[Yanel-dev] User login - prevent the same user from logging on twice

[Bruno von Rotz]

For some implementations it's important that the same user can't log on 
to the system twice.
For example if there's a subscription based revenue model you don't want 
to have the same user create two sessions using different computers 
(cookies).
I see different ways to prevent this or to monitor this:
a) through the login we can detect whether the same credentials have 
been used by different computers (cookies) at the same time. Then we can 
manually or automatically decide to lock the user or to not allow him to 
log on again
b) we can detect at log on time whether the same user is already logged 
on. I am not sure whether we actually know whether a specific user is 
already logged on. But we could store additional information to make 
sure we CAN know
c) we could also have a "flag" per user to say whether multi-login is 
allowed, as for some purposes, i.e. testing, it's practical to be able 
to use the same user many times
There may be more possibilities.
What is the best way to go depends on what and how it is already 
implemented in Yanel.
Bruno

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