HTTP Error 407 - Proxy authentication required
Introduction
Your Web server thinks that the HTTP data stream sent from the client (e.g. your Web
browser) was correct, but access to the URL resource requires the prior use of a proxy server
that needs some authentication which has not been provided. This typically means you must
log in (enter user ID and password) with the proxy server first.
A 407 error detected via a Web browser can often be resolved by navigating to the URL in a
slightly different way e.g. accessing another URL for the proxy server first. Your ISP should
be able to explain the role of the proxy server in their security setup and how you should use
it.
407 errors in the HTTP cycle
Any client (e.g. your Web browser) goes through the following cycle:
Obtain an IP address from the IP name of your site (your site URL without the leading
'http://'). This lookup (conversion of IP name to IP address) is provided by domain name
servers (DNSs).
Open an IP socket connection to that IP address.
Write an HTTP data stream through that socket.
Receive an HTTP data stream back from your Web server in response. This data stream
contains status codes whose values are determined by the HTTP protocol. Parse this data
stream for status codes and other useful information.
This error occurs in the final step above when the client receives an HTTP status code that it
recognises as '407'.
Resolving 407 errors - general
This code is similar to 401 - Unauthorized, but indicates that the client should first
authenticate with a proxy server. The same discussion applies to error 407 as to error 401,
except that an additional proxy server is involved for 407.