[c#] How can you change Network settings (IP Address, DNS, WINS, Host Name) with code in C#

I am developing a wizard for a machine that is to be used as a backup of other machines. When it replaces an existing machine, it needs to set its IP address, DNS, WINS, and host name to match the machine being replaced.

Is there a library in .net (C#) which allows me to do this programatically?

There are multiple NICs, each which need to be set individually.

EDIT

Thank you TimothyP for your example. It got me moving on the right track and the quick reply was awesome.

Thanks balexandre. Your code is perfect. I was in a rush and had already adapted the example TimothyP linked to, but I would have loved to have had your code sooner.

I've also developed a routine using similar techniques for changing the computer name. I'll post it in the future so subscribe to this questions RSS feed if you want to be informed of the update. I may get it up later today or on Monday after a bit of cleanup.

This question is related to c# .net configuration networking

The answer is


The existing answers have quite broken code. The DNS method does not work at all. Here is code that I used to configure my NIC:

public static class NetworkConfigurator
{
    /// <summary>
    /// Set's a new IP Address and it's Submask of the local machine
    /// </summary>
    /// <param name="ipAddress">The IP Address</param>
    /// <param name="subnetMask">The Submask IP Address</param>
    /// <param name="gateway">The gateway.</param>
    /// <param name="nicDescription"></param>
    /// <remarks>Requires a reference to the System.Management namespace</remarks>
    public static void SetIP(string nicDescription, string[] ipAddresses, string subnetMask, string gateway)
    {
        using (var networkConfigMng = new ManagementClass("Win32_NetworkAdapterConfiguration"))
        {
            using (var networkConfigs = networkConfigMng.GetInstances())
            {
                foreach (var managementObject in networkConfigs.Cast<ManagementObject>().Where(mo => (bool)mo["IPEnabled"] && (string)mo["Description"] == nicDescription))
                {
                    using (var newIP = managementObject.GetMethodParameters("EnableStatic"))
                    {
                        // Set new IP address and subnet if needed
                        if (ipAddresses != null || !String.IsNullOrEmpty(subnetMask))
                        {
                            if (ipAddresses != null)
                            {
                                newIP["IPAddress"] = ipAddresses;
                            }

                            if (!String.IsNullOrEmpty(subnetMask))
                            {
                                newIP["SubnetMask"] = Array.ConvertAll(ipAddresses, _ => subnetMask);
                            }

                            managementObject.InvokeMethod("EnableStatic", newIP, null);
                        }

                        // Set mew gateway if needed
                        if (!String.IsNullOrEmpty(gateway))
                        {
                            using (var newGateway = managementObject.GetMethodParameters("SetGateways"))
                            {
                                newGateway["DefaultIPGateway"] = new[] { gateway };
                                newGateway["GatewayCostMetric"] = new[] { 1 };
                                managementObject.InvokeMethod("SetGateways", newGateway, null);
                            }
                        }
                    }
                }
            }
        }
    }

    /// <summary>
    /// Set's the DNS Server of the local machine
    /// </summary>
    /// <param name="nic">NIC address</param>
    /// <param name="dnsServers">Comma seperated list of DNS server addresses</param>
    /// <remarks>Requires a reference to the System.Management namespace</remarks>
    public static void SetNameservers(string nicDescription, string[] dnsServers)
    {
        using (var networkConfigMng = new ManagementClass("Win32_NetworkAdapterConfiguration"))
        {
            using (var networkConfigs = networkConfigMng.GetInstances())
            {
                foreach (var managementObject in networkConfigs.Cast<ManagementObject>().Where(mo => (bool)mo["IPEnabled"] && (string)mo["Description"] == nicDescription))
                {
                    using (var newDNS = managementObject.GetMethodParameters("SetDNSServerSearchOrder"))
                    {
                        newDNS["DNSServerSearchOrder"] = dnsServers;
                        managementObject.InvokeMethod("SetDNSServerSearchOrder", newDNS, null);
                    }
                }
            }
        }
    }
}

I like the WMILinq solution. While not exactly the solution to your problem, find below a taste of it :

using (WmiContext context = new WmiContext(@"\\.")) {

  context.ManagementScope.Options.Impersonation = ImpersonationLevel.Impersonate;
  context.Log = Console.Out;

  var dnss = from nic in context.Source<Win32_NetworkAdapterConfiguration>()
          where nic.IPEnabled
          select nic;

  var ips = from s in dnss.SelectMany(dns => dns.DNSServerSearchOrder)
          select IPAddress.Parse(s);
}  

http://www.codeplex.com/linq2wmi


Refactored the code from balexandre a little so objects gets disposed and the new language features of C# 3.5+ are used (Linq, var, etc). Also renamed the variables to more meaningful names. I also merged some of the functions to be able to do more configuration with less WMI interaction. I removed the WINS code as I don't need to configure WINS anymore. Feel free to add the WINS code if you need it.

