nmap
ever wonder what the IP address of that server in the corner is, you could always try scanning your network for computers using nmap.
sudo apt-get install nmap
to scan for running computers, here using sudo is optional but will provide more information, all others require root privileges
<sudo> nmap -sP 192.168.1.1/24
to scan for open ports on a computer
sudo nmap -sS 192.168.1.1/24
to include open ports and operating system information
sudo nmap -O 192.168.1.1/24
