export OpenSSH key"
4. Save file, and use this in your Java app