Networking Core

TinyCLR's networking stack implements a subset of Microsoft's standard System.Net.Sockets API. Most .NET socket code runs on TinyCLR with little or no modification — including TCP/UDP sockets, DNS lookups, and TLS. Familiarity with the standard System.Net.Sockets.Socket class transfers directly.

This page covers the common pieces — MAC addresses, IP assignment, sockets, DNS, mDNS — that apply regardless of the underlying transport (Ethernet, WiFi, cellular, PPP).

MAC addresses

Before using SITCore's built-in PHY or the ENC28-based Ethernet, you must set a MAC address — otherwise an exception is raised on enable. For internal testing, any locally-administered MAC will work; for shipped products, you need a valid, unique MAC.

If you don't have access to a registered OUI, sensible options are:

• Use a MAC address from a decommissioned computer or network card.
• Use an online MAC generator (acceptable for one-offs, not for production volumes).

warning

Two devices with the same MAC address on the same local subnet break each other — neither will communicate reliably. Plan for unique MACs on every shipped unit.

The WINC1500 WiFi module ships with a manufacturer-assigned unique MAC. That MAC is used by default, but you can override it if you need to.

IP assignment

TinyCLR supports both static and dynamic IP. With either method, a NetworkAddressChanged event fires once an IP is available so your application can react:

networkController.NetworkAddressChanged += NetworkController_NetworkAddressChanged;

void NetworkController_NetworkAddressChanged(NetworkController sender, NetworkAddressChangedEventArgs e) {
    var ipProperties = sender.GetIPProperties();
}

tip

Static IP addressing is not available on PPP connections.

Static IP

Set the address, mask, gateway, and DNS servers manually:

networkInterfaceSetting.DhcpEnabled = false;
networkInterfaceSetting.Address = new IPAddress(new byte[] { 192, 168, 1, 122 });
networkInterfaceSetting.SubnetMask = new IPAddress(new byte[] { 255, 255, 255, 0 });
networkInterfaceSetting.GatewayAddress = new IPAddress(new byte[] { 192, 168, 1, 1 });
networkInterfaceSetting.DnsAddresses = new IPAddress[] {
    new IPAddress(new byte[] { 75, 75, 75, 75 }),
    new IPAddress(new byte[] { 75, 75, 75, 76 }),
};

Dynamic IP

A single setting enables DHCP. The device tries to lease an IP from a DHCP server first; if that fails, it falls back to AutoIP (self-assigning a link-local address). Both paths can take a few seconds — wait for the NetworkAddressChanged event to know when the IP is ready.

networkInterfaceSetting.DhcpEnabled = true;

tip

AutoIP addresses always fall in the 169.254.x.x range. Check the assigned address against that range to know whether DHCP succeeded or AutoIP took over.

TCP and UDP sockets

TCP and UDP are accessed through the standard System.Net.Sockets.Socket API. Most desktop .NET examples for these protocols work with little or no change on TinyCLR.

TCP

using System.Net;
using System.Net.Sockets;
using System.Text;

using var s = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);

try {
    var ip = IPAddress.Parse("192.168.1.87");
    s.Connect(new IPEndPoint(ip, 80));
    s.Send(Encoding.UTF8.GetBytes("I am SITCore\r\n"));
}
catch {
    // Connection or send failed.
}

UDP

using System.Diagnostics;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;

var socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
var ip = new IPAddress(new byte[] { 192, 168, 1, 87 });
var endPoint = new IPEndPoint(ip, 2000);

socket.Connect(endPoint);

byte[] bytesToSend = Encoding.UTF8.GetBytes(msg);

while (true) {
    socket.SendTo(bytesToSend, bytesToSend.Length, SocketFlags.None, endPoint);

    while (socket.Poll(2_000_000, SelectMode.SelectRead)) {
        if (socket.Available > 0) {
            byte[] inBuf = new byte[socket.Available];
            var recEndPoint = new IPEndPoint(IPAddress.Any, 0);
            socket.ReceiveFrom(inBuf, ref recEndPoint);

            // Ignore packets that didn't come from the address we're talking to.
            if (!recEndPoint.Equals(endPoint))
                continue;

            Debug.WriteLine(new string(Encoding.UTF8.GetChars(inBuf)));
        }
    }

    Thread.Sleep(100);
}

DNS

Resolve a hostname to an IP address with Dns.GetHostEntry:

using System;
using System.Net;

var hostEntry = Dns.GetHostEntry(hostName);

if (hostEntry != null && hostEntry.AddressList.Length > 0) {
    IPAddress remoteIpAddress = null;
    for (int i = 0; i < hostEntry.AddressList.Length; i++) {
        if (hostEntry.AddressList[i] != null) {
            remoteIpAddress = hostEntry.AddressList[i];
            break;
        }
    }

    if (remoteIpAddress == null)
        throw new Exception("No usable address returned for " + hostName);
}
else {
    throw new Exception("Server not found: " + hostName);
}

mDNS

Multicast DNS lets devices discover each other on the local network without a central DNS server. Not all client operating systems include an mDNS responder — macOS and recent Windows do; some Linux distributions require avahi.

networkInterfaceSetting.MulticastDnsEnable = true;

networkController.Enable();

MulticastDns.Start("MyServer", TimeSpan.FromHours(1));      // TTL: 1 hour

Once started, the device responds to lookups for MyServer.local on the local subnet.

Secure sockets (TLS)

TLS 1.2 is natively supported and integrates with the standard socket API. See the TLS page for the full reference.

API reference

Namespace	Description
GHIElectronics.TinyCLR.Networking	Socket, DNS, and mDNS networking classes
GHIElectronics.TinyCLR.Devices.Network	Network interface controller (MAC address, IP config)