| HTTP |
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| Request methods |
| Header fields |
| Response status codes |
| Security access control methods |
| Security vulnerabilities |
HTTP 403 is an HTTP status code meaning access to the requested resource is forbidden. The server understood the request, but will not fulfill it, if it was correct.
HTTP 403 provides a distinct error case from HTTP 401; while HTTP 401 is returned when the client has not authenticated, and implies that a successful response may be returned following valid authentication, HTTP 403 is returned when the client is not permitted access to the resource despite providing authentication such as insufficient permissions of the authenticated account. [lower-alpha 1]
Error 403: "The server understood the request, but is refusing to authorize it." (RFC 7231) [1]
Error 401: "The request requires user authentication. The response MUST include a WWW-Authenticate header field (section 14.47) containing a challenge applicable to the requested resource. The client MAY repeat the request with a suitable Authorization header field (section 14.8). If the request already included Authorization credentials, then the 401 response indicates that authorization has been refused for those credentials." (RFC 2616) [2]
The Apache web server returns 403 Forbidden in response to requests for URL [3] paths that corresponded to file system directories when directory listings have been disabled in the server and there is no Directory Index directive to specify an existing file to be returned to the browser. Some administrators configure the Mod proxy extension to Apache to block such requests and this will also return 403 Forbidden. Microsoft IIS responds in the same way when directory listings are denied in that server. In WebDAV, the 403 Forbidden response will be returned by the server if the client issued a PROPFIND request but did not also issue the required Depth header or issued a Depth header of infinity. [3]
A 403 status code can occur for the following reasons: [4]
Client request: [5]
GET/securedpage.phpHTTP/1.1Host:www.example.orgServer response: [5]
HTTP/1.1403ForbiddenContent-Type:text/html<html><head><title>403 Forbidden</title></head><body><h1>Forbidden</h1><p>You don't have permission to access /securedpage.php on this server.</p></body></html>
The following nonstandard codes are returned by Microsoft's Internet Information Services, and are not officially recognized by IANA. [6]
The Hypertext Transfer Protocol (HTTP) is an application layer protocol in the Internet protocol suite model for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web, where hypertext documents include hyperlinks to other resources that the user can easily access, for example by a mouse click or by tapping the screen in a web browser.
The Session Initiation Protocol (SIP) is a signaling protocol used for initiating, maintaining, and terminating communication sessions that include voice, video and messaging applications. SIP is used in Internet telephony, in private IP telephone systems, as well as mobile phone calling over LTE (VoLTE).
A web server is computer software and underlying hardware that accepts requests via HTTP or its secure variant HTTPS. A user agent, commonly a web browser or web crawler, initiates communication by making a request for a web page or other resource using HTTP, and the server responds with the content of that resource or an error message. A web server can also accept and store resources sent from the user agent if configured to do so.
In computer network communications, the HTTP 404, 404 not found, 404, 404 error, page not found, or file not found error message is a hypertext transfer protocol (HTTP) standard response code, to indicate that the browser was able to communicate with a given server, but the server could not find what was requested. The error may also be used when a server does not wish to disclose whether it has the requested information.
An email client, email reader or, more formally, message user agent (MUA) or mail user agent is a computer program used to access and manage a user's email.
The File Transfer Protocol (FTP) is a standard communication protocol used for the transfer of computer files from a server to a client on a computer network. FTP is built on a client–server model architecture using separate control and data connections between the client and the server. FTP users may authenticate themselves with a plain-text sign-in protocol, normally in the form of a username and password, but can connect anonymously if the server is configured to allow it. For secure transmission that protects the username and password, and encrypts the content, FTP is often secured with SSL/TLS (FTPS) or replaced with SSH File Transfer Protocol (SFTP).
In computer networking, a proxy server is a server application that acts as an intermediary between a client requesting a resource and the server providing that resource. It improves privacy, security, and performance in the process.
WebDAV is a set of extensions to the Hypertext Transfer Protocol (HTTP), which allows user agents to collaboratively author contents directly in an HTTP web server by providing facilities for concurrency control and namespace operations, thus allowing Web to be viewed as a writeable, collaborative medium and not just a read-only medium. WebDAV is defined in RFC 4918 by a working group of the Internet Engineering Task Force (IETF).
Remote Authentication Dial-In User Service (RADIUS) is a networking protocol that provides centralized authentication, authorization, and accounting (AAA) management for users who connect and use a network service. RADIUS was developed by Livingston Enterprises in 1991 as an access server authentication and accounting protocol. It was later brought into IEEE 802 and IETF standards.
In the context of an HTTP transaction, basic access authentication is a method for an HTTP user agent to provide a user name and password when making a request. In basic HTTP authentication, a request contains a header field in the form of Authorization: Basic <credentials>, where <credentials> is the Base64 encoding of ID and password joined by a single colon :.
Digest access authentication is one of the agreed-upon methods a web server can use to negotiate credentials, such as username or password, with a user's web browser. This can be used to confirm the identity of a user before sending sensitive information, such as online banking transaction history. It applies a hash function to the username and password before sending them over the network. In contrast, basic access authentication uses the easily reversible Base64 encoding instead of hashing, making it non-secure unless used in conjunction with TLS.
On the World Wide Web, HTTP 301 is the HTTP response status code for 301 Moved Permanently. It is used for permanent redirecting, meaning that links or records returning this response should be updated. The new URL should be provided in the Location field, included with the response. The 301 redirect is considered a best practice for upgrading users from HTTP to HTTPS.
HTTP Status Code 402, also known as "Payment Required," is a standard response
The HTTP Location header field is returned in responses from an HTTP server under two circumstances:
WebSocket is a computer communications protocol, providing simultaneous two-way communication channels over a single Transmission Control Protocol (TCP) connection. The WebSocket protocol was standardized by the IETF as RFC 6455 in 2011. The current specification allowing web applications to use this protocol is known as WebSockets. It is a living standard maintained by the WHATWG and a successor to The WebSocket API from the W3C.
In computer networking, HTTP 451 Unavailable For Legal Reasons is a proposed standard error status code of the HTTP protocol to be displayed when the user requests a resource which cannot be served for legal reasons, such as a web page censored by a government. The number 451 is a reference to Ray Bradbury's 1953 dystopian novel Fahrenheit 451, in which books are outlawed. 451 provides more information than HTTP 403, which is often used for the same purpose. This status code is currently a proposed standard in RFC 7725 but is not yet formally a part of HTTP, as of RFC 9110.
The Session Initiation Protocol (SIP) is the signaling protocol selected by the 3rd Generation Partnership Project (3GPP) to create and control multimedia sessions with multiple participants in the IP Multimedia Subsystem (IMS). It is therefore a key element in the IMS framework.
