networking - How do I obtain the physical (MAC) address of an IP address using C#?

Question

From C#, I want to do the equivalent of the following:

arp -a |findstr 192.168.1.254

Alternatively, the answer could call the SendARP function and get the results.

This will allow my application to do some other processing that requires the MAC address.

Answer 1

SendARP P/Invoke goes like this:

[DllImport("iphlpapi.dll", ExactSpelling=true)]
public static extern int SendARP( int destIp, int srcIP, byte[] macAddr, ref uint physicalAddrLen );

PInvoke.NET has this example:

IPAddress dst = IPAddress.Parse("192.168.2.1"); // the destination IP address

byte[] macAddr = new byte[6];
uint macAddrLen = (uint)macAddr.Length;

if (SendARP(BitConverter.ToInt32(dst.GetAddressBytes(), 0), 0, macAddr, ref macAddrLen) != 0)
     throw new InvalidOperationException("SendARP failed.");

string[] str = new string[(int)macAddrLen];
for (int i=0; i<macAddrLen; i++)
     str[i] = macAddr[i].ToString("x2");

Console.WriteLine(string.Join(":", str));