Apparently, I have completely misunderstood its semantics. I thought of something like this:
A client downloads JavaScript code MyCode.js from http://siteA - the origin.
The response header of MyCode.js contains Access-Control-Allow-Origin: http://siteB, which I thought meant that MyCode.js was allowed to make cross-origin references to the site B.
The client triggers some functionality of MyCode.js, which in turn make requests to http://siteB, which should be fine, despite being cross-origin requests.
Well, I am wrong. It does not work like this at all. So, I have read Cross-origin resource sharing and attempted to read Cross-Origin Resource Sharing in w3c recommendation.
One thing is sure - I still do not understand how I am supposed to use this header.
I have full control of both site A and site B. How do I enable the JavaScript code downloaded from the site A to access resources on the site B using this header?
P.S.: I do not want to utilize JSONP.
Access-Control-Allow-Origin is a CORS (cross-origin resource sharing) header.
When Site A tries to fetch content from Site B, Site B can send an Access-Control-Allow-Origin response header to tell the browser that the content of this page is accessible to certain origins. (An origin is a domain, plus a scheme and port number.) By default, Site B's pages are not accessible to any other origin; using the Access-Control-Allow-Origin header opens a door for cross-origin access by specific requesting origins.
For each resource/page that Site B wants to make accessible to Site A, Site B should serve its pages with the response header:
Access-Control-Allow-Origin: http://siteA.com
Modern browsers will not block cross-domain requests outright. If Site A requests a page from Site B, the browser will actually fetch the requested page on the network level and check if the response headers list Site A as a permitted requester domain. If Site B has not indicated that Site A is allowed to access this page, the browser will trigger the XMLHttpRequest's error event and deny the response data to the requesting JavaScript code.
Non-simple requests
What happens on the network level can be slightly more complex than explained above. If the request is a "non-simple" request, the browser first sends a data-less "preflight" OPTIONS request, to verify that the server will accept the request. A request is non-simple when either (or both):
using an HTTP verb other than GET or POST (e.g. PUT, DELETE)
using non-simple request headers; the only simple requests headers are:
Accept
Accept-Language
Content-Language
Content-Type (this is only simple when its value is application/x-www-form-urlencoded, multipart/form-data, or text/plain)
If the server responds to the OPTIONS preflight with appropriate response headers (Access-Control-Allow-Headers for non-simple headers, Access-Control-Allow-Methods for non-simple verbs) that match the non-simple verb and/or non-simple headers, then the browser sends the actual request.
Supposing that Site A wants to send a PUT request for /somePage, with a non-simple Content-Type value of application/json, the browser would first send a preflight request:
OPTIONS /somePage HTTP/1.1
Origin: http://siteA.com
Access-Control-Request-Method: PUT
Access-Control-Request-Headers: Content-Type
Note that Access-Control-Request-Method and Access-Control-Request-Headers are added by the browser automatically; you do not need to add them. This OPTIONS preflight gets the successful response headers:
Access-Control-Allow-Origin: http://siteA.com
Access-Control-Allow-Methods: GET, POST, PUT
Access-Control-Allow-Headers: Content-Type
When sending the actual request (after preflight is done), the behavior is identical to how a simple request is handled. In other words, a non-simple request whose preflight is successful is treated the same as a simple request (i.e., the server must still send Access-Control-Allow-Origin again for the actual response).
The browsers sends the actual request:
PUT /somePage HTTP/1.1
Origin: http://siteA.com
Content-Type: application/json
{ "myRequestContent": "JSON is so great" }
And the server sends back an Access-Control-Allow-Origin, just as it would for a simple request:
Access-Control-Allow-Origin: http://siteA.com
See Understanding XMLHttpRequest over CORS for a little more information about non-simple requests.
Cross-Origin Resource Sharing - CORS (A.K.A. Cross-Domain AJAX request) is an issue that most web developers might encounter, according to Same-Origin-Policy, browsers restrict client JavaScript in a security sandbox, usually JS cannot directly communicate with a remote server from a different domain. In the past developers created many tricky ways to achieve Cross-Domain resource request, most commonly using ways are:
Use Flash/Silverlight or server side as a "proxy" to communicate
with remote.
JSON With Padding (JSONP).
Embeds remote server in an iframe and communicate through fragment or window.name, refer here.
