
Ask HN: How to recognize web logins from new devices? - scrpn
For my project I want to notify the users by email in case there is a new login from a new device i.e. web browser. How are Google&#x2F;Twitter&#x2F;Facebook doing this? Is there a technical article describing this?
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phillipseamore
What I've done in the past is to have an identifier in a cookie or
localStorage that isn't cleared on logout. A new device would be one that
doesn't have that identifier.

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scrpn
what you put in that cookie and how did you matched on server side? could you
share some pointers?

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phillipseamore
For something really basic a simple hash like "username+my_secret" does the
trick and is easy to check with nothing stored on the server side. I however
have always created a uuid for each new device login and store in DB so the
user can see a list of all devices used to login.

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scrpn
sounds good!

