diff --git a/collects/net/sendurl.ss b/collects/net/sendurl.ss
index eb93e480dc..201f0e0f3b 100644
--- a/collects/net/sendurl.ss
+++ b/collects/net/sendurl.ss
@@ -11,7 +11,8 @@
 
   ; : any -> bool
   (define (browser-preference? x)
-    (or (not x) (memq x unix-browser-list) (custom-browser? x)))
+    (or (not x) (memq x unix-browser-list) (custom-browser? x)
+        (procedure? x)))
 
   (define external-browser
     (make-parameter
@@ -30,6 +31,8 @@
                        [current-error-port null-output]
                        [current-output-port null-output])
           (cond
+            [(procedure? (external-browser))
+             ((external-browser) url-str)]
             [(eq? (system-type) 'macos)
              (if (regexp-match "Blue Box" (system-type #t))
                  ;; Classic inside OS X:
diff --git a/collects/net/tcp-redirect.ss b/collects/net/tcp-redirect.ss
new file mode 100644
index 0000000000..b996411854
--- /dev/null
+++ b/collects/net/tcp-redirect.ss
@@ -0,0 +1,129 @@
+(module tcp-redirect mzscheme
+  (provide tcp-redirect)
+  
+  (require (lib "unitsig.ss")
+           (lib "channel.ss" "web-server")
+           (lib "etc.ss")
+           "tcp-sig.ss")
+  
+  (define raw:tcp-abandon-port tcp-abandon-port)
+  (define raw:tcp-accept tcp-accept) 
+  (define raw:tcp-accept-ready? tcp-accept-ready?)
+  (define raw:tcp-addresses tcp-addresses)
+  (define raw:tcp-close tcp-close)
+  (define raw:tcp-connect tcp-connect)
+  (define raw:tcp-connect/enable-break tcp-connect/enable-break)
+  (define raw:tcp-listen tcp-listen)
+  (define raw:tcp-listener? tcp-listener?)
+  
+  ; I cannot follow the data definiton well because I don't have
+  ; predicates tcp-port? or pipe-port?.  I could print them out and
+  ; look at the string, but that's ugly, too.  Instead I use with-handlers.
+  
+  ; For tcp-listeners, I do have suitable predicates, but I still use
+  ; an else branch in the conds since I want the same error message as
+  ; the raw primitive for bad inputs.
+  
+  ; : (listof nat) -> (unit/sig () -> net:tcp^)
+  (define (tcp-redirect redirected-ports)
+    (unit/sig net:tcp^
+      (import)
+      
+      ; : (make-pipe-listener nat (channel (cons iport oport)))
+      (define-struct pipe-listener (port channel))
+      
+      ; : port -> void
+      (define (tcp-abandon-port tcp-port)
+	(with-handlers ([exn:application:type? void])
+	  (raw:tcp-abandon-port tcp-port)))
+      
+      ; : listener -> iport oport
+      (define (tcp-accept tcp-listener)
+        (cond
+          [(pipe-listener? tcp-listener)
+           (let ([in-out (channel-get (pipe-listener-channel tcp-listener))])
+             (values (car in-out) (cdr in-out)))]
+          [else (raw:tcp-accept tcp-listener)]))
+      
+      ; : tcp-listener -> iport oport
+      ; FIX - check channel queue size
+      (define (tcp-accept-ready? tcp-listener)
+        (cond
+          [(pipe-listener? tcp-listener) #t]
+          [else (raw:tcp-accept-ready? tcp-listener)]))
+      
+      ; : tcp-port -> str str
+      (define (tcp-addresses tcp-port)
+        (with-handlers ([exn:application:type?
+			 (lambda (exn) (values local-address local-address))])
+          (raw:tcp-addresses tcp-port)))
+      
+      ; : port -> void
+      (define (tcp-close tcp-listener)
+        (with-handlers ([exn:application:type?
+			 (lambda (exn)
+			   (hash-table-remove!
