Hi I would like to know the difference between a php session and a cookie
The main difference being that session data is stored on the server, while cookie data is stored on the client. Therefore, a client can easily modify the cookie contents, but will have to work way harder to modify the session contents.
Cookies are a means to store information in the end-user's browser, so that the server can track the end-user.
Sessions are also implemented by using cookies, but the actual data is not in the browser; rather, it is stored in the user's session record on the server. In the case of sessions, cookies are used to identify a particular end-user's session identifier on the server records. Hence, they are a more secure way of storing user information.
A cookie is a ~piece of data stored on the client side.
Data stored in session is stored on the server side, and the various sessions are identified by cookies.
There are session and Cookies, both are used to store values or data. But there are some key differences between session and cookie: a cookie stores the data in your browser and a session is stored on the server. Cookie data is available in your browser up to expiration date and session data available for the browser run, after closing the browser we will lose the session information.
A cookie is often used to identify a user. A cookie is a small file that the server embeds on the user's computer. Each time the same computer requests a page with a browser, it will send the cookie too.
A session variable is used to store information about, or change settings for a user session. Session variables hold information about one single user, and are available to all pages in one application.
A cookie is an unique information that the user sends to the web server with each request in order to identify him. This unique id could be used to store information about this specific user on the server (session).
Cookies will only expire on expiry time or if you explicitly clean cookie / cache of your browser. Cookies will retain into the system even after you open your browser next day.
Cookies are stored on client's system so they are less secure.
Session will expire on its expiry time or if the browser has been closed. As session is stored on server so it is more secure.
So for a login module, a combination of session and cookie should be used
Cookies stored client side but session stored server side.
cookies is without sign out of the your email account and close it. once again can not enter username and password but your email account is open.
session is close the webpage once again open to starting page appier
best example to illustrate the difference bet. Session and Cookies is:-
when you Login as a member in any Site it Creates Sessions until you log out...
that is Session..
and Cookies when you browse websites the are stored on your computer's Main Memory that is Cookies
i-e Session is Server side
and cookies is Client side
We got three differences in general. The key difference would be cookies are stored in client side and sessions are stored in server side. The second difference would be cookies can only store strings. We can store our objects in sessions. Storing objects in sessions were really useful according to my experience. Another difference was that we could be save cookie for future reference, but session couldn’t. When users close their browser, they also lost the session.
PHP Sessions
PHP has built-in functions to save session variables. The variables are stored in state files. These state files need not be explicitly created and managed. The following are the steps for saving and retrieving values of session variables.
The setcookie() command must be issued before any printed output occurs because the cookie must be written as part of the HTTP header. PHP automatically parses any HTTP_COOKIE string into an associative array $_COOKIE. The value of the cookie can be retrieved from the cookie thus:
$_COOKIE["some_var"]
Cookie: A key/value pair that is stored by the user's browser and is available in the superglobal $_COOKIE array available in PHP. The cookie request is initiated with an explicitly defined expiration date. For example:
setcookie('cookieName', $some_value, time()+3600, "/", ".example.com")
On the next server request, $_COOKIE['cookieName'] will be available. If you use a browser tool to look at the cookie, it will have an expiration date.
Session Cookie: Identical to the above but defined without an expiration date. If you use the same browser tool it will say that the cookie expires at the end of the session; which is ultimately when you close your browser. For example:
setcookie('cookieName', $some_value);
PHP Session: a server side mechanism that will associate a bunch of data with a session id. Every time a session is invoked, it serializes/unserializes it. This could be more data than just a single key/value pair that a cookie supports, but the way of associating this data with a user is by creating a cookie (regular or session as described above) in their browser that contains the session id. This way, the right data can be retrieved for a given user based on the value of that cookie.
Both are super global, i.e, they can be used anywhere in the site.
Differences between sessions and cookies:
Cookies are stored in the browser (client side) while sessions are stored in the server (host).
Cookies are remembered till they are deleted while sessions are deleted when the user closes the tab/browser (depending on the browser).
Cookies can be seen by the user while sessions cannot.
Due to the reasons above, I would recommend to not store sensitive data in cookies and store the data that is to be remembered even after the user has left in cookies.
