diff --git a/udp.rkt b/udp.rkt
index b51f3bf..4841c68 100644
--- a/udp.rkt
+++ b/udp.rkt
@@ -38,8 +38,12 @@
   (or (udp-handle? x)
       (udp-listener? x)))
 
+;; USER-level protocol
 (struct udp-packet (source destination body) #:prefab)
 
+;; KERNEL-level protocol
+(struct udp-datagram (source-ip source-port destination-ip destination-port body) #:prefab)
+
 (define any-remote (udp-remote-address ? ?))
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
@@ -56,11 +60,18 @@
 			   (send (port-allocation-request
 				  'udp
 				  (lambda (port local-ips) (spawn-udp-relay port handle))))))
-   (spawn-port-allocator 'udp
-			 (list (project-subs (udp-packet (udp-remote-address (?!) (?!)) ? ?))
-			       (project-subs (udp-packet ? (udp-remote-address (?!) (?!)) ?))))
+   (spawn-udp-port-allocator)
    (spawn-kernel-udp-driver)))
 
+(define (spawn-udp-port-allocator)
+  (define udp-projector (project-pubs (udp-datagram (?!) (?!) ? ? ?)))
+  (spawn-port-allocator 'udp
+			(list udp-projector)
+			(lambda (g local-ips)
+			  (for/set [(e (gestalt-project/keys g udp-projector))
+				    #:when (set-member? local-ips (car e))]
+			    (cadr e)))))
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; Relaying
 
@@ -75,18 +86,14 @@
 				 (pub (udp-packet any-remote local-user-addr ?))
 				 (sub (udp-packet local-user-addr any-remote ?))))]
 	[(ip (in-set local-ips))]
-      (define hostname (ip-address->hostname ip))
-      (define local-network-addr (udp-remote-address hostname local-port))
       (gestalt-union g
-		     (sub (udp-packet any-remote local-network-addr ?))
-		     (pub (udp-packet local-network-addr any-remote ?)))))
+		     (sub (udp-datagram ? ? ip local-port ?))
+		     (pub (udp-datagram ip local-port ? ? ?)))))
 
   (spawn (lambda (e local-ips)
-	   (log-info "RELAY ~v" e)
 	   (match e
 	     [(routing-update g)
 	      (define new-local-ips (gestalt->local-ip-addresses g))
-	      (log-info "Updating relay gestalt:\n~a" (gestalt->pretty-string (compute-gestalt new-local-ips)))
 	      (transition new-local-ips
 			  (list
 			   (when (gestalt-empty? (gestalt-filter g local-peer-gestalt)) (quit))
@@ -94,11 +101,18 @@
 	     [(message (udp-packet (== local-user-addr) remote-addr bs) _ _)
 	      ;; Choose arbitrary local IP address for outbound packet!
 	      ;; TODO: what can be done? Must I examine the routing table?
-	      (define local-network-addr
-		(udp-remote-address (ip-address->hostname (set-first local-ips)) local-port))
-	      (transition local-ips (send (udp-packet local-network-addr remote-addr bs)))]
-	     [(message (udp-packet remote-addr (udp-remote-address _ _) bs) _ _)
-	      (transition local-ips (send (udp-packet remote-addr local-user-addr bs)))]
+	      (match-define (udp-remote-address remote-host remote-port) remote-addr)
+	      (define remote-ip (ip-string->ip-address remote-host))
+	      (transition local-ips (send (udp-datagram (set-first local-ips)
+							local-port
+							remote-ip
+							remote-port
+							bs)))]
+	     [(message (udp-datagram si sp _ _ bs) _ _)
+	      (transition local-ips (send (udp-packet (udp-remote-address (ip-address->hostname si)
+									  sp)
+						      local-user-addr
+						      bs)))]
 	     [_ #f]))
 	 (set)
 	 (compute-gestalt (set))))
@@ -115,8 +129,6 @@
 	      (transition (gestalt->local-ip-addresses g) '())]
 	     [(message (ip-packet source-if src-ip dst-ip _ _ body) _ _)
 	      #:when (and source-if (set-member? local-ips dst-ip))
-	      (define src-host (ip-address->hostname src-ip))
-	      (define dst-host (ip-address->hostname dst-ip))
 	      (bit-string-case body
 		([ (src-port :: integer bytes 2)
 		   (dst-port :: integer bytes 2)
@@ -126,39 +138,38 @@
 		 (bit-string-case data
 		   ([ (payload :: binary bytes (- length 8)) ;; min UDP header size is 8 bytes
 		      (:: binary) ]
-		    (transition local-ips (send (udp-packet (udp-remote-address src-host src-port)
-							    (udp-remote-address dst-host dst-port)
-							    (bit-string->bytes payload)))))
+		    (transition local-ips (send (udp-datagram src-ip
+							      src-port
+							      dst-ip
+							      dst-port
+							      (bit-string->bytes payload)))))
 		   (else #f)))
 		(else #f))]
-	     [(message (udp-packet (udp-remote-address sh sp) (udp-remote-address dh dp) bs) _ _)
-	      (define src-ip (ip-string->ip-address sh))
-	      (define dst-ip (ip-string->ip-address dh))
-	      (and (set-member? local-ips src-ip)
-		   (let* ((payload (bit-string (sp :: integer bytes 2)
-					       (dp :: integer bytes 2)
-					       ((+ 8 (bit-string-byte-count bs))
-						:: integer bytes 2)
-					       (0 :: integer bytes 2) ;; checksum location
-					       (bs :: binary)))
-			  (pseudo-header (bit-string (src-ip :: binary bytes 4)
-						     (dst-ip :: binary bytes 4)
-						     0
-						     PROTOCOL-UDP
-						     ((bit-string-byte-count payload)
-						      :: integer bytes 2)))
-			  (checksummed-payload (ip-checksum #:pseudo-header pseudo-header
-							    6 payload)))
-		     (transition local-ips (send (ip-packet #f
-							    src-ip
-							    dst-ip
-							    PROTOCOL-UDP
-							    #""
-							    checksummed-payload)))))]
+	     [(message (udp-datagram src-ip src-port dst-ip dst-port bs) _ _)
+	      #:when (set-member? local-ips src-ip)
+	      (let* ((payload (bit-string (src-port :: integer bytes 2)
+					  (dst-port :: integer bytes 2)
+					  ((+ 8 (bit-string-byte-count bs))
+					   :: integer bytes 2)
+					  (0 :: integer bytes 2) ;; checksum location
+					  (bs :: binary)))
+		     (pseudo-header (bit-string (src-ip :: binary bytes 4)
+						(dst-ip :: binary bytes 4)
+						0
+						PROTOCOL-UDP
+						((bit-string-byte-count payload)
+						 :: integer bytes 2)))
+		     (checksummed-payload (ip-checksum #:pseudo-header pseudo-header
+						       6 payload)))
+		(transition local-ips (send (ip-packet #f
+						       src-ip
+						       dst-ip
+						       PROTOCOL-UDP
+						       #""
+						       checksummed-payload))))]
 	     [_ #f]))
 	 (set)
 	 (gestalt-union (pub (ip-packet #f ? ? PROTOCOL-UDP ? ?))
 			(sub (ip-packet ? ? ? PROTOCOL-UDP ? ?))
-			(sub (udp-packet any-remote any-remote ?))
-			(pub (udp-packet any-remote any-remote ?))
+			(sub (udp-datagram ? ? ? ? ?))
 			observe-local-ip-addresses-gestalt)))