Problem with isReachable in InetAddress class

Question

As an assignment I have to find all the alive computers on a LAN. For which I am using isReachable function of InetAddress class. But problem is

Answer 1

I found interesting solution. If you can't run your aplication as root, you may set raw socket capability on java:

sudo setcap cap_net_raw=ep /usr/lib/jvm/jdk/bin/java

And then ICMP protocol will be used istead of echo request on 7 TCP port.