I've got access to two computers (A and B) on a network. Both have got a static IP address with a subnet mask of 255.255.255.128 (I checked that a DHCP server was not being used). I want to configure multiple IP addresses to the same machine and hence I want to know what all IP addresses are already being used in the subnet.
From an earlier question, I tried
nmap -sP -PR 172.16.128.* command, but, I'm skeptical about its result as the same command gives different results on my two computers (A and B). On A, the result shows, a list of 8 IP addresses which are (supposedly) already being used, including that of A and B.
Nmap done: 256 IP addresses (8 hosts up) scanned in 1.23 seconds
But on B, the result is different i.e.,
Nmap done: 256 IP addresses (0 hosts up) scanned in 0.00 seconds
The result on B is not even showing its own IP address as well as the IP address of A!
What exactly am I doing wrong here? Is there any foolproof way in Red Hat Linux (RHEL) of discovering all IP addresses being used in the subnet of which my computer is a part of?
RHEL: 6.5 Nmap version: 5.51