Cookie - Stored data in browser and will work on browser related and client side only...For example if you are trying to log in gmail account with username and password,After entered login successful if you close the current tab and after sometime opening same page the login page won't come it will open directly with login details..This is cookie..
Session - Stored data in server side for example same as cookie example after entered login details you will get notification as successful once you close the browser then open after some time it will ask again login details(more example shopping also)
Related
In Internet Explorer, for example, you can enable first party cookies, third party cookies and allow session cookies.
I know the difference between:
a first party cookie and a third party cookie, and
a PHP session and a cookie.
But what is a session cookie? And how can you set one using PHP?
For example, you cannot log into Facebook without cookies enabled. However, if you allow session cookies, you can log into Facebook.
So, how does a session cookie differ from other kinds of cookies?
A cookie has a lifetime, after which it will expire (As denoted by the Expires directive). If you don't set a timeout, the browser will expire the cookie when you close the browser. This is called a session cookie.
These kind of cookies are often used to track a users current session state on the server side (E.g. php's sessions), but there is not a strong relation between the two uses of the word "session"
A session cookie holds the unique identifier that PHP generates when session_start() is called, so that each client can be associated with a session, and no two sessions can have the same ID at the same time.
The session cookie is usually destroyed when the browser window is closed, or can be done manually using session_destroy().
From Wikipedia:
Older definition: (2011-12-17)
A session cookie is created when no Expires directive is provided when
the cookie is created.
Latest definition:
A session cookie, also known as an in-memory cookie or transient
cookie, exists only in temporary memory while the user navigates the
website.[18] Web browsers normally delete session cookies when the
user closes the browser.[19] Unlike other cookies, session cookies do
not have an expiration date assigned to them, which is how the browser
knows to treat them as session cookies.
In PHP, when you use session_start() it creates a session, this will create a session cookie in the client browser, PHP needs the client to send this info back with each request so that PHP can tell the session ID.
I have a question regarding session hijacking in PHP. I have been reading about it this morning and I have a few questions that just weren't answered clearly in the documentation I read.
Can a user change their session on my website? i.e. if they have a session of X when the login, can they change that session to Y, or Z, if they so choose?
I thought that sessions were set by the browser and they couldn't be changed, but all of this session hijacking stuff I've been reading has put some doubt in my mind.
The term "session" is overloaded to mean different things on the server and in the browser. Browser sessions are at best tenuously connected to server sessions. "Session hijacking" refers to server sessions.
Server-side, a session has an ID (which is passed between the client and server), content (stored on the server) and potentially other properties, such as last access time. The session ID is usually passed as a cookie. In PHP the default name for the cookie is "PHPSESSID". If cookies aren't available, PHP will (optionally) use a query string parameter of the same name ("PHPSESSID"). This cookie (or query param) can easily be changed and therefore the session identifier can be changed too.
The contents of a session (i.e. containing the login state of a user) cannot be changed by the client, the data is stored on the server and can only be changed by a PHP script on that server. Note that in a shared-hosting environment (shared by other services or users), the sessions can be overwritten if using the default session storage directory (/tmp). To protect against that, either use a database through session_set_save_handler() or set a custom session directory using session.save_path with the proper directory permissions set (preferably 700 which means that only the owner (the PHP user) can read and write to it).
To protect against session hijacking, you must have other ways to identify the user against a session. This can be a user agent, IP address or another cookie. The previously mentioned methods are just workarounds, best way to protect against stealing of the session cookie is by using HTTPS if a session is involved. Do not forget to set the httponly flag to true using session_set_cookie_params()
Client-side, "session" is again overloaded and used in various contexts (e.g. session managers, which restore open pages when a browser is opened, session cookies and sessionStorage). We can try to combine these meanings (into what is by no means a standard one) by saying a browser session consists of a collection of views and their associated data. (By "view" I mean roughly tabs in tabbed browsers and windows in non-tabbed browsers; the DOM window object exposes a view to JS.) Each view has a history, a current page and page data. Page data for pages in the same domain is shared between views in a session; if two pages are in different domains or different sessions, they don't share data. Exiting the browser closes all open session(s), possibly saving part of the session(s) (e.g. histories, current pages, sessionStorage) so that a session manager can re-open them. Session cookies are cookies that are discarded when a session is closed; in other words, session cookies are non-persistant. Though a session cookie may hold a session ID, the two concepts are orthogonal (sense 4; session cookies can hold things other than session IDs, and session IDs can be stored in persistant cookies).
