Do something like this to filter out the IPV6 addresses:
foreach (UnicastIPAddressInformation address in ipInterfaceProperties.UnicastAddresses)
{
if (address.Address.AddressFamily == AddressFamily.InternetworkV4)
{
ipAddressInfoList.Add(new IPNetworkInterfaceInfo(address.Address, address.IPv4Mask));
}
}
BTW, you could have easily found this on google.