diff --git a/CMakeLists.txt b/CMakeLists.txt
index 81f2fdd..4933e1f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -10,7 +10,7 @@ if (DEFINED ENV{IDF_PATH})
    INCLUDE_DIRS "./src" ${HTTP_INCLUDE_PUBLIC_DIRS} ${MQTT_INCLUDE_PUBLIC_DIRS}
    REQUIRES mbedtls srtp json esp_netif
   )
-  add_definitions("-DESP32 -DHTTP_DO_NOT_USE_CUSTOM_CONFIG -DMQTT_DO_NOT_USE_CUSTOM_CONFIG")
+  add_definitions("-DCONFIG_USE_LWIP=1" "-DCONFIG_USE_USRSCTP=0" "-DCONFIG_AUDIO_BUFFER_SIZE=8096" "-DCONFIG_DATA_BUFFER_SIZE=102400" "-DHTTP_DO_NOT_USE_CUSTOM_CONFIG" "-DMQTT_DO_NOT_USE_CUSTOM_CONFIG")
   return()
 endif()
 
diff --git a/README.md b/README.md
index ad00fcc..9dd0bc9 100644
--- a/README.md
+++ b/README.md
@@ -41,4 +41,5 @@ $ ./generic/sample/sample
 
 ### Examples for Platforms
 - [ESP32](https://github.com/sepfy/libpeer/tree/main/examples/esp32): MJPEG over datachannel
+- [PICO](https://github.com/sepfy/libpeer/tree/main/examples/pico): Ping pong with datachannel
 - [Raspberry Pi](https://github.com/sepfy/libpeer/tree/main/examples/raspberrypi): Video and two-way audio stream
diff --git a/examples/esp32/main/app_main.c b/examples/esp32/main/app_main.c
index a45377f..da2685a 100644
--- a/examples/esp32/main/app_main.c
+++ b/examples/esp32/main/app_main.c
@@ -130,8 +130,6 @@ void app_main(void) {
   peer_signaling_set_config(&service_config);
   peer_signaling_join_channel();
 