Whether two different views are in the same collection depends on the browser. For example, one browser may consider a session to consist of all tabs within a single window; separate windows are separate sessions. IE8 lets users create new sessions via the "New session" menu item. Otherwise, new windows and tabs are opened in the same session. Privacy modes also create new sessions.
In summary, browser sessions are indeed set by the browser, though it provides users various means of controlling browser sessions: creating new sessions, changing the history and current page in a view by browsing, saving and restoring sessions. A user could even change session data by editing sessions saved on disk, though this isn't a feature afforded by the browser. None of this has anything to do with session hijacking. Server sessions are created and managed by the server, but users can (attempt to) switch server sessions by changing the session ID their browser passes back to the server, which is the basis for session hijacking.
See also PHP Session Fixation / Hijacking.
A user can change his session at any time. It's just a random string stored in a cookie in the users browser, and therefore it is very simple for the user to change it.
As the actual content of the session is stored on your server, you could for instance store the user's ip address, user agent or similar to make it harder to steal sessions from each other, by checking if this information still matches each time a new http request is made.
No actually user can not change the actual session value at your website but can change the session id that is used to track the session this session id is stored on client browser by your website usually name "PHPSESSID" in cookie which are also known as session cookie. When a session is started on a site it stores the unique id corresponding to that session in the respective client browser in form of cookie named as "PHPSESSID". So if user is able to get PHPSESSID of any other user and it can replace his PHPSESSID with the victims PHPSESSID and it will result in session hijacking.
I am using PHP context here.
What is the distinction between Sessions and Cookies in PHP?
A cookie is a bit of data stored by the browser and sent to the server with every request.
A session is a collection of data stored on the server and associated with a given user (usually via a cookie containing an id code)
Cookies are used to identify sessions. Visit any site that is using cookies and pull up either Chrome inspect element and then network or FireBug if using Firefox.
You can see that there is a header sent to a server and also received called Cookie. Usually it contains some personal information (like an ID) that can be used on the server to identify a session. These cookies stay on your computer and your browser takes care of sending them to only the domains that are identified with it.
If there were no cookies then you would be sending a unique ID on every request via GET or POST. Cookies are like static id's that stay on your computer for some time.
A session is a group of information on the server that is associated with the cookie information. If you're using PHP you can check the session.save_path location and actually "see sessions". They are either files on the server filesystem or backed in a database.
The main difference between a session and a cookie is that session data is stored on the server, whereas cookies store data in the visitor’s browser.
Sessions are more secure than cookies as it is stored in server. Cookie can be turned off from browser.
Data stored in cookie can be stored for months or years, depending on the life span of the cookie. But the data in the session is lost when the web browser is closed.
Cookie
is a small amount of data saved in the browser (client-side)
can be set from PHP with setcookie and then will be sent to the client's browser (HTTP response header Set-cookie)
can be set directly client-side in Javascript: document.cookie = 'foo=bar';
if no expiration date is set, by default, it will expire when the browser is closed.
Example: go on http://example.com, open the Console, do document.cookie = 'foo=bar';. Close the tab, reopen the same website, open the Console, do document.cookie: you will see foo=bar is still there. Now close the browser and reopen it, re-visit the same website, open the Console ; you will see document.cookie is empty.
you can also set a precise expiration date other than "deleted when browser is closed".
