diff -uNr tcpdump-3.6.1.orig/addrtoname.c tcpdump-3.6.1/addrtoname.c
--- tcpdump-3.6.1.orig/addrtoname.c	Sat Jan 13 20:01:00 2001
+++ tcpdump-3.6.1/addrtoname.c	Sat Jan 13 19:59:23 2001
@@ -581,7 +581,7 @@
 
 		while (table->name)
 			table = table->nxt;
-		if (nflag) {
+		if (nflag > 1) {
 			(void)snprintf(buf, sizeof(buf), "%d", port);
 			table->name = strdup(buf);
 		} else
@@ -745,7 +745,7 @@
 		f_localnet = localnet;
 		f_netmask = mask;
 	}
-	if (nflag)
+	if (nflag > 1)
 		/*
 		 * Simplest way to suppress names.
 		 */
diff -uNr tcpdump-3.6.1.orig/tcpdump.1 tcpdump-3.6.1/tcpdump.1
--- tcpdump-3.6.1.orig/tcpdump.1	Sat Jan 13 19:51:47 2001
+++ tcpdump-3.6.1/tcpdump.1	Sat Jan 13 19:50:19 2001
@@ -175,7 +175,11 @@
 ``tcpdump\ \ \-l \ \ > dat\ \ &\ \ tail\ \ \-f\ \ dat''.
 .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.  E.g.,