# 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.
# 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.
{| width="40%" align="right" cellpadding="10"|- valign="top"|{{Admon/note | Network Ports |}}|}<ol><li value="12"># 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?</li><li># Without the <code>-n</code> option <code>netstat</code> attempts to resolve IP addresses to host names (using '''/etc/hosts''') and port numbers to service names (using '''/etc/services''')</li><li># Examine the '''/etc/services''' file and find which ports are used for the services: '''ssh''', '''sftp''', '''http'''</li><li># Now execute the command <b><code><span style="color:#3366CC;font-size:1.2em;">netstat -au</span></code></b> What is the difference between the options: '''-at''' and '''-au'''?</li><li># When examining UDP ports why is there no state?</li></ol>
'''Answer Part 2 observations / questions in your lab log book.'''
'''Answer Part 2 observations / questions in your lab log book.'''
== Part 3: Introduction to Firewalls: iptables ==