make the example parseable (quotes around macros)

from sam smith, thx
henning@ ok

src/etc/pf.conf

@@ -1,12 +1,12 @@
-#	$OpenBSD: pf.conf,v 1.7 2002/11/16 12:55:22 ian Exp $
+#	$OpenBSD: pf.conf,v 1.8 2002/11/24 19:56:45 pb Exp $
 #
 # See pf.conf(5) for syntax and examples
 # General order: options, scrub rules, NAT/rdr, and filter rules.
 # Note that NAT is first match while packet filters are last match, 
 #
-ext_if=ext0	# replace with actual external interface name i.e., dc0
-internal_net=10.1.1.1/8
-external_addr=192.168.1.1
+ext_if="ext0"	# replace with actual external interface name i.e., dc0
+internal_net="10.1.1.1/8"
+external_addr="192.168.1.1"
 
 # Normalize: reassemble fragments and resolve or reduce traffic ambiguities
 # scrub in all