-  peer_signaling_join_channel(deviceid, g_pc);
-
 #if defined(CONFIG_ESP32S3_XIAO_SENSE)
   StackType_t* stack_memory = (StackType_t*)heap_caps_malloc(8192 * sizeof(StackType_t), MALLOC_CAP_SPIRAM);
   StaticTask_t task_buffer;
diff --git a/examples/esp32/main/idf_component.yml b/examples/esp32/main/idf_component.yml
index a885894..d1cfb88 100644
--- a/examples/esp32/main/idf_component.yml
+++ b/examples/esp32/main/idf_component.yml
@@ -1,6 +1,8 @@
 ## IDF Component Manager Manifest File
 dependencies:
-  sepfy/libpeer: ">=0.0.2"
+  sepfy/libpeer:
+    path: ../../../
+    version: ">=0.0.2"
   espressif/esp_audio_codec: "^2.0.0"
   espressif/esp32-camera: "^2.0.4"
   protocol_examples_common:
diff --git a/examples/esp32/sdkconfig.defaults b/examples/esp32/sdkconfig.defaults
index 531431e..3c991cf 100644
--- a/examples/esp32/sdkconfig.defaults
+++ b/examples/esp32/sdkconfig.defaults
@@ -1,13 +1,9 @@
 # This file was generated using idf.py save-defconfig. It can be edited manually.
 # Espressif IoT Development Framework (ESP-IDF) 5.2.2 Project Minimal Configuration
 #
-CONFIG_IDF_TARGET="esp32s3"
 CONFIG_APP_RETRIEVE_LEN_ELF_SHA=16
 CONFIG_ESPTOOLPY_FLASHSIZE_4MB=y
 CONFIG_PARTITION_TABLE_CUSTOM=y
-CONFIG_ESP32S3_XIAO_SENSE=y
-CONFIG_EXAMPLE_WIFI_SSID="myssid"
-CONFIG_EXAMPLE_WIFI_PASSWORD="mypassword"
 CONFIG_EXAMPLE_CONNECT_IPV6=n
 CONFIG_ESP_PHY_REDUCE_TX_POWER=y
 CONFIG_SPIRAM=y
@@ -17,9 +13,7 @@ CONFIG_ESP_SYSTEM_EVENT_TASK_STACK_SIZE=2048
 CONFIG_ESP_MAIN_TASK_STACK_SIZE=4096
 CONFIG_ESP_TASK_WDT_CHECK_IDLE_TASK_CPU1=n
 CONFIG_ESP_IPC_TASK_STACK_SIZE=2048
-CONFIG_ESP_WIFI_DYNAMIC_RX_BUFFER_NUM=16
 CONFIG_ESP_WIFI_STATIC_TX_BUFFER_NUM=32
-CONFIG_ESP_WIFI_CACHE_TX_BUFFER_NUM=64
 CONFIG_LWIP_IPV6_AUTOCONFIG=y
 CONFIG_LWIP_IPV6_DHCP6=y
 CONFIG_LWIP_TCP_SND_BUF_DEFAULT=5744
diff --git a/examples/pico/.gitignore b/examples/pico/.gitignore
new file mode 100644
index 0000000..378eac2
--- /dev/null
+++ b/examples/pico/.gitignore
@@ -0,0 +1 @@
+build
diff --git a/examples/pico/CMakeLists.txt b/examples/pico/CMakeLists.txt
new file mode 100644
index 0000000..5381860
--- /dev/null
+++ b/examples/pico/CMakeLists.txt
@@ -0,0 +1,126 @@
+cmake_minimum_required(VERSION 3.13)
+
+set(PICO_BOARD pico_w)
+
+include($ENV{PICO_SDK_PATH}/pico_sdk_init.cmake)
+
+project(pico-peer)
+pico_sdk_init()
+
+include(FreeRTOS_Kernel_import.cmake)
+
+include(${CMAKE_CURRENT_LIST_DIR}/../../third_party/coreHTTP/httpFilePaths.cmake)
+include(${CMAKE_CURRENT_LIST_DIR}/../../third_party/coreMQTT/mqttFilePaths.cmake)
+include_directories(
+  ${CMAKE_CURRENT_LIST_DIR}/
+  ${CMAKE_BINARY_DIR}/
+  ${CMAKE_CURRENT_LIST_DIR}/../../third_party/libsrtp/include/
+  ${CMAKE_CURRENT_LIST_DIR}/../../third_party/libsrtp/crypto/include/
+  ${CMAKE_CURRENT_LIST_DIR}/../../third_party/cJSON/
+  ${CMAKE_CURRENT_LIST_DIR}/../../src/
+  ${HTTP_INCLUDE_PUBLIC_DIRS}
+  ${MQTT_INCLUDE_PUBLIC_DIRS}
+)
+
+set(PICO_SDK_LIBS
+  pico_stdlib
+  pico_cyw43_arch_lwip_sys_freertos
+  pico_mbedtls
+  FreeRTOS-Kernel-Heap4
+)
+
+# Build libsrtp
+file(GLOB LIBSRTP_SRC
+  ../../third_party/libsrtp/srtp/srtp.c
+  ../../third_party/libsrtp/crypto/cipher/cipher.c
+  ../../third_party/libsrtp/crypto/cipher/null_cipher.c
+  ../../third_party/libsrtp/crypto/cipher/aes.c
+  ../../third_party/libsrtp/crypto/cipher/aes_icm.c
+  ../../third_party/libsrtp/crypto/cipher/cipher_test_cases.c
+  ../../third_party/libsrtp/crypto/hash/auth.c
+  ../../third_party/libsrtp/crypto/hash/null_auth.c
+  ../../third_party/libsrtp/crypto/hash/hmac.c
+  ../../third_party/libsrtp/crypto/hash/sha1.c
+  ../../third_party/libsrtp/crypto/hash/auth_test_cases.c
+  ../../third_party/libsrtp/crypto/kernel/alloc.c
+  ../../third_party/libsrtp/crypto/kernel/crypto_kernel.c
+  ../../third_party/libsrtp/crypto/kernel/err.c
+  ../../third_party/libsrtp/crypto/kernel/key.c
+  ../../third_party/libsrtp/crypto/math/datatypes.c
+  ../../third_party/libsrtp/crypto/math/stat.c
+  ../../third_party/libsrtp/crypto/replay/rdb.c
+  ../../third_party/libsrtp/crypto/replay/rdbx.c
+  ../../third_party/libsrtp/crypto/replay/ut_sim.c
+)
+
+add_library(srtp STATIC
+  ${LIBSRTP_SRC}
+)
+
+target_compile_definitions(srtp PRIVATE
+  HAVE_CONFIG_H
+  PRIx64=PRIx32
+)
+
+target_link_libraries(srtp
+  ${PICO_SDK_LIBS}
+)
+
+add_custom_command(TARGET srtp
+  POST_BUILD
+  COMMAND ${CMAKE_COMMAND} -E make_directory ${CMAKE_BINARY_DIR}/srtp2/
+  COMMAND ${CMAKE_COMMAND} -E copy
+  ../../../third_party/libsrtp/include/srtp.h
+  ${CMAKE_BINARY_DIR}/srtp2/
+)
+
+# Build cJSON
+add_library(cjson STATIC
+  ../../third_party/cJSON/cJSON.c
+)
+
+# Build peer
+file(GLOB LIBPEER_SRC "../../src/*.c")
+add_library(peer STATIC
+  ${LIBPEER_SRC}
+  ${HTTP_SOURCES}
+  ${MQTT_SOURCES}
+  ${MQTT_SERIALIZER_SOURCES}
+)
+
+target_compile_definitions(peer PRIVATE
+  __BYTE_ORDER=__LITTLE_ENDIAN
+  CONFIG_USE_LWIP=1
+  CONFIG_USE_USRSCTP=0
+  CONFIG_MBEDTLS_2_X=1
+  CONFIG_DATA_BUFFER_SIZE=4096
+  HTTP_DO_NOT_USE_CUSTOM_CONFIG
+  MQTT_DO_NOT_USE_CUSTOM_CONFIG
+)
+
+target_link_libraries(peer
+  ${PICO_SDK_LIBS}
+  srtp
+  cjson
+)
+
+# Build pico_peer
+add_executable(pico_peer
+  main.c
+)
+
+target_compile_definitions(pico_peer PRIVATE
+  WIFI_SSID="$ENV{WIFI_SSID}"
+  WIFI_PASSWORD="$ENV{WIFI_PASSWORD}"
+  PICO_HEAP_SIZE=0x20000
+  #PICO_DEBUG_MALLOC=1
+)
+
+target_link_libraries(pico_peer
+  ${PICO_SDK_LIBS}
+  peer
+)
+
+pico_enable_stdio_usb(pico_peer 1)
+pico_enable_stdio_uart(pico_peer 0)
+pico_add_extra_outputs(pico_peer)
diff --git a/examples/pico/FreeRTOSConfig.h b/examples/pico/FreeRTOSConfig.h
new file mode 100644
index 0000000..2f5fee9
--- /dev/null
+++ b/examples/pico/FreeRTOSConfig.h
@@ -0,0 +1,113 @@
+#ifndef FREERTOS_CONFIG_H
+#define FREERTOS_CONFIG_H
+
+/* Scheduler Related */
+#define configUSE_PREEMPTION 1
+#define configUSE_TICKLESS_IDLE 0
+#define configUSE_IDLE_HOOK 0
+#define configUSE_TICK_HOOK 0
+#define configTICK_RATE_HZ ((TickType_t)1000)
+#define configMAX_PRIORITIES 32
+#define configMINIMAL_STACK_SIZE (configSTACK_DEPTH_TYPE)512
+#define configUSE_16_BIT_TICKS 0
+
+#define configIDLE_SHOULD_YIELD 1
+
+/* Synchronization Related */
+#define configUSE_MUTEXES 1
+#define configUSE_RECURSIVE_MUTEXES 1
+#define configUSE_APPLICATION_TASK_TAG 0
+#define configUSE_COUNTING_SEMAPHORES 1
+#define configQUEUE_REGISTRY_SIZE 8
+#define configUSE_QUEUE_SETS 1
+#define configUSE_TIME_SLICING 1
+#define configUSE_NEWLIB_REENTRANT 0
+// todo need this for lwip FreeRTOS sys_arch to compile
+#define configENABLE_BACKWARD_COMPATIBILITY 1
+#define configNUM_THREAD_LOCAL_STORAGE_POINTERS 5
+
+/* System */
+#define configSTACK_DEPTH_TYPE uint32_t
+#define configMESSAGE_BUFFER_LENGTH_TYPE size_t
+
+/* Memory allocation related definitions. */
+#define configSUPPORT_STATIC_ALLOCATION 0
+#define configSUPPORT_DYNAMIC_ALLOCATION 1
+#define configTOTAL_HEAP_SIZE (48 * 1024)
+#define configAPPLICATION_ALLOCATED_HEAP 0
+
+/* Hook function related definitions. */
+#define configCHECK_FOR_STACK_OVERFLOW 0
+#define configUSE_MALLOC_FAILED_HOOK 0
+#define configUSE_DAEMON_TASK_STARTUP_HOOK 0
+
+/* Run time and task stats gathering related definitions. */
+#define configGENERATE_RUN_TIME_STATS 0
+#define configUSE_TRACE_FACILITY 1
+#define configUSE_STATS_FORMATTING_FUNCTIONS 0
+
+/* Co-routine related definitions. */
+#define configUSE_CO_ROUTINES 0
+#define configMAX_CO_ROUTINE_PRIORITIES 1
+
+/* Software timer related definitions. */
+#define configUSE_TIMERS 1
+#define configTIMER_TASK_PRIORITY (configMAX_PRIORITIES - 1)
+#define configTIMER_QUEUE_LENGTH 10
+#define configTIMER_TASK_STACK_DEPTH 1024
+
+/* Interrupt nesting behaviour configuration. */
+/*
+#define configKERNEL_INTERRUPT_PRIORITY         [dependent of processor]
+#define configMAX_SYSCALL_INTERRUPT_PRIORITY    [dependent on processor and application]
+#define configMAX_API_CALL_INTERRUPT_PRIORITY   [dependent on processor and application]
+*/
+
+#define configNUMBER_OF_CORES 2
+/* SMP (configNUMBER_OF_CORES > 1) only */
+#define configTICK_CORE 0
+#define configRUN_MULTIPLE_PRIORITIES 1
+#if configNUMBER_OF_CORES > 1
+#define configUSE_CORE_AFFINITY 1
+#endif
+#define configUSE_PASSIVE_IDLE_HOOK 0
+
+/* Armv8-M */
+
+/* Not currently supported */
+#define configENABLE_MPU 0
+#define configENABLE_FPU 1
+/* Not currently supported */
+#define configENABLE_TRUSTZONE 0
+#define configRUN_FREERTOS_SECURE_ONLY 1
+// see https://www.freertos.org/RTOS-Cortex-M3-M4.html
+#define configMAX_SYSCALL_INTERRUPT_PRIORITY 16
+
+/* RP2xxx specific */
+#define configSUPPORT_PICO_SYNC_INTEROP 1
+#define configSUPPORT_PICO_TIME_INTEROP 1
+
+#include <assert.h>
+/* Define to trap errors during development. */
+#define configASSERT(x) assert(x)
+
+/* Set the following definitions to 1 to include the API function, or zero
+to exclude the API function. */
+#define INCLUDE_vTaskPrioritySet 1
+#define INCLUDE_uxTaskPriorityGet 1
+#define INCLUDE_vTaskDelete 1
+#define INCLUDE_vTaskSuspend 1
+#define INCLUDE_vTaskDelayUntil 1
+#define INCLUDE_vTaskDelay 1
+#define INCLUDE_xTaskGetSchedulerState 1
+#define INCLUDE_xTaskGetCurrentTaskHandle 1
+#define INCLUDE_uxTaskGetStackHighWaterMark 1