For the case anybody likes to use the refactored/modernized code I put it back into the community here.

/// <summary>
/// Helper class to set networking configuration like IP address, DNS servers, etc.
/// </summary>
public class NetworkConfigurator
{
    /// <summary>
    /// Set's a new IP Address and it's Submask of the local machine
    /// </summary>
    /// <param name="ipAddress">The IP Address</param>
    /// <param name="subnetMask">The Submask IP Address</param>
    /// <param name="gateway">The gateway.</param>
    /// <remarks>Requires a reference to the System.Management namespace</remarks>
    public void SetIP(string ipAddress, string subnetMask, string gateway)
    {
        using (var networkConfigMng = new ManagementClass("Win32_NetworkAdapterConfiguration"))
        {
            using (var networkConfigs = networkConfigMng.GetInstances())
            {
                foreach (var managementObject in networkConfigs.Cast<ManagementObject>().Where(managementObject => (bool)managementObject["IPEnabled"]))
                {
                    using (var newIP = managementObject.GetMethodParameters("EnableStatic"))
                    {
                        // Set new IP address and subnet if needed
                        if ((!String.IsNullOrEmpty(ipAddress)) || (!String.IsNullOrEmpty(subnetMask)))
                        {
                            if (!String.IsNullOrEmpty(ipAddress))
                            {
                                newIP["IPAddress"] = new[] { ipAddress };
                            }

                            if (!String.IsNullOrEmpty(subnetMask))
                            {
                                newIP["SubnetMask"] = new[] { subnetMask };
                            }

                            managementObject.InvokeMethod("EnableStatic", newIP, null);
                        }

                        // Set mew gateway if needed
                        if (!String.IsNullOrEmpty(gateway))
                        {
                            using (var newGateway = managementObject.GetMethodParameters("SetGateways"))
                            {
                                newGateway["DefaultIPGateway"] = new[] { gateway };
                                newGateway["GatewayCostMetric"] = new[] { 1 };
                                managementObject.InvokeMethod("SetGateways", newGateway, null);
                            }
                        }
                    }
                }
            }
        }
    }

    /// <summary>
    /// Set's the DNS Server of the local machine
    /// </summary>
    /// <param name="nic">NIC address</param>
    /// <param name="dnsServers">Comma seperated list of DNS server addresses</param>
    /// <remarks>Requires a reference to the System.Management namespace</remarks>
    public void SetNameservers(string nic, string dnsServers)
    {
        using (var networkConfigMng = new ManagementClass("Win32_NetworkAdapterConfiguration"))
        {
            using (var networkConfigs = networkConfigMng.GetInstances())
            {
                foreach (var managementObject in networkConfigs.Cast<ManagementObject>().Where(objMO => (bool)objMO["IPEnabled"] && objMO["Caption"].Equals(nic)))
                {
                    using (var newDNS = managementObject.GetMethodParameters("SetDNSServerSearchOrder"))
                    {
                        newDNS["DNSServerSearchOrder"] = dnsServers.Split(',');
                        managementObject.InvokeMethod("SetDNSServerSearchOrder", newDNS, null);
                    }
                }
            }
        }
    }
}

This maybe more clear:

static NetworkInterface GetNetworkInterface(string macAddress)
{
    foreach(NetworkInterface ni in NetworkInterface.GetAllNetworkInterfaces())
    {
        if (macAddress == ni.GetPhysicalAddress().ToString())
            return ni;
    }
    return null;
}
static ManagementObject GetNetworkInterfaceManagementObject(string macAddress)
{
    NetworkInterface ni = GetNetworkInterface(macAddress);
    if (ni == null)
        return null;
    ManagementClass managementClass = new ManagementClass("Win32_NetworkAdapterConfiguration");
    ManagementObjectCollection moc = managementClass.GetInstances();
    foreach(ManagementObject mo in moc)
    {
        if (mo["settingID"].ToString() == ni.Id)
            return mo;
    }
    return null;
}
static bool SetupNIC(string macAddress, string ip, string subnet, string gateway, string dns)
{
    try
    {
        ManagementObject mo = GetNetworkInterfaceManagementObject(macAddress);

