httpstatuses/contents/codes/407.md

set	code	title	references
4	407	Proxy Authentication Required	Rails HTTP Status Symbol Go HTTP Status Constant :proxy_authentication_required http.StatusProxyAuthRequired

Similar to 401 Unauthorized, but it indicates that the client needs to authenticate itself in order to use a proxy.

The proxy MUST send a Proxy-Authenticate header field¹ containing a challenge applicable to that proxy for the target resource. The client MAY repeat the request with a new or replaced Proxy-Authorization header field².

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• ¹ Proxy-Authenticate RFC7235 Section 4.3
• ² Proxy-Authorization RFC7235 Section 4.4
• Source: RFC7235 Section 3.2