I'm using php sesions with mongodb by defining the
session_set_save_handler()
if every user has a role (client, admin, employee) ,
with every page I load after getting the session id i'm checking the value of the role
is this a secure approach ? or they can by pass that ?
The session data should contain the "state" (i.e. logged in or not logged in) of a user, but not specific details like a user's role.
So once a user is authenticated, you can then lookup information on the user in the database. If that user has the required role, then load the page; if not, then don't.
What you shouldn't be doing is logging the user in, creating a session for that user and also storing in that session the role. If you do it this way, you're potentially leaving your website vulnerable to loop-holes (especially on shared hosting). Also, what if a user's role changes during the lifetime of the session? Either you ask the user to login again, or the change in role isn't actually "registered" until the session is destroyed (which could be long time, depending on configuration).
Related
When starting a session, an authentication is made to the database through a query. If this authentication is granted, one or more session variables are filled with data. This allows the user to transfer through multiple pages without having to re-authenticate - which is great. However, if a session variable that is being used is changed within the database, i.e. username change, access privileges change, the changes are not rippled through to the session (obviously).
How is it possible to get the database changes to trigger, or ripple to, the PHP session variables.
An example is being logged into a website where you have access privileges x that allows you to access pages 1,2,3. Your privileges are now taken away for some reason and you now have access privileges y which allows you to only access page 1. If the user is already authenticated within the site, these changes will not affect the users current session, and will still be able to access pages 2 and 3. This could be an issue in many situations.
Currently my solution to the problem is to re-authenticate the user every page, and update the session variables accordingly. This definitively seems the wrong way to accomplish this task from my limited understanding of how sessions (should) work.
Essentially, I would like a way for database updates to trigger a re-authenticate of the current logged in user. i.e. if user john12 has his database row altered, then his session should require re-authentication.
At the moment I can't think of any way to accomplish this without querying the database every time a page is loaded.
Any tips or solutions would be greatly appreciated.
How I usually do it is by having 4 fields for authentication is my database.
Username
Password (usually hashed)
Token
Logged IP
I remember the user's auth data in cookies. When user has entered the right username and password the website generates a new token and sets two cookies - username and token. On every page load you check if the username, token and logged IP match (to prevent token steal).If one of them isn't right remove all of them and redirect to login page.
In your case if you want to relogin on password change just delete the token when it has been changed.
The only con here is that only one machine can be logged at a given time.
I don't see why you don't want to query the database for user permissions, SQL databases are incredibly fast even with lots of records especially if searching by primary key.
I have a website which has a login/logout feature. How can I ensure, 100%, also in a stable technique, that a user won't be a able to login to the same account from two different computers?
Javascript can't be used for this, since it's easy to disable it.
For example, .NET has a Session_End function that executes when a user aborts the connection with the server. How that can be done with PHP?
Thanks, Guy
Note: This technique would effectively logout the account on the first computer when logging in on a 2nd.
When a user logs in, log the session id for the user to the database or equivalent. On each page request, ensure the session id of the user matches the session id stored in the store for their account. Requests from a logged in account with a mismatched session id should be rejected and the user should be logged out.
It depends on how in depth you want to go. Most commonly:
Create a unique session id cookie on login and saved it in the database
All web pages check the session cookie to make sure it's valid
if the session isn't valid, the user is redirected to the login page
When another user tries to log in, it overwrites the previous session
This essentially kicks out the first user
Large companies will also store the IP address in the database as well (so session cookies can't be stolen)
A feature that is currently missing from one of my web apps is that a single user can only be logged in on one machine at a time. That is, if the users logs in elsewhere, his previous session will be logged off.
This is due to my current users table having the columns:
user: id, username, hash, salt... cursession
When each user logs in, the session ID is put into the "cursession" field and on each page-load, is checked against the database. As a result, only one "session" can be active at a time.
Is the current table structure and method secure and standard? This system was pretty much improvised, and I have no professional experience.
What would be a way to allow multiple simultaneous logins? I'm simply thinking of adding a "sessions" table with more userid-cursession relations, but what's the standard method for doing this?
I propose that you put the current logged in userid in the user's session (as a session variable), and drop the cursession field from the table altogether. You don't need to reinvent session handling since PHP already has it built-in.
That way the user can be logged in at multiple computers at once. Session variables are safe too, since they're not manipulated by the browser. The only thing kept in the browser is a session id which identifies the current session, all other data is stored on the server-side. The only thing that will happen if the user changes his browser cookies is that he will be logged out (start an empty session), so he can't force himself to log in as someone else.
I am developing the user management portion of a website that will host a webcast. The goal is to prrevent the same user nam (email address) from being used concurrently. That is, we don't want two individuals using one login to view the event.
I've already setup a table that holds the user registration data with regID as primary key. My thought is to create a login history table with username as primary key, foreign key to user name in registration table. The login history table would simply timestamp when the user logs into the site. However, this won't accomplsih my goal of preventing more than one individual from using the same login name.
