I am trying to find a solution to control the number of logins on asp.net application.
I need to install the application in the client server, and set the number of licences. e.g. only 10 users are allowed to access the app.
Every time someone tries to login I need to check how many user are logged in, compare with the total allowed then authorize that user to proceed.
I tried with Certificate, but I couldn't see where to match the number of logged in users with the max number of allowed user.
Also I would like to use the IP address as identifier, then if I open 3 browser windows, it count only one user logged.
Basically this web application will be sold by licences. We need to control the logins per computer, and not per user, and block logins if the limit of logins are reached.
Please forgive me, if i am not clear with the description.
Thanks for any help.
I would use the SessionID in the Session object as the key, I'd store that along with the UserID for the logged in user in a database or some kind of backing store. I'd use Session_End in the global.asax to remove the records above for any session expiring and also remove them in any logout function. You should find it fairly simple to count the number of active sessions you have and confirm that it's not the same user logging in again, if that's allowed.
What I would do is use the global.asax file and increment a counter in session_start and decrement on session_end.
Since the session is stored in a cookie, several sessions on the same computer only create one session.
Here is a good refrence for the global.asax file:
http://aspalliance.com/1114_Understanding_the_Globalasax_file.3
I would use the Membership.GetNumberOfUsersOnline method, if you are using the Membership API, to determine the number of active users.
I believe this number only counts the number of users you have authenticated so it is safe to use in your scenario.
Related
We have a log-in form in ASP.Net Webforms. and when user logs in we save the user id to session state.
Session["CurrentUserId"] = user.Id;
So this is how we know a user is logged in.
if(Session["CurrentUserId"] == null) Redirect("Login.aspx");
This is all we use Session for. I am storing session in DynamoDB because we have many load balanced servers. But sometimes DynamoDB gets overloaded or gives errors. So I trying to get rid of session state to avoid these errors and to simplify a login process.
So what alternatives are there? How do modern websites log people in and remember they are logged in, and timeout after x minutes?
Is there a way to use a secure cookie to just do it? And how would you expire it if user doesnt do anything for 20 minutes? It has to work over a collection of web servers.
Storing user ID in session is not necessarily bad but has to be combined with other things in order to secure the site against things like session fixation attack and CSRF (also known as "session riding"). It is also problematic in a web farm if you are using in-proc session state.
In ASP.NET web forms, the standard way to authenticate is to use forms authentication, which places an encrypted cookie ("authentication ticket") on the browser. You may also want to put the user ID somewhere in session and compare it to the authentication ticket in order to ensure they match.
if you using the standard FBA login providers?
You can get user logon ID with this:
Membership.GetUser.ProviderUserKey
And you can get user email with this:
Membership.GetUser.Email
So, the user logon id can be fetched with above.
As for session() being a bottle neck?
Well, it not all that bad - you not "updating" the session() value by doing this, so it certainly does not have to be written back each time (for a post) and also it means that a lock on session() during post backs etc. should not occur.
I would however consider one of the above two approaches, since then session() re-sets or anything else would not matter to get the user ID, or email.
As noted, this much depends on what security and authentication provider you are using here.
Consider the case of forms authentication with persistent cookies.
If the same user logged in using two different browsers or two different machines, when user logs out from one of the browser/machine, wouldn't still he be able to login from the other browser/machine?
Usually, how do web applications handle this case?
I have to agree with Srinivas for the most part. Here is my take on the subject
On Login create an HTTP Only cookie with a guid generated at login this will be your browser/computer key. Closing browser will remove cookie
Get user id
Persist in the pair in user table ex: user:a, key:12345
On subsequent requests authentication algorithm after user has been authenticated
Get the last used key in the db with current user id
Check that the cookie is present, if not then completely unauthenticate
Check that the cookie value is the same as that in the database, if not then completely unauthenticate
With this method any subsequent login will cause a required reauthentication & invalidate any other authentications. In effect forcing the user to use only 1 browser/computer
I usually do it this way : I have a session column in my user table(in database) When the user logs in I store the value Y in it.I change it to N when he logs out.Every time the user tries to log in, I check the value in the corresponding session column and if it is Y I tell the user that he is already logged in and if it is N then I allow the user to log in. But we have to be careful and set the value to N when the user logs out or closes the browser.
