Index: sys/netinet/if_ether.c
===================================================================
--- sys/netinet/if_ether.c
+++ sys/netinet/if_ether.c
@@ -87,7 +87,6 @@
 	ARP_LLINFO_DELETED,	/* LLE is deleted */
 };
 
-SYSCTL_DECL(_net_link_ether);
 static SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, "");
 static SYSCTL_NODE(_net_link_ether, PF_ARP, arp, CTLFLAG_RW, 0, "");
 
Index: sys/netinet/in.c
===================================================================
--- sys/netinet/in.c
+++ sys/netinet/in.c
@@ -85,6 +85,12 @@
 VNET_DECLARE(struct inpcbinfo, ripcbinfo);
 #define	V_ripcbinfo			VNET(ripcbinfo)
 
+static VNET_DEFINE(int, arpaccept) = 0;
+#define	V_arpaccept		VNET(arpaccept)
+SYSCTL_INT(_net_link_ether, OID_AUTO, arp_accept, CTLFLAG_VNET | CTLFLAG_RW,
+	&VNET_NAME(arpaccept), 0,
+	"Define behavior for gratuitous ARP frames who's IP is not already present in the ARP table");
+
 static struct sx in_control_sx;
 SX_SYSINIT(in_control_sx, &in_control_sx, "in_control");
 
@@ -1316,7 +1322,7 @@
 	 * verify this.
 	 */
 	if (!(flags & LLE_IFADDR) &&
-	    in_lltable_rtcheck(ifp, flags, l3addr) != 0)
+	    in_lltable_rtcheck(ifp, flags, l3addr) != 0 && !V_arpaccept)
 		return (NULL);
 
 	lle = in_lltable_new(sin->sin_addr, flags);
Index: sys/netinet/in_var.h
===================================================================
--- sys/netinet/in_var.h
+++ sys/netinet/in_var.h
@@ -316,6 +316,7 @@
 }
 
 #ifdef SYSCTL_DECL
+SYSCTL_DECL(_net_link_ether);
 SYSCTL_DECL(_net_inet);
 SYSCTL_DECL(_net_inet_ip);
 SYSCTL_DECL(_net_inet_raw);