diff --git a/Documentation/NuttxPortingGuide.html b/Documentation/NuttxPortingGuide.html
index a750a04a2f..9cf518cb52 100644
--- a/Documentation/NuttxPortingGuide.html
+++ b/Documentation/NuttxPortingGuide.html
@@ -2921,6 +2921,9 @@ build
   <li>
     <code>CONFIG_NET_ARPTAB_SIZE</code>: The size of the ARP table
   </li>
+  <li>
+    <code>CONFIG_NET_ARP_IPIN</code>: Harvest IP/MAC address mappings for the ARP table from incoming IP packets.
+  </li>
   <li>
     <code>CONFIG_NET_BROADCAST</code>: Incoming UDP broadcast support
   </li>
diff --git a/TODO b/TODO
index 52ba42407e..99e5600d9f 100644
--- a/TODO
+++ b/TODO
@@ -214,11 +214,9 @@ o Network (net/, drivers/net)
   Description: Outgoing packets are dropped and overwritten by ARP packets
                if the destination IP has not been mapped to a MAC.  Could
                improve send() performance by explicitly performing ARP before
-               sending the packet.
-               ---
-               Or by enabling arpin() logic.  NOTE: From the uIP forum: "You
-               can use the function but it has a bug. You'll need to comment
-               this line: uip_len -= sizeof(struct uip_eth_hdr);"
+               sending the packet (or by enabling CONFIG_NET_ARP_IPIN logic. 
+               This could, however have negative impacts on busy networks and
+               could require a large value for CONFIG_NET_ARPTAB_SIZE).
   Status:      Open
   Priority:    Medium
 
diff --git a/configs/README.txt b/configs/README.txt
index 2f393d8535..bda94884ef 100644
--- a/configs/README.txt
+++ b/configs/README.txt
@@ -595,6 +595,8 @@ defconfig -- This is a configuration file similar to the Linux
 		CONFIG_NET_RECEIVE_WINDOW - The size of the advertised receiver's
 		  window
 		CONFIG_NET_ARPTAB_SIZE - The size of the ARP table
+        CONFIG_NET_ARP_IPIN - Harvest IP/MAC address mappings from the ARP table
+          from incoming IP packets.
 		CONFIG_NET_BROADCAST - Incoming UDP broadcast support
 		CONFIG_NET_MULTICAST - Outgoing multi-cast address support
 		CONFIG_NET_LLH_LEN - The link level header length
diff --git a/include/net/uip/uip-arp.h b/include/net/uip/uip-arp.h
index 47b5b99929..b77addde51 100644
--- a/include/net/uip/uip-arp.h
+++ b/include/net/uip/uip-arp.h
@@ -2,7 +2,7 @@
  * include/net/uip/uip-arch.h
  * Macros and definitions for the ARP module.
  *
- *   Copyright (C) 2007, 2009 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007, 2009-2010 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
  *
  * Derived from uIP with has a similar BSD-styple license:
@@ -114,7 +114,7 @@ extern "C" {
 EXTERN void uip_arp_init(void);
 
 /****************************************************************************
- * Name: uip_arp_init
+ * Name: uip_arp_ipin
  *
  * Description:
  *   The uip_arp_ipin() function should be called whenever an IP packet
@@ -125,7 +125,11 @@ EXTERN void uip_arp_init(void);
  *
  ****************************************************************************/
 
-#define uip_arp_ipin()
+#ifdef CONFIG_NET_ARP_IPIN
+EXTERN void uip_arp_ipin(void);
+#else
+# define uip_arp_ipin()
+#endif
 
 /****************************************************************************
  * Name: uip_arp_arpin
diff --git a/net/uip/uip_arp.c b/net/uip/uip_arp.c
index 270bddd640..90f1ef2d32 100644
--- a/net/uip/uip_arp.c
+++ b/net/uip/uip_arp.c
@@ -176,6 +176,34 @@ static void uip_arp_dump(struct arp_hdr *arp)
  * Public Functions
  ****************************************************************************/
 
+/* ARP processing for incoming IP packets
+ *
+ * This function should be called by the device driver when an IP packet has
+ * been received. The function will check if the address is in the ARP cache,
+ * and if so the ARP cache entry will be refreshed. If no ARP cache entry was
+ * found, a new one is created.
+ *
+ * This function expects an IP packet with a prepended Ethernet header in the
+ * d_buf[] buffer, and the length of the packet in the variable d_len.
+ */
+
+#ifdef CONFIG_NET_ARP_IPIN
+void uip_arp_ipin(void)
+{
+  in_addr_t srcipaddr;
+
+  /* Only insert/update an entry if the source IP address of the incoming IP
+   * packet comes from a host on the local network.
+   */
+
+  srcipaddr = uip_ip4addr_conv(IPBUF->srcipaddr);
+  if (!uip_ipaddr_maskcmp(ipaddr, dev->d_ipaddr, dev->d_netmask))
+    {
+      uip_arp_update(IPBUF->srcipaddr, ETHBUF->src);
+    }
+}
+#endif /* CONFIG_NET_ARP_IPIN */
+
 /* ARP processing for incoming ARP packets.
  *
  * This function should be called by the device driver when an ARP
@@ -194,7 +222,7 @@ static void uip_arp_dump(struct arp_hdr *arp)
  *
  * This function expects an ARP packet with a prepended Ethernet
  * header in the d_buf[] buffer, and the length of the packet in the
- * global variable d_len.
+ * variable d_len.
  */
 
 void uip_arp_arpin(struct uip_driver_s *dev)