Interesting, thanks @Ultranomad !
Terminating unused apps doesn’t prevent the device from going online and doing spurious transfers.
The ADL product doesn’t need firewalling or proxy servers because the Iridium connection is (AIUI) set up to not be an open internet connection. So any app trying to connect won’t see anything – except their own app which will go to their own server (which may be on a fixed IP, and being on a fixed IP is more efficient because there is no DNS involved).
I think the Satsleeve is just as vulnerable to this problem as anything else where an open internet connection is provided. The Satsleeve does the same thing as the Thuraya XT phone but instead of USB it provides a WIFI access point.
The Thuraya SatSleeve-Hotspot is doing exactly what is needed. Wifi connection to your tablet and with an app, you enable to disable the connection. And if you don’t want to have spurious download, just use the way described in section 2 of this document (well for ipad!)
Has anyone discussed:
if already discussed, i would be happy for links to those threads :)
Jonas
Exactly…
Nothing on Ebay right now. I sold two 7100s on there recently, about 150 quid each. The last one went with a complete vehicle kit, car holder, antenna, etc.
This would be a nice thing with mating a satphone with a Raspberry Pi 3 – you can build a wireless access point with a very good and smart proxy server built in (run something like Squid proxy) and no one’s doing anything you don’t specifically authorize. The nice thing about a proper proxy server versus just a plain old packet inspecting firewall is that you can get much more fine grained, right down to blocking just parts of a website you don’t want to download, blocking all files of certain filetypes etc, and of course running on the access point this applies to all devices that connect to it. It could also be set up to use a parent proxy running on a server somewhere else, for instance if you need to get to a site that’s being blocked to IP addresses from certain countries.
The RPi can also do the heartbeat, and make the proxy server software emit a useful message when it fails.
The Pi can also be used to add other things by adding a software defined radio.
I’m sort of tempted to see if I can find a suitable satphone on ebay…
On the problems with tcp, while it would take significantly more hacking, with the aid of a server at home you could design something that used UDP to fetch the data instead, with an ordering/retransmit method more suitable for high latency connections, although this is now turning into more serious development.
The 7100 is RS232 and emulates a Hayes modem. The AT commands are published e.g. here [ local copy ]
The only challenge is making it hang up reliably. One has to do the ~~+++~~ATH0 stuff and drop DTR; that usually works. But really the pilot needs to have visibility of the phone’s screen, to make sure, at $1/minute
The XT phone is USB only. There may be a serial interface but it is not documented. USB drivers exist for winXP through to win8 and that’s it, AFAIK.
The other Thuraya phones (between the 710x and the XT) are crap.
The other challenge, often discussed here, is that the sat phone connection gets swamped by all the crap which modern devices send back to their Church of Apple / Church of Google / Church of Microsoft. This is very frustrating because it hits you right when you least expect it – on a flight when you need the connection but some bloody app decides to send a 5MB report to Google Cache or whatever. The ADL approach of running only to your own server (and firewalling everything else) solves that but you don’t get open internet access even if the connection was fast enough (which on Iridium it isn’t). I now have everything firewalled except 2 private wx sites and Telegram’s hopefully fixed IP.
BTW Telegram needs the XT’s speed; it won’t work usefully on the 7100.
Thuraya also do / used to do modules, which is the logical way to build any satcomms product.
There are various gotchas with Thuyaya; from memory -
Peter wrote:
I did this route here with the Thuraya 7100 phone, with a colleague under linux. 9600bits/sec, $1/minute, RS232, cheap, but strictly for computer anoraks Even the Thuraya XT phone I now use, 50000bits/sec and $6/MB flat rate, is just for anoraks and could never be sold in the context of a commercial product.
I just read that article of yours, very interesting. An approach I would consider is putting the Thuraya phone and a Raspberry Pi 3 (has built-in WiFi) together in a box and using it as a “satellite MiFi” (that’s presuming the Thuraya phone doesn’t have a weird proprietary software interface for its USB connection, or if it does, someone’s made libusb drivers for it). The Pi has enough grunt that it could not only run a firewall but a local proxy server which would give a great deal of control over what goes on with the internet connection, and will allow it to be shared with any tablet computer (e.g. an iPad running Skydemon, and allow all the features of Skydemon to be used while flying – Skydemon now has cloud/radar overlays which presumably only fetches the data it needs since the base map is already on your device).
Plus of course all the other features of the phone its connected to (ability to send text messages, or use iMessage if your tablet is an Apple device, etc. etc.)
Sure it would still be a “computer anorak” thing but I think there’s quite a few of those amongst the LAA membership, and they aren’t afraid to get their hands dirty :-)
Iridium/Thuraya also implies it has to be two-way and not a broadcast (and as such, roll-your-own with a software defined radio is out of the question). Probably for UK VFR flying, tuning into VOLMET will still be the order of the day!