        //Set IP
        ManagementBaseObject mboIP = mo.GetMethodParameters("EnableStatic");
        mboIP["IPAddress"] = new string[] { ip };
        mboIP["SubnetMask"] = new string[] { subnet };
        mo.InvokeMethod("EnableStatic", mboIP, null);

        //Set Gateway
        ManagementBaseObject mboGateway = mo.GetMethodParameters("SetGateways");
        mboGateway["DefaultIPGateway"] = new string[] { gateway };
        mboGateway["GatewayCostMetric"] = new int[] { 1 };
        mo.InvokeMethod("SetGateways", mboGateway, null);

        //Set DNS
        ManagementBaseObject mboDNS = mo.GetMethodParameters("SetDNSServerSearchOrder");
        mboDNS["DNSServerSearchOrder"] = new string[] { dns };
        mo.InvokeMethod("SetDNSServerSearchOrder", mboDNS, null);

        return true;
    }
    catch (Exception e)
    {
        return false;
    }
}

A far more clear solution is to use the command netsh to change the IP (or setting it back to DHCP)

netsh interface ip set address "Local Area Connection" static 192.168.0.10 255.255.255.0

Where "Local Area Connection" is the name of the network adapter. You could find it in the windows Network Connections, sometimes it is simply named "Ethernet".

Here are two methods to set the IP and also to set the IP back to DHCP "Obtain an IP address automatically"

public bool SetIP(string networkInterfaceName, string ipAddress, string subnetMask, string gateway = null)
{
    var networkInterface = NetworkInterface.GetAllNetworkInterfaces().FirstOrDefault(nw => nw.Name == networkInterfaceName);
    var ipProperties = networkInterface.GetIPProperties();
    var ipInfo = ipProperties.UnicastAddresses.FirstOrDefault(ip => ip.Address.AddressFamily == AddressFamily.InterNetwork);
    var currentIPaddress = ipInfo.Address.ToString();
    var currentSubnetMask = ipInfo.IPv4Mask.ToString();
    var isDHCPenabled = ipProperties.GetIPv4Properties().IsDhcpEnabled;

    if (!isDHCPenabled && currentIPaddress == ipAddress && currentSubnetMask == subnetMask)
        return true;    // no change necessary

    var process = new Process
    {
        StartInfo = new ProcessStartInfo("netsh", $"interface ip set address \"{networkInterfaceName}\" static {ipAddress} {subnetMask}" + (string.IsNullOrWhiteSpace(gateway) ? "" : $"{gateway} 1")) { Verb = "runas" }
    };
    process.Start();
    var successful = process.ExitCode == 0;
    process.Dispose();
    return successful;
}

public bool SetDHCP(string networkInterfaceName)
{
    var networkInterface = NetworkInterface.GetAllNetworkInterfaces().FirstOrDefault(nw => nw.Name == networkInterfaceName);
    var ipProperties = networkInterface.GetIPProperties();
    var isDHCPenabled = ipProperties.GetIPv4Properties().IsDhcpEnabled;

    if (isDHCPenabled)
        return true;    // no change necessary

    var process = new Process
    {
        StartInfo = new ProcessStartInfo("netsh", $"interface ip set address \"{networkInterfaceName}\" dhcp") { Verb = "runas" }
    };
    process.Start();
    var successful = process.ExitCode == 0;
    process.Dispose();
    return successful;
}

A slightly more concise example that builds on top of the other answers here. I leveraged the code generation that is shipped with Visual Studio to remove most of the extra invocation code and replaced it with typed objects instead.

