To check if ports are open and active on an Ubuntu 20.04 server, you can use the nmap tool.
Here is an example of how to check if a specific port is open on a server:
nmap -p [port_number] [server_ip_or_hostname]
For example, to check if port 80 is open on the server with IP address 192.168.1.100:
nmap -p 80 192.168.1.100
You can also check for a range of ports by specifying the range of port numbers separated by a hyphen:
nmap -p [port_start]-[port_end] [server_ip_or_hostname]
For example, to check if ports 80 to 90 are open on the server with IP address 192.168.1.100:
nmap -p 80-90 192.168.1.100
The output will show the status of the port, including whether it is open, closed, or filtered.