Instead, would it be better to have a login status field either in the login history or user table that is set to 1 for logged in and 0 for logged out? It would need a stored procedure to update the value at login and at logout, and would need to be validated when a user logs in such that if login status = 1, user already logged in and cannot login a second time. Is this a feasible approach?
Please share other methods you've used to prevent the same login credential from being shared amongst multiple individuals.
Thanks,
Sid
If it is OK to logout an already logged in user if someone else logs in with the same credentials then you could do the following: when a user logs in generate a random ID in your database for that user and the same in a cookie session. The two must match to authenticate.
Without rolling your own session handler, you could do a little parallel tracking. When a user logs in, you can store the user's session ID and login time in the database (maybe inside the user information table). The login script could then check for the existence if this sessionID and allow/deny login based on the presence of the session ID. If the ID's null/blank, then the user logs in. If there's a session ID present, and it's more than X minutes old, allow the login. Otherwise deny them.
Of course, you'd probably want to roll your own session cleanup handler at that point, so that when stale session files get deleted, you can remove the associated IDs from the database at the same time.
The problem here is detecting the user is logged in (i.e. whether he didn't logout).
One possible way is to register in the database the time of his last activity and the time of his explicit logout. You could then deny a login if it this was attempted less than say 5 minutes ago relatively to his latest activity and if he didn't login in between.
You could force "activity" by having the website pages periodically poll the server with Javascript.
It's easy to determine when someone logs in. It's much harder to determine when someone logs out. If you have a mechanism of killing the webcast streaming to a particular user quickly, you might want to have something which pops up asking the user if they want to kill their other session if you think there might be one active.
How are you doing user sessions on the server? If you store them in the db, you could query the active sessions anytime someone attempts to log in and see if they're already in there. Of course you'd probably also have to check some kind of timestamp since you're not guaranteed that sessions will disappear at session.gc_maxlifetime.
You might want to consider making a global variable in php to store a hash array with login status. This has the benefit that if the application has to be restarted for some reason, the user isn't stuck in the wrong state in the database.
You can store a mapping from user ID to IP or session cookie and redirect requests that come with different information to the login page. If the user logs in, the other session would be invalidated and further requests in the last session forward to the login page.
how do you check if a user already has logged in?
so that if a user in another browser cant log in with the same account.
also, is this a good solution or should i let the user log in in the other browser and then log out the current user and display a message (you are logged in from another location) just like messenger does?
Using sessions is a good way to do this, and is a very common method for controlling authentication.
The flow usually looks something like this:
User visits site, and session_start() is called. A unique session identifier is set for that visitor (ie. a cookie).
User submits his login credentials to a login form
Login credentials are verified, and this fact is stored in the session data with $_SESSION['logged_in'] = true, or something similar
For the rest of the user's time on the site, you can check $_SESSION['logged_in'] to see if the user has logged in.
In order to control a user's logins, you could simply have a field in a database (users table is fine) indicating what the current session id is (retrieved with session_id()) for the user, and if it doesn't match the cookie value you just received, then you immediately call session_destroy() for that id, and consider the user as logged out.
Using $_SESSION means you don't have to worry about generating your own tokens, and gives you the power of the built-in superglobals to facilitate storing information about the user's authentication status.
Personally, I would allow multiple sessions to be active for a user for most web sites, as there's usually not a good reason not to, but it obviously depends on the nature of the site. However, storing the current active session id as mentioned above is a pretty simple way to accomplish this.
Generate a random token upon signing in (or use the sessionid), and store this in the database and in the users cookie. With each page access, ensure that the users token matches the database entry. If the two don't match, alert the user that they've logged in elsewhere.
You could also store the login time, which subsequently would be the time the token was assigned, and require 30 minutes before permitting another user to login with the same ID.
The first half of the question was answered well with how to detect the multiple users but how to treat them I think still needs a bit of work.
First if a user logs in correctly let them in, don't prevent them if they are logged on some other place. If you really don't want the user to have two open sessions then log out the old one or simply update the session id that you are saving so you can bounce out the old connection. You can inform if you want but I would only message the session that you invalidated. If you message the user logging in it becomes annoying when you are only dealing with the case of a user switching computers and they forgot to log out of the old session.
Well All solutions mentioned above will work but if on every page access you are making a call to database and checking for the session token to see weather its the same token assigned to user .. will kill your response time. what i'll suggest is use a caching mechanism instead of database in above said solutions. storing session token into database will add extra field to your database which is actually not required. Use open source caching solution like memcache.
you can make a table like userLoginStatus with fields like clockIn time & clockOut time,
and insert current time in clockIn when user is do login, leave clockOut time blank at that time, it should be updated only when user do clock over logout button,
so you can check specific user's current status, where clockOut is empty that user should be logged in. because it updated only when user do logout.