    using System;
    using System.Management;

    namespace Utils
    {
        class NetworkManagement
        {
            /// <summary>
            /// Returns a list of all the network interface class names that are currently enabled in the system
            /// </summary>
            /// <returns>list of nic names</returns>
            public static string[] GetAllNicDescriptions()
            {
                List<string> nics = new List<string>();

                using (var networkConfigMng = new ManagementClass("Win32_NetworkAdapterConfiguration"))
                {
                    using (var networkConfigs = networkConfigMng.GetInstances())
                    {
                        foreach (var config in networkConfigs.Cast<ManagementObject>()
                                                                           .Where(mo => (bool)mo["IPEnabled"])
                                                                           .Select(x=> new NetworkAdapterConfiguration(x)))
                        {
                            nics.Add(config.Description);
                        }
                    }
                }

                return nics.ToArray();
            }

            /// <summary>
            /// Set's the DNS Server of the local machine
            /// </summary>
            /// <param name="nicDescription">The full description of the network interface class</param>
            /// <param name="dnsServers">Comma seperated list of DNS server addresses</param>
            /// <remarks>Requires a reference to the System.Management namespace</remarks>
            public static bool SetNameservers(string nicDescription, string[] dnsServers, bool restart = false)
            {
                using (ManagementClass networkConfigMng = new ManagementClass("Win32_NetworkAdapterConfiguration"))
                {
                    using (ManagementObjectCollection networkConfigs = networkConfigMng.GetInstances())
                    {
                        foreach (ManagementObject mboDNS in networkConfigs.Cast<ManagementObject>().Where(mo => (bool)mo["IPEnabled"] && (string)mo["Description"] == nicDescription))
                        {
                            // NAC class was generated by opening a developer console and entering:
                            // mgmtclassgen Win32_NetworkAdapterConfiguration -p NetworkAdapterConfiguration.cs
                            // See: http://blog.opennetcf.com/2008/06/24/disableenable-network-connections-under-vista/

                            using (NetworkAdapterConfiguration config = new NetworkAdapterConfiguration(mboDNS))
                            {
                                if (config.SetDNSServerSearchOrder(dnsServers) == 0)
                                {
                                    RestartNetworkAdapter(nicDescription);
                                }
                            }
                        }
                    }
                }

                return false;
            }

            /// <summary>
            /// Restarts a given Network adapter
            /// </summary>
            /// <param name="nicDescription">The full description of the network interface class</param>
            public static void RestartNetworkAdapter(string nicDescription)
            {
                using (ManagementClass networkConfigMng = new ManagementClass("Win32_NetworkAdapter"))
                {
                    using (ManagementObjectCollection networkConfigs = networkConfigMng.GetInstances())
                    {
                        foreach (ManagementObject mboDNS in networkConfigs.Cast<ManagementObject>().Where(mo=> (string)mo["Description"] == nicDescription))
                        {
                            // NA class was generated by opening dev console and entering
                            // mgmtclassgen Win32_NetworkAdapter -p NetworkAdapter.cs
                            using (NetworkAdapter adapter = new NetworkAdapter(mboDNS))
                            {
                                adapter.Disable();
                                adapter.Enable();
                                Thread.Sleep(4000); // Wait a few secs until exiting, this will give the NIC enough time to re-connect
                                return;
                            }
                        }
                    }
                }
            }

            /// <summary>
            /// Get's the DNS Server of the local machine
            /// </summary>
            /// <param name="nicDescription">The full description of the network interface class</param>
            public static string[] GetNameservers(string nicDescription)
            {
                using (var networkConfigMng = new ManagementClass("Win32_NetworkAdapterConfiguration"))
                {
                    using (var networkConfigs = networkConfigMng.GetInstances())
                    {
                        foreach (var config  in networkConfigs.Cast<ManagementObject>()
                                                              .Where(mo => (bool)mo["IPEnabled"] && (string)mo["Description"] == nicDescription)
                                                              .Select( x => new NetworkAdapterConfiguration(x)))
                        {
                            return config.DNSServerSearchOrder;
                        }
                    }
                }

                return null;
            }

            /// <summary>
            /// Set's a new IP Address and it's Submask of the local machine
            /// </summary>
            /// <param name="nicDescription">The full description of the network interface class</param>
            /// <param name="ipAddresses">The IP Address</param>
            /// <param name="subnetMask">The Submask IP Address</param>
            /// <param name="gateway">The gateway.</param>
            /// <remarks>Requires a reference to the System.Management namespace</remarks>
            public static void SetIP(string nicDescription, string[] ipAddresses, string subnetMask, string gateway)
            {
                using (var networkConfigMng = new ManagementClass("Win32_NetworkAdapterConfiguration"))
                {
                    using (var networkConfigs = networkConfigMng.GetInstances())
                    {
                        foreach (var config in networkConfigs.Cast<ManagementObject>()
                                                                       .Where(mo => (bool)mo["IPEnabled"] && (string)mo["Description"] == nicDescription)
                                                                       .Select( x=> new NetworkAdapterConfiguration(x)))
                        {
                            // Set the new IP and subnet masks if needed
                            config.EnableStatic(ipAddresses, Array.ConvertAll(ipAddresses, _ => subnetMask));

