Scan for connected, powered on computers on a network?
Solution 1:
Have you tried other scan options from nmap? The ping option may not always work, but other scan options may be more reliable? Try,
nmap -PS 192.168.2.0/24
(TCP SYN ping)
or
nmap -PR 192.168.2.0/24
(ARP scan)
Solution 2:
Try Look@LAN to scan for powered on computers.
There are alternatives to Look@LAN and some of them are even free or free and open source.
Personally I can recommend the Angry IP Scanner which is OpenSource and multiplatform or Advanced IP Scanner which is made for Windows platforms and not OpenSource but free.
Solution 3:
ping -b the broadcast IP then arp -a
Solution 4:
It seems that the problem was the probing rate (too much packets per second?). Using the parameter --max-rate
made it performance much better. It takes ages to run, but at least it works.
$ nmap -sP --max-rate 1 192.168.2.0/24
...
Nmap done: 242 IP addresses (67 hosts up) scanned in 434.04 seconds