c# get arp cache

gistfile1.txt

 [StructLayout(LayoutKind.Sequential)]
        struct MIB_IPNETROW
        {
            [MarshalAs(UnmanagedType.U4)]
            public int dwIndex;
            [MarshalAs(UnmanagedType.U4)]
            public int dwPhysAddrLen;
            [MarshalAs(UnmanagedType.U1)]
            public byte mac0;
            [MarshalAs(UnmanagedType.U1)]
            public byte mac1;
            [MarshalAs(UnmanagedType.U1)]
            public byte mac2;
            [MarshalAs(UnmanagedType.U1)]
            public byte mac3;
            [MarshalAs(UnmanagedType.U1)]
            public byte mac4;
            [MarshalAs(UnmanagedType.U1)]
            public byte mac5;
            [MarshalAs(UnmanagedType.U1)]
            public byte mac6;
            [MarshalAs(UnmanagedType.U1)]
            public byte mac7;
            [MarshalAs(UnmanagedType.U4)]
            public int dwAddr;
            [MarshalAs(UnmanagedType.U4)]
            public int dwType;
        }

        [DllImport("IpHlpApi.dll")]
        private static extern long GetIpNetTable(IntPtr pIpNetTable, ref int pdwSize, bool bOrder);
 
 public static string ArpCache()
        {
            IntPtr buff;
            int requiredLen = 0;
            string ret = "--------------- ARP Table --------------\n";
            long result = GetIpNetTable(IntPtr.Zero, ref requiredLen, false);

            try
            {
                buff = Marshal.AllocCoTaskMem(requiredLen);
                result = GetIpNetTable(buff, ref requiredLen, false);

                int entries = Marshal.ReadInt32(buff);
                IntPtr entryBuffer = new IntPtr(buff.ToInt64() + Marshal.SizeOf(typeof(int)));

                MIB_IPNETROW[] arpTable = new MIB_IPNETROW[entries];

                for(int i = 0; i < entries; i++)
                {
                    int currentIndex = i * Marshal.SizeOf(typeof(MIB_IPNETROW));
                    IntPtr newStruct = new IntPtr(entryBuffer.ToInt64() + currentIndex);
                    arpTable[i] = (MIB_IPNETROW)Marshal.PtrToStructure(newStruct, typeof(MIB_IPNETROW));
                }

                for(int i = 0; i < entries; i++)
                {
                    MIB_IPNETROW entry = arpTable[i];
                    IPAddress addr = new IPAddress(BitConverter.GetBytes(entry.dwAddr));
                    
                    ret += String.Format("{0}: {1}-{2}-{3}-{4}-{5}-{6}\n", addr.ToString(), entry.mac0.ToString("X2"), entry.mac1.ToString("X2"), entry.mac2.ToString("X2"), entry.mac3.ToString("X2"), entry.mac4.ToString("X2"), entry.mac5.ToString("X2"));
                }

            }
            catch(Exception e)
            {
                return "[x] Exception thrown: " + e.Message;
            }
            return ret;
        }

Thank you!