                            // Set mew gateway if needed
                            if (!String.IsNullOrEmpty(gateway))
                            {
                                config.SetGateways(new[] {gateway}, new ushort[] {1});
                            }
                        }
                    }
                }
            }

        }
    }

Full source: https://github.com/sverrirs/DnsHelper/blob/master/src/DnsHelperUI/NetworkManagement.cs


A far more clear solution is to use the command netsh to change the IP (or setting it back to DHCP)

netsh interface ip set address "Local Area Connection" static 192.168.0.10 255.255.255.0

Where "Local Area Connection" is the name of the network adapter. You could find it in the windows Network Connections, sometimes it is simply named "Ethernet".

Here are two methods to set the IP and also to set the IP back to DHCP "Obtain an IP address automatically"

public bool SetIP(string networkInterfaceName, string ipAddress, string subnetMask, string gateway = null)
{
    var networkInterface = NetworkInterface.GetAllNetworkInterfaces().FirstOrDefault(nw => nw.Name == networkInterfaceName);
    var ipProperties = networkInterface.GetIPProperties();
    var ipInfo = ipProperties.UnicastAddresses.FirstOrDefault(ip => ip.Address.AddressFamily == AddressFamily.InterNetwork);
    var currentIPaddress = ipInfo.Address.ToString();
    var currentSubnetMask = ipInfo.IPv4Mask.ToString();
    var isDHCPenabled = ipProperties.GetIPv4Properties().IsDhcpEnabled;

    if (!isDHCPenabled && currentIPaddress == ipAddress && currentSubnetMask == subnetMask)
        return true;    // no change necessary

    var process = new Process
    {
        StartInfo = new ProcessStartInfo("netsh", $"interface ip set address \"{networkInterfaceName}\" static {ipAddress} {subnetMask}" + (string.IsNullOrWhiteSpace(gateway) ? "" : $"{gateway} 1")) { Verb = "runas" }
    };
    process.Start();
    var successful = process.ExitCode == 0;
    process.Dispose();
    return successful;
}

public bool SetDHCP(string networkInterfaceName)
{
    var networkInterface = NetworkInterface.GetAllNetworkInterfaces().FirstOrDefault(nw => nw.Name == networkInterfaceName);
    var ipProperties = networkInterface.GetIPProperties();
    var isDHCPenabled = ipProperties.GetIPv4Properties().IsDhcpEnabled;

    if (isDHCPenabled)
        return true;    // no change necessary

    var process = new Process
    {
        StartInfo = new ProcessStartInfo("netsh", $"interface ip set address \"{networkInterfaceName}\" dhcp") { Verb = "runas" }
    };
    process.Start();
    var successful = process.ExitCode == 0;
    process.Dispose();
    return successful;
}

This maybe more clear:

static NetworkInterface GetNetworkInterface(string macAddress)
{
    foreach(NetworkInterface ni in NetworkInterface.GetAllNetworkInterfaces())
    {
        if (macAddress == ni.GetPhysicalAddress().ToString())
            return ni;
    }
    return null;
}
static ManagementObject GetNetworkInterfaceManagementObject(string macAddress)
{
    NetworkInterface ni = GetNetworkInterface(macAddress);
    if (ni == null)
        return null;
    ManagementClass managementClass = new ManagementClass("Win32_NetworkAdapterConfiguration");
    ManagementObjectCollection moc = managementClass.GetInstances();
    foreach(ManagementObject mo in moc)
    {
        if (mo["settingID"].ToString() == ni.Id)
            return mo;
    }
    return null;
}
static bool SetupNIC(string macAddress, string ip, string subnet, string gateway, string dns)
{
    try
    {
        ManagementObject mo = GetNetworkInterfaceManagementObject(macAddress);

        //Set IP
        ManagementBaseObject mboIP = mo.GetMethodParameters("EnableStatic");
        mboIP["IPAddress"] = new string[] { ip };
        mboIP["SubnetMask"] = new string[] { subnet };
        mo.InvokeMethod("EnableStatic", mboIP, null);

