First off: the technical info you can get about these cards is *very* much limited IMHO. There's lots of cool "support" articles on their homepage, but all deal with the "end user view" and don't go into much tech details, if at all. So finding out what kind of network communication is happening and what packet goes to which network was quite impossible without trying it out myself.
So the decision was made: get one, try it and (if needed) debug it.
Thanks to Amazon's stupid marketplace rules/terms I could only get a "4GB Connect X2" version shipped to my home address - everything more up-to-date (like the Pro X2) was distributed by 3rd parties and "we cannot ship to this address" restrictions. Customer reviews also didn't provide much of an insight, other than "works gread" and "doesn't work at all" posts that are quite common.
One problem though: the EyeFi cards are SD-cards... the camera I have uses CF-cards exclusively. Bummer. Just about every post about using CF/SD "adapters" said: "doesn't work with EyeFi" - until I found this little gem here: http://www.amazon.de/gp/product/B00DVK1YT2/ - it explicitly states "works with EyeFi cards!" - so, order it along with the EyeFi card.
Received the adapter on Monday, the EyeFi card today (Thursday) and started testing right away.
First off: the software REQUIRES you to register with the online server. WTF? I do not want to upload any images to public servers at all... why should I have to register? At least they aren't asking for any personal data - e-mail address and password is all they wanted, so it's all they got... thank god for "one-time-addresses" :)
Second bummer: if the software isn't connected to the internet, the oh-so-comfy configure your card wizard will also fail dramatically. Why? Not the slightest idea. I don't have internet-access where I want to use that card... and I don't see why I have to. Oh, the support page states "you can configure the networks without internet connection" but that doesn't apply to the initial config-wizard, only to "add network" at a later time. (EDIT) What I'm slightly worried about is: are they transmitting the SSID/Key combos to their network too? Or do I net "only" to validate connectivity from the card to their server?
Third bummer: The mentioned "upload to FTP" option is available as a "share online" plugin, but it doesn't work from the card: the card uploads the images to the EyeFi image service which will forward the image to the configured FTP site - which means that you are essentially sharing FTP-Addresses, usernames and passwords with EyeFi. Great. Oh, and because of this oh-so-user-friendly configuration, I now have to push the images out onto the internet for them to return back to my local FTP server... which has to be public... ARGHS! Who comes up with such ideas???
At least the adapter worked with my camera and the EyeFi card. It required me to change the file settings in the camera to "RAW + JPEG(S)" to get the RAW files with sidecar JPGs because the EyeFi will only transfer things that look like JPG files. Newer versions should support RAW transfers but I haven't found an option for that. In my use case, I'd require "preview quality only" anyhow, so small JPGs is not a bummer for me but might for others.
Observation: When operating inside a camera, the EyeFi card doesn't seem to send out any traffic to the internet, as long as the PC that it wants to send data to is connected. I have no idea yet as of how the card "detects" that PC, given that both of them have dynamic IPs but in my test the router/firewall didn't receive any packets from the EyeFi device which means that the WiFi access point must have handled them before the firewall got involved. According to the internet however, if the EyeFi card doesn't "see" the PC, it will connect to the public eyefi network and push the image there, with the PC software downloading it again. Since this is done with HTTPS, there seems to be no easy way of blocking such traffic.
Up next: get "unofficial" support from the internet. My research found out the following interesting sites to go with the eyefi:
- https://github.com/tachang/EyeFiServer - A free, open source (Python) server that handles eye-fi uploads locally. Have to find out how to make sure the card doesn't connect to the internet still, but that's a start.
- http://hackaday.com/2009/03/15/standalone-eye-fi-upload/ - success story that involves the above server.
- http://git.sr71.net/cgi-bin/gitweb.cgi?p=eyefi-config.git;a=summary - an open configuration utility for the card.
- http://dave-hansen.blogspot.co.at/2009/10/eye-fi-releases-source-code.html - an interesting post that might lead to custom firmware for the card itself eventually... one without any hardcoded internet connections hopefully.