In our example, we'll try to connect to port 80 of hackepedia.org. (The common www port, often hidden in your Browser).
- Can you resolve DNS?
- Can you ping the server? (Verifying the machine is up)
- Do you have to allow outbound access to this port on your firewall? on your router?
- telnet to the port (we prefer netcat over telnet for this if you it installed)
$ telnet hackepedia.org 80 Trying 18.104.22.168... Connected to hackepedia.org. Escape character is '^]'.
This tells me that the port is listening. Just for fun, here is an example showing that there is no daemon listening on port 79 of this server:
$ telnet hackepedia.org 79 Trying 22.214.171.124... telnet: Unable to connect to remote host: Connection refused