Re: Determining Network Server Reachability
Re: Determining Network Server Reachability
- Subject: Re: Determining Network Server Reachability
- From: "Daniel Ellis" <email@hidden>
- Date: Thu, 21 Jun 2007 19:39:39 -0700
Neither SCNetworkCheckReachabilityByName() nor
SCNetworkCheckReachabilityByAddress() can tell you whether you can
successfully communicate with a given machine. The only reliable way to do
that is to try to communicate with that machine.
'"Reachability" reflects whether a data packet, sent by an application
into the network stack, can leave the local computer. Note that
reachability does not guarantee that the data packet will actually be
received by the host.'
http://developer.apple.com/documentation/Networking/Reference/SysConfig/SCNetwork/CompositePage.html
In practice, reachability is true if the address given is a LAN address
and the local machine has an interface using Bonjour, or the address given
is a global Internet address and the local machine has (or thinks it could
establish by dialup) a connection to some Internet router. This doesn't
mean that the network between the two machines is working, that the remote
machine is listening or capable of responding, or that the firewalls in
between would allow your particular packets through.
So does anyone have any suggestions as to a good way to determine
reachability in this case?
Daniel
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