diff --git a/CMakeLists.txt b/CMakeLists.txt
index 33b20e1..8431d75 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -17,13 +17,21 @@ set (PROJECT_SOURCE_DIR "${CMAKE_SOURCE_DIR}/src")
 option(RELEASE "Release build, debug build if disabled" ON)
 option(LINK_SUPPORT "Allow hub linking" OFF)
 option(SSL_SUPPORT "Enable SSL support" ON)
+option(USE_OPENSSL "Use OpenSSL's SSL support" OFF)
 option(SQLITE_SUPPORT "Enable SQLite support" ON)
 option(ADC_STRESS "Enable the stress tester client" OFF)
 
 find_package(Git)
 
 if (SSL_SUPPORT)
-	find_package(OpenSSL REQUIRED)
+	if (USE_OPENSSL)
+		find_package(OpenSSL)
+	else()
+		find_package(GnuTLS)
+	endif()
+	if (NOT GNUTLS_FOUND AND NOT OPENSSL_FOUND)
+		message(FATAL_ERROR "Neither OpenSSL nor GnuTLS are not found!")
+	endif()
 endif()
 
 if (MSVC)
@@ -156,16 +164,26 @@ else()
 endif()
 
 if(OPENSSL_FOUND)
-	add_definitions(-DSSL_SUPPORT=1)
+	set(SSL_LIBS ${OPENSSL_LIBRARIES})
+	add_definitions(-DSSL_SUPPORT=1 -DSSL_USE_OPENSSL=1)
 	include_directories(${OPENSSL_INCLUDE_DIR})
-	target_link_libraries(uhub ${OPENSSL_LIBRARIES})
+endif()
+
+if (GNUTLS_FOUND)
+	set(SSL_LIBS ${GNUTLS_LIBRARIES})
+	add_definitions(-DSSL_SUPPORT=1 -DSSL_USE_GNUTLS=1 ${GNUTLS_DEFINITIONS})
+	include_directories(${GNUTLS_INCLUDE_DIR})
+endif()
+
+if(SSL_SUPPORT)
+	target_link_libraries(uhub ${SSL_LIBS})
 	if(UNIX)
-		target_link_libraries(uhub-admin ${OPENSSL_LIBRARIES})
+		target_link_libraries(uhub-admin ${SSL_LIBS})
 	endif()
-	target_link_libraries(mod_welcome ${OPENSSL_LIBRARIES})
-	target_link_libraries(mod_logging ${OPENSSL_LIBRARIES})
+	target_link_libraries(mod_welcome ${SSL_LIBS})
+	target_link_libraries(mod_logging ${SSL_LIBS})
 	if (ADC_STRESS)
-		target_link_libraries(adcrush ${OPENSSL_LIBRARIES})
+		target_link_libraries(adcrush ${SSL_LIBS})
 	endif()
 endif()
 
diff --git a/src/core/hub.c b/src/core/hub.c
index 714f8ec..25f9608 100644
--- a/src/core/hub.c
+++ b/src/core/hub.c
@@ -731,6 +731,7 @@ static int load_ssl_certificates(struct hub_info* hub, struct hub_config* config
 {
 	if (config->tls_enable)
 	{
+#ifdef SSL_USE_OPENSSL
 		hub->ssl_method = (SSL_METHOD*) SSLv23_method(); /* TLSv1_method() */
 		hub->ssl_ctx = SSL_CTX_new(hub->ssl_method);
 
@@ -754,18 +755,21 @@ static int load_ssl_certificates(struct hub_info* hub, struct hub_config* config
 			return 0;
 		}
 		LOG_INFO("Enabling TLS, using certificate: %s, private key: %s", config->tls_certificate, config->tls_private_key);
+#endif /* SSL_USE_OPENSSL */
 	}
 	return 1;
 }
 
 static void unload_ssl_certificates(struct hub_info* hub)
 {
+#ifdef SSL_USE_OPENSSL
 	if (hub->ssl_ctx)
 	{
 		SSL_CTX_free(hub->ssl_ctx);
 	}
+#endif /* SSL_USE_OPENSSL */
 }
-#endif
+#endif /* SSL_SUPPORT */
 
 struct hub_info* hub_start_service(struct hub_config* config)
 {
diff --git a/src/core/hub.h b/src/core/hub.h
index b0edee0..d313e9c 100644
--- a/src/core/hub.h
+++ b/src/core/hub.h
@@ -116,8 +116,10 @@ struct hub_info
 	struct uhub_plugins* plugins;        /* Plug-ins loaded for this hub instance. */
 
