I have an application which asks for a registration through facebook but before a user can proceed to the registration, the system should first determine if there is an active session. If a user is logged in to facebook, it should then automatically logout for a fresh start.
But here is where I'm stuck. The SDKs only let the user log out from facebook if he is connected to your app. It uses the app's access token. But what if he is still not registered to your app? Their log out means to log out from your app, and not really from facebook.
My requirement :
1. How can i log out from facebook.
2. How can i clear the browser cookies?
Not on a specific app but the whole facebook session.
[from comments] But to use the getLogoutUrl() function, the user has to be connected to your app. What I need is to logout from the whole facebook and not just from the app
If the user is connected to your app, then the URL provided by the getLogoutUrl method does that – log the user out of your app (web-app) and out of facebook.com.
If the user is not connected to your app however, you don’t have an active user access token – and then logging out of Facebook is not possible. The obvious reason being that if it was, every website that I visit could log me out of Facebook in a “drive-by” manner – without me actively wanting that, so people would get annoyed quite quickly.
If a user is logged in to facebook, it should then automatically logout for a fresh start.
If this is a security consideration, then you are in fact looking for re-authentication, which can be done using the auth_type parameter, quote from docs:
In apps where security is very important, you may want to double-check someone's identity - perhaps before they make a purchase within the app, or use it to access some sensitive personal data.
To prevent situations where a user could leave a device logged in or man-in-the-middle hijacking of the user session, re-authentication forces a person to re-enter their Facebook password before they can continue to use your app.
Be aware to use the server-side Auth flow though – because in the client-side flow, using the JS SDK, there is a bug that allows the user to bypass re-entering his password by simply closing the popup, which is still open: https://developers.facebook.com/bugs/248632218597467 (Has been assigned Priority: High, but received still nothing more than a “we will follow up” response yet.)
Use the logout.php url.
https://developers.facebook.com/docs/reference/php/facebook-getLogoutUrl/
Basically,
http://facebook.com/logout.php?next=YOUR_NEXT_URL_FOR_LOGOUT&access_token=USER_TOKEN
1) logging out from facebook by using
facebook=>getLogoutUrl();
2) clearing the session by using :
$facebook->destroySession();
example:
Log Out
logout.php page codes as follow:
<?php
require 'facebook.php';
$facebook->destroySession();
header( "location:index.php" );
?>
Related
The Facebook Platform Policies section 1.6 clearly states
Your website must offer an explicit "Log Out" option that also logs the user out of Facebook.
The Login Flow for Web without Javascript SDK says on Logging people out
You can log people out of your app by undoing whatever login status indicator you added, for example deleting the session that indicates a person is logged in. You should also remove the stored access token.
On the other hand the Login Flow for Web says about Logging people out
Note: This function call will also log the person out of Facebook. The reason for this is that someone may have logged into your app and into Facebook during the login flow. If this is the case, they might not expect to still be logged into Facebook when they log out of your app. To avoid confusing people and to protect personal security, we enforce this logout behavior.
So in my understanding the Login Flow with JS SDK does what the policy says, it logs the user out of Facebook as well. How do I implement the Login Flow without JS JSDK correctly, such that i do not violate the Facebook Platform Policy? So far i don't see that the Graph API offers a similar functionality.
That should be easy, looking at the PHP SDK’s method getLogoutUrl, that creates an URL of the following scheme:
https://www.facebook.com/logout.php?next=FOO&access_token=USER_ACCESS_TOKEN
For FOO you just place the URL of your website where you want the user to be redirected to after they are successfully logged out of Facebook (don’t forget to properly URL-encode that value), and USER_ACCESS_TOKEN should be self-explanatory. (You need an active user access token to log the user out of Facebook – obviously, because otherwise every site on the web could just redirect me to this address and log me out of Facebook, without me actually wanting that to happen.)
I am working with integration of a website with facebook.
I have a specific requirement where-in the user should get logged-out from facebook if he/she doesn't grant permissions to my facebook-app (on first use).
Now, If user denies access for my facebook-app, I am redirected to the redirect_uri, but the problem is that on the page that handles the redirection, I cannot log the user out from facebook since my app won't have permission to perform logout.
Can anyone please tell me what is the workaround I could try?
I have a specific requirement where-in the user should get logged-out from facebook if he/she doesn't grant permissions to my facebook-app (on first use).
Is this in a very special environment (like a kiosk application or something) …?
Because otherwise, I’d hate it if random apps logged me out of FB while I’m browsing on my own computer, just because I don’t want to connect to them.
Now, If user denies access for my facebook-app, I am redirected to the redirect_uri, but the problem is that on the page that handles the redirection, I cannot log the user out from facebook since my app won't have permission to perform logout.