+#define INCLUDE_xTaskGetIdleTaskHandle 1
+#define INCLUDE_eTaskGetState 1
+#define INCLUDE_xTimerPendFunctionCall 1
+#define INCLUDE_xTaskAbortDelay 1
+#define INCLUDE_xTaskGetHandle 1
+#define INCLUDE_xTaskResumeFromISR 1
+#define INCLUDE_xQueueGetMutexHolder 1
+
+#endif  // FREERTOS_CONFIG_H
diff --git a/examples/pico/FreeRTOS_Kernel_import.cmake b/examples/pico/FreeRTOS_Kernel_import.cmake
new file mode 100644
index 0000000..15d8e77
--- /dev/null
+++ b/examples/pico/FreeRTOS_Kernel_import.cmake
@@ -0,0 +1,91 @@
+# This is a copy of <FREERTOS_KERNEL_PATH>/portable/ThirdParty/GCC/RP2040/FREERTOS_KERNEL_import.cmake
+
+# This can be dropped into an external project to help locate the FreeRTOS kernel
+# It should be include()ed prior to project(). Alternatively this file may
+# or the CMakeLists.txt in this directory may be included or added via add_subdirectory
+# respectively.
+
+if (DEFINED ENV{FREERTOS_KERNEL_PATH} AND (NOT FREERTOS_KERNEL_PATH))
+    set(FREERTOS_KERNEL_PATH $ENV{FREERTOS_KERNEL_PATH})
+    message("Using FREERTOS_KERNEL_PATH from environment ('${FREERTOS_KERNEL_PATH}')")
+endif ()
+
+# first pass we look in old tree; second pass we look in new tree
+foreach(SEARCH_PASS RANGE 0 1)
+    if (SEARCH_PASS)
+        # ports may be moving to submodule in the future
+        set(FREERTOS_KERNEL_RP2040_RELATIVE_PATH "portable/ThirdParty/Community-Supported-Ports/GCC")
+        set(FREERTOS_KERNEL_RP2040_BACK_PATH "../../../../..")
+    else()
+        set(FREERTOS_KERNEL_RP2040_RELATIVE_PATH "portable/ThirdParty/GCC")
+        set(FREERTOS_KERNEL_RP2040_BACK_PATH "../../../..")
+    endif()
+
+    if(PICO_PLATFORM STREQUAL "rp2040")
+        set(FREERTOS_KERNEL_RP2040_RELATIVE_PATH "${FREERTOS_KERNEL_RP2040_RELATIVE_PATH}/RP2040")
+    else()
+        if (PICO_PLATFORM STREQUAL "rp2350-riscv")
+            set(FREERTOS_KERNEL_RP2040_RELATIVE_PATH "${FREERTOS_KERNEL_RP2040_RELATIVE_PATH}/RP2350_RISC-V")
+        else()
+            set(FREERTOS_KERNEL_RP2040_RELATIVE_PATH "${FREERTOS_KERNEL_RP2040_RELATIVE_PATH}/RP2350_ARM_NTZ")
+        endif()
+    endif()
+
+    if (NOT FREERTOS_KERNEL_PATH)
+        # check if we are inside the FreeRTOS kernel tree (i.e. this file has been included directly)
+        get_filename_component(_ACTUAL_PATH ${CMAKE_CURRENT_LIST_DIR} REALPATH)
+        get_filename_component(_POSSIBLE_PATH ${CMAKE_CURRENT_LIST_DIR}/${FREERTOS_KERNEL_RP2040_BACK_PATH}/${FREERTOS_KERNEL_RP2040_RELATIVE_PATH} REALPATH)
+        if (_ACTUAL_PATH STREQUAL _POSSIBLE_PATH)
+            get_filename_component(FREERTOS_KERNEL_PATH ${CMAKE_CURRENT_LIST_DIR}/${FREERTOS_KERNEL_RP2040_BACK_PATH} REALPATH)
+        endif()
+        if (_ACTUAL_PATH STREQUAL _POSSIBLE_PATH)
+            get_filename_component(FREERTOS_KERNEL_PATH ${CMAKE_CURRENT_LIST_DIR}/${FREERTOS_KERNEL_RP2040_BACK_PATH} REALPATH)
+            message("Setting FREERTOS_KERNEL_PATH to ${FREERTOS_KERNEL_PATH} based on location of FreeRTOS-Kernel-import.cmake")
+            break()
+        elseif (PICO_SDK_PATH AND EXISTS "${PICO_SDK_PATH}/../FreeRTOS-Kernel")
+            set(FREERTOS_KERNEL_PATH ${PICO_SDK_PATH}/../FreeRTOS-Kernel)
+            message("Defaulting FREERTOS_KERNEL_PATH as sibling of PICO_SDK_PATH: ${FREERTOS_KERNEL_PATH}")
+            break()
+        endif()
+    endif ()
+
+    if (NOT FREERTOS_KERNEL_PATH)
+        foreach(POSSIBLE_SUFFIX Source FreeRTOS-Kernel FreeRTOS/Source)
+            # check if FreeRTOS-Kernel exists under directory that included us
+            set(SEARCH_ROOT ${CMAKE_CURRENT_SOURCE_DIR})
+            get_filename_component(_POSSIBLE_PATH ${SEARCH_ROOT}/${POSSIBLE_SUFFIX} REALPATH)
+            if (EXISTS ${_POSSIBLE_PATH}/${FREERTOS_KERNEL_RP2040_RELATIVE_PATH}/CMakeLists.txt)
+                get_filename_component(FREERTOS_KERNEL_PATH ${_POSSIBLE_PATH} REALPATH)
+                message("Setting FREERTOS_KERNEL_PATH to '${FREERTOS_KERNEL_PATH}' found relative to enclosing project")
+                break()
+            endif()
+        endforeach()
+        if (FREERTOS_KERNEL_PATH)
+            break()
+        endif()
+    endif()
+
+    # user must have specified
+    if (FREERTOS_KERNEL_PATH)
+        if (EXISTS "${FREERTOS_KERNEL_PATH}/${FREERTOS_KERNEL_RP2040_RELATIVE_PATH}")
+            break()
+        endif()
+    endif()
+endforeach ()
+
+if (NOT FREERTOS_KERNEL_PATH)
+    message(FATAL_ERROR "FreeRTOS location was not specified. Please set FREERTOS_KERNEL_PATH.")
+endif()
+
+set(FREERTOS_KERNEL_PATH "${FREERTOS_KERNEL_PATH}" CACHE PATH "Path to the FreeRTOS Kernel")
+
+get_filename_component(FREERTOS_KERNEL_PATH "${FREERTOS_KERNEL_PATH}" REALPATH BASE_DIR "${CMAKE_BINARY_DIR}")
+if (NOT EXISTS ${FREERTOS_KERNEL_PATH})
+    message(FATAL_ERROR "Directory '${FREERTOS_KERNEL_PATH}' not found")
+endif()
+if (NOT EXISTS ${FREERTOS_KERNEL_PATH}/${FREERTOS_KERNEL_RP2040_RELATIVE_PATH}/CMakeLists.txt)
+    message(FATAL_ERROR "Directory '${FREERTOS_KERNEL_PATH}' does not contain a '${PICO_PLATFORM}' port here: ${FREERTOS_KERNEL_RP2040_RELATIVE_PATH}")
+endif()
+set(FREERTOS_KERNEL_PATH ${FREERTOS_KERNEL_PATH} CACHE PATH "Path to the FreeRTOS_KERNEL" FORCE)
+
+add_subdirectory(${FREERTOS_KERNEL_PATH}/${FREERTOS_KERNEL_RP2040_RELATIVE_PATH} FREERTOS_KERNEL)
diff --git a/examples/pico/README.md b/examples/pico/README.md
new file mode 100644
index 0000000..fb49b6c
--- /dev/null
+++ b/examples/pico/README.md
@@ -0,0 +1,50 @@
+# RP2040 PICO W
+Establish a DataChannel connection between PICO and the web
+
+## Supported Devices
+| Device |Image|
+|---|---|
+| [PICO W](https://www.raspberrypi.com/products/raspberry-pi-pico/) |<img src="https://piepie.s3.ap-northeast-1.amazonaws.com/wp-content/uploads/2023/02/04114837/Raspberry-Pi-Pico-W-1.png" width="64">|
+
+## Setup Instructions
+### Download Required Libraries
+```
+$ git clone --recursive https://github.com/sepfy/libpeer
+$ git clone --recurisve https://github.com/raspberrypi/pico-sdk
+$ git clone --recursive https://github.com/FreeRTOS/FreeRTOS-Kernel
+```
+### Apply a patch
+Modify `libpeer/third_party/libsrtp/include/srtp.h`
+
+```patch
+@@ -614,7 +614,7 @@ srtp_err_status_t srtp_add_stream(srtp_t session, const srtp_policy_t *policy);
+  *    - [other]           otherwise.
+  *
+  */
+-srtp_err_status_t srtp_remove_stream(srtp_t session, unsigned int ssrc);
++srtp_err_status_t srtp_remove_stream(srtp_t session, uint32_t ssrc);
+
+ /**
+  * @brief srtp_update() updates all streams in the session.
+```
+
+### Configure Your Build
+```
+$ export PICO_SDK_PATH=<your PICO SDK path>/pico-sdk
+$ export FREERTOS_KERNEL_PATH=<your FreeRTOS kernel path>/FreeRTOS-Kernel
+$ export WIFI_SSID=<your WIFI SSID>
+$ export WIFI_PASSWORD=<your WIFI password>
+```
+
+### Build the Project
+```
+$ cd libpeer/examples/pico
+$ mkdir build
+$ cd build
+$ cmake ..
+```
+
+### Flash and Test
+```
+$ sudo picotool load -f pico_peer.uf2
+```
diff --git a/examples/pico/config.h b/examples/pico/config.h
new file mode 100644
index 0000000..b7f1ecd
--- /dev/null
+++ b/examples/pico/config.h
@@ -0,0 +1,115 @@
+/* clang-format off */
+
+/* Define to the full name and version of this package. */
+#define PACKAGE_VERSION "2.3.0"
+
+/* Define to the version of this package. */
+#define PACKAGE_STRING "pico 2.3.0"
+
+/* Define to enabled debug logging for all mudules. */
+/* #undef ENABLE_DEBUG_LOGGING */
+
+/* Logging statments will be writen to this file. */
+/* #undef ERR_REPORTING_FILE */
+
+/* Define to redirect logging to stdout. */
+/* #undef ERR_REPORTING_STDOUT */
+
+/* Define this to use OpenSSL crypto. */
+/* #undef OPENSSL */
+
+/* Define this to use AES-GCM. */
+/* #undef GCM */
+
+/* Define if building for a CISC machine (e.g. Intel). */
+#define CPU_CISC 1
+
+/* Define if building for a RISC machine (assume slow byte access). */
+/* #undef CPU_RISC */
+
+/* Define to use X86 inlined assembly code */
+/* #undef HAVE_X86 */
+
+/* Define WORDS_BIGENDIAN to 1 if your processor stores words with the most
+ significant byte first (like Motorola and SPARC, unlike Intel). */
+/* #undef WORDS_BIGENDIAN */
+
+/* Define to 1 if you have the <arpa/inet.h> header file. */
+#define HAVE_ARPA_INET_H 1
+
+/* Define to 1 if you have the <byteswap.h> header file. */
+/* #undef HAVE_BYTESWAP_H */
+
+/* Define to 1 if you have the <inttypes.h> header file. */
+#define HAVE_INTTYPES_H 1
+
+/* Define to 1 if you have the <machine/types.h> header file. */
+#define HAVE_MACHINE_TYPES_H 1
+
+/* Define to 1 if you have the <netinet/in.h> header file. */
+#define HAVE_NETINET_IN_H 1
+
+/* Define to 1 if you have the <stdint.h> header file. */
+#define HAVE_STDINT_H 1
+
+/* Define to 1 if you have the <stdlib.h> header file. */
+#define HAVE_STDLIB_H 1
+
+/* Define to 1 if you have the <sys/int_types.h> header file. */
+/* #undef HAVE_SYS_INT_TYPES_H */
+
+/* Define to 1 if you have the <sys/socket.h> header file. */
+#define HAVE_SYS_SOCKET_H 1
+
+/* Define to 1 if you have the <sys/types.h> header file. */
+#define HAVE_SYS_TYPES_H 1
+
+/* Define to 1 if you have the <unistd.h> header file. */
+#define HAVE_UNISTD_H 1
+
+/* Define to 1 if you have the <windows.h> header file. */
