Add FreeRTOS echo-server example

.gitmodules

@@ -4,3 +4,15 @@
 [submodule "make-testsuite/wolfssh"]
 	path = make-testsuite/wolfssh
 	url = https://github.com/wolfSSL/wolfssh.git
+[submodule "echo-server/wolfssl"]
+	path = echo-server/wolfssl
+	url = https://github.com/wolfSSL/wolfssl.git
+[submodule "echo-server/wolfssh"]
+	path = echo-server/wolfssh
+	url = https://github.com/wolfSSL/wolfssh.git
+[submodule "echo-server/FreeRTOS-Kernel"]
+	path = echo-server/FreeRTOS-Kernel
+	url = https://github.com/FreeRTOS/FreeRTOS-Kernel.git
+[submodule "echo-server/FreeRTOS-Plus-TCP"]
+	path = echo-server/FreeRTOS-Plus-TCP
+	url = https://github.com/FreeRTOS/FreeRTOS-Plus-TCP.git

README.md

@@ -23,6 +23,13 @@ The following examples are available for Espressif devices:
 * [ESP32-SSH-Server](./Espressif/ESP8266/ESP8266-SSH-Server/README.md)
 SSH-to-UART.
 
+## echo-server
+
+A minimal SSH echo server running on FreeRTOS with FreeRTOS-Plus-TCP networking.
+Targets PIC32MZ with Microchip Harmony but runnable on Linux using the FreeRTOS
+POSIX simulator and a libpcap-based network interface. Uses a Makefile and has a
+preconfigured user_settings.h file.
+
 ## make-testsuite
 
 This example isn't manufacturer specific, but it has only been tested on

echo-server/.gitignore

@@ -0,0 +1,5 @@
+*.o
+*.a
+obj/
+keys/
+echo-server

echo-server/FreeRTOSConfig.h

@@ -0,0 +1,102 @@
+/* FreeRTOSConfig.h
+ *
+ * Copyright (C) 2026 wolfSSL Inc.
+ *
+ * wolfSSH is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * wolfSSH is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with wolfSSH.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef FREERTOS_CONFIG_H
+#define FREERTOS_CONFIG_H
+
+/* Scheduler */
+#define configUSE_PREEMPTION                    1
+#define configUSE_PORT_OPTIMISED_TASK_SELECTION 0
+#define configUSE_TICKLESS_IDLE                 0
+#define configCPU_CLOCK_HZ                      ( ( unsigned long ) 60000000 )
+#define configTICK_RATE_HZ                      ( ( TickType_t ) 1000 )
+#define configMAX_PRIORITIES                    5
+#define configMINIMAL_STACK_SIZE                ( ( unsigned short ) 8192 )
+#define configMAX_TASK_NAME_LEN                 16
+#define configUSE_16_BIT_TICKS                  0
+#define configIDLE_SHOULD_YIELD                 1
+#define configUSE_TASK_NOTIFICATIONS            1
+#define configTASK_NOTIFICATION_ARRAY_ENTRIES   3
+#define configUSE_MUTEXES                       1
+#define configUSE_RECURSIVE_MUTEXES             1
+#define configUSE_COUNTING_SEMAPHORES           1
+#define configQUEUE_REGISTRY_SIZE               10
+#define configUSE_QUEUE_SETS                    0
+#define configUSE_TIME_SLICING                  1
+#define configUSE_NEWLIB_REENTRANT              0
+#define configENABLE_BACKWARD_COMPATIBILITY     1
+#define configNUM_THREAD_LOCAL_STORAGE_POINTERS 5
+#define configUSE_MINI_LIST_ITEM                1
+
+/* Memory */
+#define configSUPPORT_STATIC_ALLOCATION         0
+#define configSUPPORT_DYNAMIC_ALLOCATION        1
+#define configTOTAL_HEAP_SIZE                   ( ( size_t ) ( 256 * 1024 ) )
+#define configAPPLICATION_ALLOCATED_HEAP        0
+
+/* Hook functions */
+#define configUSE_IDLE_HOOK                     1
+#define configUSE_TICK_HOOK                     0
+#define configCHECK_FOR_STACK_OVERFLOW          0
+#define configUSE_MALLOC_FAILED_HOOK            0
+#define configUSE_DAEMON_TASK_STARTUP_HOOK      0
+
+/* Stats */
+#define configGENERATE_RUN_TIME_STATS           0
+#define configUSE_TRACE_FACILITY                0
+#define configUSE_STATS_FORMATTING_FUNCTIONS    0
+
+/* Co-routines */
+#define configUSE_CO_ROUTINES                   0
+#define configMAX_CO_ROUTINE_PRIORITIES         1
+
+/* Software timers */
+#define configUSE_TIMERS                        1
+#define configTIMER_TASK_PRIORITY               ( configMAX_PRIORITIES - 1 )
+#define configTIMER_QUEUE_LENGTH                10
+#define configTIMER_TASK_STACK_DEPTH            configMINIMAL_STACK_SIZE
+
+/* Logging — used by FreeRTOS-Plus-TCP's FreeRTOS_printf / FreeRTOS_debug_printf */
+#define configPRINTF( X )    printf X
+
+/* Trap errors during development */
+#define configASSERT( x )
+
+/* Optional functions */
+#define INCLUDE_vTaskPrioritySet                1
+#define INCLUDE_uxTaskPriorityGet               1
+#define INCLUDE_vTaskDelete                     1
+#define INCLUDE_vTaskSuspend                    1
+#define INCLUDE_xResumeFromISR                  1
+#define INCLUDE_vTaskDelayUntil                 1
+#define INCLUDE_vTaskDelay                      1
+#define INCLUDE_xTaskGetSchedulerState          1
+#define INCLUDE_xTaskGetCurrentTaskHandle       1
+#define INCLUDE_uxTaskGetStackHighWaterMark     0
+#define INCLUDE_xTaskGetIdleTaskHandle          0
+#define INCLUDE_eTaskGetState                   0
+#define INCLUDE_xEventGroupSetBitFromISR        1
+#define INCLUDE_xTimerPendFunctionCall          0
+#define INCLUDE_xTaskAbortDelay                 0
+#define INCLUDE_xTaskGetHandle                  0
+#define INCLUDE_xTaskResumeFromISR              1
+
+/* POSIX port */
+#define configPOSIX_STACK_SIZE                  ( ( unsigned short ) 65536 )
+
+#endif /* FREERTOS_CONFIG_H */

