I am trying to login an user for 2 weeks if user login with remember me check then i have set some variables in session and cookie set for 2 weeks. It is set correctly i have printed it and got the value session_cookie_lifetime = 1209600 and session_gc_maxlifetime = 1209600. I also print session and got correct value in $_SESSION.
After login in my site when i shut down my computer and reopen my site it seems that it is working (it is keeping me as login user). But when i shut down my computer and next day when i open my browser it is not working and it is showing that i am not login on my site. I have printed $_COOKIE and $_session . It shows that in cookie there is :
[PHPSESSID] => svikos35bgclmebk2cqraiddt2
But session is empty.
I got this form modx stuff:
MODx automatically starts and ends sessions with each request made to the site. You can simply save values into the $_SESSION array and they will be saved in between requests so you can use them on subsequent pages (so long as you have the same user session). Not really any magic to it other than don’t call the session functions yourself to start, end, or otherwise manipulate the session configuration—that can all be done via settings in MODx.
I am using modx revo. It is a bit descriptive question. let me know you need something else.
Anything that may help me (blog link,any settings, any suggestion ) will be highly appreciated.
Thanks in advance
This only happens after a day?
Could tmpwatch be deleting session files from the server?
session_cookie_lifetime and session_gc_maxlifetime doesn't garantee you, that session will be saved for a week. GC kill unused sessions. Check PHP documentation about this parameters and you see, that you can't be sure, that your session will be on the server and you don't be sure, that your sesssion will be destroed after this time. GC is async.
You need to recreate $_SESSION after login (and autologin) if it doesn't exists.
Check this article (in russian, try google translate:
PHP GC: unexpected behavior
The basic idea behind SESSION is that, When you create or call session_start() method your server generate a session id and store it on server memory. Also the server create a cookie on your client machine that cookie contains an id that is related to your server side session id. When you call session_destroy() method server delete that id on server side but the client side cookie doesn't. That is why your session id still shown. You can also check by cache and cookie clearing. When you clear cookie your session will destroyed.
Related
I have an application where the login and logout works correctly. Once the user logs out, and tries to access a page he needs authentication for, he is redirected to the login screen.
Where my problem lies is. If while I am logged in, if I copy the cookie values and save them on a file. After logout, I alter the cookie and add the same values, I get logged back in into the application as the same user.
On logout I have written a function that loops over all the cookies and deletes them.
My understanding is that cookies are both on the client and also on the server side. So if the cookies are getting deleted, they are getting deleted on both the sides and that the server would not recognize them after they have been cleared, even if the browser sends them back again(apparently that is not the case, i think).
The reason why I am doing this is because this is one of the points raised by our security auditor, and I need to get a way to fix this hole. (At this point doing https is not feasible)
I'd be happy if someone can give me pointers on how I can clear out the cookies on the server side as well, so, when the next time someone hits the server with the same cookie, it does not accept it as a valid cookie.
Edit:
I am using codeigniter sessions and tank_auth as the authentication library. At logout, the library itself calls
$this->ci->session->sess_destroy();
to be extra sure, I tried the following after a few attempts :
session_start();
session_unset();
session_destroy();
session_write_close();
setcookie(session_name(),'',0,'/');
session_regenerate_id(true);
My regular logout works, and if I try to access the page directly it does not open.
But if while I am logged in, I take my cookie, save it somewhere -- log-out successfully and replace the cookie with my older one, I get right back into the session.
Is there a way to stop this behavior -- Where the server side will not entertain a session after it has been destroyed. I also made sure that my server and php are on the same timezone (setting it with date_default_timezone_set).
Cookies are not stored on the server at all. Those are stored in the browser and then sent to the server in the request headers. You can easily find software and plugins for browsers that allow you to create/edit/delete cookies. For that reason you should never store sensitive information in cookies. Essentially what you want to do is store the user data in a session and then store the session name in a cookie. Usually this is done automatically in php when you use the function session_start().
If you are using Codeigniter, the php session functions are wrapped in a CI session library that is auto loaded on each page load. So instead of storing data in $_COOKIE you will want to get/set your data via the userdata method in the session library:
//in your controller
//save session data
$userdata = array(
"isLoggedIn"=>true,
"username"=>$_POST['username']
);
$this->session->set_userdata($userdata);
//get session data later
$isLoggedIn = $this->session->userdata("isLoggedIn");
if(!$isLoggedIn){
//if the user is not logged in, destroy the session and send to the login screen
$this->session->sess_destroy();
redirect("/");
}
Note that the code above is not tested and is only supposed to give you an idea on where to go. If the session methods aren't working for you, you may need to load the library in manually:
//in the __construct method of your controller:
$this->load->library("session");
You can find more information here:
http://ellislab.com/codeigniter/user-guide/libraries/sessions.html
and here:
http://www.php.net/manual/en/book.session.php
Thanks for you answers guys.
