You can test a network port connection using the “nc” command on Linux and “telnet” on Windows.
Format:
$ nc -zv domain.com port
C:\> telnet domain.com port
$ nc -zv domain.com 80
Connection to domain.com 80 port [tcp/http] succeeded!
C:\> telnet -zv domain.com 80
Connecting To domain.com...Could not open connection to the host, on port 80: Connect failed
For Telnet, if a connection is successful, it returns no message.