I'm currently planning my web application. I was thinking using Session to store user profile (user name, current database, permissions, etc...). Common scenario is where user opens several tabs for different pages.
Now, I need to have an option for user to change the database. Basically needs to choose the database from list, enter a log in information and it's done. Not sure how to handle this. It seems that browser tab where user initiated the change should somehow tell server that he needs a new session here or server has to inform browser that new session is generated?
Basically if user has 4 tabs open and initiates a database change on one tab then he should end up with two sessions? Is this correct or is there a better way to handle this?
As far as I am getting your problem, one thing can be done that whenever the user selects a new database and enters the log-in information then on selecting the new database, you need to clear out the old session details for the database and on entering the new session for login information, override the login details.
Also, store the old information into another session and whenever a conflict occurs you can navigate to the error page saying that "Login information and databse have been changed" or any custom message.
Only work around needs to be thought of for this scenario as in same browser the session value will be same throughout.
Related
I have built an ASP.Net MVC site using Forms Authentication for a client.
Recently, they have requested that an authenticated user be restricted to a single browser session. That is, if the user raises a new browser instance, or opens a new tab on the original browser window, that he/she be logged out of the original. They insist on the added security.
Does anyone know how I might approach this? Thanks in advance.
Personally, I would push back and ask exactly what security this is bringing. Maintaining state like this counter to web architecture and is only going to bring you and your users grief.
Here is what I would do if presented with this problem:
Store the username of the user in your database (i.e. LoggedOn table).
When a user logs on, check to see if their username is already present in the LoggedOn table.
If the user isn't already logged on, insert a row into the table with the username and the current time; otherwise present the user with a message informing them that they can only log into the system from one device at a time.
Include logic to expire and delete the rows in the table if a user's session expires or if the user logs out.
First a disclaimer: I'm no expert in web programming.
Perhaps you might try a system where every user interaction requires the submission of a random value that's been generated for that page (much like what's used for CSRF protection.) That key could be kept under the user's session information on the server, and if a page is ever requested without the correct key as a URL parameter, the session is invalidated. The URL from one browser won't work in another, either, since once a URL is gone to, the user's session key has changed. The only way for a user to transfer a session between tabs would be to copy the URL of an unclicked link and paste it in a new tab's address bar. Switching browsers would be even more complex assuming that ASP.Net uses a session cookie: the user would have to transfer the cookie from one browser to another. Going back would also fail, as all the links on the previous page, and the URL for the page, would carry an incorrect session key.
Also, for reference, I believe the US Gov't TreasuryDirect site works in the way you've described, though I've never looked at how they manage it.
Thanks, people for the suggestions. Each had strong merits, however I had to take a hybrid approach. I found an incredibly simple suggestion from this post.
I implemented table of active users as Karl suggested as well. This will give the client the ability of deactivating the user on demand.
Thanks again.
Think of it as one active view at a time instead of one browser or tab. Or convince the customer to view it this way.
You can always issue a unique cookie for the browser session (ASP.NET Session) and allow communication to the latest cookie issued effectively making only one session active at a time, and therefore rendering other open sessions (browsers, tabs, etc) useless with the app by disallowing them communication any longer or serving up an error page for them. To do so you have to recognize who the user is and authenticate them against your app. This is half the puzzle and will force the user down to use your app in only a single browser at a time on their machine.
The other part of the problem is to pare down the windows and tabs that are part of the same browsing session of that browser, to allow only one view to be active at a time. To do so you can issue a unique sequential ID to the viewstate of each page for postback to the server to uniquely identify that page apart from other pages sharing the same session state (whether that page be in a browser tab, a frame or new window, etc). Or a code of your choice that's traceable. You then know which page is posting back within the session and can disallow others or deactivate previous ones by, again, shutdown down communication in some manner or serving up an error page, etc.
A new browser instance or a new tab may or may not be part of the same browsing session depending on how the browser is configured. I believe, for example, IE provides a setting that allows the behaviour to be set of whether a tab opens in a new process or session or shares the session. You won't necessarily get expected consistency across browsers to rely on for this feature, therefore you need to take programming steps to reign it in, like those described above.
You can additional steps like disallowing the user to be connected from a different IP# at the same time.
In my appliation,all pages are protected,so they must login to visit the pages.
And the admin of the system can add users.
Now some people told me that I have to prevent people login at the sametime using the same account.
That's to say if there is a user named "John" logined to the system,so other people cannot login with "John" again event he know the password.
Also,if one user find that someone have logined use the account he wanted,he can make the former user offline. If so I have to judge if the current user have been offed ornot in each page. This is not a work can be done easily.
