<p>grepcidr is usually available from your distribution's default repositories, so on Debian based systems you could install it with:</p>

<pre><code>sudo apt install grepcidr</code></pre>

<p>Example of grepcidr use:</p>

<pre><code>grepcidr 40.10.32.0/22 /var/log/syslog</code></pre>

<p>You can read more about CIDR notation on the <a href="https://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing">Wikipedia page for CIDR</a></p>
