I am currently working on a project that spans accross multiple domains. What I want is for the user to be able to login on one site and be logged in on all the others at the same time.
The users session is stored in the database, the cookies that I set on each domain contain the session id.
So basically when a user logs in to example.com a cookie is created with their session id, the session data is stored in the database. Once this is done a cookie needs to be created on all the other domains with this unique session id so that as the user travels from site to site they will automatically be logged in.
Now I have found a way to do this in Firefox (using image tags that executes PHP scripts on the other domains, essentially creating the different cookies on the different domains) but this method doesn't work in IE (havn't tested Opera or Safari etc. yet).
Does anyone have any ideas about how I can get this to work in IE?
Have a look at my question Cross Domain User Tracking.
What you need to do is to add another HTTP header to the "image".
Quote from Session variables are lost if you use FRAMESET in Internet Explorer 6:
You can add a P3P compact policy
header to your child content, and you
can declare that no malicious actions
are performed with the data of the
user. If Internet Explorer detects a
satisfactory policy, then Internet
Explorer permits the cookie to be set.
A simple compact policy that fulfills
this criteria follows:
P3P: CP="CAO PSA OUR"
This code sample shows that your site
provides you access to your own
contact information (CAO), that any
analyzed data is only
"pseudo-analyzed", which means that
the data is connected to your online
persona and not to your physical
identity (PSA), and that your data is
not supplied to any outside agencies
for those agencies to use (OUR).
You can set this header if you use the
Response.AddHeader method in an ASP
page. In ASP.NET, you can use the
Response.AppendHeader method. You can
use the IIS Management Snap-In
(inetmgr) to add to a static file.
Follow these steps to add this header
to a static file:
Click Start, click Run, and then type inetmgr.
In the left navigation page, click the appropriate file or
directory in your Web site to which
you want to add the header,
right-click the file, and then click
Properties.
Click the HTTP Headers tab.
In the Custom HTTP Headers group box, click Add.
Type P3P for the header name, and then for the compact policy
string, type CP=..., where "..." is
the appropriate code for your compact
policy.
Not sure if it a good suggestion at this point in your development, but you should definitely look at Single Sign-on if you want to do it the "right" way.
Is it just me, or does it sound like your CSRFing yourself with your technique using images that works in Firefox?
Interesting approach, although I hope you're not opening yourself up to a security threat there.
I haven't done this myself, but I think you're going the right way. I would probably do the same, except instead of an image I would use a Javascript file. It would be generated on the serverer side and would update the cookies on the client side.
Possibly me being a bit silly, but could you not set the cookies for each domain name on login? So rather than them having one cookie when they login to Site A, they have five, or however many sites you have?
setcookie(A, $sessid, expire, path, domainA.com);
setcookie(B, $sessid, expire, path, domainB.com);
setcookie(C, $sessid, expire, path, domainC.com);
setcookie(D, $sessid, expire, path, domainD.com);
Related
I have an application which records users visits. None of these visits are directly accessed, 100% of these visits are referred from another site.
I am passing $_SERVER['HTTP_REFERER'] through to the database. Approximately 35% of the logged entrees pass a referer, the rest are blank.
Is there a reason for this?
There are a couple of number of reasons why HTTP_REFERER might be blank.
You have to understand it's an environment variable given by the browser. Meaning users can remove it or even change it, if they so intend to.
Users accessing the link from a bookmark, history or by typing the link manually do not have a referer.
IE has also been known to remove the referer in situations revolving around javascript. Such as window.open, window.location and even setting target="_blank" in anchors or meta refresh.
Clicking an embedded link in a chat application, PDF/Word/Excel document, will also not set a referer.
Using AJAX, file_get_contents, fopen and other similar functions in other languages will probably not set a referer request.
cURL, fsockopen, applications that have browser-like components might not set a referer.
There are probably more situations when this could happen, I'll update if I can think of anything that seems reasonable.
If a user visits your site directly, there is no referrer. It's also possible they have set it up so their browser never sends the referrer.
According to this answer, browsers do not necessarily send a referrer when doing a meta refresh.
Browsers sometimes will include the referer in the request. But it is not mandatory to do so (the referer is 100% voluntary). Indeed there are various privacy and security issues surrounding the referer (for example, if an HTTPS site refers you to an HTTP site, the browser should not include the referring site as the referer). So don't rely on it.