 #ifdef SSL_SUPPORT
+#ifdef SSL_USE_OPENSSL
 	SSL_METHOD* ssl_method;
 	SSL_CTX* ssl_ctx;
+#endif // SSL_USE_OPENSSL
 #endif /*  SSL_SUPPORT */
 };
 
diff --git a/src/core/probe.c b/src/core/probe.c
index 293cf45..276d6f1 100644
--- a/src/core/probe.c
+++ b/src/core/probe.c
@@ -85,7 +85,9 @@ static void probe_net_event(struct net_connection* con, int events, void *arg)
 					{
 						probe->connection = 0;
 					}
+#ifdef SSL_USE_OPENSSL
 					net_con_ssl_handshake(con, net_con_ssl_mode_server, probe->hub->ssl_ctx);
+#endif /* SSL_USE_OPENSSL */
 				}
 				else
 				{
diff --git a/src/network/backend.c b/src/network/backend.c
index b74d798..97b8426 100644
--- a/src/network/backend.c
+++ b/src/network/backend.c
@@ -180,12 +180,14 @@ void net_con_close(struct net_connection* con)
 	g_backend->handler.con_del(g_backend->data, con);
 
 #ifdef SSL_SUPPORT
+#ifdef SSL_USE_OPENSSL
 	if (con->ssl)
 	{
 		SSL_shutdown(con->ssl);
 		SSL_clear(con->ssl);
 	}
-#endif
+#endif /* SSL_USE_OPENSSL */
+#endif /* SSL_SUPPORT */
 
 	net_close(con->sd);
 	con->sd = -1;
diff --git a/src/network/common.h b/src/network/common.h
index 014ddfb..8f60477 100644
--- a/src/network/common.h
+++ b/src/network/common.h
@@ -35,10 +35,17 @@
 	net_connection_cb    callback;  /** Callback function */ \
 	struct timeout_evt*  timeout;   /** timeout event handler */
 
+#ifdef SSL_USE_OPENSSL
 #define NET_CON_STRUCT_SSL \
 	SSL*                 ssl;       /** SSL handle */ \
 	uint32_t             ssl_state; /** SSL state */ \
-	size_t               write_len; /** Length of last SSL_write(), only used if flags is NET_WANT_SSL_READ. */ \
+	size_t               write_len; /** Length of last SSL_write(), only used if flags is NET_WANT_SSL_READ. */
+#endif
+
+#ifdef SSL_USE_GNUTLS
+#define NET_CON_STRUCT_SSL \
+	uint32_t             ssl_state; /** SSL state */
+#endif
 
 #ifdef SSL_SUPPORT
 #define NET_CON_STRUCT_COMMON \
diff --git a/src/network/connection.c b/src/network/connection.c
index b30b46c..ef3c6fe 100644
--- a/src/network/connection.c
+++ b/src/network/connection.c
@@ -32,6 +32,7 @@ enum uhub_tls_state
 	tls_st_disconnecting,
 };
 
+#ifdef SSL_USE_OPENSSL
 static int handle_openssl_error(struct net_connection* con, int ret)
 {
 	uhub_assert(con);
@@ -72,15 +73,18 @@ static int handle_openssl_error(struct net_connection* con, int ret)
 	}
 	return -1;
 }
+#endif /* SSL_USE_OPENSSL */
 
 ssize_t net_con_ssl_accept(struct net_connection* con)
 {
 	uhub_assert(con);
 	con->ssl_state = tls_st_accepting;
-	ssize_t ret = SSL_accept(con->ssl);
+	ssize_t ret;
+#ifdef SSL_USE_OPENSSL
+	ret = SSL_accept(con->ssl);
 #ifdef NETWORK_DUMP_DEBUG
 	LOG_PROTO("SSL_accept() ret=%d", ret);
-#endif
+#endif /* NETWORK_DUMP_DEBUG */
 	if (ret > 0)
 	{
 		net_con_update(con, NET_EVENT_READ);
@@ -90,18 +94,20 @@ ssize_t net_con_ssl_accept(struct net_connection* con)
 	{
 		return handle_openssl_error(con, ret);
 	}
+#endif /* SSL_USE_OPENSSL */
 	return ret;
 }
 
