How to create static ARP cache entries programatically in Windows XP

Question

Is there are way to set ARP cache entry in C#?

The only way I have found is related to use of arp utility Address Resolution Protocol

Static entries added with the arp -s command are not expired from the cache.

There are related post about How do I access ARP-protocol information through .NET?

score 1 · Accepted Answer · answered Jan 20 '11 at 15:14

It wouldn't be purely .NET obviously, but you should be able to do it via the Win32 API in the IP Helper API library - namely the CreateIpNetEntry and SetIpNetEntry methods. You would likely want to do this via P/Invoke or a wrapped managed C++ library.

http://msdn.microsoft.com/en-us/library/aa366071(v=vs.85).aspx

score 0 · Answer 2 · answered Sep 20 '13 at 15:24

You can simply run the command ARP -s inet_addr eth_adr where inet_addr is the IP address and eth_adr is the hardware address.

  Process process = new Process();
  process.StartInfo.FileName = "arp -s 220.0.0.161 00-50-04-62-F7-23";
  process.StartInfo.CreateNoWindow = true; //Don't show window
  process.Start();

score 0 · Answer 3 · answered Dec 23 '10 at 18:00

The simple solution I am using right now is to run batch command that will add this static entry into ARP table. On Vista and up this will require administrator user rights.

' arp -s 192.168.1.12 01-02-03-04-05-06
Public Sub UpdateArpTable(IpAddress as string, MacAddress as string)
    Dim outputMessage As string = ""
    Dim errorMessage As string = ""
    Dim command As String = String.Format("-s {0} {1}", Address, MacAddress)
    ExecuteShellCommand("arp", command, outputMessage, errorMessage)
End Sub


Public Shared Sub ExecuteShellCommand(FileToExecute As String, CommandLine As String)
    Dim Process As System.Diagnostics.Process = Nothing
    Try
        Process = New System.Diagnostics.Process()
        Dim CMDProcess As String = String.Format("{0}\cmd.exe", Environment.SystemDirectory)

        Dim Arguments As String = String.Format("/C {0}", FileToExecute)

        If CommandLine IsNot Nothing AndAlso CommandLine.Length > 0 Then
            Arguments += String.Format(" {0}", CommandLine)
        End If
        Dim ProcessStartInfo As New System.Diagnostics.ProcessStartInfo(CMDProcess, Arguments)
        ProcessStartInfo.CreateNoWindow = True
        ProcessStartInfo.UseShellExecute = False
        ProcessStartInfo.RedirectStandardOutput = True
        ProcessStartInfo.RedirectStandardInput = True
        ProcessStartInfo.RedirectStandardError = True
        Process.StartInfo = ProcessStartInfo

        Process.Start()
        Process.WaitForExit()
        Process.WaitForExit()
    Finally
        ' close process and do cleanup
        Process.Close()
        Process.Dispose()
        Process = Nothing
    End Try
End Sub

Iulian M. · Answer 4 · 2020-12-11T16:20:19.523

Try this one. (credits to Zach) Make sure to guard the sensible parts with try/catch

using System;
using System.Net;
using System.Runtime.InteropServices;

namespace CreateArpEntry
{
    class Program
    {
        [DllImport("iphlpapi.dll", SetLastError = true)]
        [return: MarshalAs(UnmanagedType.U4)]
        public static extern int CreateIpNetEntry(ref MIB_IPNETROW tableEntry);

        static void Main(string[] args)
        {
            IPAddress.TryParse("192.168.1.2", out IPAddress parsedIpAddress);
            byte[] macBytes = {0,0x0b,0x3b,0,0,1,0,0}; // pad the MAC address with zeros

            MIB_IPNETROW arpEntry = new MIB_IPNETROW
            {
                Index = 20,
                Addr = BitConverter.ToInt32(parsedIpAddress.GetAddressBytes(), 0),
                PhysAddr = macBytes,
                PhysAddrLen = 8,
                Type = 4, // it can only be static
            };

            int a = CreateIpNetEntry(ref arpEntry);
        }

    }

    [StructLayout(LayoutKind.Sequential)]
    public struct MIB_IPNETROW
    {
        /// <summary>
        /// The index of the adapter (Not constant may change for example by disable / enable  
        /// </summary>
        [MarshalAs(UnmanagedType.U4)]
        public int Index;

        /// <summary>
        /// The length of the physical address ( MAC Address) 
        /// </summary>
        [MarshalAs(UnmanagedType.U4)]
        public int PhysAddrLen;

        /// <summary>
        /// The physical / MAC Address
        /// </summary>
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 8)]
        public byte[] PhysAddr;

        /// <summary>
        /// The IP Address
        /// </summary>
        [MarshalAs(UnmanagedType.U4)]
        public int Addr;

        /// <summary>
        /// The IP Address Type
        /// Other = 1, Invalid = 2, Dynamic = 3, Static = 4 
        /// </summary>
        [MarshalAs(UnmanagedType.U4)]
        public int Type;
    }
}

How to create static ARP cache entries programatically in Windows XP

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