Test which ports are open for outbound connection

Question

I have a computer located on a Internet network that has some security policies, which I don't have control over. I am looking for a program, user script, or web service that can give me a list of which ports are open for outbound connections (outbound connections = connections from my computer to a server located outside my computer's network).

It should work on Microsoft Windows or Linux. Any price or license is fine.

Answer 1

The website portquiz.net can be used to check which ports are open for outbound connection, e.g. as follows (I took the command from http://thomasmullaly.com/2013/04/13/outgoing-port-tester/):

sudo apt-get install -y nmap
nmap -Pn --top-ports 1000 portquiz.net

Another way to do so, from https://gist.github.com/enginefeeder101/0805faf3862d88a97d66:

#!/bin/bash

task(){
  LC_ALL=C nc -vzw5 portquiz.net $1 2>&1 | grep -v 'Connection timed out'
}

N=50                               # Specify number of ports to check at once
(
  for port in {1..65535}; do       # Specify port range to check here
    ((i=i%N)); ((i++==0)) && wait
    task "$port" &
  done
)