Forms Authentication with cookies (regardless of whether they are persistent or not) is browser session based (persistent cookie would of course work across multiple sessions of same browser (on same user account on same machine). So two browser sessions (or two different browsers or browser on two machines etc) would be treated as different scope as far forms authentication is concerned.
So user can make multiple login from different browser sessions and logout in one will not affect other. Its is up to web application whether to allow multiple concurrent logins for same user or not. For example, online banking sites would restrict to only one user session - so if user logs in from different session then earlier session is invalidated (i.e. user is logged out). One has to write custom implementation in ASP.NET to do so - typical implementation would make every user session entry into database (typically required for audit purposes anyway) - so whenever new entry is added, a check is made to see if there is any active session for same user and if yes then that session is marked inactive. Every request would check if current user session is active or not, if not then it would flag such message to user.
I've made an asp.net site, which uses Session objects to store information for each logged in user. To check if a user is still logged in, I check if a certain object exists in the Session.
The system used Jasig CAS authentication, and the single sign on part works (as in: after the log in, the Session object of the user is set up correctly).
CAS also supports single sign out. The way this happens is that CAS calls a url on my site, with some parameters about the CAS session.
What I need to do now, is invalidate all Session objects for the specified user.
How can I, from a page on my site, invalid the Session object of a random other user? Is there a db I can clear, is it all in memory (I can look at web.config if I know what to look for)?
I've seen this question asked before, and most answers are "keep a global variable next to the Session global variable, and check that one too to see if the user should be logged out or not", but I don't like that solution...
Cheers!
The session is by design private to individual users. Therefore to abandon it, it has to be done by the user.
So you might have to use another a list & check that.
Ideally though, you shouldn't tie your authentication state to the session. Whether the user is authenticated or not should be independent. You can then choose to abandon the session by querying the authentication state. It also makes it easier to implement mechanisms like counting logged in users & ensuring login from only 1 location - should you require these.
The Setup:
Account controller with the typical logon / logoff stuff that comes baked in from the template. Not much modification here on the logon page. Using a custom membership provider (SQL), but I don't think that is impacting what I am trying to do here.
The Requirements:
The client wants to handle licensing by limiting concurrent users and not by total users. So, after referencing this post here, I set out to make this work for what I need to do. And that is to track maximum and current users for each organization that has signed up for our application. No problem, just have an application("max") and application ("current") which are both hashtables with the key being the organization id and the value being current or max users for the organization. On Session_Start, I would increment the current users, check if it exceeds max and either a) redirect to an error page or b) let them go on with what they need to do. On Session_End, I would decrement the count.
The Problem:
When using formsService.signIn, what is actually stored in session? I cannot seem to gather any information about my session in the session_start except for the session ID. So, I cannot increment the correct number for user tracking. And I cannot add a variable to session as session_start will have already fired before I get the opportunity.
The notion that session is somehow connected with authentication is a myth. They are entirely independent of each other. Session can even be shared between multiple users if they happen to share their session key; that's why you never put security-sensitive info in session. Session can also expire while you're logged in. Likewise, your session is still active after logout unless you explicitly abandon it.
Session is more like a user-specific cache.
So you need to accept this fact and adapt to it. Look and see if the current user is authenticated during session start. You'll need to increment during logon as well, since the session will have already started. Etc.
I am trying to find out in my asp.net application the users that are currently logged in the application by searching on the session info. Currently, I am only able to see my current session, but I cannot find out if there are other users using it. Is there a way to see if there are other users using the application by looking at the session information
Session state is per user - Application state (global) seems to be what you're looking for.
There are 2 hashes Session and Application, in which you can store key-value pairs.
A way to do it would be to update Application[UserNamesList] whenever there is a successful login. This would then be visible to all users. Application state would however be lost whenever the App Web Server recycles or restarts... but that shouldn't be a problem in this case.
A session is supposed to only give you information about the currently logged-in user.
If you need to keep track of all logged-in users, you could consider writing the users into a global variable. Here is info on how that works. Note that sessions expire. You would have to write, for each user, the time the user was last seen (i.e. each time they hit a new page, update their record). When the time they were last seen is greater than your session timeout, it's safe to assume they are no longer logged in and you can remove them from the list of current users. If they just up and close their browser, you will not be alerted and you will still think they are logged in even though they are not.