This is what I figured, later. I am not sure what was causing this but the sessions were not getting invalidated after trying everything. I moved the sessions on codeigniter to the database. Then the logouts started working correctly, where after logout if the 'stolen'/'saved' cookie was put in the browser again it would Not log the user back in.
So, thats what solved it.
Today I had skype interview for a job as PHP developer, one of the questions asked was about Cookies and PHP Sessions.
The question was, can PHP session be set and read, used, if Cookies are disabled in users Browser?
I told them not, beacuse PHP Sessions by default depends on setting a session cookie. When PHP session starts, new session Cookie is set with default name PHPSESSID, and that cookie holds value of that session id, for example: ftu63d8al491s5gatuobj39gk7
Then on apache server in tmp folder file sess_ftu63d8al491s5gatuobj39gk7 is created and it holds content of that session, for example: test1|s:12:"SessionTest1";test2|s:12:"SessionTest2";
They told me that's not true, and that you can use PHP Sessions even if user disables cookies in his browser.
Then I told them that you can do that, but then session id would be passed through URL as GET variable. And that's not secure and you must set it up in php.ini.
They were talking how you can use PHP Sessions even if Cookies are disabled in browser. And what if we are building web shop, and some granny uses our web shop and disables cookies and she joust don't care. And that PHP Sessions are great because you can use them even if user disables Cookies. I was like wtf, wtf wtf?!?!
I made test with two files, index.php starts session and sets session variables. And then session.php tries to read that session variables.
This is how it looks:
index.php
<p>This is where I start and set php sessions.</p>
<?php
session_start();
$_SESSION['test1'] = "SessionTest1";
$_SESSION['test2'] = "SessionTest2";
?>
<p>This is a link, that starts new HTTP Request, and tries to read session set on this page:</p>
<p>Read Session</p>
session.php
<?php
session_start();
var_export($_SESSION);
?>
<p>Back</p>
Now, if you enable cookies in your browser, visit index.php, and the visit session.php , session would be printed out.
But, if you clear your browser history and cookies, and then visit index.php, and then visit session.php, you would see empty array right?
So basically my question is, am I right?
Can you use PHP sessions if you disable cookies in your browser?
And do PHP Session mechanism by default, depends on setting a session COOKIE?
Update:
I was going mad about this, so I called back the guy I was talking with. And asked him, can PHP session work without cookies by default? The guy said "yes". Then I told him he is wrong and he said: "yes, yes, if you say so..." and start laughing. Then I told him, ok if PHP session can work without setting cookie, how would server know current user/browser session id, if its not stored in a session cookie? (I wanted to see if he knows that session id can be passed as GET variable) And he was quiet for at least 20s, and told me that he is a System Administrator, and that I should ask that the Developer guy. And that he is 43 years old and has huge experience of 13 years in the bussines (he started with 30? wtf?), but he trusts me on this one. And I explained him how Session work and that you can use it without Cookie but then session id is passed as GET variable, and told him I told them that on interview, but they ware telling me no, no no... :S
So basically, the guy didn't have a clue about PHP and PHP Sessions, and yes he was the one that asked me about sessions telling me that PHP Session can work without cookie, even when I told him it cant be done, and that there is a way to use PHP Sessions without cookies but it won't work by default. He was like, no no no...
At the end he told me that he was thinking that sessions can work without cookies because he, as System Admin on his servers, can never see sessions in tmp folder?!?!?
Anyway, those guys suck at PHP, there is no way I will accept job offer from them, and after all this I dont think they will offer me a job anyway...
Thanks for all the comments!
"A visitor accessing your web site is assigned a unique id, the
so-called session id. This is either stored in a cookie on the user
side or is propagated in the URL. "
Sessions: Introduction
If session.use_cookies = 1 (Cookie enabled.)
If session.use_cookies = 0 (Cookie disabled.)
If session.use_cookies = 1 then session stores the sessionId into cookie. Calling session_id() get the stored sessionId from cookie and saved data into session array will be found on all the pages. If session.use_cookies = 0 In this case session does not store sessionId into cookie and you will get each time a new sessionId using session_id() and data stored into session on other pages will not be found on another pages.
