Get IPv4 addresses from Dns.GetHostEntry()

Question

I've got some code here that works great on IPv4 machines, but on our build server (an IPv6) it fails. In a nutshell:

IPHostEntry ipHostEntry = Dns.GetHostEntry(string.Empty);

The documentation for GetHostEntry says that passing in string.Empty will get you the IPv4 address of the localhost. This is what I want. The problem is that it's returning the string "::1:" on our IPv6 machine, which I believe is the IPv6 address.

Pinging the machine from any other IPv4 machine gives a good IPv4 address... and doing a "ping -4 machinename" from itself gives the correct IPv4 address.... but pinging it regularly from itself gives "::1:".

How can I get the IPv4 for this machine, from itself?

score 67 · Accepted Answer · answered Jun 29 '09 at 17:50

67

Have you looked at all the addresses in the return, discard the ones of family InterNetworkV6 and retain only the IPv4 ones?

answered Jun 29 '09 at 17:50

Remus Rusanu

288,378
40
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My call is only returning ipv6, no ipv4 entries. If I do `Resolve-DnsName -Type A` in PowerShell I get the IPv4 back (default type it returns in this case is AAAA). – kamranicus Sep 03 '15 at 20:54
@subkamran please ask that as a separate question, not as a comment – Remus Rusanu Sep 04 '15 at 08:09
It's due to Direct Access on my corporate PC. Disregard. – kamranicus Oct 01 '15 at 22:46
Why can't we use IPv6? – Storm Muller Nov 12 '18 at 21:39
@StormMuller because the OP asks "Get IPv4 addresses..." – Remus Rusanu Nov 13 '18 at 12:29

score 52 · Answer 2 · answered Apr 15 '11 at 17:19

52

To find all local IPv4 addresses:

IPAddress[] ipv4Addresses = Array.FindAll(
    Dns.GetHostEntry(string.Empty).AddressList,
    a => a.AddressFamily == AddressFamily.InterNetwork);

or use Array.Find or Array.FindLast if you just want one.

answered Apr 15 '11 at 17:19

Gary

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19

score 12 · Answer 3 · answered Mar 21 '16 at 21:04

12

IPHostEntry ipHostInfo = Dns.GetHostEntry(serverName);
IPAddress ipAddress = ipHostInfo.AddressList
    .FirstOrDefault(a => a.AddressFamily == AddressFamily.InterNetwork);

answered Mar 21 '16 at 21:04

Milan Švec

1,675
17
21

Unfortunately is the VirtualBox-address before computer ip address on my machine. I can't select the real ip address because both have the "InterNetwork" flag. – Georg Nov 21 '18 at 08:02

score 5 · Answer 4 · edited Oct 12 '12 at 21:57

    public Form1()
    {
        InitializeComponent();

        string myHost = System.Net.Dns.GetHostName();
        string myIP = null;

        for (int i = 0; i <= System.Net.Dns.GetHostEntry(myHost).AddressList.Length - 1; i++)
        {
            if (System.Net.Dns.GetHostEntry(myHost).AddressList[i].IsIPv6LinkLocal == false)
            {
                myIP = System.Net.Dns.GetHostEntry(myHost).AddressList[i].ToString();
            }
        }
    }

Declare myIP and myHost in public Variable and use in any function of the form.

score 2 · Answer 5 · answered Feb 05 '15 at 21:33

    public static string GetIPAddress(string hostname)
    {
        IPHostEntry host;
        host = Dns.GetHostEntry(hostname);

        foreach (IPAddress ip in host.AddressList)
        {
            if (ip.AddressFamily == System.Net.Sockets.AddressFamily.InterNetwork)
            {
                //System.Diagnostics.Debug.WriteLine("LocalIPadress: " + ip);
                return ip.ToString();
            }
        }
        return string.Empty;
    }

score -1 · Answer 6 · answered Mar 14 '13 at 06:48

To find all valid address list this is the code I have used

public static IEnumerable<string> GetAddresses()
{
      var host = Dns.GetHostEntry(Dns.GetHostName());
      return (from ip in host.AddressList where ip.AddressFamily == AddressFamily.lo select ip.ToString()).ToList();
}

score -1 · Answer 7 · edited Feb 18 '22 at 17:38

-1

You can get all IPv4 address from the DNS using this code:

IPs[] ipv4Addresses = Array.FindAll(
           Dns.GetHostEntry(string.Empty).AddressList,
           address => address.AddressFamily == AddressFamily.InterNetwork);

edited Feb 18 '22 at 17:38

bryanbcook

16,210
2
40
69

answered Feb 18 '22 at 13:15

haqsek2 group

11
1
3

score -5 · Answer 8 · answered Feb 19 '15 at 21:12

-5

IPv6

lblIP.Text = System.Net.Dns.GetHostEntry(System.Net.Dns.GetHostName).AddressList(0).ToString()

IPv4

lblIP.Text = System.Net.Dns.GetHostEntry(System.Net.Dns.GetHostName).AddressList(1).ToString()

answered Feb 19 '15 at 21:12

not nor

1

2

System.Net.Dns.GetHostName is a method, not a property. – RenniePet Jul 12 '15 at 12:15
can get 2 of ipv6 , 0 not equal ipv4, can be another set of ipv6 – Neo Yap Apr 11 '20 at 15:24

Get IPv4 addresses from Dns.GetHostEntry()

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