        //Set Gateway
        ManagementBaseObject mboGateway = mo.GetMethodParameters("SetGateways");
        mboGateway["DefaultIPGateway"] = new string[] { gateway };
        mboGateway["GatewayCostMetric"] = new int[] { 1 };
        mo.InvokeMethod("SetGateways", mboGateway, null);

        //Set DNS
        ManagementBaseObject mboDNS = mo.GetMethodParameters("SetDNSServerSearchOrder");
        mboDNS["DNSServerSearchOrder"] = new string[] { dns };
        mo.InvokeMethod("SetDNSServerSearchOrder", mboDNS, null);

        return true;
    }
    catch (Exception e)
    {
        return false;
    }
}

Refactored the code from balexandre a little so objects gets disposed and the new language features of C# 3.5+ are used (Linq, var, etc). Also renamed the variables to more meaningful names. I also merged some of the functions to be able to do more configuration with less WMI interaction. I removed the WINS code as I don't need to configure WINS anymore. Feel free to add the WINS code if you need it.

For the case anybody likes to use the refactored/modernized code I put it back into the community here.

/// <summary>
/// Helper class to set networking configuration like IP address, DNS servers, etc.
/// </summary>
public class NetworkConfigurator
{
    /// <summary>
    /// Set's a new IP Address and it's Submask of the local machine
    /// </summary>
    /// <param name="ipAddress">The IP Address</param>
    /// <param name="subnetMask">The Submask IP Address</param>
    /// <param name="gateway">The gateway.</param>
    /// <remarks>Requires a reference to the System.Management namespace</remarks>
    public void SetIP(string ipAddress, string subnetMask, string gateway)
    {
        using (var networkConfigMng = new ManagementClass("Win32_NetworkAdapterConfiguration"))
        {
            using (var networkConfigs = networkConfigMng.GetInstances())
            {
                foreach (var managementObject in networkConfigs.Cast<ManagementObject>().Where(managementObject => (bool)managementObject["IPEnabled"]))
                {
                    using (var newIP = managementObject.GetMethodParameters("EnableStatic"))
                    {
                        // Set new IP address and subnet if needed
                        if ((!String.IsNullOrEmpty(ipAddress)) || (!String.IsNullOrEmpty(subnetMask)))
                        {
                            if (!String.IsNullOrEmpty(ipAddress))
                            {
                                newIP["IPAddress"] = new[] { ipAddress };
                            }

                            if (!String.IsNullOrEmpty(subnetMask))
                            {
                                newIP["SubnetMask"] = new[] { subnetMask };
                            }

                            managementObject.InvokeMethod("EnableStatic", newIP, null);
                        }

                        // Set mew gateway if needed
                        if (!String.IsNullOrEmpty(gateway))
                        {
                            using (var newGateway = managementObject.GetMethodParameters("SetGateways"))
                            {
                                newGateway["DefaultIPGateway"] = new[] { gateway };
                                newGateway["GatewayCostMetric"] = new[] { 1 };
                                managementObject.InvokeMethod("SetGateways", newGateway, null);
                            }
                        }
                    }
                }
            }
        }
    }

    /// <summary>
    /// Set's the DNS Server of the local machine
    /// </summary>
    /// <param name="nic">NIC address</param>
    /// <param name="dnsServers">Comma seperated list of DNS server addresses</param>
    /// <remarks>Requires a reference to the System.Management namespace</remarks>
    public void SetNameservers(string nic, string dnsServers)
    {
        using (var networkConfigMng = new ManagementClass("Win32_NetworkAdapterConfiguration"))
        {
            using (var networkConfigs = networkConfigMng.GetInstances())
            {
                foreach (var managementObject in networkConfigs.Cast<ManagementObject>().Where(objMO => (bool)objMO["IPEnabled"] && objMO["Caption"].Equals(nic)))
                {
                    using (var newDNS = managementObject.GetMethodParameters("SetDNSServerSearchOrder"))
                    {
                        newDNS["DNSServerSearchOrder"] = dnsServers.Split(',');
                        managementObject.InvokeMethod("SetDNSServerSearchOrder", newDNS, null);
                    }
                }
            }
        }
    }
}

A slightly more concise example that builds on top of the other answers here. I leveraged the code generation that is shipped with Visual Studio to remove most of the extra invocation code and replaced it with typed objects instead.

