Re: How to detect no internet connection?
Re: How to detect no internet connection?
- Subject: Re: How to detect no internet connection?
- From: Laurent Daudelin <email@hidden>
- Date: Mon, 25 Jan 2010 14:30:51 -0800
On Jan 25, 2010, at 13:58, Jens Alfke wrote:
>
> On Jan 25, 2010, at 1:50 PM, Laurent Daudelin wrote:
>
>> What is the best way to detect that there is no internet connection from my Cocoa app?
>
> SystemConfiguration.framework. It can even send you notifications in real-time as the network status changes.
>
>> Detecting no network would work too but I'd like to be able even if the Macintosh is connected to a network that it can't reach the internet. I know I could use a test connection but is there a better way?
>
> A reasonable request, but the problem is that "reach the internet" is too vague a question. The main situation where it breaks down is on an intranet that requires use of a proxy to reach the outside world. In this case you are literally not connected to the Internet, even with a 1000baseT plug jacked into your computer, even though your web browser and email work fine.
>
> If on the other hand you just mean "can I ping the router", this will be true on a home 802.11 network even when the DSL/cable modem is down, and there are no outside hosts reachable.
>
> Basically you have to decide based on the specific functionality of your app. In a lot of cases what the app wants to know is "can I reach my server at foobar.com:12345?", and SystemConfiguration will let you ask that question. It won't be 100% accurate, though, because it gets its answer only from consulting the local routing tables, not from actually sending any packets.
>
> —Jens
Thanks, Jens, I'll start with SystemConfiguration!
-Laurent.
--
Laurent Daudelin
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