I wonder if this is necessary?
Since I found so many websites nowdays do not limit this,for exmaple,you can use the same account login your gmail/stackoverflow/yahoo and ect in different machine at the same time.
So Any one can give me a suggestion?
Update:
Now,we use the asp.net's form authenciation,(we do not use the membership yet). And in the t_user table in the databse,we have a column named "isOnline" and "last_login_time".
When user login,we set the "isOnline" to 1,and store the login time.
When another user try to login again,we check the "isOnline" and the time:
if("isOnline"==1 && DateTime.now-LastLogiTIme <40min) // where the 40 min is the form authenaication timeout.
thisAccountHasLogined=true;
But suppose a user logined yet,then he clean the browser cookie,then if he refresh the page,he will be redirected to the login page,but not he can never login again before the form authentication time out because the "isOnline" in the db is 1 and the time span from his login to now does not large than the form timeout.
I am confused.
In some scenarios, I could understand not having multiple logins, but in reality, I have never had to implement it.
Unfortunately, I do not believe there is a standard mechanism for determining if a user is already logged in and this would need to be done by additional logic. In our application, we use a database for storing session information and using this, it would be a simple process to see if a session already exists within this for the user and not allow login if so.
Update
I was interested in this myself and found this;
http://msdn.microsoft.com/en-us/library/system.web.security.membershipusercollection.aspx
and this
http://msdn.microsoft.com/en-us/library/system.web.security.membershipuser.aspx
Using those, it may be possible to get this information with the .IsOnline() However, this does make the assumption you are using standard asp.net membership
the table where you store user name and password add a column status
when a user attempt to login update status to "Online" when logout update status "Logout"
During login check status, if status is online , terminate process. This may be an approch to implement this, hope it will help you
How woulld I set this up:
I wanna save what links a user clicks on in a website. I thought of creating a jquery function that would save the link name everytime a link is clicked , then ajax the info to the db after the user closes the site.
Does that sound like a proper way. Anyone have samples of that?
Since there are multiple pages with multpile links, I wanna create something equivalient to a Session variable in javascript so I can append info to it everytime a user clicks a link and send the info only once to the db, instead of everytime a user clicks a link open a db connection and send the info.
The links are products so I wanna save related products, so I wanna save related product infomation. Maybe I need a cookie instead?
Waiting till the user leaves the site is nice in theory but never in practice. Because you can't really know for sure when a user is leaving -- or it might be to late (eg a user shuts down the computer.) What you really want to do is keep track of the actions of the user as they happen using ajax.
To do this you need to assign every user session a unique id. ASP.NET does this for you (there is a session cookie created for every visitor to the site.) Using the ASP.NET session identifier will save you a lot of work.
Every time a user performs an action you want to save you just have jQuery make an ajax call (you don't care about the return) to a service that logs to your DB.
Here is the Microsoft docs about the automatic SessionID MS Doc
Or simply use the following code to get the unique id:
string sessID = System.Web.SessionState.SessionID;
Simpler way is just give user unique cookie. On server you always know on what page user come in. ($_SERVER in php) so your server side script could save it in database (with SID).
use localStorage for HTML5 browsers or cookies for older browsers.
$("a").click(function() {
car links = localStorage["links"];
links = JSON.parse(links);
links.push(this.href);
localStorage["links"] = JSON.stringify(links);
});
Then listen to the onbeforeunload event and make an ajax call to the browser sending it the localStorage["links"] JSON.
So its a ASP.NET problem where two users using the same machine, same browser.
User 1 logs in the domain.
User 1 changes some data without saving it.
User 2 logs in the domain in a separate tab.
User 1 switches back to his tab and saves the data.
User 1 actually saved the data into User 2!!
This is caused by the following mechanism:
Different tabs in the same browser seems to share the same session id.
We are storing user auth in cookie and the cookie is shared between tabs (same domain)
Therefore, when User 1 request to save, it is recognized as User 2 since the cookie has been updated to User 2.
So I'm wondering if there's any other methods to prevent this from happening, other than:
1. Use cookieless session so the session is embedded in uri.
2. Always include a hidden field in page to indicate which user owns the page.
Regards,
You could add some fields in the database to track that the user is logged in, and grab their IP address, and restrict access that way.
IE8 has a "New Session" command in the file menu that opens a new window, but that's pretty much like using 2 different browsers.
Hiding the login form until the current user is logged out will raise awareness that another user is logged in but won't prevent the above scenario. If the logout process could refresh each page in the browser on the domain then it might work, although user1 would loose all modified data.
I used the trick of opening a new window with a specific name and always make sure that any page will open always use that window.
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.