echo-server/FreeRTOSIPConfig.h

@@ -0,0 +1,91 @@
+/* FreeRTOSIPConfig.h
+ *
+ * Copyright (C) 2026 wolfSSL Inc.
+ *
+ * wolfSSH is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * wolfSSH is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with wolfSSH.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef FREERTOS_IP_CONFIG_H
+#define FREERTOS_IP_CONFIG_H
+
+/* Use the backward-compatible single-interface FreeRTOS_IPInit() API */
+#define ipconfigIPv4_BACKWARD_COMPATIBLE        1
+#define ipconfigUSE_IPv6                        0
+
+/* TCP/IP task */
+#define ipconfigIP_TASK_PRIORITY                ( configMAX_PRIORITIES - 2 )
+#define ipconfigIP_TASK_STACK_SIZE_WORDS         ( configMINIMAL_STACK_SIZE * 4 )
+
+/* Protocol support */
+#define ipconfigUSE_TCP                         1
+#define ipconfigUSE_DNS                         0
+#define ipconfigUSE_DHCP                        0
+
+/* Network tuning */
+#define ipconfigNUM_NETWORK_BUFFER_DESCRIPTORS  60
+#define ipconfigNETWORK_MTU                     1500
+#define ipconfigTCP_MSS                         ( ipconfigNETWORK_MTU - 40 )
+#define ipconfigTCP_RX_BUFFER_LENGTH            ( 16 * 1024 )
+#define ipconfigTCP_TX_BUFFER_LENGTH            ( 16 * 1024 )
+#define ipconfigTCP_WIN_SEG_COUNT               64
+
+/* Event processing */
+#define ipconfigETHERNET_DRIVER_FILTERS_FRAME_TYPES  1
+#define ipconfigETHERNET_MINIMUM_PACKET_BYTES        0
+#define ipconfigBUFFER_PADDING                       0
+#define ipconfigPACKET_FILLER_SIZE                   2
+#define ipconfigEVENT_QUEUE_LENGTH                   ( ipconfigNUM_NETWORK_BUFFER_DESCRIPTORS + 5 )
+
+/* ARP */
+#define ipconfigUSE_ARP_REMOVE_ENTRY            1
+#define ipconfigUSE_ARP_REVERSED_LOOKUP         1
+#define ipconfigARP_CACHE_ENTRIES               6
+#define ipconfigMAX_ARP_RETRANSMISSIONS         5
+#define ipconfigMAX_ARP_AGE                     150
+
+/* TCP parameters */
+#define ipconfigTCP_HANG_PROTECTION             1
+#define ipconfigTCP_HANG_PROTECTION_TIME        30
+#define ipconfigTCP_KEEP_ALIVE                  1
+#define ipconfigTCP_KEEP_ALIVE_INTERVAL         20
+
+/* Misc */
+#define ipconfigZERO_COPY_TX_DRIVER             0
+#define ipconfigZERO_COPY_RX_DRIVER             0
+#define ipconfigDRIVER_INCLUDED_TX_IP_CHECKSUM  0
+#define ipconfigDRIVER_INCLUDED_RX_IP_CHECKSUM  0
+#define ipconfigSUPPORT_OUTGOING_PINGS          1
+#define ipconfigREPLY_TO_INCOMING_PINGS         1
+#define ipconfigSUPPORT_SELECT_FUNCTION         0
+#define ipconfigFILTER_OUT_NON_ETHERNET_II_FRAMES  1
+#define ipconfigBYTE_ORDER                      pdFREERTOS_LITTLE_ENDIAN
+#define ipconfigHAS_DEBUG_PRINTF                0
+#define ipconfigHAS_PRINTF                      1
+
+/* Linux pcap network interface.
+ * Override at compile time with -DipconfigNETWORK_INTERFACE_TO_USE=N */
+#ifndef ipconfigNETWORK_INTERFACE_TO_USE
+    #define ipconfigNETWORK_INTERFACE_TO_USE    2
+#endif
+
+/* Linux NetworkInterface.c requires these defines */
+#define configNETWORK_INTERFACE_TO_USE          ipconfigNETWORK_INTERFACE_TO_USE
+#define configMAC_ISR_SIMULATOR_PRIORITY        ( configMAX_PRIORITIES - 1 )
+#define configWINDOWS_MAC_INTERRUPT_SIMULATOR_DELAY  ( 2 / portTICK_PERIOD_MS )
+#define configNET_MASK0                         255
+#define configNET_MASK1                         255
+#define configNET_MASK2                         255
+#define configNET_MASK3                         0
+
+#endif /* FREERTOS_IP_CONFIG_H */