How to determine your proxy ip address and port using curl

This is very easy, what you have to do is use curl to access any site, and curl will let you know what is the proxy address if you have not put in your authentication details. See below example:

foobar@ubuntu-vm:~$ curl www.google.com -IL
HTTP/1.1 302 authenticationrequired
Date: Tue, 26 Jan 2016 06:46:15 GMT
Location: http://10.155.120.23:9090/mwg-internal/de5fs23hu73ds/plugin?target=Auth&reason=Auth&ClientID=2297288988&ttl=600&url=aHR0cDovL3d3dy5nb29nbGUuY29tLw==&rnd=1453790775
Connection: Keep-Alive
Content-Type: text/html
Cache-Control: no-cache

HTTP/1.1 401 authenticationrequired
Date: Tue, 26 Jan 2016 06:46:15 GMT
Connection: Keep-Alive
Content-Type: text/html
Cache-Control: no-cache
WWW-Authenticate: NTLM
WWW-Authenticate: Basic realm="MY COMPANY WEB GATEWAY"

You can see from above that my proxy ip address is 10.155.120.23, and my proxy port is 9090.