Those tricky ways have more or less some issues, for example JSONP might result in security hole if developers simply "eval" it, and #3 above, although it works, both domains should build strict contract between each other, it neither flexible nor elegant IMHO:)
W3C had introduced Cross-Origin Resource Sharing (CORS) as a standard solution to provide a safe, flexible and a recommended standard way to solve this issue.
The Mechanism
From a high level we can simply deem CORS as a contract between client AJAX call from domain A and a page hosted on domain B, a typical Cross-Origin request/response would be:
DomainA AJAX request headers
Host DomainB.com
User-Agent Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0) Gecko/20100101 Firefox/4.0
Accept text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8,application/json
Accept-Language en-us;
Accept-Encoding gzip, deflate
Keep-Alive 115
Origin http://DomainA.com
DomainB response headers
Cache-Control private
Content-Type application/json; charset=utf-8
Access-Control-Allow-Origin DomainA.com
Content-Length 87
Proxy-Connection Keep-Alive
Connection Keep-Alive
The blue parts I marked above were the kernal facts, "Origin" request header "indicates where the cross-origin request or preflight request originates from", the "Access-Control-Allow-Origin" response header indicates this page allows remote request from DomainA (if the value is * indicate allows remote requests from any domain).
As I mentioned above, W3 recommended browser to implement a "preflight request" before submiting the actually Cross-Origin HTTP request, in a nutshell it is an HTTP OPTIONS request:
OPTIONS DomainB.com/foo.aspx HTTP/1.1
If foo.aspx supports OPTIONS HTTP verb, it might return response like below:
HTTP/1.1 200 OK
Date: Wed, 01 Mar 2011 15:38:19 GMT
Access-Control-Allow-Origin: http://DomainA.com
Access-Control-Allow-Methods: POST, GET, OPTIONS, HEAD
Access-Control-Allow-Headers: X-Requested-With
Access-Control-Max-Age: 1728000
Connection: Keep-Alive
Content-Type: application/json
Only if the response contains "Access-Control-Allow-Origin" AND its value is "*" or contain the domain who submitted the CORS request, by satisfying this mandtory condition browser will submit the actual Cross-Domain request, and cache the result in "Preflight-Result-Cache".
I blogged about CORS three years ago: AJAX Cross-Origin HTTP request
According to this Mozilla Developer Network article,
A resource makes a cross-origin HTTP request when it requests a resource from a different domain, or port than the one which the first resource itself serves.
An HTML page served from http://domain-a.com makes an <img> src request for http://domain-b.com/image.jpg.
Many pages on the web today load resources like CSS style sheets, images and scripts from separate domains (thus it should be cool).
Same-Origin Policy
For security reasons, browsers restrict cross-origin HTTP requests initiated from within scripts.
For example, XMLHttpRequest and Fetch follow the same-origin policy.
So, a web application using XMLHttpRequest or Fetch could only make HTTP requests to its own domain.
Cross-Origin Resource Sharing (CORS)
To improve web applications, developers asked browser vendors to allow cross-domain requests.
The Cross-origin resource sharing (CORS) mechanism gives web servers cross-domain access controls, which enable secure cross-domain data transfers.
Modern browsers use CORS in an API container - such as XMLHttpRequest or fetch - to mitigate risks of cross-origin HTTP requests.
How CORS works (Access-Control-Allow-Origin header)
Wikipedia:
The CORS standard describes new HTTP headers which provide browsers and servers a way to request remote URLs only when they have permission.
Although some validation and authorization can be performed by the server, it is generally the browser's responsibility to support these headers and honor the restrictions they impose.
Example
The browser sends the OPTIONS request with an Origin HTTP header.
The value of this header is the domain that served the parent page. When a page from http://www.example.com attempts to access a user's data in service.example.com, the following request header would be sent to service.example.com:
Origin: http://www.example.com
The server at service.example.com may respond with:
An Access-Control-Allow-Origin (ACAO) header in its response indicating which origin sites are allowed.
For example:
Access-Control-Allow-Origin: http://www.example.com
An error page if the server does not allow the cross-origin request
An Access-Control-Allow-Origin (ACAO) header with a wildcard that allows all domains:
Access-Control-Allow-Origin: *
Whenever I start thinking about CORS, my intuition about which site hosts the headers is incorrect, just as you described in your question. For me, it helps to think about the purpose of the same-origin policy.