the cookies that are stored in the browser are sent to the server in the headers of every request of the same website (see Cookie). You can see this for example with Chrome by opening Developer tools > Network, click on the request, see Headers:
can be read client-side with document.cookie
can be read server-side with $_COOKIE['foo']
Bonus: it can also be set/get with another language than PHP. Example in Python with "bottle" micro-framework (see also here):
from bottle import get, run, request, response
#get('/')
def index():
if request.get_cookie("visited"):
return "Welcome back! Nice to see you again"
else:
response.set_cookie("visited", "yes")
return "Hello there! Nice to meet you"
run(host='localhost', port=8080, debug=True, reloader=True)
Session
is some data relative to a browser session saved server-side
each server-side language may implement it in a different way
in PHP, when session_start(); is called:
a random ID is generated by the server, e.g. jo96fme9ko0f85cdglb3hl6ah6
a file is saved on the server, containing the data: e.g. /var/lib/php5/sess_jo96fme9ko0f85cdglb3hl6ah6
the session ID is sent to the client in the HTTP response headers, using the traditional cookie mechanism detailed above: Set-Cookie: PHPSESSID=jo96fme9ko0f85cdglb3hl6ah6; path=/:
(it can also be be sent via the URL instead of cookie but not the default behaviour)
you can see the session ID on client-side with document.cookie:
the PHPSESSID cookie is set with no expiration date, thus it will expire when the browser is closed. Thus "sessions" are not valid anymore when the browser is closed / reopened.
can be set/read in PHP with $_SESSION
the client-side does not see the session data but only the ID: do this in index.php:
<?php
session_start();
$_SESSION["abc"]="def";
?>
The only thing that is seen on client-side is (as mentioned above) the session ID:
because of this, session is useful to store data that you don't want to be seen or modified by the client
you can totally avoid using sessions if you want to use your own database + IDs and send an ID/token to the client with a traditional Cookie
A session is a chunk of data maintained at the server that maintains state between HTTP requests. HTTP is fundamentally a stateless protocol; sessions are used to give it statefulness.
A cookie is a snippet of data sent to and returned from clients. Cookies are often used to facilitate sessions since it tells the server which client handled which session. There are other ways to do this (query string magic etc) but cookies are likely most common for this.
Cookies are stored in browser as a text file format.It stores limited amount of data, up to 4kb[4096bytes].A single Cookie can not hold multiple values but yes we can have more than one cookie.
Cookies are easily accessible so they are less secure. The setcookie() function must appear BEFORE the tag.
Sessions are stored in server side.There is no such storage limit on session .Sessions can hold multiple variables.Since they are not easily accessible hence are more secure than cookies.
One part missing in all these explanations is how are Cookies and Session linked- By SessionID cookie. Cookie goes back and forth between client and server - the server links the user (and its session) by session ID portion of the cookie.
You can send SessionID via url also (not the best best practice) - in case cookies are disabled by client.
Did I get this right?
Session
Session is used for maintaining a dialogue between server and user.
It is more secure because it is stored on the server, we cannot easily access it.
It embeds cookies on the user computer. It stores unlimited data.
Cookies
Cookies are stored on the local computer. Basically, it maintains user identification, meaning it tracks visitors record. It is less secure than session.
It stores limited amount of data, and is maintained for a limited time.
I'm making a forum for learning mostly but hopefully it will have a couple of users some day.
What im wondering is should you use sessions or cookies for user authentication?
A cookie is a short piece of arbitrary data that the server sends through a header; the client stores it locally and sends it back on the next request. This mechanism can be used to maintain state from one request to the next even though HTTP itself is a stateless protocol. Cookies have two disadvantages: They offer only very limited amount of space (4 kB), and because they are sent back and forth in plain, a malicious client can fiddle with the contents before sending it back to the server, effectively making cookie data untrusted.
A session is a file on the server, identified by a unique ID which is sent back and forth between client and server so that the server can identify the client. The most popular way of sending the session ID is through the cookie mechanism, but it is also possible to pass the session ID through the URL (this is why you often see links that contain the URL parameter 'phpsessid'). This solves the two problems with cookies mentioned above: A file on the server can be as large as required, and the client cannot access the data other than through your own scripts.
Authentication is typically solved using cookie-based sessions; once authenticated, a new session is created, and the user ID is stored in it, and when logging out, the session is cleared and a new session ID is generated. Alternatively, you could store username and password in the session, and check them on every request.
Use a session.
A session is identified by a cookie, true, but not the same as storing user auth info in the client cookie, which is bad for security. A session cookie stores a guid or a hash in the cookie, then identifies the session (either database or file system based, depending on your server's php settings) based on that.
I recommend you store the primary key from your user table, not any other info, then look up the user info every time - this allows you to change their validation status, or security level on the fly while they are logged in; otherwise they will have to log out and back in before your administrative changes take effect for them - IE. you can't boot them.