Yes session will work when cookies is disabled.
But first apache check php configuration settings.
Like:
--enable-trans-sid
and
--enable-track-vars
if these value are set true the session will passed by POST automatically.
If "--enable-trans-sid" and "--enable-track-vars" values are set to FALSE, we need to pass session id by using the SID constant.
< a href="index.php?<?= SID ?>" >Navigate from here< /a >
Need to set php.ini
ini_set("session.use_cookies", 0);
ini_set("session.use_trans_sid", 1);
So basically my question is, am I right?
Mostly. In the real world: YES.
Can you use PHP sessions if you disable cookies in your browser?
You CAN use PHP sessions without cookies, as long as the browser identity is obtained somehow and yields a unique value (and this value is passed to the PHP session layer):
session ID in GET (which is the "standard" PHP way if cookies are not allowed, and the "other" way you described). This value is then propagated automatically by PHP, e.g. added to all A HREF's and so on. Where it is not propagated because the automagical link recognition failed (e.g. complex URL built in Javascript), it is your responsibility to provide accordingly.
Or - and here we're not in Kansas anymore:
passed among the nonces with Auth Digest (this is a dirty trick, and of course requires that the whole site is behind an Auth-Digest access authentication scheme. And you can no longer use a "dummy auth" (i.e. http://welcome:guest#www.example.com ) because some browsers, e.g. Internet Explorer, do not support them anymore for security reasons)
recognizing the browser some other way ("fingerprinting") (this is normally(1) suicidal)
Use LSO (Local Shared Objects) to generate a random UUID if it's not there already, and store it so that it can be retrieved on subsequent accesses.
other ways ( see http://en.wikipedia.org/wiki/Evercookie )
(1) if you were in a LAN where you can trust the IPs, you could associate a "session" to the user IP. You might enforce a strict "no cookies" policy in a small firm and still have user sessions without resorting to _GET/_POST for your session ID.
You are right, Session cannot work without cookies.
To illustrate this try doing the following actions.
Login To Gmail.
After login disabled the cookies.
Refresh the page.
You will be redirected to the login page again as the server cannot identify the session.
Now again enable the cookies.
Refresh the page. (Note: Don't click on login button).
You will be automatically redirected to the Gmail inbox.
Hence, we can say without cookies session will not work.
Also, If you are trying to login into the gmail( taking as example you can take any website) with diabled cookies then it will message as "Your browser has cookies disabled. Make sure your cookies are enabled and try again."
If it was me, I would say "Yes"
Since you could store session in form / url somewhere to passed to next page (very bad idea). So, based on his question "can PHP session be set and read, used, if Cookies are disabled in users Browser?"
Then, it should be yes. It can read and used.
However, If user close browser, then it's gone, and that's it. (since that guy didn't ask about this part)
Yes.. It will Work
1.PHP will pass one GET parameter in URL with the name PHPSESSID but it can be changed session.name in php.ini file.
2. It add one hidden input in forms with same name.
You will need to put the session ID in the URL. You will need to make a change in your php.ini file so if you are on a shared host you will need to contact them to see what they will do for you.
// tell the PHP we want to use cookies from the session
ini_set('session.use_cookies', '0');
ini_set('session.use_only_cookies', '0');
ini_set('session.use_trans_sid','1');
session_start();
// then pass the session ID in the URL(inspect, navigate the network refresh the page you will see in the headers your session ID)
I'm going to use cookies and sessions to indentify the user. So, sessions will be used only when user chose the 'Don't remeber me' option.
I include the identification file in the top of every page of website.
User's session looks like $_SESSION['user']
And than is my question:
Must I place to the authentication file session_start() instruction? I asked it because new session creates every time I use this instruction.
Update
http://pastebin.com/Nh3zj6mR user identification script
Yes, you have to place session_start() at top of every php page (before any output was generated, no headers must have sent before) to tell php to accept / start session, expect your php.ini is setup, that sessions start automatic.
I asked it because new session creates every time I use this instruction.<<
That is a hint, that your browser ignore (disallow) session cookies
Unless you execute session_start(), PHP's session mechanism will NOT activate. The $_SESSION will be present, you'll be able to read/modify it, but its values will NOT be persisted - e.g... the contents will be lost when the script exits.
If you are running session_start() in every script that uses session data, but the session data is not showing up, then there's probably a misconfiguration causing the session cookie to be lost, and PHP is creating a new session each time.
