diff --git a/control_tab.c b/control_tab.c
index b6674a0..2a9eed5 100644
--- a/control_tab.c
+++ b/control_tab.c
@@ -1,15 +1,89 @@
+#include <unistd.h>
+#include <netinet/in.h>
 #include <gtk/gtk.h>
+#include <errno.h>
 
-static gboolean connected = FALSE;
+#include "tcpsocket.h"
+#include "sockaddr.h"
 
-static void connect_cb(GtkWidget *widget, gpointer data)
+enum {
+	STAT_DISCONNECTED = 0,
+	STAT_CONNECTING,
+	STAT_CONNECTED
+};
+
+static GtkWidget *button_connect;
+static int connect_status = STAT_DISCONNECTED;
+
+static gint socket_tag;
+static int socket_fd;
+
+static void update_connect_button(void)
 {
-	connected = !connected;
-
-	if (connected)
-		gtk_button_set_label(GTK_BUTTON(widget), "Disconnect");
+	if (connect_status == STAT_DISCONNECTED)
+		gtk_button_set_label(GTK_BUTTON(button_connect),  "Connect");
 	else
-		gtk_button_set_label(GTK_BUTTON(widget), "Connect");
+		gtk_button_set_label(GTK_BUTTON(button_connect),  "Disconnect");
+}
+
+static void read_cb(gpointer data, gint source, GdkInputCondition condition)
+{
+	char buf[64];
+
+	int len = read(source, buf, sizeof(buf));
+	if (len <= 0) {
+		g_warning("gtdc:read_cb:read:%s", g_strerror(errno));
+		connect_status = STAT_DISCONNECTED;
+		update_connect_button();
+
+		gdk_input_remove(socket_tag);
+		close(socket_fd);
+	}
+}
+
+static void connect_cb(gpointer data, gint source, GdkInputCondition condition)
+{
+	gdk_input_remove(socket_tag);
+
+	if (tcp_connect_error(source) < 0) {
+		g_warning("gtdc:connect_cb:tcp_connect_error:%s", g_strerror(errno));
+		connect_status = STAT_DISCONNECTED;
+		close(socket_fd);
+
+	} else {
+		connect_status = STAT_CONNECTED;
+		socket_tag = gdk_input_add(socket_fd, GDK_INPUT_READ, read_cb, NULL);
+
+		//TODO: clear variable data
+		//TODO: send TDC_HELLO
+	}
+
+	update_connect_button();
+}
+
+static void connect_button_cb(GtkWidget *widget, gpointer data)
+{
+	switch (connect_status) {
+	case STAT_DISCONNECTED:
+		connect_status = STAT_CONNECTING;
+
+		struct sockaddr_in sa;
+		parse_sockaddr("127.0.0.1:5000", &sa);
+		socket_fd = tcp_connect_nonblock(&sa);
+
+		socket_tag = gdk_input_add(socket_fd, GDK_INPUT_WRITE, connect_cb, NULL);
+		break;
+
+	case STAT_CONNECTING:
+	case STAT_CONNECTED:
+		connect_status = STAT_DISCONNECTED;
+
+		gdk_input_remove(socket_tag);
+		close(socket_fd);
+		break;
+	}
+
+	update_connect_button();
 }
 
 gint control_tab_init(GtkNotebook *notebook)
@@ -17,9 +91,9 @@ gint control_tab_init(GtkNotebook *notebook)
 	GtkWidget *table = gtk_table_new(10, 10, FALSE);
 	gtk_container_set_border_width(GTK_CONTAINER(table), 10);
 
-	GtkWidget *button = gtk_button_new_with_label("Connect");
-	gtk_table_attach(GTK_TABLE(table), button, 0, 1, 0, 1, 0, 0, 10, 10);
-	g_signal_connect(G_OBJECT(button), "clicked", G_CALLBACK(connect_cb), NULL);
+	button_connect = gtk_button_new_with_label("Connect");
+	gtk_table_attach(GTK_TABLE(table), button_connect, 0, 1, 0, 1, 0, 0, 10, 10);
+	g_signal_connect(G_OBJECT(button_connect), "clicked", G_CALLBACK(connect_button_cb), NULL);
 
 	GtkWidget *label = gtk_label_new(" Control ");
 	return gtk_notebook_append_page(GTK_NOTEBOOK(notebook), table, label);