- 0-1023 – are “Well Known Ports” associated with services considered as critical or essential. They are also referred to as System Ports.
- 1024-49151 – are Registered Ports or User Ports and as the name indicates, can be reserved by sending a request to the Internet Assigned Numbers Authority (IANA).
- 49152-65535 – are called Dynamic Ports and are suggested for private use. They also referred to as the Private Ports.
Do you wish to find out open ports or listening on a network? Read on.There are a number of ways and tools that are available for checking ports which might be listening on your network.
Let us look at a few ways.
- By using nmap. Note. Nmap is capable of revealing a lot of information which can make system administrators think that you are of an ill intent. So, therefore, only use nmap on your local systems as done here.
You need to first install nmap with the following command (Ubuntu).
- By using netstat command to find open ports – enter the following command –
-l = only services which are listening on some port
-n = show port number, don’t try to resolve the service name
-t = enables listing of tcp ports
-u = enables listing of udp ports
- By using the ss command – enter the following command to list all open TCP and UDP ports.
- By using the lsof command
To display the list of open ports, enter the following command –