diff -uprN bird-1.2.1/proto/ospf/packet.c bird-1.2.1-/proto/ospf/packet.c
--- bird-1.2.1/proto/ospf/packet.c	2010-01-14 11:06:27.000000000 +0100
+++ bird-1.2.1-/proto/ospf/packet.c	2010-03-22 13:51:40.000000000 +0100
@@ -179,7 +179,7 @@ ospf_pkt_checkauth(struct ospf_neighbor 
         return 0;
       }
 
-      if (ntohs(pkt->length) + OSPF_AUTH_CRYPT_SIZE != size)
+      if (ntohs(pkt->length) + OSPF_AUTH_CRYPT_SIZE > size)
       {
         OSPF_TRACE(D_PACKETS, "OSPF_auth: size mismatch (%d vs %d)",
 	  ntohs(pkt->length) + OSPF_AUTH_CRYPT_SIZE, size);