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From: | Sergio R. Caprile |
Subject: | Re: [lwip-users] elegant way to detect network connection |
Date: | Wed, 9 Nov 2016 11:31:58 -0300 |
User-agent: | Mozilla/5.0 (Windows NT 6.1; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 |
Hi Noam,I was about to say you could sniff how windows 7+ does it; but I don't think they would do it in an elegant, not even standard, way... ;^)
I don't know if I get the whole picture, but I bet your problem is an "application ping". Do you actually need to know link is present or another device like yours or server or @ access or ?
Yes, ICMP Echo Requests might be discarded by the router, I think it is a bad idea on an internal network, but some admins think otherwise. That is why I suggest "application ping", as long as your devices can see each other, you know you have a link. It is usually done on a separate UDP port, but some guys like to dedicate in-band commands to that purpose, like a keep-alive message. What I suggest is sort of a discovery protocol on UDP broadcasts, or a directed app ping if you know your neighbors addresses.
Toying with your DHCP server every half a second might pester some net admins and get you enemies for free... I wouldn't go that way, I think your application's problems have to be solved by your application. Just my 2 cents.
Regards!
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