Also, don't store the username/password, because that requires a less efficient query than by the indexed primary key (even if they are indexed as well).
They are essentially the same, working hand-in-hand. When you create a session..say through PHP, a cookie is created to store the session id too. On the other hand, you would create another cookie if you want to implement a "Remember Me" option to prevent your users from logging in every time.
I'm not a PHP expert, but Session and Cookie are related. In other programming languages you have the option of creating "Cookie based session" or "Cookie-less session". I'm not sure about PHP though so maybe you are referring to different concepts.
I feel using session is much more safe and easy then using cookies. The reasons are as follows:
1) In cookie we can only store a single piece of information, whereas in a session we can store as many information as we want.
2) Being stored on hard disk of user, cookies can be played with. Being a person interested in hacking, I have done that and gathered useful information about the user. Sessions cannot be used for such a thing.
If its a small amount of data (just one variable), I would use a cookie. Here is the code...
setcookie("cookie name", "cookie value or variable name", time+ 3600, "\");
this code sets a cookie that is readable for any of your webpages. It also will delete its self in one hour.
You can also see if the cookie exists like this (to see if it has deleted its self).
if (isset($_COOKIE['cookiename']))
{
}
to collect a value from a cookie...
$value = $_COOKIE['cookiename']; //makes a variable for this cookie for your program
I have never wanted to allow a user to stay logged in for any length of time so I never saw a use for a "remember me" feature. I started thinking about how it's done though and would like some clarification.
I'm currently storing my sessions in a database. What has always perplexed me was how, even though I do not explicitly set a cookie, one is placed in my browser. I'm a little confused because a session is a session and a cookie is a cookie. I don't see how a session sets a cookie.
I'd also like to know if, simply setting another session variable in the session array to keep the user logged in, would be sufficient or would I still need to set a cookie?
In order to pull the session data back from your database a key is needed. This is called the Session ID.
The session ID needs to be stored somewhere. Either as part of the URL string that the client posts back or, more commonly, in a cookie on the client. When the request is posted, session reads the value from the cookie and knows which record to pull back from session storage.
This happens automatically.
The only reason to use session is if the data you want to keep is greater than 4KB (browser limitations); or if the time required to pull the data from your server is greater than reading it from session storage.
If the amount of data you are storing is less than 4KB I would highly recommend you just set that in the cookie to begin with. I generally store things like the user id, user first name, and a couple other attributes. Bear in mind that it is trivial to inspect a cookies value, so this information should be encrypted prior to going to the client.
Another thing is if the query time to pull the data you need from the original source is small, then elect to do that instead of placing it in session. That way you only get it when you actually need it instead of with every single page load.
What has always perplexed me was how, even though I do not explicitly set a cookie, one is placed in my browser.
A session handler has to identify which session belongs to which user.
The vast majority of session libraries do this by setting a cookie.
(Is) setting another session variable in the session array to keep the user logged in would be sufficient or would I still need to set a cookie?
Most session libraries set session cookies. These are cookies without a specified expiry time. They expire when the browser closes and are not sufficient to implement a "Remember Me" feature (which is expected to persist across browser restarts, so must have an explicit expiry time).
Explaining the relationship between Cookie and Session:
PHP uses Cookie to uniquely identify the session for each user. That's the only more reliable way because cookie is sent each time you request a file from the server. Using the token in the cookie, which is also the Session identifier, PHP will look up the tmp directory to see if the session exists. If the session exists, the variables are loaded from the correct file and you will be able to access the variables on that session.
Therefore, cookies store the session identifier which is required to identify which user uses which session. This is also how Session Hijacking come about, when people can change the session identifying cookie to use another person's session identifier.
The underlying PHP session implementation sets the cookie. You can alter this and have the session ID value passed in the query string, but I don't recommend it. You don't use the cookie, PHP does. It references the session ID value stored in the cookie to perform lookups to session data.
I'd also like to know, if simply setting another session variable in the session array to keep the user logged in would be sufficient or would I still need to set a cookie?
As soon as the user closes the browser, the session is killed and the cookie is deleted. I don't believe any mechanism exits to persist the session value, and for good reason.