diff --git a/src/Makefile b/src/Makefile
index d90c864d..c7642981 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -273,6 +273,9 @@ mosquitto_passwd.o : mosquitto_passwd.c
 plugin_defer.so : plugin_defer.c mosquitto_plugin.h mosquitto_broker.h mosquitto_broker_internal.h
 	${CROSS_COMPILE}${CC} -I. -I../lib -fPIC -shared $< -o $@
 
+plugin_debug.so : plugin_debug.c mosquitto_plugin.h mosquitto_broker.h mosquitto_broker_internal.h
+	${CROSS_COMPILE}${CC} -I. -I../lib -fPIC -shared $< -o $@
+
 install : all
 	$(INSTALL) -d "${DESTDIR}$(prefix)/sbin"
 	$(INSTALL) ${STRIP_OPTS} mosquitto "${DESTDIR}${prefix}/sbin/mosquitto"
diff --git a/src/plugin_debug.c b/src/plugin_debug.c
new file mode 100644
index 00000000..9913daf6
--- /dev/null
+++ b/src/plugin_debug.c
@@ -0,0 +1,113 @@
+/*
+Copyright (c) 2015-2019 Roger Light <roger@atchoo.org>
+
+All rights reserved. This program and the accompanying materials
+are made available under the terms of the Eclipse Public License v1.0
+and Eclipse Distribution License v1.0 which accompany this distribution.
+ 
+The Eclipse Public License is available at
+   http://www.eclipse.org/legal/epl-v10.html
+and the Eclipse Distribution License is available at
+  http://www.eclipse.org/org/documents/edl-v10.php.
+ 
+Contributors:
+   Roger Light - initial implementation and documentation.
+*/
+
+/* This is a skeleton authentication and access control plugin that print a
+ * message when each check occurs. It allows everything. */
+
+#include <stdio.h>
+
+#include "mosquitto_broker.h"
+#include "mosquitto_plugin.h"
+#include "mosquitto.h"
+
+#define ANSI_GREEN "\e[0;32m"
+#define ANSI_BLUE "\e[0;34m"
+#define ANSI_MAGENTA "\e[0;35m"
+#define ANSI_RESET "\e[0m"
+
+void print_col(struct mosquitto *client)
+{
+	switch(mosquitto_client_protocol(client)){
+		case mp_mqtt:
+			printf("%s", ANSI_GREEN);
+			break;
+		case mp_websockets:
+			printf("%s", ANSI_MAGENTA);
+			break;
+		default:
+			break;
+	}
+}
+
+int mosquitto_auth_plugin_version(void)
+{
+	printf(ANSI_BLUE "PLUGIN ::: mosquitto_auth_plugin_version()" ANSI_RESET "\n");
+	return MOSQ_AUTH_PLUGIN_VERSION;
+}
+
+int mosquitto_auth_plugin_init(void **user_data, struct mosquitto_opt *auth_opts, int auth_opt_count)
+{
+	printf(ANSI_BLUE "PLUGIN ::: mosquitto_auth_plugin_init(,,%d)" ANSI_RESET "\n", auth_opt_count);
+	return MOSQ_ERR_SUCCESS;
+}
+
+int mosquitto_auth_plugin_cleanup(void *user_data, struct mosquitto_opt *auth_opts, int auth_opt_count)
+{
+	printf(ANSI_BLUE "PLUGIN ::: mosquitto_auth_plugin_cleanup(,,%d)" ANSI_RESET "\n", auth_opt_count);
+	return MOSQ_ERR_SUCCESS;
+}
+
+int mosquitto_auth_security_init(void *user_data, struct mosquitto_opt *auth_opts, int auth_opt_count, bool reload)
+{
+	printf(ANSI_BLUE "PLUGIN ::: mosquitto_auth_security_init(,,%d, %d)" ANSI_RESET "\n", auth_opt_count, reload);
+	return MOSQ_ERR_SUCCESS;
+}
+
+int mosquitto_auth_security_cleanup(void *user_data, struct mosquitto_opt *auth_opts, int auth_opt_count, bool reload)
+{
+	printf(ANSI_BLUE "PLUGIN ::: mosquitto_auth_security_cleanup(,,%d, %d)" ANSI_RESET "\n", auth_opt_count, reload);
+	return MOSQ_ERR_SUCCESS;
+}
+
+int mosquitto_auth_acl_check(void *user_data, int access, struct mosquitto *client, const struct mosquitto_acl_msg *msg)
+{
+	print_col(client);
+	printf("PLUGIN ::: mosquitto_auth_acl_check(%p, %d, %s, %s)" ANSI_RESET "\n",
+			user_data, access, mosquitto_client_username(client), msg->topic);
+	return MOSQ_ERR_SUCCESS;
+}
+
+int mosquitto_auth_unpwd_check(void *user_data, struct mosquitto *client, const char *username, const char *password)
+{
+	print_col(client);
+	printf("PLUGIN ::: mosquitto_auth_unpwd_check(%p, %s, %s)" ANSI_RESET "\n",
+			user_data, mosquitto_client_username(client), username);
+	return MOSQ_ERR_SUCCESS;
+}
+
+int mosquitto_auth_psk_key_get(void *user_data, struct mosquitto *client, const char *hint, const char *identity, char *key, int max_key_len)
+{
+	print_col(client);
+	printf("PLUGIN ::: mosquitto_auth_psk_key_get(%p, %s, %s)" ANSI_RESET "\n",
+			user_data, mosquitto_client_username(client), hint);
+	return MOSQ_ERR_SUCCESS;
+}
+
+int mosquitto_auth_start(void *user_data, struct mosquitto *client, const char *method, bool reauth, const void *data_in, uint16_t data_in_len, void **data_out, uint16_t *data_out_len)
+{
+	print_col(client);
+	printf("PLUGIN ::: mosquitto_auth_start(%p, %s, %s, %d, %d, %hn)" ANSI_RESET "\n",
+			user_data, mosquitto_client_username(client), method, reauth, data_in_len, data_out_len);
+	return MOSQ_ERR_SUCCESS;
+}
+
+int mosquitto_auth_continue(void *user_data, struct mosquitto *client, const char *method, const void *data_in, uint16_t data_in_len, void **data_out, uint16_t *data_out_len)
+{
+	print_col(client);
+	printf("PLUGIN ::: mosquitto_auth_continue(%p, %s, %s, %d, %hn)" ANSI_RESET "\n",
+			user_data, mosquitto_client_username(client), method, data_in_len, data_out_len);
+	return MOSQ_ERR_SUCCESS;
+}