You can use arp-scan to scan the IPs of all computers connected to your local network:
me@pc ~ $ sudo arp-scan -l
Password:
Interface: enp2s0, datalink type: EN10MB (Ethernet)
Starting arp-scan 1.9 with 256 hosts (http://www.nta-monitor.com/tools/arp-scan/)
192.168.1.96 10:1d:s3:2j:34:c9 Buffalo Inc.
192.168.1.73 60:x1:50:d3:9k:72 Murata Manufactuaring Co.,Ltd.
192.168.1.253 55:jd:s5:9d:4c:4c (Unknown)
192.168.1.254 58:k8:3t:sd:78:5s Technicolor
192.168.1.70 00:02:s4:30:a4:db Hewlett-Packard Company
5 packets received by filter, 0 packets dropped by kernel
Ending arp-scan 1.9: 256 hosts scanned in 2.421 seconds (105.74 hosts/sec). 5 responded.
Btw ‘Murata Manufactuaring Co.,Ltd.’ turned out to be my mobile phone!
You could alternatively use nmap:
me@pc ~ $ nmap -sP 192.168.1.*
Starting Nmap 6.25 ( http://nmap.org ) at 2013-07-12 14:02 BST
Nmap scan report for 192.168.1.60
Host is up (0.00040s latency).
Nmap scan report for android-96d32y81s5hf2d4f.lan (192.168.1.83)
Host is up (0.043s latency).
Nmap scan report for 192.168.1.253
Host is up (0.0060s latency).
Nmap scan report for router (192.168.1.254)
Host is up (0.0011s latency).
Nmap done: 256 IP addresses (4 hosts up) scanned in 6.22 seconds
