Multiple IP's with same MAC Address

[sevensins]

AOA,

on my network I have 4 subnets. People on one subnet add the other subnet free ip address to bypass the gateway (lynx box). e.g
# arp -aven | grep 00:16:76:94:49:BB
192.168.59.38 ether 00:16:76:94:49:BB C eth0
192.168.79.50 ether 00:16:76:94:49:BB C eth0


I was wondering is there any way to find out duplicate hosts (ip's) with same mac address?

Any help, guidance would be much appreciated.

[lambda]

I was wondering is there any way to find out duplicate hosts (ip's) with same mac address?

sure. here's a little script to help you out:

Code: Select all

#!/usr/bin/env ruby

reg = Regexp.new /^([0-9.]+)\s+\w+\s+([0-9A-F:]+)/
macs = {}

f = IO.popen '/usr/sbin/arp -aven'
f.each_line do |line|
  matches = reg.match line
  if matches
    ip = matches[1]
    ether = matches[2]
    if macs[ether]
      macs[ether] << ip
    else
      macs[ether] = [ip]
    end
  end
end

macs.each { |mac, iplist| puts "#{mac} has more than one ip: #{iplist}" if iplist.size > 1 }

exit 0

[sevensins]

thanx a lot, I will try it...

[raheelahmad]

nice one