When linking from one document to another in Internet Explorer 4.0 and later, the Referer header will not be sent when the link is from an HTTPS page to a non-HTTPS page. The Referer header also will not be sent when the link is from a non-HTTP(S) protocol, such as file://, to another page. for more info go to this link
Direct access to your page (typing URL in address bar or from bookmarks, history, etc)
Browser settings (disabled referrer or empty)
if someone requests page content with file_get_contents() function...
It is common when you are stuck finding why it is missing:
- Sometime your referer is https and you are on http, it will be lost.
Otherwise:
- User accessing by inputing url directly.
- A user has bookmarked and come from bookmarks.
- Sometime user keep the url default for browser (similar like bookmark)
- Proxy surfying may remove referer.
- accessing website as bots (search engine)
It also depends on the Transport layer, I encountered an issue where my Consumer Application A was running on the HTTP layer while the Application from where I was sending the request was running on the HTTPS layer.
Is it possible to get remote username when I get a referral link without involving any server side code from the referral link?
Do you mean like if I clicked a link to your site on Stack Overflow, you would want to be able to see that my username is "Agent Conundrum"? No, you can't do that without the help of the referring site. The only information you should be able to get is the (permanently misspelled) HTTP_REFERER in the $_SERVER superglobal array, which tells you the page the user came from. Even then, there are ways to block or change this so you shouldn't count on it being set (especially since it wouldn't be set if the user navigated directly to your page via the address bar).
Frankly, I wouldn't want to use a site that leaked personal information (and for some sites, even the username qualifies as personal information), and I wouldn't want to use a site that tries to harvest such leaked information without my knowledge.
Generally, any site where you have a legitimate reason to broadcast this information would have some sort of API built in, like FacebookConnect. Even then, it should be strictly opt-in for the user.
As a general thing: no. The HTTP protocol does not involve the transmission of a remote user name.
Hey, it could help to answer if you would be a little more specific on which kind of service are you trying to fetch the data from.
Large/Public services tend to have somekind of an accessible API that you can fork on your referrer, but other than that its mostly that you need to regexp the site and know the structure of the HTML pretty much.
We got pitched this idea yesterday. A user visits our site and are marked. Then when they visit other sites like CNN they are targeted with adds for our site. So once they are exposed to us, they start to see us everywhere, creating the illusion we are bigger than we are.
The person pitching it said it was done by cookies. I was very skeptical since I don't believe there to be anyway to see what cookies a different domain has set. So I wanted to try an figure out how it was accomplished. The salesman called this technology pixel tracking.
I have never heard of pixel tracking but from my research I have found that it is placing a 1 pixel image that references a script on another domain with parameters to be executed. My first thought was, OK maybe its possible this way.. But I still don't know how?
Can anyone explain how they are able to mark you as visited our site, and then see this mark on another site? Is it from your IP?
Included at the bottom of the (CNN) website in this case is an img tag like:
<img src="http://www.webmarketingCompany.com/pixel.php?ID=623489593479">
When a user visits the (CNN) website, and the browser renders the page, it sends http requests for all the images as well, including a request to http://www.webmarketingCompany.com for the image pixel.php which includes the ID as a get parameter. pixel.php not only returns an image, typically a 1x1 transparent gif (so it isn't visible in the rendered page), but can do a whole host of additional processing using the ID value; and it also has access to any webmarketingCompany.com cookies, which are also sent with the http request.
Of course, CNN have to agree to include the img tag in their html. Typically it's used as a tracker by third party marketing companies working on behalf of CNN to identify who is visiting their site, what pages they're viewing, etc.
But because it's a PHP script, it can do a whole host of extras, such as setting further cookies. If webmarketingCompany.com also handle ad-serving on behalf of CNN, they can do some creative selection of the ads that they choose to serve.
Such cross-client "pollination" is frowned upon, certainly here in the UK.
What you are describing is pretty standard for all advertisement networks. The only difference here is that they will place that cookie on your site as well.
As long as the browser has "accept third party cookies" set to true, this will work as the salesman said. Most browsers has the setting set to true by default, the only exception I can think of is Safari.
two years ago I had to design a system to share authentication data across multiple domains, all of them shared the same server/db. I was able to pull this off with a complex system of cookie sharing which, to date still works.
