--- /dev/null
+--- a/bgpd/bgp_aspath.c
++++ b/bgpd/bgp_aspath.c
+@@ -1122,6 +1122,42 @@ aspath_private_as_check (struct aspath *
+ return 1;
+ }
+
++/* AS path confed check. If aspath contains confed set or sequence then return 1. */
++int
++aspath_confed_check (struct aspath *aspath)
++{
++ struct assegment *seg;
++
++ if ( !(aspath && aspath->segments) )
++ return 0;
++
++ seg = aspath->segments;
++
++ while (seg)
++ {
++ if (seg->type == AS_CONFED_SET || seg->type == AS_CONFED_SEQUENCE)
++ return 1;
++ seg = seg->next;
++ }
++ return 0;
++}
++
++/* Leftmost AS path segment confed check. If leftmost AS segment is of type
++ AS_CONFED_SEQUENCE or AS_CONFED_SET then return 1. */
++int
++aspath_left_confed_check (struct aspath *aspath)
++{
++
++ if ( !(aspath && aspath->segments) )
++ return 0;
++
++ if ( (aspath->segments->type == AS_CONFED_SEQUENCE)
++ || (aspath->segments->type == AS_CONFED_SET) )
++ return 1;
++
++ return 0;
++}
++
+ /* Merge as1 to as2. as2 should be uninterned aspath. */
+ static struct aspath *
+ aspath_merge (struct aspath *as1, struct aspath *as2)
+--- a/bgpd/bgp_aspath.h
++++ b/bgpd/bgp_aspath.h
+@@ -88,6 +88,8 @@ extern unsigned int aspath_key_make (voi
+ extern int aspath_loop_check (struct aspath *, as_t);
+ extern int aspath_private_as_check (struct aspath *);
+ extern int aspath_firstas_check (struct aspath *, as_t);
++extern int aspath_confed_check (struct aspath *);
++extern int aspath_left_confed_check (struct aspath *);
+ extern unsigned long aspath_count (void);
+ extern unsigned int aspath_count_hops (struct aspath *);
+ extern unsigned int aspath_count_confeds (struct aspath *);
+--- a/bgpd/bgp_attr.c
++++ b/bgpd/bgp_attr.c
+@@ -872,6 +872,17 @@ static int bgp_attr_aspath_check( struct
+
+ bgp = peer->bgp;
+
++ /* Confederation sanity check. */
++ if ((peer_sort (peer) == BGP_PEER_CONFED && ! aspath_left_confed_check (attr->aspath)) ||
++ (peer_sort (peer) == BGP_PEER_EBGP && aspath_confed_check (attr->aspath)))
++ {
++ zlog (peer->log, LOG_ERR, "Malformed AS path from %s", peer->host);
++ bgp_notify_send (peer,
++ BGP_NOTIFY_UPDATE_ERR,
++ BGP_NOTIFY_UPDATE_MAL_AS_PATH);
++ return -1;
++ }
++
+ /* First AS check for EBGP. */
+ if (bgp != NULL && bgp_flag_check (bgp, BGP_FLAG_ENFORCE_FIRST_AS))
+ {