Linux basic commands-Network Management 2

1. How do I check whether a port is open?

A:Netstat-lThis command will list all listening ports or useTelnet localhost 22This command tries to connect to port 22. If the port is not open, the following error message is returned:

Vadi @ vadi-LAPTOP :~ $ Telnet localhost 22
Trying 127.0.0.1...
TELNET: Unable to connect to remote host: Connection refused

 

2. How to install a firewall?

A:Sudo apt-Get install firestarter

3. I have already set up a firewall. Why is connection refused always reported every time I use putty for remote connection?

A: Probably the SSH service is not enabled. Run this command to solve the problem:Sudo apt-Get install OpenSSH-server.This is my second Linux problem. Google is really easy to use.