    using System;
    using System.Management;

    namespace Utils
    {
        class NetworkManagement
        {
            /// <summary>
            /// Returns a list of all the network interface class names that are currently enabled in the system
            /// </summary>
            /// <returns>list of nic names</returns>
            public static string[] GetAllNicDescriptions()
            {
                List<string> nics = new List<string>();

                using (var networkConfigMng = new ManagementClass("Win32_NetworkAdapterConfiguration"))
                {
                    using (var networkConfigs = networkConfigMng.GetInstances())
                    {
                        foreach (var config in networkConfigs.Cast<ManagementObject>()
                                                                           .Where(mo => (bool)mo["IPEnabled"])
                                                                           .Select(x=> new NetworkAdapterConfiguration(x)))
                        {
                            nics.Add(config.Description);
                        }
                    }
                }

                return nics.ToArray();
            }

            /// <summary>
            /// Set's the DNS Server of the local machine
            /// </summary>
            /// <param name="nicDescription">The full description of the network interface class</param>
            /// <param name="dnsServers">Comma seperated list of DNS server addresses</param>
            /// <remarks>Requires a reference to the System.Management namespace</remarks>
            public static bool SetNameservers(string nicDescription, string[] dnsServers, bool restart = false)
            {
                using (ManagementClass networkConfigMng = new ManagementClass("Win32_NetworkAdapterConfiguration"))
                {
                    using (ManagementObjectCollection networkConfigs = networkConfigMng.GetInstances())
                    {
                        foreach (ManagementObject mboDNS in networkConfigs.Cast<ManagementObject>().Where(mo => (bool)mo["IPEnabled"] && (string)mo["Description"] == nicDescription))
                        {
                            // NAC class was generated by opening a developer console and entering:
                            // mgmtclassgen Win32_NetworkAdapterConfiguration -p NetworkAdapterConfiguration.cs
                            // See: http://blog.opennetcf.com/2008/06/24/disableenable-network-connections-under-vista/

                            using (NetworkAdapterConfiguration config = new NetworkAdapterConfiguration(mboDNS))
                            {
                                if (config.SetDNSServerSearchOrder(dnsServers) == 0)
                                {
                                    RestartNetworkAdapter(nicDescription);
                                }
                            }
                        }
                    }
                }

                return false;
            }

            /// <summary>
            /// Restarts a given Network adapter
            /// </summary>
            /// <param name="nicDescription">The full description of the network interface class</param>
            public static void RestartNetworkAdapter(string nicDescription)
            {
                using (ManagementClass networkConfigMng = new ManagementClass("Win32_NetworkAdapter"))
                {
                    using (ManagementObjectCollection networkConfigs = networkConfigMng.GetInstances())
                    {
                        foreach (ManagementObject mboDNS in networkConfigs.Cast<ManagementObject>().Where(mo=> (string)mo["Description"] == nicDescription))
                        {
                            // NA class was generated by opening dev console and entering
                            // mgmtclassgen Win32_NetworkAdapter -p NetworkAdapter.cs
                            using (NetworkAdapter adapter = new NetworkAdapter(mboDNS))
                            {
                                adapter.Disable();
                                adapter.Enable();
                                Thread.Sleep(4000); // Wait a few secs until exiting, this will give the NIC enough time to re-connect
                                return;
                            }
                        }
                    }
                }
            }

            /// <summary>
            /// Get's the DNS Server of the local machine
            /// </summary>
            /// <param name="nicDescription">The full description of the network interface class</param>
            public static string[] GetNameservers(string nicDescription)
            {
                using (var networkConfigMng = new ManagementClass("Win32_NetworkAdapterConfiguration"))
                {
                    using (var networkConfigs = networkConfigMng.GetInstances())
                    {
                        foreach (var config  in networkConfigs.Cast<ManagementObject>()
                                                              .Where(mo => (bool)mo["IPEnabled"] && (string)mo["Description"] == nicDescription)
                                                              .Select( x => new NetworkAdapterConfiguration(x)))
                        {
                            return config.DNSServerSearchOrder;
                        }
                    }
                }

