Implementing remember me functionality – part 1

It’s quite common requirement to have long running sessions within OpenAM, so I’m going to try to enumerate the different ways to achieve “persistent” sessions and provide some comparison.
There is two main way to achieve long running sessions:

  • Using built-in functionality
  • Implementing custom authentication module + post processing class

Today we are only going to deal with the built-in persistent cookie features, the next article will describe the more user-specific solution.

Setting Expires attribute on session cookie

By default OpenAM issues session cookies without Expires attribute, meaning the cookie is only stored until the browser is stopped/restarted. This solution is especially handy if you have large session timeout values set, because in any other cases your session cookie would be saved in the browser for a good while, but the underlying session could have already time out.
Now there are two ways to enable this mode:

  • Enable persistent cookies globally for all sessions:
    Go to Configuration -> Servers and Sites -> Default Server Config -> Advanced tab, then add the following properties:

    openam.session.persist_am_cookie=true
    com.iplanet.am.cookie.timeToLive=100
    
  • After doing so you will probably need to restart the container for the changes to take effect. Any new sessions created afterwards will set the Expires attribute on the session cookie.
    When using DAS you need to set these properties in the DAS configuration file instead.

  • Allow to have persistent sessions on-demand:
    Go to Configuration -> Servers and Sites -> Default Server Config -> Advanced tab, then add the following properties:

    openam.session.allow_persist_am_cookie=true
    com.iplanet.am.cookie.timeToLive=100
    

    In this case to get a persistent cookie you need to include the openam.session.persist_am_cookie=true parameter on the Login URL (so you can’t actually put this on the Login form unfortunately)

  • When using DAS you need to set these properties in the DAS configuration file instead.

NOTE: the timeToLive value is in minutes.
NOTE 2: these properties only fully work on the core servers if you have OPENAM-1280 integrated, but if you use DAS these should work just fine.
NOTE 3: the timeToLive value only tells how long the cookie should be stored by the browser, it has absolutely NO influence to the actual session timeout intervals.

Creating a long living non-session cookie

When using this option OpenAM will create a second “DProPCookie” cookie next to the iPlanetDirectoryPro cookie with an encrypted content. This encrypted cookie stores a set of informations that are necessary to “recreate” a session when a user goes to OpenAM without a valid session cookie, but with a valid persistent cookie. OpenAM then decrypts the cookie and based on the stored information, it will create a new session.
In order to enable this persistent cookie mode you need to go to Access Control -> realm -> Authentication -> All Core Settings page and do the followings:

  • Enable the “Persistent Cookie Mode” option
  • Set “Persistent Cookie Maximum Time” option

After this when you include the “iPSPCookie=Yes” parameter on the login URL, or you have an actual checkbox on your Login.jsp submitting the exact same parameter during login, OpenAM will issue the DProPCookie persistent cookie with the configured timeout.
This method does not seem to be implemented for DAS.
NOTE: OpenAM will delete the persistent cookie as well, when the user logs out.
NOTE 2: due to a possible bug (OPENAM-1777) OpenAM may not invoke Post Authentication Processing classes when it recreates the user session.

Conclusion

As you probably noticed, the Expires on session cookie method is only really useful when you have large timeouts, also it is a global option, meaning that once you enable it, it will be set for all the different realms.
On the other hand DProPCookie is configurable per realm, but it does not seem to work when using DAS.

That’s all folks, this is how the built-in persistent cookies work, if these do not seem to match your requirements, then stay tuned for the next post.

One comment

  1. At our company, we did our own remember-me implementation, using a post-authentication handler to set a custom cookie and a custom login module to read the cookie and automatically log the user in.
    Furthermore, this allows us to force a normal login for administrative sessions. The user is also able to see a list of remember-me sessions from different devices and close them himself (a logout only closes the current session).

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