[Mono-list] IPAddress.GetAddressBytes

Dan Smithers dsmithers at talktalk.net
Wed Feb 20 04:20:02 EST 2008

Thanks for the response Chris,

I have been using the code described on many websites to get the local
IP address

string hostname = Dns.GetHostName();
IPHostEntry ip_entry = Dns.GetHostEntry(hostname);

and then had been taking ip_entry.AddressList[0] to be the address I
need. I have now spotted that this list has changed with the IPv6
address being listed before the IPv4 one.

I have now added tests for AddressFamily.InterNetworkV6 and Is
Loopback(addr) which has solved the problem. I guess it highlights a
weakness in my design which will only get worse if I need to add a
second network card.


Chris Howie wrote:
> On Feb 19, 2008 9:13 AM, Dan Smithers <dsmithers at talktalk.net> wrote:
>> I have a messaging application that was working until recently using
>> IPv4 addresses. I now seem to be getting IPv6 addresses from
>> GetAddressBytes.
>> Is this something in mono that has changed recently?
> I don't think that Mono would present an IPv4 address as an IPv6
> address unless your host OS was doing this itself.  In order to
> diagnose this we'll need to know how you are obtaining the IPAddress
> instance.
>> Is there a way of forcing IPv4 address format?
> Not if the object represents an IPv6 address.  You can check the
> IPAddress.AddressFamily property to see which version of address it
> represents.

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