Sending ngrok links via SMS to Verizon users?!

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I was publishing some funny article titles in development and wanted to share them with my partner. Naturally, I set up a ngrok link for easy sharing. I texted him the link a few times and even though my provider, t-mobile, said it sent, he never received them! He was getting all my other messages/links/etc but not the ngrok links. I've tried one other verizon user who also didn't receive my link.

Is this just a weird coincidence or does verizon block ngrok? Not seeing anything on a quick search. Note: not having an issue w/ any other mobile service providers!

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You could try sending the link via SMS through Twilio and it'll tell you in the logs if the provider blocked the message :) I wouldn't be surprised if it's blocked, since I could see spam and fraud happening using ngrok links.

 
 

Yeah I see this approach taken a lot in infosec land.

 

TL;DR
ngrok uses xxxx.ngrok.io links so that might be why they don't get past the validation checks of T-Mobile and Verizon.

FULL EXPLANATION

So weird 🤔. Only thing I could think of is that they do this for security reasons.
But their rules seem outdated..

I found this on SO: stackoverflow.com/questions/223829...

They discuss that only .com and .org seem to be able to get through T-Mobile and Verizon's SMS service. Others (like short links) get blocked.

As I'm thinking about it more and more, this might be to prevent people from getting spammed or click on links with unknown destinations...

The accepted answer in that SO link (stackoverflow.com/a/42381616) says:

I had the same issue recently. All major carriers have some basic checks in place which blocks the SMS from getting delivered if you use short links (e.g.abc.gl/1432). The SMS will get delivered as long as you have a .com in the URL (e.g. abc.gl.com/1432)

ngrok uses xxxx.ngrok.io links so that might be why they don't get past the validation checks.

//off-topic
I recently discovered ngrok to test a .Net Core backend project that uses the Fitbit API and I needed to test publish/subscribe callbacks coming back as new activity data was tracked.... In ❤️love ever since

 

I recently discovered ngrok to test a .Net Core backend project that uses the Fitbit API and I needed to test publish/subscribe callbacks coming back as new activity data was tracked.... In ❤️love ever since

Yup, perfect ngrok use case.

 

Ngrok is a thing and I didn't know about it. Now I have a new toy to play with. Thanks! :P

#TIL

 
 

Nice one! I have a new weekend project now 😝

 
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