+/* #undef HAVE_WINDOWS_H */
+
+/* Define to 1 if you have the <winsock2.h> header file. */
+/* #undef HAVE_WINSOCK2_H */
+
+/* Define to 1 if you have the `inet_aton' function. */
+#define HAVE_INET_ATON 1
+
+/* Define to 1 if you have the `sigaction' function. */
+/* #undef HAVE_SIGACTION */
+
+/* Define to 1 if you have the `usleep' function. */
+#define HAVE_USLEEP 1
+
+/* Define to 1 if the system has the type `uint8_t'. */
+#define HAVE_UINT8_T 1
+
+/* Define to 1 if the system has the type `uint16_t'. */
+#define HAVE_UINT16_T 1
+
+/* Define to 1 if the system has the type `uint32_t'. */
+#define HAVE_UINT32_T 1
+
+/* Define to 1 if the system has the type `uint64_t'. */
+#define HAVE_UINT64_T 1
+
+/* Define to 1 if the system has the type `int32_t'. */
+#define HAVE_INT32_T 1
+
+/* The size of `unsigned long', as computed by sizeof. */
+#define SIZEOF_UNSIGNED_LONG 4
+
+/* The size of `unsigned long long', as computed by sizeof. */
+#define SIZEOF_UNSIGNED_LONG_LONG 8
+
+/* Define inline to what is supported by compiler  */
+#define HAVE_INLINE 1
+/* #undef HAVE___INLINE */
+#ifndef HAVE_INLINE
+  #ifdef HAVE___INLINE
+    #define inline __inline
+  #else
+    #define inline
+  #endif
+#endif
diff --git a/examples/pico/lwipopts.h b/examples/pico/lwipopts.h
new file mode 100644
index 0000000..af3847d
--- /dev/null
+++ b/examples/pico/lwipopts.h
@@ -0,0 +1,61 @@
+#ifndef LWIPOPTS_H
+#define LWIPOPTS_H
+
+#define NO_SYS 0
+#define LWIP_SOCKET 1
+#if PICO_CYW43_ARCH_POLL
+#define MEM_LIBC_MALLOC 1
+#else
+// MEM_LIBC_MALLOC is incompatible with non polling versions
+#define MEM_LIBC_MALLOC 0
+#endif
+#define MEM_ALIGNMENT 4
+#define MEM_SIZE 4000
+#define MEMP_NUM_TCP_SEG 32
+#define MEMP_NUM_ARP_QUEUE 10
+#define PBUF_POOL_SIZE 24
+#define LWIP_ARP 1
+#define LWIP_ETHERNET 1
+#define LWIP_ICMP 1
+#define LWIP_RAW 1
+#define TCP_WND (4 * TCP_MSS)
+#define TCP_MSS 1460
+#define TCP_SND_BUF (4 * TCP_MSS)
+#define TCP_SND_QUEUELEN ((4 * (TCP_SND_BUF) + (TCP_MSS - 1)) / (TCP_MSS))
+#define LWIP_NETIF_STATUS_CALLBACK 1
+#define LWIP_NETIF_LINK_CALLBACK 1
+#define LWIP_NETIF_HOSTNAME 1
+#define LWIP_NETCONN 0
+#define MEM_STATS 0
+#define SYS_STATS 0
+#define MEMP_STATS 0
+#define LINK_STATS 0
+#define LWIP_CHKSUM_ALGORITHM 3
+#define LWIP_DHCP 1
+#define LWIP_IPV4 1
+#define LWIP_IPV6 1
+#define LWIP_IGMP 1
+#define LWIP_TCP 1
+#define LWIP_UDP 1
+#define LWIP_DNS 1
+#define LWIP_TCP_KEEPALIVE 1
+#define LWIP_NETIF_TX_SINGLE_PBUF 1
+#define DHCP_DOES_ARP_CHECK 0
+#define LWIP_DHCP_DOES_ACD_CHECK 0
+
+#if !NO_SYS
+#define TCPIP_THREAD_STACKSIZE 1024
+#define DEFAULT_THREAD_STACKSIZE 1024
+#define DEFAULT_RAW_RECVMBOX_SIZE 8
+#define DEFAULT_UDP_RECVMBOX_SIZE 8
+#define DEFAULT_TCP_RECVMBOX_SIZE 8
+#define TCPIP_MBOX_SIZE 8
+#define LWIP_TIMEVAL_PRIVATE 0
+
+// not necessary, can be done either way
+#define LWIP_TCPIP_CORE_LOCKING_INPUT 1
+
+#define LWIP_SO_RCVTIMEO 1
+#endif
+
+#endif  // LWIPOPTS_H
diff --git a/examples/pico/main.c b/examples/pico/main.c
new file mode 100644
index 0000000..cf966d6
--- /dev/null
+++ b/examples/pico/main.c
@@ -0,0 +1,109 @@
+/**
+ * Copyright (c) 2022 Raspberry Pi (Trading) Ltd.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include "FreeRTOS.h"
+#include "hardware/clocks.h"
+#include "pico/cyw43_arch.h"
+#include "pico/multicore.h"
+#include "pico/stdlib.h"
+#include "task.h"
+
+#include "peer.h"
+
+#define TEST_TASK_PRIORITY (tskIDLE_PRIORITY + 1UL)
+
+TaskHandle_t xPcTaskHandle;
+PeerConnection* g_pc;
+PeerConnectionState eState = PEER_CONNECTION_CLOSED;
+int gDataChannelOpened = 0;
+
+static void oniceconnectionstatechange(PeerConnectionState state, void* user_data) {
+  eState = state;
+  printf("state = %d\n", state);
+}
+
+static void onmessage(char* msg, size_t len, void* userdata, uint16_t sid) {
+  if (strncmp(msg, "ping", 4) == 0) {
+    printf("Got ping, send pong\n");
+    peer_connection_datachannel_send(g_pc, "pong", 4);
+  }
+}
+
+void onopen(void* userdata) {
+  gDataChannelOpened = 1;
+}
+
+static void onclose(void* userdata) {
+}
+
+void peer_connection_task() {
+  printf("Run peer connection task on the core: %d\n", portGET_CORE_ID());
+  while (1) {
+    peer_connection_loop(g_pc);
+    vTaskDelay(pdMS_TO_TICKS(1));
+  }
+}
+
+void main_task(__unused void* params) {
+  if (cyw43_arch_init()) {
+    printf("failed to initialise\n");
+    vTaskDelete(NULL);
+  }
+  cyw43_arch_enable_sta_mode();
+  printf("Connecting to Wi-Fi...\n");
+
+  while (1) {
+    if (cyw43_arch_wifi_connect_timeout_ms(WIFI_SSID, WIFI_PASSWORD, CYW43_AUTH_WPA2_AES_PSK, 100000)) {
+      printf("failed to connect.\n");
+      vTaskDelay(1000);
+    } else {
+      printf("Connected.\n");
+      break;
+    }
+  }
+
+  PeerConfiguration config = {
+      .ice_servers = {
+          {.urls = "stun:stun.l.google.com:19302"}},
+      .datachannel = DATA_CHANNEL_STRING,
+  };
+
+  peer_init();
+  g_pc = peer_connection_create(&config);
+  peer_connection_oniceconnectionstatechange(g_pc, oniceconnectionstatechange);
+  peer_connection_ondatachannel(g_pc, onmessage, onopen, onclose);
+
+  ServiceConfiguration service_config = SERVICE_CONFIG_DEFAULT();
+  service_config.client_id = "mypico";
+  service_config.pc = g_pc;
+  peer_signaling_set_config(&service_config);
+  peer_signaling_join_channel();
+
+  xTaskCreate(peer_connection_task, "PeerConnectionTask", 4096, NULL, TEST_TASK_PRIORITY, &xPcTaskHandle);
+
+  printf("Run main task on the core: %d\n", portGET_CORE_ID());
+  printf("open https://sepfy.github.io/webrtc?deviceId=mypico\n");
+  while (true) {
+    peer_signaling_loop();
+    vTaskDelay(pdMS_TO_TICKS(10));
+  }
+
+  cyw43_arch_deinit();
+}
+
+void vLaunch(void) {
+  TaskHandle_t task;
+  xTaskCreate(main_task, "TestMainThread", 4096, NULL, TEST_TASK_PRIORITY, &task);
+  vTaskCoreAffinitySet(task, 1);
+  vTaskStartScheduler();
+}
+
+int main(void) {
+  stdio_init_all();
+  // set_sys_clock_khz(200000, true);
+  vLaunch();
+  return 0;
+}
diff --git a/examples/pico/mbedtls_config.h b/examples/pico/mbedtls_config.h
new file mode 100644
index 0000000..35663c6
--- /dev/null
+++ b/examples/pico/mbedtls_config.h
@@ -0,0 +1,87 @@
+#ifndef MBEDTLS_CONFIG_H
+#define MBEDTLS_CONFIG_H
+
+/* Workaround for some mbedtls source files using INT_MAX without including limits.h */
+#include <limits.h>
+
+#define MBEDTLS_NO_PLATFORM_ENTROPY
+#define MBEDTLS_ENTROPY_HARDWARE_ALT
+
+#define MBEDTLS_ALLOW_PRIVATE_ACCESS
+#define MBEDTLS_HAVE_TIME
+
+#define MBEDTLS_CIPHER_MODE_CBC
+#define MBEDTLS_ECP_DP_SECP192R1_ENABLED
+#define MBEDTLS_ECP_DP_SECP224R1_ENABLED
+#define MBEDTLS_ECP_DP_SECP256R1_ENABLED
+#define MBEDTLS_ECP_DP_SECP384R1_ENABLED
+#define MBEDTLS_ECP_DP_SECP521R1_ENABLED
+#define MBEDTLS_ECP_DP_SECP192K1_ENABLED
+#define MBEDTLS_ECP_DP_SECP224K1_ENABLED
+#define MBEDTLS_ECP_DP_SECP256K1_ENABLED
+#define MBEDTLS_ECP_DP_BP256R1_ENABLED
+#define MBEDTLS_ECP_DP_BP384R1_ENABLED
+#define MBEDTLS_ECP_DP_BP512R1_ENABLED
+#define MBEDTLS_ECP_DP_CURVE25519_ENABLED
+#define MBEDTLS_KEY_EXCHANGE_RSA_ENABLED
+#define MBEDTLS_PKCS1_V15
+#define MBEDTLS_PKCS1_V21
+#define MBEDTLS_SHA256_SMALLER
+#define MBEDTLS_SSL_SERVER_NAME_INDICATION
+#define MBEDTLS_AES_C
+#define MBEDTLS_ASN1_PARSE_C
+#define MBEDTLS_BIGNUM_C
+#define MBEDTLS_CIPHER_C
+#define MBEDTLS_CTR_DRBG_C
+#define MBEDTLS_ENTROPY_C
+#define MBEDTLS_ERROR_C
+#define MBEDTLS_MD_C
+#define MBEDTLS_MD5_C
+#define MBEDTLS_OID_C
+#define MBEDTLS_PKCS5_C
+#define MBEDTLS_PK_C
+#define MBEDTLS_PK_PARSE_C
+#define MBEDTLS_PLATFORM_C
+#define MBEDTLS_RSA_C
+#define MBEDTLS_SHA1_C
+#define MBEDTLS_SHA224_C
+#define MBEDTLS_SHA256_C
+#define MBEDTLS_SSL_CLI_C
+#define MBEDTLS_SSL_SRV_C
+#define MBEDTLS_SSL_TLS_C
+#define MBEDTLS_X509_CRT_PARSE_C
+#define MBEDTLS_X509_USE_C
+#define MBEDTLS_AES_FEWER_TABLES
+
+/* TLS 1.2 */
+#define MBEDTLS_SSL_PROTO_TLS1_2
+
+#define MBEDTLS_DHM_C
+#define MBEDTLS_GCM_C
+#define MBEDTLS_ECDH_C
+#define MBEDTLS_ECP_C
+#define MBEDTLS_ECDSA_C
+#define MBEDTLS_ASN1_WRITE_C
+
+// The following is needed to parse a certificate
+#define MBEDTLS_PEM_PARSE_C
+#define MBEDTLS_BASE64_C
+
+#define MBEDTLS_ENTROPY_SHA256_ACCUMULATOR
+#define MBEDTLS_SSL_DTLS_SRTP
+#define MBEDTLS_SSL_EXPORT_KEYS
+
+#define MBEDTLS_DEBUG_C
+#define MBEDTLS_SSL_DTLS_HELLO_VERIFY
+#define MBEDTLS_PEM_WRITE_C
+#define MBEDTLS_X509_CRT_WRITE_C
+#define MBEDTLS_SSL_PROTO_DTLS
+#define MBEDTLS_X509_CREATE_C
+#define MBEDTLS_GENPRIME
+#define MBEDTLS_SSL_COOKIE_C
+#define MBEDTLS_PK_WRITE_C
+#define MBEDTLS_TIMING_C
+#define MBEDTLS_SSL_KEEP_PEER_CERTIFICATE
+#define __unix__
+
+#endif  // MBEDTLS_CONFIG_H
diff --git a/examples/pico/netinet/in.h b/examples/pico/netinet/in.h
new file mode 100644
index 0000000..b994c1a
--- /dev/null
+++ b/examples/pico/netinet/in.h
@@ -0,0 +1,5 @@
+#ifndef NETINET_INET_H
+#define NETINET_INET_H
+
+#include "lwip/sockets.h"
+#endif  // NETINET_INET_H
diff --git a/src/address.c b/src/address.c
index 34db93d..1618ede 100644
--- a/src/address.c
+++ b/src/address.c
@@ -1,10 +1,6 @@
-#include <arpa/inet.h>
-#include <netinet/in.h>
-#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <sys/socket.h>
 
