diff --git a/bsp_z7/lwip/lwipopts.h b/bsp_z7/lwip/lwipopts.h
index de50d11..64ea35b 100644
--- a/bsp_z7/lwip/lwipopts.h
+++ b/bsp_z7/lwip/lwipopts.h
@@ -32,12 +32,8 @@
 #ifndef LWIP_LWIPOPTS_H
 #define LWIP_LWIPOPTS_H
 
-#ifdef LWIP_OPTTEST_FILE
-#include "lwipopts_test.h"
-#else /* LWIP_OPTTEST_FILE */
-
 #define LWIP_IPV4                  1
-#define LWIP_IPV6                  1
+#define LWIP_IPV6                  0
 
 #define NO_SYS                     1
 #define LWIP_SOCKET                (NO_SYS==0)
@@ -74,7 +70,7 @@
 #define LWIP_NETIF_STATUS_CALLBACK      1
 #define LWIP_NETIF_EXT_STATUS_CALLBACK  1
 
-#define LWIP_DEBUG
+//#define LWIP_DEBUG
 
 #ifdef LWIP_DEBUG
 
@@ -320,8 +316,6 @@ a lot of data that needs to be copied, this should be set high. */
 
 #endif /* PPP_SUPPORT */
 
-#endif /* LWIP_OPTTEST_FILE */
-
 
 // Disable slip task
 #define SLIP_USE_RX_THREAD 0
diff --git a/bsp_z7/ps7_cortexa9_0/libsrc/standalone/CMakeLists.txt b/bsp_z7/ps7_cortexa9_0/libsrc/standalone/CMakeLists.txt
index 8c7ebb8..416de1f 100644
--- a/bsp_z7/ps7_cortexa9_0/libsrc/standalone/CMakeLists.txt
+++ b/bsp_z7/ps7_cortexa9_0/libsrc/standalone/CMakeLists.txt
@@ -6,7 +6,7 @@ target_sources(${TARGET_NAME} PUBLIC
     src/asm_vectors.S
     src/open.c
     src/xil_exception.c
-    src/sbrk.c
+    #src/sbrk.c
     src/xl2cc_counter.c
     src/xil_cache.c
     src/xil_spinlock.c
@@ -48,5 +48,5 @@ target_sources(${TARGET_NAME} PUBLIC
     src/outbyte.c
     src/unlink.c
     src/abort.c
-    src/_sbrk.c
+    #src/_sbrk.c
 )
\ No newline at end of file
diff --git a/mission/testIp.c b/mission/testIp.c
index 4e27025..bfcb02a 100644
--- a/mission/testIp.c
+++ b/mission/testIp.c
@@ -2,6 +2,7 @@
 #include "lwip/init.h"
 #include "lwip/sio.h"
 #include "lwip/timeouts.h"
+#include "lwip/udp.h"
 
 #include "queue.h"
 #include "task.h"
@@ -83,13 +84,42 @@ void handleUARTInt(void *) {
   /* Clear the interrupt status. */
   XUartPs_WriteReg(STDIN_BASEADDRESS, XUARTPS_ISR_OFFSET, IsrStatus);
 
+  /* directly yield if sending to the queue woke something in ourselves */
   portYIELD_FROM_ISR(xHigherPriorityTaskWoken);
 }
 
+static struct udp_pcb *udpecho_raw_pcb;
+
+static void
+udpecho_raw_recv(void *arg, struct udp_pcb *upcb, struct pbuf *p,
+                 const ip_addr_t *addr, u16_t port)
+{
+  LWIP_UNUSED_ARG(arg);
+  if (p != NULL) {
+    /* send received packet back to sender */
+    udp_sendto(upcb, p, addr, port);
+    /* free the pbuf */
+    pbuf_free(p);
+  }
+}
+
+uint8_t data[] = {'1','2','3','4','5'};
+
 void lwip_main(void *) {
+
+  struct pbuf* tx = pbuf_alloc_reference(data, sizeof(data), PBUF_REF);
+
+  ip_addr_t addr  = IPADDR4_INIT_BYTES(10,0,0,13);
+
+  udp_sendto(udpecho_raw_pcb, tx, &addr, 1177);
+
+  pbuf_free(tx);
+
   while (1) {
     // slipif_rxbyte_input() is private, so we use slipif_poll and implement
     // sio_tryread()
+    // sio_tryread() will do a blocking read with a timeout, so we get to check
+    // the timeouts even if no data is incoming
     slipif_poll(&netif);
     sys_check_timeouts();
   }
@@ -116,7 +146,9 @@ u32_t sio_tryread(sio_fd_t fd, u8_t *data, u32_t len) {
   }
 }
 
+#ifdef LWIP_DEBUG
 const char *lwip_strerr(err_t err) { return "Dafuq i know? I am a NOSYS"; }
+#endif
 
 u32_t sys_now(void) { return xTaskGetTickCount() * portTICK_PERIOD_MS; }
 
@@ -147,7 +179,19 @@ void testIp() {
   netif_set_link_up(&netif);
   netif_set_up(&netif);
 
-  vTaskDelay(pdMS_TO_TICKS(2000));
+  udpecho_raw_pcb = udp_new_ip_type(IPADDR_TYPE_ANY);
+  if (udpecho_raw_pcb != NULL) {
+    err_t err;
+
+    err = udp_bind(udpecho_raw_pcb, IP_ANY_TYPE, 7);
+    if (err == ERR_OK) {
+      udp_recv(udpecho_raw_pcb, udpecho_raw_recv, NULL);
+    } else {
+      /* TODO */
+    }
+  } else {
+    /* TODO */
+  }
 
   /* Install the UART Interrupt handler. */
   BaseType_t xStatus =
@@ -183,28 +227,4 @@ void testIp() {
                                     simple case. */
       4,              /* The priority assigned to the task. */
       xStack, &xTaskBuffer);
-
-  // puts("socket");
-
-  // int serverSocket = socket(AF_INET, SOCK_DGRAM, 0);
-  // if (serverSocket == -1) {
-  //   puts("socket failed");
-  //   return;
-  // }
-
-  // sockaddr_in serverAddr;
-
-  // memset(&serverAddr, 0, sizeof(serverAddr));
-
-  // serverAddr.sin_family = AF_INET;
-  // serverAddr.sin_port = htons(0xcafe);
-  // serverAddr.sin_addr.s_addr = inet_addr("10.0.0.13");
-
-  // uint8_t data[] = {1, 2, 3, 4, 5, 6, 7};
-
-  // puts("send");
-
-  // sendto(serverSocket, data, sizeof(data), 0, (sockaddr *)&serverAddr,
-  //        sizeof(serverAddr));
-  // puts("send done");
 }
\ No newline at end of file