Products.NoDuplicateLogin 1.0a1

Products.NoDuplicateLogin

This PAS plugin will reject multiple logins with the same user at the same time. It ensures that only one browser may be logged with the same userid at one time.

Implementation

The implementation works like this: Suppose that Anna and Karl are two people who share a login annaandkarl in our site. Anna logs in, authenticating for the first time. We generate a cookie with a unique id for Anna and remember the id ourselves. For every subsequent authentication (i.e. for every request), we will make sure that Anna’s browser has the cookie.

Now Karl decides to log in into the site with the same login annaandkarl, the one that Anna uses to surf the site right now. The plugin sees that Karl’s browser doesn’t have our cookie yet, so it generates one with a unique id for Karl’s browser, remembers it and forgets about Anna’s cookie.

What happens when Anna clicks on a link on the site? The plugin sees that Anna has our cookie but that it differs from the cookie value that it remembered (Karl’s browser has that cookie value). Anna is logged out but the plugin and sees the message “Someone else logged in under your name”.

Note

Because this implementation stores its mappings in the ZODB on attributes of the plugin itself, there may be issues with scaling.

Installation

Add Products.NoDuplicateLogin to the eggs parameter of your plone.recipe.zope2instance section:

[plone]
recipe = plone.recipe.zope2instance
eggs =
    Plone
    ...
    Products.NoDuplicateLogin

Now run buildout and restart Plone.

History

1.0a1 (12/17/2010)

• Add test harness [aclark]

• Rip out “experimental” session storage, too many ZODB conflicts. [aclark]

• Plone 4 compat [aclark]

• Re-package as egg [aclark]

1.0 svn/dev

• Plone 3 compat [perrito]

• Original implementation [nouri]