logging in twice with one user account

Is there a way to prevent one user-account from logging in twice on the
same system when using sessions?

I also put the session of a user in a mysql database :

CREATE TABLE `login_sessions` (
`login_id` int(10) unsigned NOT NULL auto_increment,
`login_session_id` varchar(32) NOT NULL default '',
`login_user_id` int(10) unsigned NOT NULL default '0',
`login_date` int(14) unsigned NOT NULL default '0',
PRIMARY KEY (`login_id`)
) ENGINE=MyISAM AUTO_INCREMENT=154 DEFAULT CHARSET=utf8
AUTO_INCREMENT=154 ;

I can check whether the user_id is already in the database, but what if
the user doesn't log out properly?

Any tips, or links to articles about this?

Thanks!

gehegerade...@gmail.com wrote:
> Is there a way to prevent one user-account from logging in twice on the
> same system when using sessions?
>
[snip]
>
> Any tips, or links to articles about this?
>
> Thanks!

You could have a 'last activity' timestamp in there (you have to do a
lot of updating on your session tracking DB, such as for every DB
access) and then if it has been a while since lass activity, grant
access.

Or you could just put up an "already logged in" mesage with a reminder
to log out properly the next time (BOFH solution)

gehegeradeaus@gmail.com schreef:
> Is there a way to prevent one user-account from logging in twice on the
> same system when using sessions?
>
> I also put the session of a user in a mysql database :
>
> CREATE TABLE `login_sessions` (
> `login_id` int(10) unsigned NOT NULL auto_increment,
> `login_session_id` varchar(32) NOT NULL default '',
> `login_user_id` int(10) unsigned NOT NULL default '0',
> `login_date` int(14) unsigned NOT NULL default '0',
> PRIMARY KEY (`login_id`)
> ) ENGINE=MyISAM AUTO_INCREMENT=154 DEFAULT CHARSET=utf8
> AUTO_INCREMENT=154 ;
>
> I can check whether the user_id is already in the database, but what if
> the user doesn't log out properly?

- Add a 'loginnumber' column to each user.
- Every time the user logs in you increment the loginnumber by one and
store it in the users session
- On every page request you verify if the loginnumber in the session is
still the persisted one

-> advantage: the previous 'loginnumber' will expire as soon as the user
logs in again. No need to think about expiring older sessions...

-> disadvantage: you have to verify the loginnumber on each page request
(but if you're going to keep track of the 'last requested' page you have
to do this too...)


--
Tim Van Wassenhove <url:http://www.timvw.be/>

Tim Van Wassenhove schreef:

> gehegeradeaus@gmail.com schreef:
> > Is there a way to prevent one user-account from logging in twice on the
> > same system when using sessions?
> >
> > I also put the session of a user in a mysql database :
> >
> > CREATE TABLE `login_sessions` (
> > `login_id` int(10) unsigned NOT NULL auto_increment,
> > `login_session_id` varchar(32) NOT NULL default '',
> > `login_user_id` int(10) unsigned NOT NULL default '0',
> > `login_date` int(14) unsigned NOT NULL default '0',
> > PRIMARY KEY (`login_id`)
> > ) ENGINE=MyISAM AUTO_INCREMENT=154 DEFAULT CHARSET=utf8
> > AUTO_INCREMENT=154 ;
> >
> > I can check whether the user_id is already in the database, but what if
> > the user doesn't log out properly?
>
> - Add a 'loginnumber' column to each user.
> - Every time the user logs in you increment the loginnumber by one and
> store it in the users session
> - On every page request you verify if the loginnumber in the session is
> still the persisted one
>
> -> advantage: the previous 'loginnumber' will expire as soon as the user
> logs in again. No need to think about expiring older sessions...
>
> -> disadvantage: you have to verify the loginnumber on each page request
> (but if you're going to keep track of the 'last requested' page you have
> to do this too...)
>
>
> --
> Tim Van Wassenhove <url:http://www.timvw.be/>

Thanks,

but I think the opposite will happen : the new user will be logged in,
and the existing session will be ended... What I want is to prevent the
new user (with the same user-account) to log-in to the system...