I'm looking for some client/server-based software that does the following:
On computer A the server part of the software runs as a service/daemon.
On computer B i execute the client program, for example, "sendcommandclient [command to execute on server computer]". Computer B sends the command to computer A, which executes it.
Does something like this exist?
To complicate things, it needs to be cross-platform, with Windows-based server part and linux client.

OpenSSH: http://www.openssh.com/

Is that possible with openssh? I use openssh between linux computers, but need to login first.
I have a Tellstick (http://www.telldus.com/products/tellstick) to control lighting at home. I used to have it connected to my desktop computer and used the provided tdtool command together with a keyboard shortcut to control receiver (for example Windows-key + F2 to turn receiver 2 on).
For various reasons i now want to have the Tellstick connected to my Windows-based server, but still want to be able to control it with keyboard shortcuts from my desktop computer (or laptop).

Please describe that further, I am not quite getting it:
1. Is tdtool a Windows or a Linux program?
2. Is it a GUI or a CLI tool?
3. Dou you use keyboard combinations to launch the command with specific parameters or do you use them after the tool started to control it?

tdtool is a CLI program to control the tellstick. I think all third-party software available for the Tellstick calls it. For example, to turn on receiver 4 you enter "tdtool --on 4". Every receiver is stored in a config file. tdtool is available both for Windows and Linux. So yes, i use keyboard combinations to launch the command with parameters.

Then SSH should do the job. Install a SSH server on your Windows machine and enable key-based authorization, so that you don't have to use passwords. Then set up keyboard combinations on the Linux machine to launch the tool like this:

After a few hours on Google i managed to get it to work. Running freesshd on the server. Had some problems getting the keys to work.
Works a treat now! Thanks for the help!

Nice that it works for you. Please mark this thread as solved using the thread tools at the top of the thread.

Moved: This thread is more suitable in the Software forum and has been moved accordingly so you can mark it solved (doesn't work in the General forum).