install IPv6 reject routes only if kernel is capable of IPv6.

src/etc/netstart

@@ -1,6 +1,6 @@
 #!/bin/sh -
 #
-#	$OpenBSD: netstart,v 1.53 1999/12/09 14:22:38 itojun Exp $
+#	$OpenBSD: netstart,v 1.54 1999/12/31 04:32:53 itojun Exp $
 
 # Returns true if $1 contains only alphanumerics
 isalphanumeric() {
@@ -43,6 +43,20 @@ ifconfig lo0 inet localhost
 route -n add -host $hostname localhost
 route -n add -net 127 127.0.0.1 -reject
 
+if ifconfig lo0 inet6 >/dev/null 2>&1; then
+	# IPv6 configurations.
+	ip6kernel=YES
+
+	# disallow scoped unicast dest without outgoing scope identifiers.
+	route add -inet6 fe80:: -prefixlen 10 ::1 -reject
+	route add -inet6 fc80:: -prefixlen 10 ::1 -reject
+	# disallow "internal" addresses to appear on the wire.
+	route add -inet6 ::ffff:0.0.0.0 -prefixlen 96 ::1 -reject
+	route add -inet6 ::0.0.0.0 -prefixlen 96 ::1 -reject
+else
+	ip6kernel=NO
+fi
+
 # configure all of the non-loopback interfaces which we know about.
 # refer to hostname.if(5) and bridgename.if(5)
 for hn in /etc/hostname.*; do
@@ -157,14 +171,6 @@ EOF
 	route -n add -net 224.0.0.0/4 -interface 127.0.0.1 -reject;;
 esac
 
-# IPv6 configurations.
-# disallow scoped unicast dest without outgoing scope identifiers.
-route add -inet6 fe80:: -prefixlen 10 ::1 -reject
-route add -inet6 fc80:: -prefixlen 10 ::1 -reject
-# disallow "internal" addresses to appear on the wire.
-route add -inet6 ::ffff:0.0.0.0 -prefixlen 96 ::1 -reject
-route add -inet6 ::0.0.0.0 -prefixlen 96 ::1 -reject
-	
 # Configure NAT after configuring network interfaces
 if [ "${ipnat}" = "YES" -a "${ipfilter}" = "YES" -a -f "${ipnat_rules}" ]; then
 	echo 'configuring NAT'