 #include "address.h"
 #include "utils.h"
diff --git a/src/address.h b/src/address.h
index 8dbbbf8..6f8eb78 100644
--- a/src/address.h
+++ b/src/address.h
@@ -1,9 +1,14 @@
 #ifndef ADDRESS_H_
 #define ADDRESS_H_
 
-#include <netinet/in.h>
-#include <stdint.h>
+#include "config.h"
+#if CONFIG_USE_LWIP
+#include <lwip/sockets.h>
+#else
+#include <arpa/inet.h>
 #include <sys/socket.h>
+#endif
+#include <stdint.h>
 
 #define ADDRSTRLEN INET6_ADDRSTRLEN
 
diff --git a/src/agent.c b/src/agent.c
index 5f1745a..c0942ac 100644
--- a/src/agent.c
+++ b/src/agent.c
@@ -1,12 +1,9 @@
-#include <arpa/inet.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/select.h>
-#include <sys/socket.h>
 #include <unistd.h>
 
-#include <pthread.h>
 #include "agent.h"
 #include "base64.h"
 #include "ice.h"
@@ -16,7 +13,7 @@
 #include "utils.h"
 
 #define AGENT_POLL_TIMEOUT 1
-#define AGENT_CONNCHECK_MAX 300
+#define AGENT_CONNCHECK_MAX 1000
 #define AGENT_CONNCHECK_PERIOD 100
 #define AGENT_STUN_RECV_MAXTIMES 1000
 
@@ -61,18 +58,24 @@ void agent_destroy(Agent* agent) {
 static int agent_socket_recv(Agent* agent, Address* addr, uint8_t* buf, int len) {
   int ret = -1;
   int i = 0;
-  int maxfd = 0;
+  int maxfd = -1;
   fd_set rfds;
   struct timeval tv;
+  int addr_type[] = { AF_INET,
+#if CONFIG_IPV6
+                      AF_INET6,
+#endif
+  };
+
   tv.tv_sec = 0;
   tv.tv_usec = AGENT_POLL_TIMEOUT * 1000;
   FD_ZERO(&rfds);
 
-  for (i = 0; i < 2; i++) {
+  for (i = 0; i < sizeof(addr_type) / sizeof(addr_type[0]); i++) {
     if (agent->udp_sockets[i].fd > maxfd) {
       maxfd = agent->udp_sockets[i].fd;
     }
-    if (agent->udp_sockets[i].fd > 0) {
+    if (agent->udp_sockets[i].fd >= 0) {
       FD_SET(agent->udp_sockets[i].fd, &rfds);
     }
   }
diff --git a/src/agent.h b/src/agent.h
index 027303a..86da0e5 100644
--- a/src/agent.h
+++ b/src/agent.h
@@ -1,15 +1,11 @@
 #ifndef AGENT_H_
 #define AGENT_H_
 
-#include <arpa/inet.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <sys/socket.h>
 #include <unistd.h>
 
-#include <pthread.h>
-
 #include "base64.h"
 #include "ice.h"
 #include "socket.h"
diff --git a/src/config.h b/src/config.h
index 7b7cdf9..83de727 100644
--- a/src/config.h
+++ b/src/config.h
@@ -3,17 +3,39 @@
 
 #define SCTP_MTU (1200)
 #define CONFIG_MTU (1300)
-#define RSA_KEY_LENGTH 1024
 
-#ifdef ESP32
-#define VIDEO_RB_DATA_LENGTH (CONFIG_MTU * 64)
-#define AUDIO_RB_DATA_LENGTH (CONFIG_MTU * 64)
-#define DATA_RB_DATA_LENGTH (SCTP_MTU * 128)
+#ifndef CONFIG_USE_LWIP
+#define CONFIG_USE_LWIP 0
+#endif
+
+#ifndef CONFIG_MBEDTLS_DEBUG
+#define CONFIG_MBEDTLS_DEBUG 0
+#endif
+
+#ifndef CONFIG_MBEDTLS_2_X
+#define CONFIG_MBEDTLS_2_X 0
+#endif
+
+#if CONFIG_MBEDTLS_2_X
+#define RSA_KEY_LENGTH 512
 #else
-#define HAVE_USRSCTP
-#define VIDEO_RB_DATA_LENGTH (CONFIG_MTU * 256)
-#define AUDIO_RB_DATA_LENGTH (CONFIG_MTU * 256)
-#define DATA_RB_DATA_LENGTH (SCTP_MTU * 128)
+#define RSA_KEY_LENGTH 1024
+#endif
+
+#ifndef CONFIG_USE_USRSCTP
+#define CONFIG_USE_USRSCTP 1
+#endif
+
+#ifndef CONFIG_VIDEO_BUFFER_SIZE
+#define CONFIG_VIDEO_BUFFER_SIZE (CONFIG_MTU * 256)
+#endif
+
+#ifndef CONFIG_AUDIO_BUFFER_SIZE
+#define CONFIG_AUDIO_BUFFER_SIZE (CONFIG_MTU * 256)
+#endif
+
+#ifndef CONFIG_DATA_BUFFER_SIZE
+#define CONFIG_DATA_BUFFER_SIZE (SCTP_MTU * 128)
 #endif
 
 #define AUDIO_LATENCY 20  // ms
diff --git a/src/dtls_srtp.c b/src/dtls_srtp.c
index 49f012d..65b5bd1 100644
--- a/src/dtls_srtp.c
+++ b/src/dtls_srtp.c
@@ -1,4 +1,3 @@
-#include <arpa/inet.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -7,7 +6,12 @@
 #include "address.h"
 #include "config.h"
 #include "dtls_srtp.h"
+#if CONFIG_MBEDTLS_DEBUG
+#include "mbedtls/debug.h"
+#endif
+#include "mbedtls/sha256.h"
 #include "mbedtls/ssl.h"
+#include "ports.h"
 #include "socket.h"
 #include "utils.h"
 
