diff --git a/keyring.c b/keyring.c
index 7ef7816a..a94e6338 100644
--- a/keyring.c
+++ b/keyring.c
@@ -1132,7 +1132,6 @@ int keyring_mapping_request(keyring_file *k,overlay_mdp_frame *req)
       +crypto_sign_edwards25519sha512batch_PUBLICKEYBYTES
       +slen;
     overlay_mdp_swap_src_dst(req);
-    #warning disabled crypt and sign for debugging.
     req->packetTypeAndFlags=MDP_TX; /* crypt and sign */
     WHY("Sent SID:SAS mapping mutual-signature");
     printf("%d byte reply is from %s:%u\n           to %s:%u\n",
@@ -1173,8 +1172,28 @@ int keyring_mapping_request(keyring_file *k,overlay_mdp_frame *req)
 	if (bcmp(plain,req->out.src.sid,SID_SIZE))
 	  return WHY("key mapping signed block is for wrong SID");
 	WHY("Key mapping looks valid");
-      }
-      WHY("Not implemented");
+
+	/* work out where to put it */
+	int i;
+	for(i=0;i<sid_sas_mapping_count;i++)
+	  if (!bcmp(req->out.src.sid,sid_sas_mappings[i].sid,SID_SIZE)) break;
+
+	if (i>=MAX_SID_SAS_MAPPINGS) i=random()%MAX_SID_SAS_MAPPINGS;
+	if (i>=sid_sas_mapping_count) sid_sas_mapping_count=i+1;
+
+	/* now put it */
+	bcopy(&req->out.src.sid,&sid_sas_mappings[i].sid[0],SID_SIZE);
+	bcopy(sas_public,&sid_sas_mappings[i].sas_public[0],
+	      crypto_sign_edwards25519sha512batch_PUBLICKEYBYTES);
+	fprintf(stderr,"Mapping #%d (count=%d) SID=%s to SAS=%s*\n",i,
+		sid_sas_mapping_count,
+		overlay_render_sid(sid_sas_mappings[i].sid),
+		overlay_render_sid(sid_sas_mappings[i].sas_public));
+	sid_sas_mappings[i].validP=1;
+	sid_sas_mappings[i].last_request_time_in_ms=0;
+	WHY("Stored mapping");
+	return 0;
+      }      
       break;
     default:
       WHY("Key mapping response for unknown key type. Oh well.");
diff --git a/overlay_abbreviations.c b/overlay_abbreviations.c
index 23105064..0d9756aa 100644
--- a/overlay_abbreviations.c
+++ b/overlay_abbreviations.c
@@ -228,7 +228,7 @@ int overlay_abbreviate_append_address(overlay_buffer *b,unsigned char *a)
   int count=0;
   ob_makespace(b,SID_SIZE+3);
   int r=overlay_abbreviate_address(a,&b->bytes[b->length],&count);
-  if (DEBUG_PACKETCONSTRUCTION) {
+  if (debug&DEBUG_PACKETCONSTRUCTION) {
     fprintf(stderr,"address %s abbreviates as shown in this ",
 	    overlay_render_sid(a));
     dump(NULL,&b->bytes[b->length],count);
diff --git a/overlay_mdp.c b/overlay_mdp.c
index a31f2d46..c9c37e91 100644
--- a/overlay_mdp.c
+++ b/overlay_mdp.c
@@ -320,8 +320,10 @@ int overlay_saw_mdp_containing_frame(int interface,overlay_frame *f,long long no
     mdp.packetTypeAndFlags|=MDP_NOCRYPT; break;
   case OF_CRYPTO_CIPHERED|OF_CRYPTO_SIGNED:
     {
+      fflush(stderr);
       printf("crypted MDP frame for %s\n",
 	     overlay_render_sid(mdp.out.dst.sid));
+      fflush(stdout);
 
       unsigned char *k=keyring_get_nm_bytes(&mdp.out.dst,&mdp.out.src);
       unsigned char *nonce=&f->payload->bytes[0];