<h2 id="heading-lsof">lsof</h2>
<p>list of open files</p>
<pre><code class="lang-bash">lsof -i -P -n | grep LISTEN
</code></pre>
<h2 id="heading-netstat">netstat</h2>
<p>Print network connections, routing tables, interface statistics, masquerade connections, and multicast memberships </p>
<pre><code class="lang-bash">netstat -tulpn | grep LISTEN
</code></pre>
<h2 id="heading-ss">ss</h2>
<p>utility to investigate sockets</p>
<pre><code class="lang-bash">ss -tulpn | grep LISTEN
</code></pre>
<h2 id="heading-nmap">nmap</h2>
<p>network exploration tool, port scanner</p>
<pre><code class="lang-bash">nmap -open 192.168.3.34
</code></pre>
<h2 id="heading-scanning-open-ports-on-remote-ip-address">scanning open ports on remote IP address</h2>
<pre><code class="lang-bash">nc -zv 192.168.3.34 2&gt;&amp;1 1-1024 | grep -v refused
</code></pre>
<p>this scans open ports in the range of 1 to 1024 on the above IP address. redirects the error output to standard outoput and matches all lines except refused</p>
<h2 id="heading-scanning-all-open-ports-on-the-subnet-using-nmap">scanning all open ports on the subnet using nmap</h2>
<pre><code class="lang-bash">nmap -n 192.168.3.0/24
</code></pre>
<h2 id="heading-sources">Sources</h2>
<ul>
<li><p><strong>Linux for Networking Professionals</strong> by Rob VandenBrink</p>
</li>
<li><p><a target="_blank" href="https://www.cyberciti.biz/faq/unix-linux-check-if-port-is-in-use-command/">https://www.cyberciti.biz/faq/unix-linux-check-if-port-is-in-use-command/</a></p>
</li>
<li><p>man pages</p>
</li>
</ul>


## lsof

list of open files
```bash
lsof -i -P -n | grep LISTEN
```

## netstat

Print network connections, routing tables, interface statistics, masquerade connections, and multicast memberships 
```bash
netstat -tulpn | grep LISTEN
```

## ss

utility to investigate sockets
```bash
ss -tulpn | grep LISTEN
```

## nmap

network exploration tool, port scanner

```bash
nmap -open 192.168.3.34
```

## scanning open ports on remote IP address

```bash
nc -zv 192.168.3.34 2>&1 1-1024 | grep -v refused
```

this scans open ports in the range of 1 to 1024 on the above IP address. redirects the error output to standard outoput and matches all lines except refused

## scanning all open ports on the subnet using nmap

```bash
nmap -n 192.168.3.0/24
```

## Sources

* **Linux for Networking Professionals** by Rob VandenBrink
    
* [https://www.cyberciti.biz/faq/unix-linux-check-if-port-is-in-use-command/](https://www.cyberciti.biz/faq/unix-linux-check-if-port-is-in-use-command/)
    
* man pages

Scanning for open ports

lsof

netstat

ss

nmap

scanning open ports on remote IP address

scanning all open ports on the subnet using nmap

Sources