How can we get the first IP4 Address of the local machine in c#?
When we write client server or peer to peer application, a frequent task is to find the first IP4 address of local machine. A machine has multiple types of addresses besides IP4 and IP6. For this reason, we will first get the address list of the machine then will loop through all the addresses to check whether there is an IP4 address. If found then we will return the first address. Otherwise will return null.
Now the question is how we will detect IP4 address Type. There is an Enumeration named AddressFamily under System.Net.Sockets namespace which specifies the addressing type. The members of AddressFamily Enumeration are in the following:
| Member name | Description |
| Unknown | Unknown address family. |
| Unspecified | Unspecified address family. |
| Unix | Unix local to host address. |
| InterNetwork | Address for IP version 4. |
| ImpLink | ARPANET IMP address. |
| Pup | Address for PUP protocols. |
| Chaos | Address for MIT CHAOS protocols. |
| NS | Address for Xerox NS protocols. |
| Ipx | IPX or SPX address. |
| Iso | Address for ISO protocols. |
| Osi | Address for OSI protocols. |
| Ecma | European Computer Manufacturers Association (ECMA) address. |
| DataKit | Address for Datakit protocols. |
| Ccitt | Addresses for CCITT protocols, such as X.25. |
| Sna | IBM SNA address. |
| DecNet | DECnet address. |
| DataLink | Direct data-link interface address. |
| Lat | LAT address. |
| HyperChannel | NSC Hyperchannel address. |
| AppleTalk | AppleTalk address. |
| NetBios | NetBios address. |
| VoiceView | VoiceView address. |
| FireFox | FireFox address. |
| Banyan | Banyan address. |
| Atm | Native ATM services address. |
| InterNetworkV6 | Address for IP version 6. |
| Cluster | Address for Microsoft cluster products. |
| Ieee12844 | IEEE 1284.4 workgroup address. |
| Irda | IrDA address. |
| NetworkDesigners | Address for Network Designers OSI gateway-enabled protocols. |
| Max | MAX address. |
(The table is stolen from MSDN website)
The member InterNetwork of AddressFamily Enumeration indicates Address for IP version 4.Here the member InterNetwork of AddressFamily Enumeration is used to check whether this is a IP4 address or not. The routine to find the first IP4 Address of the Host (local) machine is in the following:
1: private static IPAddress ReturnMachineIP()
2: {
3: String hostName = Dns.GetHostName();
4: IPHostEntry ipEntry = Dns.GetHostEntry(hostName);
5: IPAddress[] addr = ipEntry.AddressList;
6: IPAddress ipV4 = null;
7: foreach (IPAddress item in addr)
8: {
9: if (item.AddressFamily == AddressFamily.InterNetwork)
10: {
11: ipV4 = item;
12: break;
13: }
14:
15: }
16: if (ipV4 == null)
17: {
18: throw new ApplicationException("You have no IP of Version 4.Server can not run witout it");
19: }
20: return ipV4;
21: }
Hope this will save some of your time.