It will generate a Proxy-Authenticate header field containing a digest challenge (and not Proxy-Authorize header field as written in the manual page)
The header field looks like this: Proxy-Authenticate: Digest realm=“192.168.1.15”, nonce=“462c7effba07312005e1116c8236295cad5c0c84”
The challenge is sent in a 407 (Proxy Authentication Required) reply message.
[Emin Gabrielyan, 070424]