I am beginning to learn php. I have a question regarding sessions.
Right now, I know that session_start() creates a session variable.
What I don't know is, when I access the session I created, do I need to use session_start() again?
If yes...
Why is this? Because I already created a session and I wonder why it wouldn't last the entire browsing session.
because what i understand from it is, that it is going to create a new session.
No:
session_start() creates a session or resumes the current one based on a session identifier passed via a GET or POST request, or passed via a cookie.
http://php.net/session_start
Each new page you visit is an entirely new context for PHP. session_start allows you to reestablish a previous context/session/data.
The session_start function tells PHP to enable session tracking. It doesn't wipe out the session created by a previous page. You must call session_start() before you'll have access to any variables in $_SESSION.
Because of the manual session_start()
session_start — Start new or resume existing session
the same way you would connect to database every time you want to use it. it will connect to however you're storing your sessions. The session variables are no wiped out.
Also read more here but this should help to understand how sessions work:
When you are working with an application, you open it, do some changes
and then you close it. This is much like a Session. The computer knows
who you are. It knows when you start the application and when you end.
But on the internet there is one problem: the web server does not know
who you are and what you do because the HTTP address doesn't maintain
state.
A PHP session solves this problem by allowing you to store user
information on the server for later use (i.e. username, shopping
items, etc). However, session information is temporary and will be
deleted after the user has left the website. If you need a permanent
storage you may want to store the data in a database.
Sessions work by creating a unique id (UID) for each visitor and store
variables based on this UID. The UID is either stored in a cookie or
is propagated in the URL.
Session data is stored at the Server side but the reference or id to the session is stored on the client's browser cookie. For the server to know your session id we make a call to session_start() on each page it is required (at the top) so that the first thing done is to get the id from the user and retrieve the session data. It is required on every page whenever you want to access session data.
Here is a video tutorial also. http://blip.tv/step4wd/php-sessions_en-5983086
The answer is yes. You have to do that on every page. If you don't do that you get a undefined index error.
This will work because we include the file
Index.php
<?php
session_start();
//file doesn't have session_start
include "file.php";
?>
No: it is NOT always going to create a new session. It only tells the script that this page wants to start OR maintain an existing session.
A session is nothing more that a STATE AT THE SERVER that you carry from from page to page.
It is NOT accessible from the client (browser).
The only thing the browser must do to keep the session is passing an ID (called default PHPSESSID in PHP).
This ID can be stored in a cookie, GET or POST, as long as you get it transfered to the server with each request you make.
Youve to use session_start(), everywhere you need to work with session like, creating, accessing, destroying.
Unlike cookies, you can't access or work with session unless you initiate the session.
I'm playing around with cookies. And I dont have any cookies called PHPSESSID.
Do i need it? Can i remove it?
Whats the "function" of it?
if (count($_POST)) {
setcookie("TestCookie", htmlspecialchars($_POST['val']), time()+3600);
}
print_r($_COOKIE);
Prints:
Array
(
[TestCookie] => blabla
[PHPSESSID] => el4ukv0kqbvoirg7nkp4dncpk3
)
PHP uses one of two methods to keep track of sessions. If cookies are enabled, like in your case, it uses them.
If cookies are disabled, it uses the URL. Although this can be done securely, it's harder and it often, well, isn't. See, e.g., session fixation.
Search for it, you will get lots of SEO advice. The conventional wisdom is that you should use the cookies, but php will keep track of the session either way.
PHPSESSID reveals you are using PHP. If you don't want this you can easily change the name using the session.name in your php.ini file or using the session_name() function.
It's the identifier for your current session in PHP. If you delete it, you won't be able to access/make use of session variables. I'd suggest you keep it.
Check php.ini for auto session id.
If you enable it, you will have PHPSESSID in your cookies.
PHPSESSID is an auto generated session cookie by the server which contains a random long number which is given out by the server itself
Using cookies in PHPv7.4 and Microsoft Edge browser, PHPSESSID only seems to be generated when first loading/initializing a web app. If I remove the cookie the browser setting (but keep the web application tab open), it kills the session and forces me to login again. However when I log back into the web application the PHPSESSID cookie does not regenerate and yet I still have my session variables working as expected.
I was testing this because I have a web app that loads an external form (from another site) within an iframe and when the form submits and redirects back to my web app (within the iframe) it loses the session within the iframe. Removing the PHPSESSID cookie fixed the problem of losing the session, but I'm not sure why the cookie is the problem (but that is for another thread).