The purpose of the same-origin policy is to protect you from malicious JavaScript on siteA.com accessing private information you've chosen to share only with siteB.com. Without the same-origin policy, JavaScript written by the authors of siteA.com could have your browser make requests to siteB.com, using your authentication cookies for siteB.com. In this way, siteA.com could steal the secret information you share with siteB.com.
Sometimes you need to work cross domain, which is where CORS comes in. CORS relaxes the same-origin policy for siteB.com, using the Access-Control-Allow-Origin header to list other domains (siteA.com) that are trusted to run JavaScript that can interact with siteB.com.
To understand which domain should serve the CORS headers, consider this. You visit malicious.com, which contains some JavaScript that tries to make a cross domain request to mybank.com. It should be up to mybank.com, not malicious.com, to decide whether or not it sets CORS headers that relax the same-origin policy, allowing the JavaScript from malicious.com to interact with it. If malicous.com could set its own CORS headers allowing its own JavaScript access to mybank.com, this would completely nullify the same-origin policy.
I think the reason for my bad intuition is the point of view I have when developing a site. It's my site, with all my JavaScript. Therefore, it isn't doing anything malicious, and it should be up to me to specify which other sites my JavaScript can interact with. When in fact I should be thinking: Which other sites' JavaScript are trying to interact with my site and should I use CORS to allow them?
From my own experience, it's hard to find a simple explanation why CORS is even a concern.
Once you understand why it's there, the headers and discussion becomes a lot clearer. I'll give it a shot in a few lines.
It's all about cookies. Cookies are stored on a client by their domain.
An example story: On your computer, there's a cookie for yourbank.com. Maybe your session is in there.
Key point: When a client makes a request to the server, it will send the cookies stored under the domain for that request.
You're logged in on your browser to yourbank.com. You request to see all your accounts, and cookies are sent for yourbank.com. yourbank.com receives the pile of cookies and sends back its response (your accounts).
If another client makes a cross origin request to a server, those cookies are sent along, just as before. Ruh roh.
You browse to malicious.com. Malicious makes a bunch of requests to different banks, including yourbank.com.
Since the cookies are validated as expected, the server will authorize the response.
Those cookies get gathered up and sent along - and now, malicious.com has a response from yourbank.
Yikes.
So now, a few questions and answers become apparent:
"Why don't we just block the browser from doing that?" Yep. That's CORS.
"How do we get around it?" Have the server tell the request that CORS is OK.
1. A client downloads javascript code MyCode.js from http://siteA - the origin.
The code that does the downloading - your html script tag or xhr from javascript or whatever - came from, let's say, http://siteZ. And, when the browser requests MyCode.js, it sends an Origin: header saying "Origin: http://siteZ", because it can see that you're requesting to siteA and siteZ != siteA. (You cannot stop or interfere with this.)
2. The response header of MyCode.js contains Access-Control-Allow-Origin: http://siteB, which I thought meant that MyCode.js was allowed to make cross-origin references to the site B.
no. It means, Only siteB is allowed to do this request. So your request for MyCode.js from siteZ gets an error instead, and the browser typically gives you nothing. But if you make your server return A-C-A-O: siteZ instead, you'll get MyCode.js . Or if it sends '*', that'll work, that'll let everybody in. Or if the server always sends the string from the Origin: header... but... for security, if you're afraid of hackers, your server should only allow origins on a shortlist, that are allowed to make those requests.
Then, MyCode.js comes from siteA. When it makes requests to siteB, they are all cross-origin, the browser sends Origin: siteA, and siteB has to take the siteA, recognize it's on the short list of allowed requesters, and send back A-C-A-O: siteA. Only then will the browser let your script get the result of those requests.
Using React and Axios, join a proxy link to the URL and add a header as shown below:
https://cors-anywhere.herokuapp.com/ + Your API URL
Just adding the proxy link will work, but it can also throw an error for No Access again. Hence it is better to add a header as shown below.
axios.get(`https://cors-anywhere.herokuapp.com/[YOUR_API_URL]`,{headers: {'Access-Control-Allow-Origin': '*'}})
.then(response => console.log(response:data);
}
Warning: Not to be used in production
This is just a quick fix. If you're struggling with why you're not able to get a response, you can use this.
