The Photojojo Forum

EyeFi Warning: Does not work with Sprint EVDO

The EyeFi for the most part does what it says on the tin. There are certainly some enhancements that would be nice, but it's functional, and very impressive.

I hit one brick wall, however, I have a router and an EVDO modem, and the primary reason I bought the EyeFi was to be able to get images up to the net directly from the field.

I couldn't get it to work, so used the support form and got the following response:

> The Sprint Mobile broadband uses a transparent proxy and the Eye-Fi
> card does not work with proxies. Is there any other broadband
> connection that you can use other than the Sprint mobile broadband?

Now, I'm a network engineer, and the answer doesn't make a lot of sense to me. Either the proxy is transparent or it isn't. Further, I can't find any evidence of proxying going on...the IP address for the WAN interface on my router matches the IP address in my server logs, both http and ssh.

I've asked for a better explanation of what's going on, but until this gets sorted out, those of you who were hoping for truly mobile photo uploads will be disappointed.

-Zandr

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Zandr,

Let me clarify a couple of points:

First, a transparent proxy is termed transparent not because it does not modify the traffic that goes through it, but because it requires no set-up steps for the users to have their client programs "take advantage" of it. For example, while a traditional HTTP proxy would require you to go into the Preferences panel of Firefox and set the proxy parameters, a transparent proxy would capture all traffic going to remote TCP port 80 automatically and offer proxying and caching behavior inline. Providers like Sprint Mobile often put proxies into their 2.5/3G mobile broadband networks because they not only cache data, but also do active data transformations, such as JPEG scaling and quality adjustments, to make the experience of the mobile users "better" (if you doubt this, and have access to a VPN, try the following experiment: browse a site using Sprint Mobile broadband using your browser and note the quality of the images, then establish a VPN that carries all of your traffic over the same Sprint Mobile broadband connection and browse the same site again).

There are a number of compatibility issues that may or may not be taken care of correctly by these proxies. One such issue that pertains to the Eye-Fi card is whether or not the HTTP Keep-Alive header is honored properly and the outbound connection to the Eye-Fi server is maintained on the same TCP port (note that the actual TCP port number matters - the IP address will always appear the same) across a single HTTP connection because our authentication protocol depends on the various phases of the photo transfer to appear as truly a single connection.

Second, the reason you do not notice the presence of the proxy by looking at the HTTP or SSH server logs is two-fold. In the case of HTTP, you need to actually observe the port number of the connections also, not just the IP address. What you will see is that in a case where your browser would take advantage of Keep-Alive to pipeline a number of HTTP requests over a single connection to the server (which would all appear in your server logs as a single connection), with the proxy in the path each transfer will close the connection to the server and the next request will appear to come from a different TCP port (but the IP address will be the same). In the case of SSH, proxying does not apply because SSH is an encrypted proxy and no "transparent" proxy can decode the traffic to do any intelligent traffic shaping, caching, etc., so the traffic is passed unmodified. If you want, you can use a tool called tcptraceroute to verify the presence of a transparent proxy on specific TCP ports.

I hope this clarifies the situation. We may address this in a future firmware release, but for now, it is known that the Sprint Mobile broadband connections pose a proxy incompatibility issue.

Berend

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Berend,

Thank you for taking the time to shed some light on the problem. You're correct that I didn't look at port numbers, and indeed I'll fire up a sniffer to see what Sprint is actually up to.

I would be very interested in seeing a firmware release that addresses the proxy problem, as this would open up a whole range of applications for me. And I'd be happy to test pre-releases if it would help.

Thanks again,
Zandr

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A new 3G router from CradlePoint will be shipping on December 20th that has a rechargeable battery. With this router, an EyeFi card can send files over the Verizon EVDO network, without the need of a computer or even a power outlet.

Read our new article about the PHS300 and EyeFi card here:

http://www.evdoinfo.com/content/view/2206/63/

For more information about the forthcoming PHS300, check out our full review:

http://www.evdoinfo.com/content/view/2201/63/

The CradlePoint PHS300 will initially be available only through the EVDO Experts at http://3GStore.com

the EVDO Experts are at http://3GStore.com

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For what it is worth, I have the Sprint Sierra Wireless 595U and Cradlepoint 300 router and the eye-fi works perfectly with it.

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@awm:
That's really interesting. I have a Cradlepoint 150 and a Sprint/Novatel U720, and it didn't work. Cradlepoint just released an upgrade, though, so I'll test again with the new software.

I'm planning to upgrade to the 300, but that probably won't happen until after Christmas.

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