407
HTTPERRORNotable4xx Client ErrorHIGH confidence

Proxy Authentication Required

Production Risk

Low. This is a standard part of network architecture in many corporate environments. Applications that need to operate in such environments must be designed to handle it.

What this means

This is similar to 401 (Unauthorized), but it indicates that the client must first authenticate itself with the proxy. The proxy must send a Proxy-Authenticate header field containing a challenge applicable to the proxy for the requested resource.

Why it happens
  1. 1A user is on a corporate or school network that requires authentication to access external websites.
  2. 2The client has not provided credentials for the proxy server.
  3. 3The provided proxy credentials are invalid or have expired.
How to reproduce

An employee tries to access an external website from their work computer, but the corporate proxy blocks the request until they provide their network credentials.

trigger — this will error
trigger — this will error
GET http://www.example.com/ HTTP/1.1

expected output

HTTP/1.1 407 Proxy Authentication Required
Proxy-Authenticate: Basic realm="Corporate Proxy"

Fix

Provide Proxy Credentials

WHEN Your client application needs to work behind a proxy.

Provide Proxy Credentials
curl --proxy-user user:pass --proxy http://proxy.example.com:8080 http://example.com

Why this works

Client Configuration

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