But again it's not the best answer for production.
If you are using PHP, try adding the following code at the beginning of the php file:
If you are using localhost, try this:
header("Access-Control-Allow-Origin: *");
If you are using external domains such as server, try this:
header("Access-Control-Allow-Origin: http://www.website.com");
I worked with Express.js 4, Node.js 7.4 and Angular, and I had the same problem. This helped me:
a) server side: in file app.js I add headers to all responses, like:
app.use(function(req, res, next) {
res.header('Access-Control-Allow-Origin', req.headers.origin);
res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
next();
});
This must be before all routes.
I saw a lot of added this headers:
res.header("Access-Control-Allow-Headers","*");
res.header('Access-Control-Allow-Credentials', true);
res.header('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE');
But I don’t need that,
b) client side: in sending by Ajax, you need to add "withCredentials: true," like:
$http({
method: 'POST',
url: 'url',
withCredentials: true,
data : {}
}).then(function(response){
// Code
}, function (response) {
// Code
});
If you want just to test a cross-domain application in which the browser blocks your request, then you can just open your browser in unsafe mode and test your application without changing your code and without making your code unsafe.
From macOS, you can do this from the terminal line:
open -a Google\ Chrome --args --disable-web-security --user-data-dir
In Python, I have been using the Flask-CORS library with great success. It makes dealing with CORS super easy and painless. I added some code from the library's documentation below.
Installing:
pip install -U flask-cors
Simple example that allows CORS for all domains on all routes:
from flask import Flask
from flask_cors import CORS
app = Flask(__name__)
CORS(app)
#app.route("/")
def helloWorld():
return "Hello, cross-origin-world!"
For more specific examples, see the documentation. I have used the simple example above to get around the CORS issue in an Ionic application I am building that has to access a separate flask server.
Simply paste the following code in your web.config file.
Noted that, you have to paste the following code under <system.webServer> tag
<httpProtocol>
<customHeaders>
<add name="Access-Control-Allow-Origin" value="*" />
<add name="Access-Control-Allow-Headers" value="Content-Type" />
<add name="Access-Control-Allow-Methods" value="GET, POST, PUT, DELETE, OPTIONS" />
</customHeaders>
</httpProtocol>
I can't configure it on the back-end server, but with these extensions in the browsers, it works for me:
For Firefox:
CORS Everywhere
For Google Chrome:
Allow CORS: Access-Control-Allow-Origin
Note: CORS works for me with this configuration:
For cross origin sharing, set header: 'Access-Control-Allow-Origin':'*';
Php: header('Access-Control-Allow-Origin':'*');
Node: app.use('Access-Control-Allow-Origin':'*');
This will allow to share content for different domain.
Nginx and Apache
As an addition to apsiller's answer, I would like to add a wiki graph which shows when a request is simple or not (and OPTIONS pre-flight request is send or not)
For a simple request (e.g., hotlinking images), you don't need to change your server configuration files, but you can add headers in the application (hosted on the server, e.g., in PHP) like Melvin Guerrero mentions in his answer - but remember: if you add full CORS headers in your server (configuration) and at same time you allow simple CORS in the application (e.g., PHP), this will not work at all.
And here are configurations for two popular servers:
turn on CORS on Nginx (nginx.conf file)
location ~ ^/index\.php(/|$) {
...
add_header 'Access-Control-Allow-Origin' "$http_origin" always; # if you change "$http_origin" to "*" you shoud get same result - allow all domain to CORS (but better change it to your particular domain)
add_header 'Access-Control-Allow-Credentials' 'true' always;
if ($request_method = OPTIONS) {
add_header 'Access-Control-Allow-Origin' "$http_origin"; # DO NOT remove THIS LINES (doubled with outside 'if' above)
add_header 'Access-Control-Allow-Credentials' 'true';
add_header 'Access-Control-Max-Age' 1728000; # cache preflight value for 20 days
add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS'; # arbitrary methods
add_header 'Access-Control-Allow-Headers' 'My-First-Header,My-Second-Header,Authorization,Content-Type,Accept,Origin'; # arbitrary headers
add_header 'Content-Length' 0;
add_header 'Content-Type' 'text/plain charset=UTF-8';
return 204;
}
}
turn on CORS on Apache (.htaccess file)
