<p>Nmap 3.70 released -&gt; <a class="reference" href="http://www.insecure.org/">http://www.insecure.org/</a></p> <p>this simple command allows to know which local hosts are up:</p> <pre class="literal-block"> nmap -sP &lt;masked IP network&gt; (ex: nmap -sP 192.168.1.0/24 ) </pre> <p>This friendly scanning can be added to the crontab, allowing a daily report of the open ports:</p> <pre class="literal-block"> nmap -sT -P0 -sV &lt;host&gt; 2&gt;&amp;1 | mail -b &lt;your mail&gt; \ -s &quot;[nmap] `date -I` scan report&quot; &lt;host_owner_mail&gt; </pre> <p>For IPv6:</p> <pre class="literal-block"> nmap -sT -6 -P0 -sV &lt;host|ipv6&gt; </pre> http://home.zyrianes.net/blog/Articles/144/