X-Git-Url: https://git.distorted.org.uk/~mdw/firewall/blobdiff_plain/a4d8cae3892c13a32f941ef96b24eaa6930500cb..994ac8d0782c89a636f47b02a2dc096c72ff58c5:/bookends.m4

diff --git a/bookends.m4 b/bookends.m4
index 38b4e91..1004b76 100644
--- a/bookends.m4
+++ b/bookends.m4
@@ -38,6 +38,8 @@ preserve_chains="filter:fail2ban filter:fail2ban-* $preserve_chains"
 ## Take the various IP versions in turn.
 unref=nil
 for ip in ip ip6; do
+  if [ "$FW_NOACT" ]; then break; fi
+
   for table in $(cat /proc/net/${ip}_tables_names); do
 
     ## Step 1: clear out the builtin chains.
@@ -105,8 +107,23 @@ m4_divert(32)m4_dnl
 
 ## Set forwarding options.  Apparently setting ip_forward clobbers other
 ## settings, so put this first.
+case $host_type_<::>FWHOST in
+  router) forward=1 host=0 ;;
+  server) forward=0 host=0 ;;
+  client) forward=0 host=1 ;;
+esac
 setopt ip_forward $forward
 setdevopt forwarding $forward
+for i in \
+  accept_ra accept_ra_defrtr accept_ra_pinfo accept_ra_info_max_plen \
+  accept_redirects
+do
+  setdevopt $i $host
+done
+case $forward in
+  0) inchains="INPUT" ;;
+  1) inchains="INPUT FORWARD" ;;
+esac
 
 ## Set dynamic port allocation.
 setopt ip_local_port_range $open_port_min $open_port_max
@@ -120,22 +137,24 @@ setopt icmp_echo_ignore_broadcasts 0
 ## Turn off iptables filtering for bridges.  We'll use ebtables if we need
 ## to; but right now the model is that we do filtering at the borders, and
 ## are tolerant of things which are local.
-if [ -x /sbin/brctl ]; then
+if [ -x /sbin/brctl ] || [ -x /usr/sbin/brctl ]; then
   modprobe bridge || :
-  if [ -d /proc/sys/net/bridge ]; then
-    for filter in arptables iptables ip6tables; do
-      run sysctl -q net.bridge.bridge-nf-call-$filter=0
-    done
-  fi
+fi
+if [ -d /proc/sys/net/bridge ]; then
+  for filter in arptables iptables ip6tables; do
+    run sysctl -q net.bridge.bridge-nf-call-$filter=0
+  done
 fi
 
-## Turn on the reverse-path filter, and log weird things.
-setdevopt rp_filter $rp_filter
-setdevopt log_martians $log_martians
+## Turn off the reverse-path filter.  It's basically useless: the filter does
+## nothing at all for single-homed hosts; and multi-homed hosts tend to have
+## routing aysmmetries if there's any kind of cycle.
+setdevopt rp_filter 0
+setdevopt log_martians 0
 
 ## Turn off things which can mess with our routing decisions.
 setdevopt accept_source_route 0
-setdevopt accept_redirects 0
+setdevopt secure_redirects 1
 
 ## If we're maent to stop the firewall, then now is the time to do it.
 $exit_after_clearing
@@ -158,6 +177,10 @@ errorchain bad-source-address DROP
 ## Packet arrived on wrong interface for its source address.  Drops the
 ## packet, since there's nowhere sensible to send an error.
 
+errorchain dns-rate-limit DROP
+## Dropped incoming DNS query due to rate limiting.  The source address is
+## suspicious, so don't produce ICMP.
+
 errorchain bad-destination-address REJECT
 ## Packet arrived on non-loopback interface with loopback destination.
 
@@ -179,26 +202,36 @@ run ip6tables -A INPUT -g bad-destination-address \
 	-d ::1
 
 ## We shouldn't be asked to forward things with link-local addresses.
-run iptables -A FORWARD -g bad-source-address \
-	-s 169.254.0.0/16
-run iptables -A FORWARD -g bad-destination-address \
-	-d 169.254.0.0/16
-run ip6tables -A FORWARD -g bad-source-address \
-	-s fe80::/10
-run ip6tables -A FORWARD -g bad-destination-address \
-	-d fe80::/10
+case $forward in
+  1)
+    run iptables -A FORWARD -g bad-source-address \
+	    -s 169.254.0.0/16
+    run iptables -A FORWARD -g bad-destination-address \
+	    -d 169.254.0.0/16
+    run ip6tables -A FORWARD -g bad-source-address \
+	    -s fe80::/10
+    run ip6tables -A FORWARD -g bad-destination-address \
+	    -d fe80::/10
+    ;;
+esac
 
 ## Also, don't forward link-local broadcast or multicast.
-run iptables -A FORWARD -g bad-destination-address \
-	-d 255.255.255.255
-run iptables -A FORWARD -g bad-destination-address \
-	-m addrtype --dst-type BROADCAST
-run iptables -A FORWARD -g bad-destination-address \
-	-d 224.0.0.0/24
-for x in 0 1 2 3 4 5 6 7 8 9 a b c d e f; do
-  run ip6tables -A FORWARD -g bad-destination-address \
-	-d fe${x}2::/16
-done
+case $forward in
+  1)
+    run iptables -A FORWARD -g bad-destination-address \
+	    -d 255.255.255.255
+    run iptables -A FORWARD -g bad-destination-address \
+	    -m addrtype --dst-type BROADCAST
+    run iptables -A FORWARD -g bad-destination-address \
+	    -d 224.0.0.0/24
+    clearchain check-fwd-multi
+    for x in 0 1 2 3 4 5 6 7 8 9 a b c d e f; do
+      run ip6tables -A check-fwd-multi -g bad-destination-address \
+	    -d ff${x}2::/16
+    done
+    run ip6tables -A FORWARD -j check-fwd-multi -d ff00::/8
+    ;;
+esac
 
 ## Add a hook for fail2ban.
 clearchain fail2ban
@@ -229,5 +262,17 @@ for ip in ip ip6; do
   done
 done
 
+## Dump the resulting configuration.
+if [ "$FW_DEBUG" ]; then
+  for ip in ip ip6; do
+    for table in mangle filter; do
+      echo "----- $ip $table -----"
+      echo
+      ${ip}tables -t $table -nvL
+      echo
+    done
+  done
+fi
+
 m4_divert(-1)
 ###----- That's all, folks --------------------------------------------------