# curl_cli [--proxy IP_or_HostName:Port] -v -k https://updates.checkpoint.com -x
* About to connect() to proxy (#0)
* Trying (proxy IP) (#0)
* Establish HTTP proxy tunnel to updates.checkpoint.com:443
< HTTP/1.1 407 Proxy Authentication Required
< Proxy-Authenticate: NEGOTIATE
< Proxy-Authenticate: NTLM
< Proxy-Authenticate: BASIC realm=""
< Cache-Control: no-cache
< Pragma: no-cache
< Content-Type: text/html; charset=utf-8
< Proxy-Connection: close
< Connection: close
< Content-Length: 849
* Ignore 849 bytes of response-body
* Received HTTP code 407 from proxy after CONNECT
* Closing connection #0
curl: (56) Received HTTP code 407 from proxy after CONNECT
The use of NTLM for the authentication method is currently not supported.
The reply of 'HTTP code 407' means - Proxy Authentication Required.