 ssize_t net_con_ssl_connect(struct net_connection* con)
 {
 	uhub_assert(con);
-
+	ssize_t ret;
 	con->ssl_state = tls_st_connecting;
-	ssize_t ret = SSL_connect(con->ssl);
+#ifdef SSL_USE_OPENSSL
+	ret = SSL_connect(con->ssl);
 #ifdef NETWORK_DUMP_DEBUG
 	LOG_PROTO("SSL_connect() ret=%d", ret);
-#endif
+#endif /* NETWORK_DUMP_DEBUG */
 	if (ret > 0)
 	{
 		con->ssl_state = tls_st_connected;
@@ -111,12 +117,15 @@ ssize_t net_con_ssl_connect(struct net_connection* con)
 	{
 		return handle_openssl_error(con, ret);
 	}
+#endif /* SSL_USE_OPENSSL */
 	return ret;
 }
 
+#ifdef SSL_USE_OPENSSL
 ssize_t net_con_ssl_handshake(struct net_connection* con, enum net_con_ssl_mode ssl_mode, SSL_CTX* ssl_ctx)
 {
 	uhub_assert(con);
+
 	SSL* ssl = 0;
 
 	if (ssl_mode == net_con_ssl_mode_server)
@@ -138,7 +147,9 @@ ssize_t net_con_ssl_handshake(struct net_connection* con, enum net_con_ssl_mode
 		net_con_set_ssl(con, ssl);
 		return net_con_ssl_connect(con);
 	}
+
 }
+#endif /* SSL_USE_OPENSSL */
 #endif /* SSL_SUPPORT */
 
 #ifdef SSL_SUPPORT
@@ -150,7 +161,9 @@ ssize_t net_con_send(struct net_connection* con, const void* buf, size_t len)
 {
 	int ret;
 #ifdef SSL_SUPPORT
+#ifdef SSL_USE_OPENSSL
 	if (!con->ssl)
+#endif /* SSL_USE_OPENSSL */
 	{
 #endif
 		ret = net_send(con->sd, buf, len, UHUB_SEND_SIGNAL);
@@ -168,6 +181,7 @@ ssize_t net_con_send(struct net_connection* con, const void* buf, size_t len)
 		}
 #ifdef SSL_SUPPORT
 	}
+#ifdef SSL_USE_OPENSSL
 	else
 	{
 		con->write_len = len;
@@ -182,7 +196,8 @@ ssize_t net_con_send(struct net_connection* con, const void* buf, size_t len)
 			 net_stats_add_tx(ret);
 		}
 	}
-#endif
+#endif /* SSL_USE_OPENSSL */
+#endif /* SSL_SUPPORT */
 	return ret;
 }
 
@@ -214,6 +229,7 @@ ssize_t net_con_recv(struct net_connection* con, void* buf, size_t len)
 	}
 	else
 	{
+#ifdef SSL_USE_OPENSSL
 		if (con->ssl_state == tls_st_error)
 			return -1;
 
@@ -228,8 +244,9 @@ ssize_t net_con_recv(struct net_connection* con, void* buf, size_t len)
 		{
 			return handle_openssl_error(con, ret);
 		}
+#endif /* SSL_USE_OPENSSL */
 	}
-#endif
+#endif /* SSL_SUPPORT */
 	return ret;
 }
 
@@ -254,11 +271,15 @@ ssize_t net_con_peek(struct net_connection* con, void* buf, size_t len)
 }
 
 #ifdef SSL_SUPPORT
+
 int net_con_is_ssl(struct net_connection* con)
 {
+#ifdef SSL_USE_OPENSSL
 	return con->ssl != 0;
+#endif
 }
 
+#ifdef SSL_USE_OPENSSL
 SSL* net_con_get_ssl(struct net_connection* con)
 {
 	return con->ssl;
@@ -268,6 +289,7 @@ void net_con_set_ssl(struct net_connection* con, SSL* ssl)
 {
 	con->ssl = ssl;
 }
+#endif /* SSL_USE_OPENSSL */
 #endif /* SSL_SUPPORT */
 
 int net_con_get_sd(struct net_connection* con)
@@ -283,7 +305,9 @@ void* net_con_get_ptr(struct net_connection* con)
 void net_con_destroy(struct net_connection* con)
 {
 #ifdef SSL_SUPPORT
+#ifdef SSL_USE_OPENSSL
 	SSL_free(con->ssl);
+#endif /* SSL_USE_OPENSSL */
 #endif
 	hub_free(con);
 }
@@ -301,13 +325,17 @@ void net_con_callback(struct net_connection* con, int events)
 	}
 
