I carry my phone and laptop with me everywhere, and I have many software solutions that communicate through Wi-Fi. (For example, I can play/stop/pause the music on my laptop using my cell phone).

I'd like a way for my laptop to automatically discover the new IP address of my phone upon joining a new network, like a coffee shop for instance. I could just assign a static IP to my phone, but I'd prefer to keep DHCP.

I'm thinking maybe a script that executes an arp-scan? My phone's MAC address is static, obviously. Then sets an environment variable?
I could run this script after I have seen that my phone is connected.
Just where my head is going. Thanks for your advice.

  • Something like DynDNS? Automatically updated domain name, so whenever you have new IP, domain name is updated so it always follows your IP. – rsm Aug 19 '14 at 16:50
  • I'd like this to stay within the LAN. When I say IP I mean 192.168.*.* which is assigned by a DHCP server. In my home LAN I have static leases for all my devices, but this isn't possible/feasible in a public network. – curios Aug 19 '14 at 20:20
  • And it wouldn't work, I forgot you will be assigned local IP. BUT! Maybe you can simply broadcast a custom UDP message from your mobile? en.wikipedia.org/wiki/Broadcast_address And maybe you can talk about it with this guy stackoverflow.com/questions/14080573/… "I'm developing an app that uses wifi to broadcast UDP messages between all the mobiles that are in the same network that have my app" – rsm Aug 19 '14 at 20:36

This is what IETF ZeroConf networking is for.

Android supports it (they call it Network Service Discovery or NSD), and iOS and OS X support the hell out of it, because it's what Apple calls Bonjour. Apple has a Bonjour for Windows that you can install on Windows, and Linux platforms have various options such as Avahi.

If you've got the dns-sd command-line tool installed your laptop, and you know your phone's name is "myPhone", then you can find its IP address like this:

dns-sd -G v4v6 myPhone.local

(By default dns-sd stays open looking for other results until you Ctrl-C out of it.)

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