How to do it...

To append 300 bytes of random data, open your terminal and type the following command:

# nmap -sS -PS --data-length 300 scanme.nmap.org

How it works...

The argument --data-length <# of bytes> tells Nmap to generate random bytes and append them as data in the requests.

Most of the scanning techniques are supported in this method, but it is important to note that using this argument slows down a scan since we need to transmit more data with each request.

In the following screenshot, a packet generated by a default Nmap scan, and another one where we used the argument --data-length, are shown:

There's more...

Setting the argument --data-length to 0 will force Nmap to not use any payloads in the requests:

# nmap --data-length 0 scanme.nmap.org

See also