TCP/IP Tutorial and Technical Overview - IBM Redbooks

– 413 Request Entity Too Large
– 414 Request-URI Too Long
– 415 Unsupported Media Type
► Server error (5xx)
This class of codes indicate client errors. Currently defined codes are as
follows:
– 500 Internal Server Error
– 501 Not Implemented
– 502 Bad Gateway
– 503 Service Unavailable
– 504 Gateway Timeout
– 505 HTTP Version Not Supported
Access authentication
HTTP provides an authentication mechanism to allow servers to define access
permissions on resources and clients to use these resources. The authentication
method can be one of the following:
► Basic authentication scheme
Basic authentication is based on user IDs and passwords. In this
authentication scheme, the server permits the connection only if the user ID
and password are validated. In basic authentication, user IDs and passwords
are not encrypted. They are encoded in Base64 format (see “Base64
encoding” on page 584). Therefore, the use of SSL or TLS is highly
recommended.
► Digest authentication scheme
Digest authentication scheme is an extension to HTTP and described in RFC
2617. In this authentication scheme, the user ID and a digest containing a
hash value of the password are sent to the server. The server computes a
similar digest and grants access to the protected resources if the two digests
are equal. Notice that if the digest authentication is enabled, what is sent over
the network is not simply an encrypted form of the password, which could be
decrypted if one had the correct key, but is a one-hash value of the password,
which cannot be decrypted. So, digest authentication provides a higher level
of security than the Base64 encoded password. Unfortunately, digest
authentication is not yet supported by all browsers.
Chapter 16. The Web 613