@@ -29,7 +33,7 @@ int dtls_srtp_udp_recv(void* ctx, uint8_t* buf, size_t len) {
   int ret;
 
   while ((ret = udp_socket_recvfrom(udp_socket, &udp_socket->bind_addr, buf, len)) <= 0) {
-    usleep(1000);
+    ports_sleep_ms(1);
   }
 
   LOGD("dtls_srtp_udp_recv (%d)", ret);
@@ -68,7 +72,11 @@ static int dtls_srtp_selfsign_cert(DtlsSrtp* dtls_srtp) {
   mbedtls_x509write_cert crt;
 
   unsigned char* cert_buf = NULL;
+#if CONFIG_MBEDTLS_2_X
+  mbedtls_mpi serial;
+#else
   const char* serial = "peer";
+#endif
   const char* pers = "dtls_srtp";
 
   cert_buf = (unsigned char*)malloc(RSA_KEY_LENGTH * 2);
@@ -99,14 +107,23 @@ static int dtls_srtp_selfsign_cert(DtlsSrtp* dtls_srtp) {
 
   mbedtls_x509write_crt_set_issuer_name(&crt, "CN=dtls_srtp");
 
+#if CONFIG_MBEDTLS_2_X
+  mbedtls_mpi_init(&serial);
+  mbedtls_mpi_fill_random(&serial, 16, mbedtls_ctr_drbg_random, &dtls_srtp->ctr_drbg);
+  ret = mbedtls_x509write_crt_set_serial(&crt, &serial);
+  if (ret < 0) {
+    LOGE("mbedtls_x509write_crt_set_serial failed -0x%.4x", (unsigned int)-ret);
+  }
+#else
   mbedtls_x509write_crt_set_serial_raw(&crt, (unsigned char*)serial, strlen(serial));
+#endif
 
   mbedtls_x509write_crt_set_validity(&crt, "20180101000000", "20280101000000");
 
   ret = mbedtls_x509write_crt_pem(&crt, cert_buf, 2 * RSA_KEY_LENGTH, mbedtls_ctr_drbg_random, &dtls_srtp->ctr_drbg);
 
   if (ret < 0) {
-    LOGE("mbedtls_x509write_crt_pem failed");
+    LOGE("mbedtls_x509write_crt_pem failed -0x%.4x", (unsigned int)-ret);
   }
 
   mbedtls_x509_crt_parse(&dtls_srtp->cert, cert_buf, 2 * RSA_KEY_LENGTH);
@@ -118,6 +135,12 @@ static int dtls_srtp_selfsign_cert(DtlsSrtp* dtls_srtp) {
   return ret;
 }
 
+#if CONFIG_MBEDTLS_DEBUG
+static void dtls_srtp_debug(void* ctx, int level, const char* file, int line, const char* str) {
+  LOGD("%s:%04d: %s", file, line, str);
+}
+#endif
+
 int dtls_srtp_init(DtlsSrtp* dtls_srtp, DtlsSrtpRole role, void* user_data) {
   static const mbedtls_ssl_srtp_profile default_profiles[] = {
       MBEDTLS_TLS_SRTP_AES128_CM_HMAC_SHA1_80,
@@ -139,7 +162,10 @@ int dtls_srtp_init(DtlsSrtp* dtls_srtp, DtlsSrtpRole role, void* user_data) {
   mbedtls_pk_init(&dtls_srtp->pkey);
   mbedtls_entropy_init(&dtls_srtp->entropy);
   mbedtls_ctr_drbg_init(&dtls_srtp->ctr_drbg);
-
+#if CONFIG_MBEDTLS_DEBUG
+  mbedtls_debug_set_threshold(3);
+  mbedtls_ssl_conf_dbg(&dtls_srtp->conf, dtls_srtp_debug, NULL);
+#endif
   dtls_srtp_selfsign_cert(dtls_srtp);
 
   mbedtls_ssl_conf_verify(&dtls_srtp->conf, dtls_srtp_cert_verify, NULL);
@@ -207,25 +233,15 @@ void dtls_srtp_deinit(DtlsSrtp* dtls_srtp) {
   }
 }
 
-static void dtls_srtp_key_derivation(void* context, mbedtls_ssl_key_export_type secret_type, const unsigned char* secret, size_t secret_len, const unsigned char client_random[32], const unsigned char server_random[32], mbedtls_tls_prf_types tls_prf_type) {
-  DtlsSrtp* dtls_srtp = (DtlsSrtp*)context;
-
+static int dtls_srtp_key_derivation(DtlsSrtp* dtls_srtp, const unsigned char* master_secret, const unsigned char* randbytes, mbedtls_tls_prf_types tls_prf_type) {
   int ret;
-
   const char* dtls_srtp_label = "EXTRACTOR-dtls_srtp";
-
-  unsigned char randbytes[64];
-
   uint8_t key_material[DTLS_SRTP_KEY_MATERIAL_LENGTH];
-
-  memcpy(randbytes, client_random, 32);
-  memcpy(randbytes + 32, server_random, 32);
-
   // Export keying material
-  if ((ret = mbedtls_ssl_tls_prf(tls_prf_type, secret, secret_len, dtls_srtp_label,
+  if ((ret = mbedtls_ssl_tls_prf(tls_prf_type, master_secret, sizeof(master_secret), dtls_srtp_label,
                                  randbytes, sizeof(randbytes), key_material, sizeof(key_material))) != 0) {
     LOGE("mbedtls_ssl_tls_prf failed(%d)", ret);
-    return;
+    return ret;
   }
 
 #if 0
@@ -266,7 +282,7 @@ static void dtls_srtp_key_derivation(void* context, mbedtls_ssl_key_export_type
 
   if (srtp_create(&dtls_srtp->srtp_in, &dtls_srtp->remote_policy) != srtp_err_status_ok) {
     LOGD("Error creating inbound SRTP session for component");
-    return;
+    return -1;
   }
 
   LOGI("Created inbound SRTP session");
@@ -286,11 +302,48 @@ static void dtls_srtp_key_derivation(void* context, mbedtls_ssl_key_export_type
 
   if (srtp_create(&dtls_srtp->srtp_out, &dtls_srtp->local_policy) != srtp_err_status_ok) {
     LOGE("Error creating outbound SRTP session");
-    return;
+    return -1;
   }
 
   LOGI("Created outbound SRTP session");
   dtls_srtp->state = DTLS_SRTP_STATE_CONNECTED;
+  return 0;
+}
+
+#if CONFIG_MBEDTLS_2_X
+static int dtls_srtp_key_derivation_cb(void* context,
+                                       const unsigned char* ms,
+                                       const unsigned char* kb,
+                                       size_t maclen,
+                                       size_t keylen,
+                                       size_t ivlen,
+                                       const unsigned char client_random[32],
+                                       const unsigned char server_random[32],
+                                       mbedtls_tls_prf_types tls_prf_type) {
+#else
+static void dtls_srtp_key_derivation_cb(void* context,
+                                        mbedtls_ssl_key_export_type secret_type,
+                                        const unsigned char* secret,
+                                        size_t secret_len,
+                                        const unsigned char client_random[32],
+                                        const unsigned char server_random[32],
+                                        mbedtls_tls_prf_types tls_prf_type) {
+#endif
+  DtlsSrtp* dtls_srtp = (DtlsSrtp*)context;
+
+  unsigned char master_secret[48];
+  unsigned char randbytes[64];
+
+  memcpy(randbytes, client_random, 32);
+  memcpy(randbytes + 32, server_random, 32);
+
+#if CONFIG_MBEDTLS_2_X
+  memcpy(master_secret, ms, sizeof(master_secret));
+  return dtls_srtp_key_derivation(dtls_srtp, master_secret, randbytes, tls_prf_type);
+#else
+  memcpy(master_secret, secret, sizeof(master_secret));
+  dtls_srtp_key_derivation(dtls_srtp, master_secret, randbytes, tls_prf_type);
+#endif
 }
 
 static int dtls_srtp_do_handshake(DtlsSrtp* dtls_srtp) {
@@ -300,7 +353,11 @@ static int dtls_srtp_do_handshake(DtlsSrtp* dtls_srtp) {
 
   mbedtls_ssl_set_timer_cb(&dtls_srtp->ssl, &timer, mbedtls_timing_set_delay, mbedtls_timing_get_delay);
 
-  mbedtls_ssl_set_export_keys_cb(&dtls_srtp->ssl, dtls_srtp_key_derivation, dtls_srtp);
+#if CONFIG_MBEDTLS_2_X
+  mbedtls_ssl_conf_export_keys_ext_cb(&dtls_srtp->conf, dtls_srtp_key_derivation_cb, dtls_srtp);
+#else
+  mbedtls_ssl_set_export_keys_cb(&dtls_srtp->ssl, dtls_srtp_key_derivation_cb, dtls_srtp);
+#endif
 
   mbedtls_ssl_set_bio(&dtls_srtp->ssl, dtls_srtp, dtls_srtp->udp_send, dtls_srtp->udp_recv, NULL);
 
@@ -424,9 +481,9 @@ int dtls_srtp_probe(uint8_t* buf) {
   if (buf == NULL)
     return 0;
 
