Checking the port if open or not [ telnet, nmap ]
telnet
TELNET (TELecommunication NETwork) is a network protocol used on the Internet. TELNET is a client-server protocol, based on a reliable connection-oriented transport. This command will help us to find if a particular port on the server is open or not.
Example:
root@server [~]$ telnet google.com 80
Trying 64.233.187.99…
Connected to google.com (64.233.187.99)
From the above example you could find that port 80 is open on google server. If we receive a ” connection refused ” signal, that mean’s the particular port is not open on the server.
