Sometimes we need to test the network port and make sure that there is connectivity between servers.
In many cases, the app that might be listening on the port might not be ready yet. For such use cases, you can create a port listener on any port using netcat.
nc -l 3000
This will create a listener at the port 3000 on the server. To create who has connected to the port, use the verbose mode.
nc -lv 3000
Connection from x.x.x.x port 3000 [tcp/hbci] accepted