diff -urNbp src/sbin/ifconfig/ifconfig.c src-proxyarp/sbin/ifconfig/ifconfig.c
--- src/sbin/ifconfig/ifconfig.c	2010-03-23 00:50:33.000000000 +0500
+++ src-proxyarp/sbin/ifconfig/ifconfig.c	2012-06-22 16:13:39.000000000 +0600
@@ -773,7 +773,7 @@ setifname(const char *val, int dummy __u
 #define	IFFBITS \
 "\020\1UP\2BROADCAST\3DEBUG\4LOOPBACK\5POINTOPOINT\6SMART\7RUNNING" \
 "\10NOARP\11PROMISC\12ALLMULTI\13OACTIVE\14SIMPLEX\15LINK0\16LINK1\17LINK2" \
-"\20MULTICAST\22PPROMISC\23MONITOR\24STATICARP\25NEEDSGIANT"
+"\20MULTICAST\22PPROMISC\23MONITOR\24STATICARP\25NEEDSGIANT\30PROXYARP"
 
 #define	IFCAPBITS \
 "\020\1RXCSUM\2TXCSUM\3NETCONS\4VLAN_MTU\5VLAN_HWTAGGING\6JUMBO_MTU\7POLLING" \
@@ -1037,6 +1037,8 @@ static struct cmd basic_cmds[] = {
 	DEF_CMD("noicmp",	IFF_LINK1,	setifflags),
 	DEF_CMD_ARG("mtu",			setifmtu),
 	DEF_CMD_ARG("name",			setifname),
+	DEF_CMD("proxyarp",	IFF_PROXYARP,	setifflags),
+	DEF_CMD("-proxyarp",	-IFF_PROXYARP,	setifflags),
 };
 
 static __constructor void
diff -urNbp src/sys/net/if.h src-proxyarp/sys/net/if.h
--- src/sys/net/if.h	2012-05-19 20:38:14.000000000 +0600
+++ src-proxyarp/sys/net/if.h	2012-06-22 16:13:39.000000000 +0600
@@ -151,6 +151,7 @@ struct if_data {
 #define	IFF_STATICARP	0x80000		/* (n) static ARP */
 #define	IFF_NEEDSGIANT	0x100000	/* (i) hold Giant over if_start calls */
 #define	IFF_RENAMING	0x400000	/* (n) interface is being renamed */
+#define	IFF_PROXYARP	0x800000	/* (n) enable "local-proxy-arp" mode */
 
 /*
  * Old names for driver flags so that user space tools can continue to use
diff -urNbp src/sys/netinet/if_ether.c src-proxyarp/sys/netinet/if_ether.c
--- src/sys/netinet/if_ether.c	2011-08-03 10:28:16.000000000 +0600
+++ src-proxyarp/sys/netinet/if_ether.c	2012-06-22 16:16:51.000000000 +0600
@@ -891,7 +891,7 @@ reply:
 			/* Nope, only intersted now if proxying everything. */
 			struct sockaddr_in sin;
 
-			if (!arp_proxyall)
+			if (!arp_proxyall && !(ifp->if_flags & IFF_PROXYARP))
 				goto drop;
 
 			bzero(&sin, sizeof sin);
@@ -908,10 +908,23 @@ reply:
 			 * as this one came out of, or we'll get into a fight
 			 * over who claims what Ether address.
 			 */
-			if (rt->rt_ifp == ifp) {
+			if ((rt->rt_ifp == ifp) && \
+				!(ifp->if_flags & IFF_PROXYARP)) {
+
 				RTFREE_LOCKED(rt);
 				goto drop;
 			}
+
+			/*
+			 * PROXYARP: Windows workaround
+			 */
+
+			if ((ifp->if_flags & IFF_PROXYARP) && \
+				(isaddr.s_addr == itaddr.s_addr)) {
+				RTFREE_LOCKED(rt);
+				goto drop;
+			}
+
 			(void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
 			(void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
 			RTFREE_LOCKED(rt);