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I'm gonna setup a Wireless router for a customer.
They have subnet
What can I do to check if the IP is available to set up the router? I'm on out on a local network at my workplace, the customer's network is IPVPN.

I have Access to the Linux console on the out network that can communicate with our customers. I thought that I could use Nmap command to find out if there's any equipment on the network. I tried running the command nmap -sP -PE But I dont get the response I'm looking for. What might I do different to find out if this is an available address?

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As a side note.. I've noticed that whenever I do scans of an entire subnet, I never get good results unless I set the --scan-delay option. I scanned a network here just now using your nmap string which returned 54 hosts. Adding the scan-delay, It brought back 74 hosts, which is closer to what I was expecting. – Safado Feb 25 '13 at 15:29
Can you just ping the ip address to see if there's a response? If there's no response its free? – user1527227 Jul 3 '14 at 5:16

Ask their network administrator. There is no other way that doesn't risk causing serious problems. It may belong to a machine that's off at the moment.

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Many people have decided that they are too clever for this answer, and even more people have been woken up in the middle of the night as a consequence. Thousands of dollars in labor are lost every year to ignoring this. – Andrew B Feb 4 '13 at 9:21
+1. If the customers does not have an allocation plan, he deserves what he gets - namely a clueless contractor setting up a bad ip. – TomTom Feb 25 '13 at 15:58

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