How to do it...

1. Visit https://censys.io/ in your browser, as shown in the following screenshot:

1. We must be a logged-in user to perform detailed searches, which we will cover later in this recipe. 

1. If we want to look for a particular IP, we can simply paste the IP in the search bar. As we can see in the following screenshot, it will give us basic information about the IPv4 host, such as the protocols being used and the version of SSL:

1.  We can also view the IPWHOIS by clicking on the WHOIS tab:

1. Let's try and search for a subnet: it's easy, we can simply type the subnet in the search bar and press Go.

1. In the following screenshot, we can see that by doing this, we can see all of the hosts in the subnet, along with details of their location, open ports, owner, and so on:

1. Censys also supports and/or operators. For example, if we want to search for two different subnets using an or operator, we can do this as follows:

1. But what if we want to search for public servers that either have the word Dell or Amazon within the 23.0.0.0/8 subnet? This is useful when we are trying to do a recon about an organization that has lots of publicly accessible assets. This can be done by using the following search term: