For a php page, I want to be able to ping local lan area Mac addresses of the other two macs in the house. Basically to see if they're on or off (is a newb ). When searching, I ran across ARPING. But I cannot seem to use it correctly. I keep getting errors like this one. Code: arping 00:17:f2:3f:2d:8f arping: libnet_get_ipaddr4(libnet): libnet_get_ipaddr4(): ioctl(): Can't assign requested address hmm. I don't know what the means. I am certain I have the mac addresses written right. Any suggestions on what I should do?