# ------------------------------------------------------------------------------
# | Cross-domain Ajax requests |
# ------------------------------------------------------------------------------
# Enable cross-origin Ajax requests.
# http://code.google.com/p/html5security/wiki/CrossOriginRequestSecurity
# http://enable-cors.org/
# change * (allow any domain) below to your domain
Header set Access-Control-Allow-Origin "*"
Header always set Access-Control-Allow-Methods "POST, GET, OPTIONS, DELETE, PUT"
Header always set Access-Control-Allow-Headers "My-First-Header,My-Second-Header,Authorization, content-type, csrf-token"
Header always set Access-Control-Allow-Credentials "true"
The Access-Control-Allow-Origin response header indicates whether the
response can be shared with requesting code from the given origin.
Header type Response header
-------------------------------------------
Forbidden header name no
A response that tells the browser to allow code from any origin to
access a resource will include the following:
Access-Control-Allow-Origin: *
For more information, visit Access-Control-Allow-Origin...
For .NET Core 3.1 API With Angular
Startup.cs : Add CORS
//SERVICES
public void ConfigureServices(IServiceCollection services){
//CORS (Cross Origin Resource Sharing)
//=====================================
services.AddCors();
}
//MIDDLEWARES
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
app.UseRouting();
//ORDER: CORS -> Authentication -> Authorization)
//CORS (Cross Origin Resource Sharing)
//=====================================
app.UseCors(x=>x.AllowAnyHeader().AllowAnyMethod().WithOrigins("http://localhost:4200"));
app.UseHttpsRedirection();
}
}
Controller : Enable CORS For Authorized Controller
//Authorize all methods inside this controller
[Authorize]
[EnableCors()]
public class UsersController : ControllerBase
{
//ActionMethods
}
Note: Only a temporary solution for testing
For those who can't control the backend for Options 405 Method Not Allowed, here is a workaround for theChrome browser.
Execute in the command line:
"C:\Program Files (x86)\Google\Chrome\Application\chrome.exe" --disable-web-security --user-data-dir="path_to_profile"
Example:
"C:\Program Files (x86)\Google\Chrome\Application\chrome.exe" --disable-web-security --user-data-dir="C:\Users\vital\AppData\Local\Google\Chrome\User Data\Profile 2"
Most CORS issues are because you are trying to request via client side ajax from a react, angular, jquery apps that are frontend basic libs.
You must request from a backend application.
You are trying to request from a frontend API, but the API you are trying to consume is expecting this request to be made from a backend application and it will never accept client side requests.
Related
I have a generic handler (cookiecutter.ashx) on a cloud server that sets a cookie. I need to read this cookie from my local production server. The cloud server uses a subdomain of the domain on the production server (for example the handler is at cloudserver.example.com and the production server is www.example.com). The domain of the cookie is set to ".example.com". If I browse directly to cookiecutter.ashx in a browser, the cookie gets created and is visible in the browser cookie collection (using Chrome DevTools) and I can read the cookie from www.example.com. However, if I make an ajax call(JQuery) to the handler from www.example.com, the cookie can't be read from www.example.com and does not appear in the browser cookie collection.
Why is the cookie only readable from www.example.com if I browse directly to the handler? Is there any way to get the same result when calling the handler using ajax?
I finally have it working.
When it wasn't working, I had the following HTTP Response Headers on the server where the cookie is created:
Access-Control-Allow-Origin = *, Access-Control-Allow-Methods = GET, POST, OPTIONS
The solution was:
Add the following HTTP Response Header:
Access-Control-Allow-Credentials = true
Change Access-Control-Allow-Origin to https://www.example.com (you can't use a wildcard when implementing the Access-Control-Allow-Credentials header; you have to specify the origin)
Add the following parameter to the JQuery AJAX call to the handler:
xhrFields: {withCredentials: true}
Add the Secure attribute to the cookie when it is created (theCookie.Secure=true;)
Add the following to the system.web section of the web.config file for the project that creates the cookie:
<httpCookies sameSite="None" />
I should also mention that you must be using the same machine key for the project that creates the cookie and the project(s) that read the cookie.
Finally, if the cookie is to be read by a mixture of .NET frameworks, you will also need to add a CompatabilityMode to the machine key. In my case all frameworks were .NET 2.0 or greater so I used: compatibilityMode="Framework20SP2"
More on compatabilityMode here: https://learn.microsoft.com/en-us/dotnet/api/system.web.configuration.machinekeysection.compatibilitymode?view=netframework-4.8.
