Primero averiguaremos el rango de nuestra red.

$ ifconfig

Resolverá algo similar a:

wlp2s0    Link encap:Ethernet  HWaddr 00:13:E8:F1:B0:D7  
         inet addr:192.168.1.39  Bcast:192.168.1.255  Mask:255.255.255.0
         inet6 addr: fe80::213:e8ff:fef1:b0d7/64 Scope:Link
         UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
         RX packets:38905 errors:0 dropped:0 overruns:0 frame:0
         TX packets:29562 errors:0 dropped:0 overruns:0 carrier:0
         collisions:0 txqueuelen:1000 
         RX bytes:46374473 (44.2 Mb)  TX bytes:3604981 (3.4 Mb)

Ya sabemos el rango de la ip, 192.168.1.X / 192.168.1.255, así que escribimos en terminal:

$ ping -b 192.168.1.255

Si las maquinas están configuradas por defecto para no responder a ping’s de broadcast (que es muy posible), nos devolverá error del tipo:

WARNING: pinging broadcast address
PING 192.168.1.255 (192.168.1.255) 56(84) bytes of data.

Nmap
Usaremos el comando nmap, que aunque es un poco mas intrusivo es mucho mas fiable.

sudo nmap -sP 192.168.1.1-254

Esperamos unos segundos (dependerá de los dispositivos conectados) y nos resolverá un resultado optimo, fabricante del dispositivo, la mac y la latencia de respuesta. (Pongo ejemplo)

linux-XXX:/home/sergio # sudo nmap -sP 192.168.1.1-254

Starting Nmap 6.47 ( http://nmap.org ) at 2015-04-21 22:01 CEST
Nmap scan report for 192.168.1.1
Host is up (0.018s latency).
MAC Address: 64:68:0C:4E:A8:E6 (Comtrend)
Nmap scan report for 192.168.1.33
Host is up (1.5s latency).
MAC Address: D8:E5:6D:27:51:F9 (TCT Mobile Limited)
Nmap scan report for 192.168.1.34
Host is up (0.83s latency).
MAC Address: C8:DF:7C:31:CD:22 (Nokia)
Nmap scan report for 192.168.1.36
Host is up (0.90s latency).
MAC Address: 28:CC:01:D3:FF:F5 (Samsung Electronics Co.)
Nmap scan report for 192.168.1.37
Host is up (0.91s latency).
MAC Address: 28:CC:01:D3:FF:F5 (Samsung Electronics Co.)
Nmap scan report for 192.168.1.38
Host is up (1.5s latency).
MAC Address: D8:E5:6D:DC:F3:F8 (TCT Mobile Limited)
Nmap scan report for 192.168.1.42
Host is up (1.2s latency).
MAC Address: 00:C0:CA:76:3C:7C (ALFA)
Nmap scan report for 192.168.1.44
Host is up (0.065s latency).
MAC Address: E0:CE:C3:60:8A:8B (Askey Computer)
Nmap scan report for 192.168.1.45
Host is up (1.1s latency).
MAC Address: 28:CC:01:D3:FF:F5 (Samsung Electronics Co.)
Nmap scan report for 192.168.1.46
Host is up (1.1s latency).
MAC Address: 18:CF:5E:74:45:AC (Liteon Technology)
Nmap scan report for 192.168.1.48
Host is up (1.1s latency).
MAC Address: 00:24:2C:9F:0C:9C (Hon Hai Precision Ind. Co.)
Nmap scan report for 192.168.1.50
Host is up (1.1s latency).
MAC Address: F8:A9:D0:2D:21:CA (LG Electronics)
Nmap scan report for 192.168.1.39
Host is up.
Nmap done: 254 IP addresses (13 hosts up) scanned in 19.86 seconds