Public Service Announcement: Server Name Indication (SNI)

Server Name Indication, or SNI, is an extension to the TLS protocol. It’s function, in plain English, is to allow a browser to tell a web serverwhich website it’s coming to see before starting the SSL connection. The browser then knows which SSL credentials to send back to the browser and an SSL connection can be established.

SNI is supported by all modern browsers. In fact, it’s even supported by a ton of positively ancient browsers. It’s not, however, supported by any version of Internet Explorer on Windows XP.


If you see an error like the one below, and you are using Internet Explorer on Windows XP, please, take it seriously. Don’t click through. But DO get a REAL browser, like Firefox or Chrome and use that instead, for everything you do .
Internet Explorer 8 SSL Certificate Warning


You should ideally upgrade to a newer version of Windows if you’re still on XP. You’re not getting any patches. You will get hacked. It’s not a question of if. It’s not even a question of when. You probably already have been. But I know that’s not feasible for everyone.

A couple of stats for you. Only 5.29% of the entire internet is still using IE8. IE7 holds their impressive 0.17%, and IE6 is actually 0.3%. All together, those three make up 5.76% of the internet.

The take home from all of this?

The rest of the world has moved on, and you should too.

Use Firefox or Chrome. Just do it.


This was a technology-related rant post I made on Google+. I’m copying it to this blog, mostly so I have an easy-to-read record. This one was originally published on 25 June 2014: Public Service Announcement: Server Name Indication (SNI)

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