I am issuing a request via chrome:
[org]/api/data/v8.1/accounts?$select=name,accountid&$top=3
and I get a reasonable response:
{
"#odata.context":"[org]/api/data/v8.1/$metadata#accounts(name,accountid)","value":[
{
"#odata.etag":"W/\"769209\"","name":"Telco","accountid":"c6ed63e0-9664-e411-940d-00155d104b35"
},{
"#odata.etag":"W/\"752021\"","name":"Fourth Coffee","accountid":"d1eefc0a-3ebc-e611-80be-24be051ac8a1"
},{
"#odata.etag":"W/\"768036\"","name":"Fourth Coffee","accountid":"3cbb8d24-20bd-e611-80c0-24be051ac8a1"
}
]
}
However, when attempting to do the same GET through postman, I am getting a 401 unauthorized!
I've tried with no headers at all, as well as basic auth:
Authorization:Basic Y2hybGFiXxxxxxxxxxxxxxcmQxMjM=
What am I doing wrong? Is there something I need to change within CRM to allow me to do GETs from postman?
The following are headers that Chrome uses (got this from DevTools):
Accept:text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,/;q=0.8
Accept-Encoding:gzip, deflate, sdch
Accept-Language:en-US,en;q=0.8
Authorization:Negotiate
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
Cache-Control:max-age=0
Cookie:ReqClientId=42484e9a-f488-41a9-a016-1cd6e5820b3c
Host:myhost....
Proxy-Connection:keep-alive
Upgrade-Insecure-Requests:1
User-Agent:Mozilla/5.0 (Linux; Android 6.0; Nexus 5 Build/MRA58N) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/57.0.2987.133 Mobile Safari/537.36
First, login into CRM and leave the tab sitting there.
Go into POSTMan
Enable the Interceptor (see image)
Enter the URL and hit SEND, just like that. POSTMan will take care of cookies and headers on its own, and you'll see the results.
If you logout from CRM, POSTMan will obviously no longer be able to issue the requests and will return 401 instead.
It seems like the server you are calling requires RFC 4559 (https://www.rfc-editor.org/rfc/rfc4559) authentication. More details here: https://en.wikipedia.org/wiki/SPNEGO.
The way it works in the case of a GET request from the browser:
Browser requests the required page
The server responds with HTTP 401 (Unauthorized) and provides a response header WWW-Authenticate: Negotiate. This tell the browser that RFC 4559 authentication is required.
The browser makes sure the site has permissions for this action (details on configuration here: https://ping.force.com/Support/PingFederate/Integrations/How-to-configure-supported-browsers-for-Kerberos-NTLM). Most sites will not be allowed to request such authorization without being explicitly white-listed.
If permitted, the browser requests a Kerboros ticket from the domain's Active Directory.
Active Directory responds with a ticket.
The browser forward the ticker to the server (via the Authotizarion: Negotiate xxxxx header that you see).
The server interacts with the same Active Directory and turns that ticket into username and groups/permissions information.
I am not aware of a tool that will let you do this (simulate a browser) if you are trying to automate requests against the server (which is probably an internal/intranet company site). Your best course of action may be some form of scripting (like VBS) which will use IE via COM and possibly handle this authentication for you (I have not done this, so not sure if it will indeed work).
You are trying to access from the postman chrome extension or through the postman( windows based) installed application on your system.Try to fetch the data from chrome extension.
I used the following steps and it was ok. Follow the steps, below:
Open Google Chrome
Install Postman Extention
Install Postman's Interceptor Extention
Open Postman Extention
Use Sync
Use Interceptor
In my case in .NET project i had two different authentication schemes in my Startup.cs . I removed the older one and added its auth services and it worked.
Try putting quotes around your url:
curl '[org]/api/data/v8.1/accounts?$select=name,accountid&$top=3'
The &, $, = etc. may be causing problems - I had the same problem and putting quotes was the resolution
These helped me.
Check that it is NTLM authentication both in postman and in the page hosted it is checked.
Use method post
Username and password(which you have set and need not be the access key)
This solved my issue.
