Topic: "getting HTTP status codes 500 or 503 when trying --pro

[h4x0r4fr33d0m]

iv googled "http proxy" https://www.google.ca/#q=http+proxy+list and entered the returned HTTP proxy IP from web site 137.135.166.225:8118 in below example
trying --proxy-type http --proxy 137.135.166.225:8118 (entered command) i either get "Connection refused" or HTTP status codes 500 or 503 when connecting to remote-host.org thru proxy
as show the below error exterp

entered command:

<code>
ncat -vvvvv remote-host.org -p 31337 --proxy-type http --proxy 137.135.166.225:8118
</code>

error exterp:
<code>
********@bbis:~/directory$ ncat -vvvvv remote-host.org -p 31337 --proxy-type http --proxy 123.30.238.16:8118
Ncat: Version 6.00 ( http://nmap.org/ncat )
Ncat: Proxy connection failed: Connection refused.
********@bbis:~/directory$ ncat -vvvvv remote-host.org -p 31337 --proxy-type http --proxy 46.167.210.2:8118
Ncat: Version 6.00 ( http://nmap.org/ncat )
NCAT DEBUG: Proxy returned status code 500.
Ncat: Proxy returned status code 500.
********@bbis:~/directory$ ncat -vvvvv remote-host.org -p 31337 --proxy-type http --proxy 137.135.166.225:8118
Ncat: Version 6.00 ( http://nmap.org/ncat )
NCAT DEBUG: Proxy returned status code 503.
Ncat: Proxy returned status code 503.
</code>

can someone tell me what went wrong ?

BTW is there a beginner (n00b) good tuturial on NCat --proxy-type AND --proxy options

thx