-  // LOGD("DTLS content type: %d, version: %d, epoch: %d, sequence: %d, length: %d (%.4x)", header->content_type, header->version, header->epoch, ntohs(header->seqnum_hi), ntohs(header->length), header->length);
-
-  return ((*buf >= 20) && (*buf <= 64));
+  LOGD("DTLS content type: %d", buf[0]);
+  // only handle application data
+  return (buf[0] == 0x17);
 }
 
 void dtls_srtp_decrypt_rtp_packet(DtlsSrtp* dtls_srtp, uint8_t* packet, int* bytes) {
diff --git a/src/ice.c b/src/ice.c
index a54ea57..4e33c46 100644
--- a/src/ice.c
+++ b/src/ice.c
@@ -1,10 +1,8 @@
-#include <arpa/inet.h>
 #include <inttypes.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <sys/socket.h>
 #include <sys/types.h>
 
 #include "ice.h"
diff --git a/src/mdns.c b/src/mdns.c
index fd019a2..090ea88 100644
--- a/src/mdns.c
+++ b/src/mdns.c
@@ -1,11 +1,8 @@
-#include <arpa/inet.h>
 #include <inttypes.h>
-#include <netinet/in.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/select.h>
-#include <sys/socket.h>
 #include <unistd.h>
 #include "address.h"
 #include "socket.h"
diff --git a/src/peer_connection.c b/src/peer_connection.c
index 808aaaa..1c1289c 100644
--- a/src/peer_connection.c
+++ b/src/peer_connection.c
@@ -172,13 +172,17 @@ PeerConnection* peer_connection_create(PeerConfiguration* config) {
   memset(&pc->sctp, 0, sizeof(pc->sctp));
 
   if (pc->config.datachannel) {
-    LOGI("Datachannel allocates heap size: %d", DATA_RB_DATA_LENGTH);
-    pc->data_rb = buffer_new(DATA_RB_DATA_LENGTH);
+#if (CONFIG_DATA_BUFFER_SIZE) > 0
+    LOGI("Datachannel allocates heap size: %d", CONFIG_DATA_BUFFER_SIZE);
+    pc->data_rb = buffer_new(CONFIG_DATA_BUFFER_SIZE);
+#endif
   }
 
   if (pc->config.audio_codec) {
-    LOGI("Audio allocates heap size: %d", AUDIO_RB_DATA_LENGTH);
-    pc->audio_rb = buffer_new(AUDIO_RB_DATA_LENGTH);
+#if (CONFIG_AUDIO_BUFFER_SIZE) > 0
+    LOGI("Audio allocates heap size: %d", CONFIG_AUDIO_BUFFER_SIZE);
+    pc->audio_rb = buffer_new(CONFIG_AUDIO_BUFFER_SIZE);
+#endif
 
     rtp_encoder_init(&pc->artp_encoder, pc->config.audio_codec,
                      peer_connection_outgoing_rtp_packet, (void*)pc);
@@ -188,9 +192,10 @@ PeerConnection* peer_connection_create(PeerConfiguration* config) {
   }
 
   if (pc->config.video_codec) {
-    LOGI("Video allocates heap size: %d", VIDEO_RB_DATA_LENGTH);
-    pc->video_rb = buffer_new(VIDEO_RB_DATA_LENGTH);
-
+#if (CONFIG_VIDEO_BUFFER_SIZE) > 0
+    LOGI("Video allocates heap size: %d", CONFIG_VIDEO_BUFFER_SIZE);
+    pc->video_rb = buffer_new(CONFIG_VIDEO_BUFFER_SIZE);
+#endif
     rtp_encoder_init(&pc->vrtp_encoder, pc->config.video_codec,
                      peer_connection_outgoing_rtp_packet, (void*)pc);
 
@@ -222,8 +227,11 @@ int peer_connection_send_audio(PeerConnection* pc, const uint8_t* buf, size_t le
     // LOGE("dtls_srtp not connected");
     return -1;
   }
-
+#if (CONFIG_AUDIO_BUFFER_SIZE) > 0
   return buffer_push_tail(pc->audio_rb, buf, len);
+#else
+  return rtp_encoder_encode(&pc->artp_encoder, data, bytes);
+#endif
 }
 
 int peer_connection_send_video(PeerConnection* pc, const uint8_t* buf, size_t len) {
@@ -231,8 +239,11 @@ int peer_connection_send_video(PeerConnection* pc, const uint8_t* buf, size_t le
     // LOGE("dtls_srtp not connected");
     return -1;
   }
-
+#if (CONFIG_VIDEO_BUFFER_SIZE) > 0
   return buffer_push_tail(pc->video_rb, buf, len);
+#else
+  return rtp_encoder_encode(&pc->vrtp_encoder, data, bytes);
+#endif
 }
 
 int peer_connection_datachannel_send(PeerConnection* pc, char* message, size_t len) {
@@ -245,10 +256,14 @@ int peer_connection_datachannel_send_sid(PeerConnection* pc, char* message, size
     return -1;
   }
 
+#if (CONFIG_DATA_BUFFER_SIZE) > 0
+  return buffer_push_tail(pc->data_rb, (uint8_t*)message, len);
+#else
   if (pc->config.datachannel == DATA_CHANNEL_STRING)
     return sctp_outgoing_data(&pc->sctp, message, len, PPID_STRING, sid);
   else
     return sctp_outgoing_data(&pc->sctp, message, len, PPID_BINARY, sid);
+#endif
 }
 
 static char* peer_connection_dtls_role_setup_value(DtlsSrtpRole d) {
@@ -378,18 +393,23 @@ int peer_connection_loop(PeerConnection* pc) {
       break;
     case PEER_CONNECTION_COMPLETED:
 
+#if (CONFIG_VIDEO_BUFFER_SIZE) > 0
       data = buffer_peak_head(pc->video_rb, &bytes);
       if (data) {
         rtp_encoder_encode(&pc->vrtp_encoder, data, bytes);
         buffer_pop_head(pc->video_rb);
       }
+#endif
 
+#if (CONFIG_AUDIO_BUFFER_SIZE) > 0
       data = buffer_peak_head(pc->audio_rb, &bytes);
       if (data) {
         rtp_encoder_encode(&pc->artp_encoder, data, bytes);
         buffer_pop_head(pc->audio_rb);
       }
+#endif
 
+#if (CONFIG_DATA_BUFFER_SIZE) > 0
       data = buffer_peak_head(pc->data_rb, &bytes);
       if (data) {
         if (pc->config.datachannel == DATA_CHANNEL_STRING)
@@ -398,6 +418,7 @@ int peer_connection_loop(PeerConnection* pc) {
           sctp_outgoing_data(&pc->sctp, (char*)data, bytes, PPID_BINARY, 0);
         buffer_pop_head(pc->data_rb);
       }
+#endif
 
       if ((pc->agent_ret = agent_recv(&pc->agent, pc->agent_buf, sizeof(pc->agent_buf))) > 0) {
         LOGD("agent_recv %d", pc->agent_ret);
diff --git a/src/peer_signaling.c b/src/peer_signaling.c
index 4813e3e..5e0176d 100644
--- a/src/peer_signaling.c
+++ b/src/peer_signaling.c
@@ -19,7 +19,7 @@
 #define CONNACK_RECV_TIMEOUT_MS 1000
 
 #ifndef BUF_SIZE
-#define BUF_SIZE 4096
+#define BUF_SIZE 2048
 #endif
 
 #define TOPIC_SIZE 128
diff --git a/src/ports.c b/src/ports.c
index 71f87ca..2346f60 100644
--- a/src/ports.c
+++ b/src/ports.c
@@ -1,16 +1,20 @@
-#include <arpa/inet.h>
-#include <net/if.h>
-#include <netdb.h>
+#include <errno.h>
 #include <string.h>
 #include <sys/time.h>
 #include <sys/types.h>
 #include <unistd.h>
 
-#ifdef ESP32
-#include <esp_netif.h>
+#include "config.h"
+
+#if CONFIG_USE_LWIP
+#include "lwip/ip_addr.h"
+#include "lwip/netdb.h"
+#include "lwip/netif.h"
+#include "lwip/sys.h"
 #else
-#include <errno.h>
 #include <ifaddrs.h>
+#include <net/if.h>
+#include <netdb.h>
 #include <sys/ioctl.h>
 #endif
 
@@ -20,28 +24,32 @@
 int ports_get_host_addr(Address* addr, const char* iface_prefix) {
   int ret = 0;
 
-#ifdef ESP32
-  esp_netif_t* netif = esp_netif_get_handle_from_ifkey("WIFI_STA_DEF");
-  esp_netif_ip_info_t ip_info;
-  esp_ip6_addr_t ip6_info;
-
-  switch (addr->family) {
-    case AF_INET6:
-      if (esp_netif_get_ip6_global(netif, &ip6_info) == ESP_OK) {
-        memcpy(&addr->sin6.sin6_addr, &ip6_info.addr, 16);
-        ret = 1;
-      } else if (esp_netif_get_ip6_linklocal(netif, &ip6_info) == ESP_OK) {
-        memcpy(&addr->sin6.sin6_addr, &ip6_info.addr, 16);
-        ret = 1;
-      }
-      break;
-    case AF_INET:
-    default:
-      if (esp_netif_get_ip_info(netif, &ip_info) == ESP_OK) {
-        memcpy(&addr->sin.sin_addr, &ip_info.ip.addr, 4);
-        ret = 1;
-      }
+#if CONFIG_USE_LWIP
+  struct netif* netif;
+  int i;
+  for (netif = netif_list; netif != NULL; netif = netif->next) {
+    switch (addr->family) {
+      case AF_INET6:
+        for (i = 0; i < LWIP_IPV6_NUM_ADDRESSES; i++) {
+          if (!ip6_addr_isany(netif_ip6_addr(netif, i))) {
+            memcpy(&addr->sin6.sin6_addr, netif_ip6_addr(netif, i), 16);
+            ret = 1;
+            break;
+          }
+        }
+        break;
+      case AF_INET:
+      default:
+        if (!ip_addr_isany(&netif->ip_addr)) {
+          memcpy(&addr->sin.sin_addr, &netif->ip_addr.u_addr.ip4, 4);
+          ret = 1;
+        }
+        break;
+    }
+
+    if (ret) {
       break;
+    }
   }
 #else
 
