I don't know if they inject ads, but they have the capability to do it. When I connect to an "xfinitywifi" SSID, the first HTTP page load I do will have a little "You're using XFINITY Wi-Fi. Isn't it totally awesomesauce?!"-style pop-up appear for a few seconds in the lower right corner of the browser window.

Yes, I have seen this too. They put a modal over an HTML document with a Comcast-sold IAB ad.

> Doesn't the xfinitiwifi inject ads MITM-style?

No.

I feel like this post should be longer, but I can't think else to say. The answer to your question is: No.

Well your post seems to be at odds with sibling comments. What is your source of information?

HN advice: when you feel you are right and every one else is wrong, please please quote a source.

Well I definitively saw unnatural HTML content overlays in the browser, and the only explanation I can think of is that the wifi hotspot MITM-injected javascript either in .html or .js files as they were downloaded to insert these overlays. Would love to see this proved wrong though :)

Yes it does, I've used it and it 100% does.