How to do it...

Open your terminal and enter the following command:

# nmap -p80 192.168.1.1/24 

A list of hosts with the state of port 80 will appear in the results.

Nmap scan report for 192.168.1.102 
Host is up (0.000079s latency). 
PORT STATE SERVICE 
80/tcp closed http 

Nmap scan report for 192.168.1.103 
Host is up (0.016s latency). 
PORT STATE SERVICE 
80/tcp open http 
MAC Address: 00:16:6F:7E:E0:B6 (Intel) 

Nmap scan report for 192.168.1.254 
Host is up (0.0065s latency). 
PORT STATE SERVICE 
80/tcp open http 
MAC Address: 5C:4C:A9:F2:DC:7C (Huawei Device Co.) 

Nmap done: 256 IP addresses (3 hosts up) scanned in 8.93 seconds 

How it works...

Nmap uses the flag -p for setting the port ranges to be scanned. This flag can be combined with any scanning method. In the previous example, we used the argument -p80 to indicate to Nmap that we are only interested in port 80.

The CIDR /24 in 192.168.1.1/24 is used to indicate that we want to scan all of the 256 IPs in our network.

There's more...

There are several accepted formats for the argument -p:

See also