diff -up tcpdump-3.9.8/addrtoname.c.portnumbers tcpdump-3.9.8/addrtoname.c
--- tcpdump-3.9.8/addrtoname.c.portnumbers	2007-09-26 03:59:52.000000000 +0200
+++ tcpdump-3.9.8/addrtoname.c	2008-08-29 13:53:12.000000000 +0200
@@ -704,7 +704,7 @@ init_servarray(void)
 
 		while (table->name)
 			table = table->nxt;
-		if (nflag) {
+		if (nflag > 1) {
 			(void)snprintf(buf, sizeof(buf), "%d", port);
 			table->name = strdup(buf);
 		} else
@@ -1104,7 +1104,7 @@ init_addrtoname(u_int32_t localnet, u_in
 		f_localnet = localnet;
 		f_netmask = mask;
 	}
-	if (nflag)
+	if (nflag > 1)
 		/*
 		 * Simplest way to suppress names.
 		 */
diff -up tcpdump-3.9.8/tcpdump.1.portnumbers tcpdump-3.9.8/tcpdump.1
--- tcpdump-3.9.8/tcpdump.1.portnumbers	2008-08-29 13:53:12.000000000 +0200
+++ tcpdump-3.9.8/tcpdump.1	2008-08-29 13:53:12.000000000 +0200
@@ -403,7 +403,11 @@ Use \fIsecret\fP as a shared secret for 
 TCP segments with the TCP-MD5 option (RFC 2385), if present.
 .TP
 .B \-n
-Don't convert addresses (i.e., host addresses, port numbers, etc.) to names.
+Don't convert host addresses to names.  This can be used to avoid 
+DNS lookups.
+.TP
+.B \-nn
+Don't convert protocol and port numbers etc. to names either.  
 .TP
 .B \-N
 Don't print domain name qualification of host names.