 #ifdef SSL_SUPPORT
+#ifdef SSL_USE_OPENSSL
 	if (!con->ssl)
+#endif /* SSL_USE_OPENSSL */
 	{
 #endif
 		con->callback(con, events, con->ptr);
 #ifdef SSL_SUPPORT
 	}
+#ifdef SSL_USE_OPENSSL
 	else
+#endif /* SSL_USE_OPENSSL */
 	{
 #ifdef NETWORK_DUMP_DEBUG
 		LOG_PROTO("net_con_event: events=%d, con=%p, state=%d", events, con, con->ssl_state);
diff --git a/src/network/connection.h b/src/network/connection.h
index ff69262..53fd15e 100644
--- a/src/network/connection.h
+++ b/src/network/connection.h
@@ -100,11 +100,13 @@ enum net_con_ssl_mode
 	net_con_ssl_mode_client,
 };
 
+#ifdef SSL_USE_OPENSSL
 extern ssize_t net_con_ssl_handshake(struct net_connection* con, enum net_con_ssl_mode, SSL_CTX* ssl_ctx);
-
-extern int   net_con_is_ssl(struct net_connection* con);
 extern SSL* net_con_get_ssl(struct net_connection* con);
 extern void net_con_set_ssl(struct net_connection* con, SSL*);
+#endif // SSL_USE_OPENSSL
+extern int   net_con_is_ssl(struct net_connection* con);
+
 #endif /* SSL_SUPPORT */
 
 #endif /* HAVE_UHUB_NETWORK_CONNECTION_H */
diff --git a/src/network/network.c b/src/network/network.c
index a7164d6..8268934 100644
--- a/src/network/network.c
+++ b/src/network/network.c
@@ -59,9 +59,11 @@ int net_initialize()
 		net_stats_initialize();
 
 #ifdef SSL_SUPPORT
+#ifdef SSL_USE_OPENSSL
 		LOG_TRACE("Initializing OpenSSL...");
 		SSL_library_init();
 		SSL_load_error_strings();
+#endif /* SSL_USE_OPENSSL */
 #endif /*  SSL_SUPPORT */
 
 		net_initialized = 1;
@@ -100,10 +102,12 @@ int net_destroy()
 		net_backend_shutdown();
 		
 #ifdef SSL_SUPPORT
+#ifdef SSL_USE_OPENSSL
 		ERR_free_strings();
 		EVP_cleanup();
 		CRYPTO_cleanup_all_ex_data();
-#endif
+#endif /* SSL_USE_OPENSSL */
+#endif /* SSL_SUPPORT */
 
 #ifdef WINSOCK
 		WSACleanup();
diff --git a/src/system.h b/src/system.h
index 12e5b3c..75542c1 100644
--- a/src/system.h
+++ b/src/system.h
@@ -99,8 +99,13 @@
 #endif
 
 #ifdef SSL_SUPPORT
+#ifdef SSL_USE_OPENSSL
 #include <openssl/ssl.h>
 #include <openssl/err.h>
+#endif /* SSL_USE_OPENSSL */
+#ifdef SSL_USE_GNUTLS
+#include <gnutls/gnutls.h>
+#endif /* SSL_USE_GNUTLS */
 #endif
 
 #include "version.h"
diff --git a/src/tools/adcclient.c b/src/tools/adcclient.c
index 69bb8e4..bf1402c 100644
--- a/src/tools/adcclient.c
+++ b/src/tools/adcclient.c
@@ -66,8 +66,10 @@ struct ADC_client
 	int flags;
 	void* ptr;
 #ifdef SSL_SUPPORT
+#ifdef SSL_USE_OPENSSL
 	const SSL_METHOD* ssl_method;
 	SSL_CTX* ssl_ctx;
+#endif /* SSL_USE_OPENSSL */
 #endif /*  SSL_SUPPORT */
 };