It can actually take screenshots of the VM

RemoteFrameBuffer/Client/RemoteFrameBufferClientProtocol_3_3.cs

@@ -1,4 +1,5 @@
 using RemoteFrameBuffer.Common;
+using System.Text;
 
 namespace RemoteFrameBuffer.Client
 {
@@ -8,15 +9,42 @@ namespace RemoteFrameBuffer.Client
 
         public RemoteFrameBufferClientProtocol_3_3(Stream s) : base(s)
         {
+            this.Phase = RfbClientProtocolPhase.Constructed;
         }
 
-        public override void Handshake()
+        public override void Handshake(CancellationToken token)
         {
-        }
-
-        public override void Initialization()
-        {
-
+            if (this.Phase != RfbClientProtocolPhase.Constructed)
+            {
+                throw new InvalidOperationException("In wrong phase when calling Handshake");
+            }
+            this.Phase = RfbClientProtocolPhase.Handshake;
+            Byte[] buf;
+            // Request protocol version
+            this.vncStream.Write(Encoding.ASCII.GetBytes("RFB 003.003\n"));
+            // Read security type
+            buf = new Byte[4];
+            CancellationTokenSource readTimeout = new CancellationTokenSource(TimeSpan.FromSeconds(5));
+            CancellationTokenSource readTokenSource = CancellationTokenSource.CreateLinkedTokenSource(token, readTimeout.Token);
+            this.vncStream.ReadExactlyAsync(buf, 0, buf.Length, readTokenSource.Token).AsTask().Wait();
+            if (BitConverter.IsLittleEndian)
+            {
+                Array.Reverse(buf);
+            }
+            this.SecurityType = (RemoteFramebufferSecurityType)BitConverter.ToUInt32(buf, 0);
+            Console.Error.WriteLine($"Server uses security type {this.SecurityType}");
+            switch (this.SecurityType)
+            {
+            case RemoteFramebufferSecurityType.Invalid:
+                throw new Exception("Connection failed");
+            case RemoteFramebufferSecurityType.None:
+                break;// RFB 3.3 straight up jumps to initialization here
+            case RemoteFramebufferSecurityType.VncAuthentication:
+                throw new NotImplementedException("VNC Authentication is not implemented");
+            default:
+                throw new NotSupportedException("RFB version 3.3 doesn't support the security type returned by the server");
+            }
+            this.Phase = RfbClientProtocolPhase.HandshakeDone;
         }
     }
 }