I'm now in the process of redesigning the system and I was wondering if there are better ways to achieve this without having to write cross domain cookies.
Basically the system MUST do this.
Once logged in one site the user must be logged in all of the other site seamlessly, not only following a link, but even by directly writing the domain name on the address bar.
To my knowledge the only way to achieve this are cross-domain cookies, if there are alternatives please tell me.
Thank you very much
My Idea would be to include a login-Javascript from a third domain which gets includet in all sites. This javascript sets and reads the session-cookie and calls the current domains server via ajax with the result. (No validation should be done in the JS - this simply sets and reads the cookie)
If cross domain AJAX does not work, you can still call the thirds domain server which acts like a proxy and calls the current domains server.
The StackOverflow sites have implemented something similar to this. Check out the details at the following links.
Here is a post giving an outline of how they did it.
And here is even more detail.
For this you do have to use cookies, but you can vary what you store in the cookie. The cookie doesn't have to contain user credentials but can instead contain something more like a token that you use to "centralize" your sessions.
Easies way would be to let all hosts share a single memcached server and use the content of the users cookie as your key.
The company I work for has four domains and I'm trying to set up the cookies, so one cookie can be generated and tracked across all the domains. From reading various posts on here I thought it was possible.
I've set up a sub domain on one site, to serve a cookie and 1*1 pixel image to all four sites.
But I can't get this working on the other sites.
If anyone can clarify that:
Its possible?
If I'm missing something obvious or a link to a good example?
I'm trying to do this server side with PHP.
Thanks
Are you having issues due to Internet Explorer and their Privacy stuff?
Session variables are lost if you use FRAMESET in Internet Explorer 6
Back in my former internet days, when IE6 first came out, we had to implement this because it broke some of our tracking. Its amazing that all you have to do is fake it, and everything works fine.
Your on the right track, we had a domain that hosted the tracking cgi that served the 1x1 transparent pixel and tracked what page a user was visiting. We then had a custom parser that would combine that data with Apache logs and dynamically created a graph of users traffic patterns through our website. This was using dot from the Graphviz package.
This kind of thing is pretty easy if you are just trying to do stats, but if you're actually trying to persist user data across domains you'll have to do something more complicated.
The best way to set a cross-domain cookie is to make sure all your sites are subdomains of one master domain, say initech.com. So one of your site, site1.initech.com, sets the cookie with a domain of ".initech.com" and it works fine.
It could be a problem if your sites are on totally different domains though.
Rather than try to set one cookie that each site can access, what you'll have to do is make sure that each site has its own exact duplicate of the original cookie. So, have your site, site1.com, set the cookie for itself and output three 1x1 gifs, or AJAX calls or whatever, to site2.com, site3.com and site4.com setting the same cookie to the same value.
This will be difficult to do securely and reliably ;)
To make sure somebody can't set arbitrary cookies on your domain, you'll habe to pass through a hash of the cookie value on the image tag. If the cookie to be set is "mycookieval", also pass through md5("mycookieval"."somesecretstring".$_SERVER['REMOTE_ADDR']). This is potentially bad because it might allow an attacker to set the same cookie to the same IP address, or possibly to brute-force the hash generation.
You could compensate for this by inserting a record into a backend database whenever you set the cookie, and having the other three sites check against it for validity.
This question's pretty cold, but in case anyone else stumbling on it, or the OP still has need, I've created an NPM module, which allows you to share locally-stored data across domains. It looks like this would exactly address the OP's need here, and it doesn't require all sites share a base domain.
https://www.npmjs.com/package/cookie-toss
By using an iframe hosted on Domain A, you can store all of your user data on Domain A, and reference that data by posting requests to the Domain A iframe.
Thus, Domains B, C, etc. can inject the iframe and post requests to it to store and access the desired data. Domain A becomes the hub for all shared data.
With a domain whitelist inside of Domain A, you can ensure only your dependent sites can access the data on Domain A.
The trick is to have the code inside of the iframe on Domain A which is able to recognize which data is being requested. The README in the above NPM module goes more in depth into the procedure.
Hope this helps!