Can anyone please tell me what is the workaround I could try?
I don’t know any workaround – to perform a log out on behalf of the user, you need a valid access token – doesn’t matter, if you’re trying to do it client-side or server-side.
If that wasn’t the case, any website I’m visiting could log me out of Facebook, and that would be really annoying to users.
We have exactly the same problem. We've developed a kiosk application used to checkin and post HD photos.
If the user does not accept the permissions we need to reload the application because we can't logout the user in another way.
We've tried different ways but no one was successful
well i have used the facebook api couple of times. But last day i just came across a site which was really new to me. Heres the scenario
If a user is logged in at facebook and comes to my site, he will
automatically be logged in without asking him and also if user logs
out of my site he gets logged out of facebook. But the site i saw
yesterday, they had handled it perfectly, user dose not logs in their
site automatically and even if user logs out from their site, he does
not gets logged out of facebook.
So any help? what is this technique called? or any relevant help?
Best Regards
most site handled the login/authenication by using the login status of the user at facebook ends.
to do what u wants, simply add an additional layer of authentication / login status checking at your own site.
The site level login status is to be retained only for the current session. In other words, once the user went away from the site, the site level login status is gone. With this, when the user returns, you know that he needs to login again.
when the user logged out from your site, you only log him out of your site and do nothing about facebook login
Using the Facebook SDK it will likely tell you the user is logged out when not logged into Facebook, which in theory is the correct behaviour of the whole system, as Facebook want user's to always be connected to Facebook, I quote facebook:
As long as the user is signed into Facebook, they are automatically signed into your site as well.
So if they aren't connected to Facebook, you aren't connected to other sites. In a way it's a deterrant and increases Facebooks market.
But anyhow, it's likely the site you are describing are implementing their own authentican system rather than using Facebook's own SDK, or if they are using the SDK they are using it in moderation and understand about cookies/the above.
The flow to allow the user to be logged into Facebook but out of your site is as so:
When a user logs out of their site, it will unset session data for the site's own application, and also unset Facebook cookies, etc. That way the user is still logged into Facebook but out of your site.
When they try to log in again, Facebook will detect no cookies are available and hence will re-authenticate and pass you onto the url as passed during the authentication process. Your site will then login the user to the site's own application, setting any session variables, etc.
you need to check how you are handling the FB logins and sessions at your end..
my guess is you check the is login at your site and there are some access_tokens which are as per your app id in the cookies of your browser which are helping you to log in ..
and when logging out from your site you are explicitly logging out the user from FB as well
( thats what you are describing atleast )
you seem to be explicitly calling logout or clearing the cookies for fb app id ..
I am developing and testing a facebook app for which I have granted the permissions with my facebook account. Then the app is authorized to access my info, etc. nicely. The next time I close the browser, reopen it, login to facebook successfully then access the app, facebook wants me to login to that app again. I can access the current user id, but how can I automatically authorize the app (if the user has already authorized in the past) without needing the user to press that dread 'Login' button again and again upon each session's end?
UPDATE - offline_access has been deprecated. Read this post for more details: https://developers.facebook.com/roadmap/offline-access-removal/
You will need to request a token that has offline_access so that you can use their authentication token over and over again. Then you will need to set a cookie yourself that stores something indicating who the user is. Facebook does not support a "remember me" feature in their authentication so you have to build it yourself. Store the access token in your database and set the cookie to identify the user.
Unless you are building this for a very specific reason like an app that runs on work computers only, I would really encourage you to not implement this feature. The facebook connect authorization is well understood by users and is very easy to use. You are going to get a lot more security if you make your users press the button every time. Just make sure you make this optional. You never know if somebody is on a public computer.
I have an implementation of Faceebook connect and I have noticed that if you are already logged in to facebook and hit connect, you wont be prompted for your login credentials (because it takes current session data).
Is there anyway to make Facebook connect not use the currently logged in user and force each connect to enter their login/pw?
Actually I believe if you already have the facebook application installed, it bypasses a 2nd window.
This is possible using re-authentication. Quoting:
In apps where security is very important, you may want to double-check someone's identity - perhaps before they make a purchase within the app, or use it to access some sensitive personal data.
To prevent situations where a user could leave a device logged in or man-in-the-middle hijacking of the user session, re-authentication forces a person to re-enter their Facebook password before they can continue to use your app.
For more information, see:
https://developers.facebook.com/docs/howtos/login/client-side-re-auth/
Go to facebook App settings. under Advance tab look for "Force Web OAuth Reauthentication" make that YES. and save it.
From now on your login will ask for user password every time even if facebook browser session is present.