In Postman, I copied the Access Token from Authorization tab and I have selected "No Auth" Type.
Then, I moved to Headers tab, Under Headers section, I have provided new Key with Name "Authorization" and in the Value I have passed my TOKEN prefix with Bearer.See the below screenshot
If request works from the browser, then no authentication was used.
So, in Postman, for Authentication, use No Auth. :-)
In the WebAPI application I have the Custom CORS policy implemented as described in the article: http://www.asp.net/web-api/overview/security/enabling-cross-origin-requests-in-web-api#allowed-origins but the origins are set in the web.config file in the custom section. And I have the angular client application that sends the requests to the WebAPI one.
I tried two scenarios:
1) Run the application using the localhost url.
2) Run the application using the computer name.
In both the cases I have the origins included in the web.config file. In first case everything works fine. In the second the CORS preflight requests are sent, but there is no actual GET or POST request following. In the preflight response there are the correct headers:
Access-Control-Allow-Headers: content-type, custom-session-id
Access-Control-Allow-Methods: GET, POST, PUT, PATCH, DELETE, OPTIONS
Access-Control-Allow-Origin: http://computername
What can be wrong? I would appreciate any help.
Edit: screenshot from the fiddler:
I have found the solution: there was a missing setting in the CorsPolicy object: SupportsCredentials needed to be set. I have not expected that even if I do not send the credentials I still need to set this flag.
I have a javascript AJAX call made to a code behind function running on my server, which returns to the client script (that has initiated the call), a url (from a different Domain than mine) with a query (http://www.web_server_url.com/my_query&callback=?). After returning the call, the following JQuery code is executed ('specific_div' being an existing div in the page):
$('#specific_div').load(returned_url);
Meanwhile, I obtain the following error message:
XMLHttpRequest cannot load http://www.web_server_url.com/my_query&callback=?. Origin http://localhost is not allowed by Access-Control-Allow-Origin.
Although I understand the same-origin policy, I do not quite understand why I am obtaining this error message in this scenario since the url is passed from my server. Shouldn’t it be accepted by the browser, considering that its origin is from the same Domain (local host in this case), although it is contacting another Domain?
Same origin means requested resource/information must be on the same domain (schema + host + port) as page. It does not mean "url to resource provided by the origin server".
In your particular case you have page on "http://localhost" and trying to request "http://www.web_server_url.com" - scheme ("http") and port (80) match, but domain name does not ("localhost" vs. "www.web_server_url.com").
Note that error you see explains that you need to enable CORS on destination server for this particular request.
If you don't own/control destination server (and hence can't use CORS or JSONP to securely communicate with other server client side) than you most generic option is proxy that request on your server. Note that limits on what information you can use (i.e. you can't steal cookies set on the destination domain this way).
This is more for curiosity as I'm failing to find any answers or documentation for this phenomenon, but here's the scenario:
There are 2 services/applications, both hosted on IIS 7. Service 1 receives an HTTPS request from an external source (browser, fiddler, etc.) and to validate the request it needs to call service 2, so service 1 makes its own, new, separate call over HTTP to service 2. This call has an Authorization header added to the request object. When service 2 receives this call, the authentication header is gone, as if stripped out. Thus the authentication fails, this returns to service 1 which then rejects the external call.
Does anyone have an explanation why this header, and some others from what I've seen in testing, doesn't make it through with the HTTP call? Is this a behavior of IIS, or ASP.NET, or something? If the call to service 2 was HTTPS then the headers make it through fine. I'm generating the request like so:
string uriendpoint = "http://service.test.com/testService.svc/authtest";
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uriendpoint);
request.Credentials = CredentialCache.DefaultCredentials;
var authField = MD5Hash("test:test!!2013");
request.Headers.Add(HttpRequestHeader.Authorization, authField.ToString());
request.Method = WebRequestMethods.Http.Get;
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
Most likely the "service 2" have code similar to "If incoming request is HTTP ignore authorization headers". It is very reasonable behavior as HTTP traffic can be very easily sniffed and replayed - so honest servers block callers from potentially unsecure behavior.
A co-worker of mine came across the root cause of this behavior being IIS's "URL Rewrite" module. We had it setup to do a permanent redirect of http requests to https, and this redirect is where the headers get dropped. It's a bit odd that IIS does this, but I guess I'll just try something else to get around this problem.