/// <summary>
/// Verifies that the given address is on a public network. (It is not a special address or one of the reserved private subnets.)
/// </summary>
/// <param name="addr">IP address to check</param>
/// <returns>True, if the given IP is a public, routable address.</returns>
public static bool IsPublicIP(IPAddress addr)
{
if (addr.AddressFamily != AddressFamily.InterNetwork)
{
throw new ArgumentException(String.Format("IPv4 address is required: {0}", addr.ToString()));
}
bool unroutable = PrivateClassA.IsIPInSubnet(addr) ||
PrivateClassB.IsIPInSubnet(addr) ||
PrivateClassC.IsIPInSubnet(addr) ||
Loopback.IsIPInSubnet(addr) ||
LinkLocal.IsIPInSubnet(addr) ||
SharedAddress.IsIPInSubnet(addr) ||
IETF.IsIPInSubnet(addr) ||
Dummy.IsIPInSubnet(addr) ||
PortControlAnycast.IsIPInSubnet(addr) ||
NatAnycastTraversal.IsIPInSubnet(addr) ||
Nat64Discovery.IsIPInSubnet(addr) ||
DNS64Discovery.IsIPInSubnet(addr) ||
TestNet1Documentation.IsIPInSubnet(addr) ||
AS112.IsIPInSubnet(addr) ||
AMT.IsIPInSubnet(addr) ||
Relay6to4.IsIPInSubnet(addr) ||
AS112DirectDelegation.IsIPInSubnet(addr) ||
Benchmarking.IsIPInSubnet(addr) ||
TestNet2Documentation.IsIPInSubnet(addr) ||
TestNet3Documentation.IsIPInSubnet(addr) ||
Reserved.IsIPInSubnet(addr) ||
Broadcast.IsIPInSubnet(addr);
return(!unroutable);
}
/// <summary>
/// Returns the first IPv4, unicast address on the local computer which has a gateway configured and is, therefore,
/// probably Internet-connectable.
/// </summary>
/// <returns>IP address object</returns>
public static IPAddress GetPrimaryIPAddress()
{
// This is impossible to find, but we return the first IP which has a gateway configured
List <IPAndMask> ips = new List <IPAndMask>();
NetworkInterface[] nics = NetworkInterface.GetAllNetworkInterfaces();
foreach (NetworkInterface nic in nics)
{
if (nic.OperationalStatus == OperationalStatus.Up && nic.Supports(NetworkInterfaceComponent.IPv4))
{
IPInterfaceProperties properties = nic.GetIPProperties();
if (properties.GatewayAddresses.Count == 0)
{
continue;
}
UnicastIPAddressInformationCollection unicast = properties.UnicastAddresses;
foreach (UnicastIPAddressInformation unicastIP in unicast)
{
if (unicastIP.Address.AddressFamily == AddressFamily.InterNetwork)
{
IPv4Subnet subnet = IPv4Subnet.FromSubnet(unicastIP.Address, unicastIP.IPv4Mask);
foreach (GatewayIPAddressInformation gw_addr in properties.GatewayAddresses)
{
if (gw_addr.Address.AddressFamily == AddressFamily.InterNetwork)
{
if (subnet.IsIPInSubnet(gw_addr.Address))
{
return(unicastIP.Address);
}
}
}
}
}
}
}
return(null);
}
