File synchronization between several different computers

Hi guys,

I would like to ask you one question. Imagine there are several computers, all running different OS (say, windows, mac and Linux). I have one single bunch of my data, which I want to keep synchronized on all of these computers. I'm working periodically on all computers, each time changing my data. I want the changes I make to happen immediately (or almost immediately) on other computers.

Question: Is it possible to do so?

The complications:

• The data are large, ~ 100 GB (but the changes are small, so not much to copy at once
• All computers has dynamic IP, One of them is a notebook, so may be connected in hotel, cafe or airport.
• I have no central server, where I can keep the data and access to them from outside.
• The solution must be free, open-source and if possible secure.

What I've tried:

• Ubuntu One will not help - just not enough space even for paid version. And as I understand, It can't do synchronization between computers, not having the copy on Ubuntu servers
• Other commercial services has similar limitations.
• p2p solution - i've found only Tonido, but it has no x86-64 version, so I can't use it.
• Usual synchronization software doesn't work when you have dynamic ip (of course, I can figure out some crazy way to send IP by e-mail and so on, but it is not very elegant solution)

Thank you very much in advance for help

Dropbox works great http://www.dropbox.com/pricing Win/Mac/Linux/Mobile/Web Might be worth paying for in your case

Thank you very much for suggestion. However, I've tried Dropbox, and it has a number of limitations: It stores my data on its own server, and the space is limited. Even paid version don't solve this problem.

I was thinking about something like "personal torrent", where my shared data are limited only with size of my hard drives.

This may be promising http://sparkleshare.org/ Linux only for now though

Another solution unison might be worth a look, might need some work though http://old.masker.net/2008/02/synchronize-a-folder-across-machines-over-the-internet-mac-pc-whatever