HTTP Error 407 Proxy authentication required

Introduction

The Web server (running the Web site) thinks that the HTTP data stream sent from the client (e.g. your Web browser or our CheckUpDown robot) 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.

Fixing 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.

Fixing 407 errors - CheckUpDown

Our service monitors your site for HTTP errors like 407. Because they indicate fundamental authority problems, we can only resolve 407 errors you see on your CheckUpDown account by negotiation with the personnel responsible for security on and around the Web site and any proxy servers. These discussions unfortunately may take some time, but can often be amicably resolved. You can assist by endorsing our service to the security personnel. Please contact us (email preferred) if you see persistent 407 errors, so that we can agree the best way to resolve them.


407 errors in the HTTP cycle

Any client (e.g. your Web browser or our CheckUpDown robot) goes through the following cycle when it communicates with the Web server:

(1) Obtain an IP address from the IP name of the site (the site URL without the leading 'http://'). This lookup (conversion of IP name to IP address) is provided by domain name servers (DNSs).
(2) Open an IP socket connection to that IP address.
(3) Write an HTTP data stream through that socket.
(4) Receive an HTTP data stream back from the 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'.


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