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

Nicola Pesavento

With this plugin you’ll be able to protect your WordPress login page against theft of passwords.
Colobe Security plugin allows you to use <a href="https://colobe.net/" title="Colobe" rel="nofollow ugc">Colobe Protection Service</a> in your WordPress login page, 
in order to prevent brute force attacks.
Colobe Protection Service protects your site against brute-force attacks. 
It has a dynamic list of malicious users, which is real time updated to guarantee the highest level of protection for your site.
Rather than only protecting from brute force attacks, Colobe prevents them. 
It uses its dynamic list to identify maliciuos users during the login process to block the login attempt.
To use the plugin, you need a <a href="https://colobe.net/" title="Colobe" rel="nofollow ugc">Colobe.net</a> account.
For more information, check out <a href="https://colobe.net/" title="Colobe" rel="nofollow ugc">Colobe.net</a>.

Colobe Security

With this plugin you'll be able to protect your WordPress login page against theft of passwords.

multi-login-checker vs Colobe Security