Differences

This shows you the differences between two versions of the page.

--- linux:firewall6 [2008/11/28 10:08]
greebo created
+++ linux:firewall6 [2010/01/05 16:02]
greebo
@@ Line 1: / Line 1: @@
+<code bash |>
 #!/bin/bash
+echo "*************"
+echo "* Running $0"
+echo "*************"
+echo " how iptables work in linux kernel"
+echo
+echo ">-[prerouting]->	+ >-[forward]->	+ >-[postrouting]->"
+echo "			|		|"
+echo "			[input] >--->[output]"
+# path to ip6tables
 IPT6="/sbin/ip6tables"
-PUBIF="eth0"
-echo "Starting IPv6 firewall..."
+# name of our Internet and intranet interfaces
+#
+# use INTRANET="eth1+" or INTERNET="eth0+"
+# if you have more ifaces (example: eth0:0)  towards Intranet/Internet
+INTRANET="eth1"
+INTERNET="eth0"
+# ADSL - INTERNET="ppp0"
+# what TCP ports/services we allow (and FORWARD) from Internet
+# use " " as delimiter
+TCP_PORTS="25 53 993"
+# what UDP ports/services we allow (and FORWARD) from Internet
+# use "," as delimiter
+UDP_PORTS="53"
+# which ports we forward into our intranet
+# use "," as delimiter
+#FWD_TCP_PORTS="1214,6346"
+TRUSTED_HOSTS="2001:470:1f15:404::3 \
+:15c0:1000:1003:250:8dff:fef1:738e"
+#IPv6 forward
+echo "0" > /proc/sys/net/ipv6/conf/all/forwarding
+# first we flush the tables and policy
 $IPT6 -F
 $IPT6 -X
-$IPT6 -t mangle -F
+$IPT6 -F INPUT
-$IPT6 -t mangle -X
+$IPT6 -F FORWARD
+$IPT6 -F OUTPUT
+# reci ne natu!
+#$IPT6 -t nat -F
-#unlimited
+# default policy
-$IPT6 -A INPUT -i lo -j ACCEPT
-$IPT6 -A OUTPUT -o lo -j ACCEPT
-# DROP all incomming traffic
 $IPT6 -P INPUT DROP
 $IPT6 -P OUTPUT DROP
 $IPT6 -P FORWARD DROP
+# separate/new queue
+$IPT6 -N ssh-access
+$IPT6 -N http-access
+# port redirection (transparent proxy)
+# redirect all outgoing traffic that is NOT for the GW to local (GW) ports
+#$IPT6 -t nat -A PREROUTING -i ! $INTERNET -p tcp -s $LAN -d ! $LAN --dport 53 -j REDIRECT
+#$IPT6 -t nat -A PREROUTING -i ! $INTERNET -p udp -s $LAN -d ! $LAN --dport 53 -j REDIRECT
+#$IPT6 -t nat -A PREROUTING -i ! $INTERNET -p tcp -s $LAN -d ! $LAN --dport 25 -j REDIRECT --to-ports 25
+# we allow all traffic from $INTRANET and localhost interfaces
+##$IPT6 -A INPUT -i $INTRANET -j ACCEPT
+$IPT6 -A INPUT -i lo -j ACCEPT
 # Allow full outgoing connection but no incomming stuff
 $IPT6 -A INPUT  -m state --state ESTABLISHED,RELATED -j ACCEPT
+#
 $IPT6 -A OUTPUT -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
+# Connection limit for SSH connections (3 connection per minute) - usefull agains ssh scanners if you MUST open SSH for every IP!
+# it is wise to use sshaccess input table (TRUSTED_HOSTS)
+#$IPT6 -A INPUT -p tcp -m state --syn --state NEW --dport 22 -m limit --limit 3/minute --limit-burst 1 -j ACCEPT
+#$IPT6 -A INPUT -p tcp -m state --syn --state NEW --dport 22 -j DROP
+$IPT6 -A INPUT -p tcp -m state --syn --state NEW --dport 22 -j ssh-access
+$IPT6 -A INPUT -p tcp -m state --syn --state NEW --dport 80 -j http-access
+# ssh
+for sshhostese in $TRUSTED_HOSTS;
+        do
+        $IPT6 -A ssh-access -s $sshhostese -j ACCEPT
+        done
+# ssh
+# http
+for httphostese in $TRUSTED_HOSTS;
+        do
+        $IPT6 -A http-access -s $httphostese -j ACCEPT
+        done
+# http
+# what we allow from Internet
+for i in $TCP_PORTS
+	do
+		$IPT6 -A INPUT -p tcp -m state --syn --state NEW  --dport $i -j ACCEPT
+    done
+$IPT6 -A INPUT -p udp -m multiport --dport $UDP_PORTS -j ACCEPT
+# identd requests
+$IPT6 -A INPUT -p tcp --dport 113 -j REJECT --reject-with tcp-reset
+# traceroute?
+$IPT6 -A INPUT -p udp -m limit --limit 3/second  --sport 32769:65535 --dport 33434:33523 -j ACCEPT
 # allow incoming ICMP ping pong stuff
 $IPT6 -A INPUT -p ipv6-icmp -j ACCEPT
+# allow outgoing ICMP ping pong stuff
 $IPT6 -A OUTPUT -p ipv6-icmp -j ACCEPT
-############# add your custom rules below ############
+##$IPT6  -A INPUT --protocol icmpv6 --icmpv6-type echo-request -j ACCEPT --match limit --limit 30/minute
-$IPT6 -A INPUT -p tcp --destination-port 22 -j ACCEPT
-#### no need to edit below ###
 # log everything else
 $IPT6 -A INPUT -j LOG
 $IPT6 -A INPUT -j DROP
-##ip6tables -A INPUT --protocol icmpv6 --icmpv6-type echo-request -j ACCEPT --match limit --limit 30/minute
+# list the rules
+$IPT6 -L -v -n
+</code>