storyday

force user login into wordpress only from one browser at the same time 
the last login action will kick out the already logged user 
this is a security plugin for wordpress,install this plugin to avoid simultaneously login

multi-login-checker

force user login into wordpress only from one browser at the same time

Julio Potier

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PLEASE CHECK YOUR EMAIL SETTINGS IN YOUR PROFILE BEFORE LOGOUT THE FIRST TIME AND WAIT FOR THE MAIL CONTAINING THE SECURE CARD. THANK YOU –
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A new field is added below the password one.
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<li>It requires a new code, this code is on a “MSL Secure Card” (png or html table).</li>
<li>This card contains 64 codes, each code contains 4 chars. You have to print it!</li>
<li>Now when someone wants to log on any account, even if he knows the password, he can not use it without the code.</li>
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This kind of authentication is called “Strong Authentication”, strong authentication is associated with at least two-factor authentication. 
Your usual password is the first and only factor, this plugin adds an external factor : a MSL Secure Card. 
Now, you have 2 secure factors to log in.
When someone wants to log in any account, he has to fill the username, password and now a “MSL Code” field. 
This code is printed on a card (you have to print it) and contains a code from A1 to H8. 
Without this code, he can not log in!
The codes are not stored in your DB, all codes are hashed like your password is. So, the codes are as secure as your password is.
Every blog which needs to improve its login’s security needs this plugin.

More Secure Login

This is a strong authentication plugin. You have to fill a second field, kind of password but this one comes from a printed card you own (FR/EN).

multi-login-checker vs More Secure Login