Error binding socket to :::25, status = EADDRINUSE (Solved)

Centos 

$ yum install net-tools 

Fedora: 

$ sudo dnf install net-tools 

Debian, Ubuntu: 

$ sudo apt install net-tools

netstat -tulpn

netstat -tulpn | grep -w 2500

Result: tcp     0         0 0.0.0.0:2500             0.0.0.0:*

kill 942

How to check TCP, UDP Domain Socket using NetCat

 Install the netcat Using the fllowing command:

$ yum install nc      [On CentOS/RHEL]

$ dnf install nc      [On Fedora 22+ and RHEL 8]

$ sudo apt-get install Netcat      [On Debian/Ubuntu]

NetCat commands:

$ nc -v -w 2 z 192.168.56.1 22     #scan a single port

OR

$ nc -v -w 2 z 192.168.56.1 22 80  #scan multiple ports

OR

$ nc -v -w 2 z 192.168.56.1 20-25  #scan range of ports