@@ -139,3 +147,11 @@ uint32_t ports_get_epoch_time() {
   gettimeofday(&tv, NULL);
   return (uint32_t)tv.tv_sec * 1000 + tv.tv_usec / 1000;
 }
+
+void ports_sleep_ms(int ms) {
+#if CONFIG_USE_LWIP
+  sys_msleep(ms);
+#else
+  usleep(ms * 1000);
+#endif
+}
diff --git a/src/ports.h b/src/ports.h
index 9ca5d60..3c2c84d 100644
--- a/src/ports.h
+++ b/src/ports.h
@@ -12,4 +12,6 @@ int ports_get_host_addr(Address* addr, const char* iface_prefix);
 
 uint32_t ports_get_epoch_time();
 
+void ports_sleep_ms(int ms);
+
 #endif  // PORTS_H_
diff --git a/src/rtcp.c b/src/rtcp.c
index 49fafe4..117b58c 100644
--- a/src/rtcp.c
+++ b/src/rtcp.c
@@ -1,7 +1,7 @@
-#include <arpa/inet.h>
 #include <stdio.h>
 #include <string.h>
 
+#include "address.h"
 #include "rtcp.h"
 #include "rtp.h"
 
diff --git a/src/rtcp.h b/src/rtcp.h
index d3bbbb7..f888d05 100644
--- a/src/rtcp.h
+++ b/src/rtcp.h
@@ -1,8 +1,10 @@
 #ifndef RTCP_H_
 #define RTCP_H_
 
-#include <stdint.h>
-#ifdef __APPLE__
+#ifdef __BYTE_ORDER
+#define __BIG_ENDIAN 4321
+#define __LITTLE_ENDIAN 1234
+#elif __APPLE__
 #include <machine/endian.h>
 #else
 #include <endian.h>
diff --git a/src/rtp.c b/src/rtp.c
index b1edb1b..3898b84 100644
--- a/src/rtp.c
+++ b/src/rtp.c
@@ -1,7 +1,7 @@
-#include <arpa/inet.h>
 #include <stdio.h>
 #include <string.h>
 
+#include "address.h"
 #include "peer_connection.h"
 #include "rtp.h"
 #include "utils.h"
diff --git a/src/rtp.h b/src/rtp.h
index 12ab068..2df6657 100644
--- a/src/rtp.h
+++ b/src/rtp.h
@@ -2,7 +2,11 @@
 #define RTP_H_
 
 #include <stdint.h>
-#ifdef __APPLE__
+
+#ifdef __BYTE_ORDER
+#define __BIG_ENDIAN 4321
+#define __LITTLE_ENDIAN 1234
+#elif __APPLE__
 #include <machine/endian.h>
 #else
 #include <endian.h>
@@ -11,12 +15,6 @@
 #include "config.h"
 #include "peer_connection.h"
 
-#ifdef ESP32
-#define __BIG_ENDIAN 4321
-#define __LITTLE_ENDIAN 1234
-#define __BYTE_ORDER __LITTLE_ENDIAN
-#endif
-
 typedef enum RtpPayloadType {
 
   PT_PCMU = 0,
diff --git a/src/sctp.c b/src/sctp.c
index c684f2d..301b4e5 100644
--- a/src/sctp.c
+++ b/src/sctp.c
@@ -1,9 +1,8 @@
-#include <arpa/inet.h>
 #include <stdlib.h>
 #include <string.h>
 
 #include "sctp.h"
-#ifdef HAVE_USRSCTP
+#if CONFIG_USE_USRSCTP
 #include <usrsctp.h>
 #endif
 
@@ -104,7 +103,7 @@ static int sctp_outgoing_data_cb(void* userdata, void* buf, size_t len, uint8_t
 }
 
 int sctp_outgoing_data(Sctp* sctp, char* buf, size_t len, SctpDataPpid ppid, uint16_t sid) {
-#ifdef HAVE_USRSCTP
+#if CONFIG_USE_USRSCTP
   int res;
   struct sctp_sendv_spa spa = {0};
 
@@ -223,7 +222,7 @@ void sctp_incoming_data(Sctp* sctp, char* buf, size_t len) {
   if (!sctp)
     return;
 
-#ifdef HAVE_USRSCTP
+#if CONFIG_USE_USRSCTP
   sctp_handle_sctp_packet(sctp, buf, len);
   usrsctp_conninput(sctp, buf, len, 0);
 #else
@@ -389,7 +388,7 @@ void sctp_incoming_data(Sctp* sctp, char* buf, size_t len) {
 }
 
 static int sctp_handle_incoming_data(Sctp* sctp, char* data, size_t len, uint32_t ppid, uint16_t sid, int flags) {
-#ifdef HAVE_USRSCTP
+#if CONFIG_USE_USRSCTP
   switch (ppid) {
     case DATA_CHANNEL_PPID_CONTROL:
       break;
@@ -412,7 +411,7 @@ static int sctp_handle_incoming_data(Sctp* sctp, char* data, size_t len, uint32_
   return 0;
 }
 
-#ifdef HAVE_USRSCTP
+#if CONFIG_USE_USRSCTP
 
 static void sctp_process_notification(Sctp* sctp, union sctp_notification* notification, size_t len) {
   if (notification->sn_header.sn_length != (uint32_t)len) {
@@ -470,7 +469,7 @@ int sctp_create_socket(Sctp* sctp, DtlsSrtp* dtls_srtp) {
   sctp->local_port = 5000;
   sctp->remote_port = 5000;
   sctp->tsn = 1234;
-#ifdef HAVE_USRSCTP
+#if CONFIG_USE_USRSCTP
   int ret = -1;
   usrsctp_init(0, sctp_outgoing_data_cb, NULL);
   usrsctp_sysctl_set_sctp_ecn_enable(0);
@@ -579,7 +578,7 @@ int sctp_is_connected(Sctp* sctp) {
 }
 
 void sctp_destroy(Sctp* sctp) {
-#ifdef HAVE_USRSCTP
+#if CONFIG_USE_USRSCTP
   if (sctp) {
     if (sctp->sock) {
       usrsctp_shutdown(sctp->sock, SHUT_RDWR);
diff --git a/src/sctp.h b/src/sctp.h
index 6489603..5956bba 100644
--- a/src/sctp.h
+++ b/src/sctp.h
@@ -6,7 +6,7 @@
 #include "dtls_srtp.h"
 #include "utils.h"
 
-#ifndef HAVE_USRSCTP
+#if !CONFIG_USE_USRSCTP
 
 typedef enum DecpMsgType {
 
diff --git a/src/socket.c b/src/socket.c
index 2d5efaa..6f7d8ef 100644
--- a/src/socket.c
+++ b/src/socket.c
@@ -1,13 +1,5 @@
-#include <arpa/inet.h>
 #include <errno.h>
-#include <fcntl.h>
-#include <net/if.h>
-#include <netdb.h>
-#include <netinet/in.h>
 #include <string.h>
-#include <sys/ioctl.h>
-#include <sys/socket.h>
-#include <sys/types.h>
 #include <unistd.h>
 
 #include "socket.h"
@@ -70,8 +62,7 @@ int udp_socket_open(UdpSocket* udp_socket, int family, int port) {
 
   do {
     if ((ret = setsockopt(udp_socket->fd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse))) < 0) {
-      LOGE("reuse failed");
-      break;
+      LOGW("reuse failed. ignore");
     }
 
     if ((ret = bind(udp_socket->fd, sa, sock_len)) < 0) {
diff --git a/src/ssl_transport.c b/src/ssl_transport.c
index 1db239c..909f9e9 100644
--- a/src/ssl_transport.c
+++ b/src/ssl_transport.c
@@ -29,10 +29,14 @@ static int ssl_transport_mbedtls_recv_timeout(void* ctx, unsigned char* buf, siz
   if (ret < 0) {
     return -1;
   } else if (ret == 0) {
-    return MBEDTLS_ERR_SSL_TIMEOUT;
+    // timeout
+  } else {
+    if (FD_ISSET(((TcpSocket*)ctx)->fd, &read_fds)) {
+      ret = tcp_socket_recv((TcpSocket*)ctx, buf, len);
+    }
   }
 
-  return tcp_socket_recv((TcpSocket*)ctx, buf, len);
+  return ret;
 }
 
 static int ssl_transport_mbedlts_send(void* ctx, const uint8_t* buf, size_t len) {
@@ -135,7 +139,7 @@ int32_t ssl_transport_send(NetworkContext_t* net_ctx, const void* buf, size_t le
 
   while ((ret = mbedtls_ssl_write(&net_ctx->ssl, buf, len)) <= 0) {
     if (ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE) {
-      LOGE("");
+      LOGE("ssl write error: -0x%x", (unsigned int)-ret);
     }
   }
 
diff --git a/src/utils.c b/src/utils.c
index f4060b1..020b8ac 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -1,14 +1,10 @@
-#include <arpa/inet.h>
-#include <netdb.h>
+#include "utils.h"
+#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <sys/socket.h>
-#include <time.h>
-
-#include <stdint.h>
 #include <string.h>
+#include <time.h>
 #include "mbedtls/md.h"
-#include "utils.h"
 
 void utils_random_string(char* s, const int len) {
   int i;