pub const PROXY_AUTHENTICATE: HeaderName;
Defines the authentication method that should be used to gain access to a proxy.
proxy-authenticate header field applies
only to the next outbound client on the response chain. This is because
only the client that chose a given proxy is likely to have the
credentials necessary for authentication. However, when multiple proxies
are used within the same administrative domain, such as office and
regional caching proxies within a large corporate network, it is common
for credentials to be generated by the user agent and passed through the
hierarchy until consumed. Hence, in such a configuration, it will appear
as if Proxy-Authenticate is being forwarded because each proxy will send
the same challenge set.
proxy-authenticate header is sent along with a
407 Proxy Authentication Required.