+			    port-table
+			    (pipe-listener-port tcp-listener)))])
+	  (raw:tcp-close tcp-listener)))
+      
+      ; : (str nat -> iport oport) -> str nat -> iport oport
+      (define (gen-tcp-connect raw)
+	(lambda (hostname-string port)
+	  (if (and (string=? local-address hostname-string)
+		   (redirect? port))
+	      (let-values ([(to-in from-out) (make-pipe)]
+                           [(from-in to-out) (make-pipe)])
+		(channel-put
+		 (pipe-listener-channel
+		  (hash-table-get
+		   port-table
+		   port
+		   (lambda ()
+		     (raise (make-exn:i/o:tcp
+			     (format "tcp-connect: connection to ~a, port ~a failed (nobody is listening)"
+				     hostname-string port)
+			     (current-continuation-marks))))))
+		 (cons to-in to-out))
+		(values from-in from-out))
+	      (raw hostname-string port))))
+      
+      ; : str nat -> iport oport
+      (define tcp-connect (gen-tcp-connect raw:tcp-connect))
+      
+      ; : str nat -> iport oport
+      (define tcp-connect/enable-break (gen-tcp-connect raw:tcp-connect/enable-break))
+      
+      ; FIX - support the reuse? flag.
+      (define tcp-listen
+        (opt-lambda (port [max-allow-wait 4] [reuse? #f] [hostname-string #f])
+	  (hash-table-get
+	   port-table
+	   port
+	   (lambda ()
+	     (if (redirect? port)
+		 (let ([listener (make-pipe-listener port (create-channel))])
+		   (hash-table-put! port-table port listener)
+		   listener)
+		 (raw:tcp-listen port max-allow-wait reuse? hostname-string))))))
+      
+      ; : tst -> bool
+      (define (tcp-listener? x)
+        (or (pipe-listener? x) (raw:tcp-listener? x)))
+      
+      ; ---------- private ----------
+      
+      ; : (hash-table nat[port] -> tcp-listener)
+      (define port-table (make-hash-table))
+      
+      (define redirect-table
+        (let ([table (make-hash-table)])
+          (for-each (lambda (x) (hash-table-put! table x #t))
+                    redirected-ports)
+          table))
+      
+      ; : nat -> bool
+      (define (redirect? port)
+        (hash-table-get redirect-table port (lambda () #f)))))
+  
+  (define local-address "127.0.0.1"))
\ No newline at end of file
diff --git a/collects/net/tcp-sig.ss b/collects/net/tcp-sig.ss
new file mode 100644
index 0000000000..a00b1d3483
--- /dev/null
+++ b/collects/net/tcp-sig.ss
@@ -0,0 +1,14 @@
+(module tcp-sig mzscheme
+  (provide net:tcp^)
+  (require (lib "unitsig.ss"))
+  
+  (define-signature net:tcp^
+    (tcp-abandon-port
+     tcp-accept
+     tcp-accept-ready?
+     tcp-addresses
+     tcp-close
+     tcp-connect
+     tcp-connect/enable-break
+     tcp-listen
+     tcp-listener?)))
\ No newline at end of file
diff --git a/collects/net/tcp-unit.ss b/collects/net/tcp-unit.ss
new file mode 100644
index 0000000000..7cf917a3cd
--- /dev/null
+++ b/collects/net/tcp-unit.ss
@@ -0,0 +1,32 @@
+(module tcp-unit mzscheme
+  (provide tcp@)
+  (require (lib "unitsig.ss")
+           "tcp-sig.ss")
+  
+  ; Okay, this file looks retarded.  Something is clearly wrong.
+  
+  
+  (define raw:tcp-abandon-port tcp-abandon-port)
+  (define raw:tcp-accept tcp-accept) 
+  (define raw:tcp-accept-ready? tcp-accept-ready?)
+  (define raw:tcp-addresses tcp-addresses)
+  (define raw:tcp-close tcp-close)
+  (define raw:tcp-connect tcp-connect)
+  (define raw:tcp-connect/enable-break tcp-connect/enable-break)
+  (define raw:tcp-listen tcp-listen)
+  (define raw:tcp-listener? tcp-listener?)
+  
+  (define tcp@
+    (unit/sig net:tcp^
+      (import)
+      
+      (define tcp-abandon-port raw:tcp-abandon-port)
+      (define tcp-accept raw:tcp-accept) 
+      (define tcp-accept-ready? raw:tcp-accept-ready?)
+      (define tcp-addresses raw:tcp-addresses)
+      (define tcp-close raw:tcp-close)
+      (define tcp-connect raw:tcp-connect)
+      (define tcp-connect/enable-break raw:tcp-connect/enable-break)
+      (define tcp-listen raw:tcp-listen)
+      (define tcp-listener? raw:tcp-listener?)
+      )))
\ No newline at end of file