How to use SSL with the digi.xbee.xsocket module?

Other & Legacy Products
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TL;DR: I am following the example at https://github.com/digidotcom/xbee-python/blob/master/examples/communication/socket/SocketTCPClientSample/SocketTCPClientSample.py to POST data to our server but cannot figure out how to use SSL with it.

I have an XBIB-U-DEV board with an embedded LTE Cat 1 cellular modem. This modem is currently connected through USB to a Raspberry Pi 3 running Kali Linux. I want to be able to run a python script on the Kali OS that will Try a requests.post to our server with a fallback from ethernet to wifi to cellular.

I was provided Digi’s SocketTCPClientSample.py example (link in TL;DR) by a colleague and have been able to adapt that to our needs with one exception: making the call over SSL. I cannot simply ssl.wrap_socket as I am using xsocket.socket per the example. Attempting to do so just reveals that an xsocket.socket is not a socket with the error of “AttributeError: ‘socket’ object has no attribute ‘getsockopt’”.

  • I do not have a static IP which limits options a bit.
  • Yes, the cellular contract is active; I can run the original example without ssl just fine.
  • When I make the POST with cellular and thus no SSL, I receive a response of 400 Bad Request with “The plain HTTP request was sent to HTTPS port” but using wifi with with the same exact payload succeeds with 200 OK.
2

I don’t know of a Python example but there is a Micro Python example at http://cms.digi.com/resources/documentation/digidocs/90002219/#reference/r_ussl.htm?Highlight=SSL

3

Unfortunately, that does not help me much as the socket I am creating is on the host system using xsocket and CellularDevice from the digi.xbee package.

Unless there is a way on the modem to upload the certs and tell it to always use ussl for all socket connections but I am not seeing how that is practical as the sockets are being created on the host system.

4

Yes, you can upload certificates to the radio and set the radio to use SSL. That is part of what that section of the document shows.

5

For anyone wanting to know what was needed for this…

Can’t believe I missed this in the docs as well (facepalm moment)…

In the SocketTCPClientSample.py, I just needed to add the protocol to the socket creation.

Instead of simply with xsocket.socket(device) as sock:…
Change to with xsocket.socket(device, IPProtocol.TCP_SSL) as sock:.