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# Check the contents of the cache again by using the command: <b><code><span style="color:#3366CC;font-size:1.2em;">arp -n</span></code></b>
# What was the difference in output? For what other command did the option '''-n''' have a similar effect?<br>{| width="40%" align="right" cellpadding="10"
# On your CentOS host execute the command: <b><code><span style="color:#3366CC;font-size:1.2em;">netstat -at</span></code></b>
# This command will list all active TCP ports. Note the state of your ports.
# From one of your VM's login to your host using '''ssh'''
# On the CentOS host rerun the command and in addition to the LISTEN port it should list a 2nd entry with a state of ESTABLISHED. This shows that there is a current connection to your ssh server.
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|{{Admon/note | Network Ports | When our CentOS system provides any services on a network, those services are accessible through a port number. All network services are configured to be accessed on a particular port number. By examining which ports are active on our system we can know what services (and points of attack) are available on our system. The ability to examine this information is important for troubleshooting network services and securing our systems. One great tool for this is the <code>netstat</code> command.}}
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# Exit your ssh connection from the VM and rerun the command on the CentOS host. Instead of ESTABLISHED it should now show a state of CLOSE_WAIT. Indicating that the TCP connection is being closed.
# On your CentOS host try the command <b><code><span style="color:#3366CC;font-size:1.2em;">netstat -atn</span></code></b>. How is this output different?