                return null;
            }

            /// <summary>
            /// Set's a new IP Address and it's Submask of the local machine
            /// </summary>
            /// <param name="nicDescription">The full description of the network interface class</param>
            /// <param name="ipAddresses">The IP Address</param>
            /// <param name="subnetMask">The Submask IP Address</param>
            /// <param name="gateway">The gateway.</param>
            /// <remarks>Requires a reference to the System.Management namespace</remarks>
            public static void SetIP(string nicDescription, string[] ipAddresses, string subnetMask, string gateway)
            {
                using (var networkConfigMng = new ManagementClass("Win32_NetworkAdapterConfiguration"))
                {
                    using (var networkConfigs = networkConfigMng.GetInstances())
                    {
                        foreach (var config in networkConfigs.Cast<ManagementObject>()
                                                                       .Where(mo => (bool)mo["IPEnabled"] && (string)mo["Description"] == nicDescription)
                                                                       .Select( x=> new NetworkAdapterConfiguration(x)))
                        {
                            // Set the new IP and subnet masks if needed
                            config.EnableStatic(ipAddresses, Array.ConvertAll(ipAddresses, _ => subnetMask));

                            // Set mew gateway if needed
                            if (!String.IsNullOrEmpty(gateway))
                            {
                                config.SetGateways(new[] {gateway}, new ushort[] {1});
                            }
                        }
                    }
                }
            }

        }
    }

Full source: https://github.com/sverrirs/DnsHelper/blob/master/src/DnsHelperUI/NetworkManagement.cs


The existing answers have quite broken code. The DNS method does not work at all. Here is code that I used to configure my NIC:

public static class NetworkConfigurator
{
    /// <summary>
    /// Set's a new IP Address and it's Submask of the local machine
    /// </summary>
    /// <param name="ipAddress">The IP Address</param>
    /// <param name="subnetMask">The Submask IP Address</param>
    /// <param name="gateway">The gateway.</param>
    /// <param name="nicDescription"></param>
    /// <remarks>Requires a reference to the System.Management namespace</remarks>
    public static void SetIP(string nicDescription, string[] ipAddresses, string subnetMask, string gateway)
    {
        using (var networkConfigMng = new ManagementClass("Win32_NetworkAdapterConfiguration"))
        {
            using (var networkConfigs = networkConfigMng.GetInstances())
            {
                foreach (var managementObject in networkConfigs.Cast<ManagementObject>().Where(mo => (bool)mo["IPEnabled"] && (string)mo["Description"] == nicDescription))
                {
                    using (var newIP = managementObject.GetMethodParameters("EnableStatic"))
                    {
                        // Set new IP address and subnet if needed
                        if (ipAddresses != null || !String.IsNullOrEmpty(subnetMask))
                        {
                            if (ipAddresses != null)
                            {
                                newIP["IPAddress"] = ipAddresses;
                            }

                            if (!String.IsNullOrEmpty(subnetMask))
                            {
                                newIP["SubnetMask"] = Array.ConvertAll(ipAddresses, _ => subnetMask);
                            }

                            managementObject.InvokeMethod("EnableStatic", newIP, null);
                        }

                        // Set mew gateway if needed
                        if (!String.IsNullOrEmpty(gateway))
                        {
                            using (var newGateway = managementObject.GetMethodParameters("SetGateways"))
                            {
                                newGateway["DefaultIPGateway"] = new[] { gateway };
                                newGateway["GatewayCostMetric"] = new[] { 1 };
                                managementObject.InvokeMethod("SetGateways", newGateway, null);
                            }
                        }
                    }
                }
            }
        }
    }

    /// <summary>
    /// Set's the DNS Server of the local machine
    /// </summary>
    /// <param name="nic">NIC address</param>
    /// <param name="dnsServers">Comma seperated list of DNS server addresses</param>
    /// <remarks>Requires a reference to the System.Management namespace</remarks>
    public static void SetNameservers(string nicDescription, string[] dnsServers)
    {
        using (var networkConfigMng = new ManagementClass("Win32_NetworkAdapterConfiguration"))
        {
            using (var networkConfigs = networkConfigMng.GetInstances())
            {
                foreach (var managementObject in networkConfigs.Cast<ManagementObject>().Where(mo => (bool)mo["IPEnabled"] && (string)mo["Description"] == nicDescription))
                {
                    using (var newDNS = managementObject.GetMethodParameters("SetDNSServerSearchOrder"))
                    {
                        newDNS["DNSServerSearchOrder"] = dnsServers;
                        managementObject.InvokeMethod("SetDNSServerSearchOrder", newDNS, null);
                    }
                }
            }
        }
    }
}

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