HTTP Basic Authentication - what's the expected web browser experience?

260
votes

When a server allows access via Basic HTTP Authentication, what is the experience expected to be in a web browser?

Ignoring the web browser for a moment, here's how to create a Basic Auth request with curl:

curl -u myusername:mypassword http://somesite.com

But what about in a Web Browser? What I've seen on some websites, is I visit the URL, and then the server returns response code 401. The browser then displays a username/password prompt.

However, on somesite.com, I'm not getting an authorization prompt at all, just a page that says I'm not authorized. Did somesite not implement the Basic Auth workflow correctly, or is there something else I need to do?

6
basic-authentication
Are you sure you use Basic Auth and not Digest? – b_erb
not sure of the difference, unless you are asking if I base-64 encode. if i was doing that programatically it would, but curl does that for me. – bpapa
You can find out what authentication is used from WWW-Authenticate response header (value: Digest or Basic). – Kniganapolke
I think this question needs to be rephrased. More than one respondent thinks it's a question about curl rather than the browser. – Mr. Lance E Sloan
Do you mean "authentication" when you use term "authorization" ? – Tarun

6 Answers

161
votes

To help everyone avoid confusion, I will reformulate the question in two parts.

First : "how can make an authenticated HTTP request with a browser, using BASIC auth?".

In the browser you can do a http basic auth first by waiting the prompt to come, or by editing the URL if you follow this format: http://myusername:[email protected]

NB: the curl command mentionned in the question is perfectly fine, if you have a command-line and curl installed. ;)

References:

Also according to the CURL manual page https://curl.haxx.se/docs/manual.html

HTTP

  Curl also supports user and password in HTTP URLs, thus you can pick a file
  like:

      curl http://name:[email protected]/full/path/to/file

  or specify user and password separately like in

      curl -u name:passwd http://machine.domain/full/path/to/file

  HTTP offers many different methods of authentication and curl supports
  several: Basic, Digest, NTLM and Negotiate (SPNEGO). Without telling which
  method to use, curl defaults to Basic. You can also ask curl to pick the
  most secure ones out of the ones that the server accepts for the given URL,
  by using --anyauth.

  NOTE! According to the URL specification, HTTP URLs can not contain a user
  and password, so that style will not work when using curl via a proxy, even
  though curl allows it at other times. When using a proxy, you _must_ use
  the -u style for user and password.

The second and real question is "However, on somesite.com, I'm not getting an authorization prompt at all, just a page that says I'm not authorized. Did somesite not implement the Basic Auth workflow correctly, or is there something else I need to do?"

The curl documentation says the -u option supports many method of authentication, Basic being the default.

69
votes

Have you tried ? 

curl somesite.com --user username:password
15
votes

You might have old invalid username/password cached in your browser. Try clearing them and check again.

If you are using IE and somesite.com is in your Intranet security zone, IE may be sending your windows credentials automatically.

9
votes

WWW-Authenticate header

You may also get this if the server is sending a 401 response code but not setting the WWW-Authenticate header correctly - I should know, I've just fixed that in out own code because VB apps weren't popping up the authentication prompt.

7
votes

If there are no credentials provided in the request headers, the following is the minimum response required for IE to prompt the user for credentials and resubmit the request.

Response.Clear();
Response.StatusCode = (Int32)HttpStatusCode.Unauthorized;
Response.AddHeader("WWW-Authenticate", "Basic");
5
votes

You can use Postman a plugin for chrome. It gives the ability to choose the authentication type you need for each of the requests. In that menu you can configure user and password. Postman will automatically translate the config to a authentication header that will be sent with your request.