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diff --git a/doc/src/quickstart-firewall.html b/doc/src/quickstart-firewall.html deleted file mode 100644 index 53c27b5af..000000000 --- a/doc/src/quickstart-firewall.html +++ /dev/null @@ -1,187 +0,0 @@ -<html> -<head> - <meta http-equiv="Content-Type" content="text/html"> - <title>Quick FreeS/WAN installation and configuration</title> - <meta name="keywords" - content="Linux, IPsec, VPN, security, FreeSWAN, installation, quickstart"> - <!-- - - Written by Sandy Harris for the Linux FreeS/WAN project - Revised by Claudia Schmeing for same - Freely distributable under the GNU General Public License - - More information at www.freeswan.org - Feedback to users@lists.freeswan.org - - RCS ID: $Id: quickstart-firewall.html,v 1.1 2004/03/15 20:35:24 as Exp $ - Last changed: $Date: 2004/03/15 20:35:24 $ - Revision number: $Revision: 1.1 $ - - CVS revision numbers do not correspond to FreeS/WAN release numbers. - --> -</head> -<BODY> -<H1><A name="quick_firewall">FreeS/WAN quick start on firewalling</A></H1> -<P>This firewalling information supplements our -<A HREF="quickstart.html#quick_guide">quickstart guide.</A></P> -<P>It includes tips for firewalling:</P> -<UL> -<LI><A HREF="#firewall.standalone">a standalone system with initiator-only -opportunism</A></LI> -<LI><A HREF="#incoming.opp.firewall">incoming opportunistic connections</A></LI> -<LI><A HREF="#opp.gate.firewall">an opportunistic gateway</A></LI> -</UL> -<P>and a list of helpful <A HREF="#resources">resources</A>.</P> -<H2><A name="firewall.standalone">Firewalling a standalone system</A></H2> -<P>Firewall rules on a standalone system doing IPsec can be very simple.</P> -<P>The first step is to allow IPsec packets (IKE on UDP port 500 plus - ESP, protocol 50) in and out of your gateway. A script to set up - iptables(8) rules for this is:</P> -<PRE># edit this line to match the interface you use as default route -# ppp0 is correct for many modem, DSL or cable connections -# but perhaps not for you -world=ppp0 -# -# allow IPsec -# -# IKE negotiations -iptables -A INPUT -p udp -i $world --sport 500 --dport 500 -j ACCEPT -iptables -A OUTPUT -p udp -o $world --sport 500 --dport 500 -j ACCEPT -# ESP encryption and authentication -iptables -A INPUT -p 50 -i $world -j ACCEPT -iptables -A OUTPUT -p 50 -o $world -j ACCEPT</PRE> -<P>Optionally, you could restrict this, allowing these packets only to - and from a list of known gateways.</P> -<P>A second firewalling step -- access controls built into the IPsec - protocols -- is automatically applied:</P> -<DL> -<DT><A href="glossary.html#Pluto">Pluto</A> -- the FreeS/WAN keying - daemon -- deals with the IKE packets.</DT> -<DD>Pluto authenticates its partners during the IKE negotiation, and - drops negotiation if authentication fails.</DD> -<DT><A href="glossary.html#KLIPS">KLIPS</A> -- the FreeS/WAN kernel - component -- handles the ESP packets.</DT> -<DD> -<DL> -<DT>KLIPS drops outgoing packets</DT> -<DD>if they are routed to IPsec, but no tunnel has been negotiated for - them</DD> -<DT>KLIPS drops incoming unencrypted packets</DT> -<DD>if source and destination addresses match a tunnel; the packets - should have been encrypted</DD> -<DT>KLIPS drops incoming encrypted packets</DT> -<DD>if source and destination address do not match the negotiated - parameters of the tunnel that delivers them</DD> -<DD>if packet-level authentication fails</DD> -</DL> -</DD> -</DL> -<P>These errors are logged. See our <A href="trouble.html"> - troubleshooting</A> document for details.</P> -<P>As an optional third step, you may wish to filter packets emerging from - your opportunistic tunnels. - These packets arrive on an interface such as <VAR>ipsec0</VAR>, rather than - <VAR>eth0</VAR>, <VAR>ppp0</VAR> or whatever. For example, in an iptables(8) - rule set, you would use:</P> -<DL> -<DT><VAR>-i ipsec+</VAR></DT> -<DD>to specify packets arriving on any ipsec device</DD> -<DT><VAR>-o ipsec+</VAR></DT> -<DD>to specify packets leaving via any ipsec device</DD> -</DL> -<P>In this way, you can apply whatever additional filtering you like to these -packets.</P> -<P>The packets emerging on <VAR>ipsec0</VAR> are likely - to be things that a client application on your machine requested: web - pages, e-mail, file transfers and so on. However, any time you initiate - an opportunistic connection, you open a two-way connection to - another machine (or network). It is conceivable that a Bad Guy there - could take advantage of your link.</P> -<P>For more information, read the next section.</P> -</P> -<H2><A name="incoming.opp.firewall">Firewalling incoming opportunistic - connections</A></H2> -<P>The basic firewalling for IPsec does not change when you support - incoming connections as well as connections you initiate. You must - still allow IKE (UDP port 500) and ESP (protocol 50) packets to and - from your machine, as in the rules given <A href="#firewall.standalone"> - above</A>.</P> -<P>However, there is an additional security concern when you allow - incoming opportunistic connections. Incoming opportunistic packets - enter your machine via an IPSec tunnel. That is, they all appear as - ESP (protocol 50) packets, concealing whatever port and protocol - characteristics the packet within the tunnel has. Contained - in the tunnel as they pass through <VAR>ppp0</VAR> or <VAR>eth0</VAR>, - these packets can bypass your usual firewall rules on these interfaces. -<P>Consequently, you will want to firewall your <VAR>ipsec</VAR> interfaces - the way you would any publicly accessible interface.</P> -<P>A simple way to do this is to create one iptables(8) table with - all your filtering rules for incoming packets, and apply the entire table to - all public interfaces, including <VAR>ipsec</VAR> interfaces.</P> - -<H2><A name="opp.gate.firewall">Firewalling for opportunistic gateways</A></H2> -<P>On a gateway, the IPsec-related firewall rules applied for input and - output on the Internet side are exactly as shown -<A HREF="#firewall.standalone">above</A>. A gateway - exchanges exactly the same things -- UDP 500 packets and IPsec packets - -- with other gateways that a standalone system does, so it can use - exactly the same firewall rules as a standalone system would.</P> -<P>However, on a gateway there are additional things to do:</P> -<UL> -<LI>you have other interfaces and need rules for them</LI> -<LI>packets emerging from ipsec processing must be correctly forwarded</LI> -</UL> -<P>You need additional rules to handle these things. For example, adding - some rules to the set shown above we get:</P> -<PRE># edit this line to match the interface you use as default route -# ppp0 is correct for many modem, DSL or cable connections -# but perhaps not for you -world=ppp0 -# -# edit these lines to describe your internal subnet and interface -localnet=42.42.42.0/24 -internal=eth1 -# -# allow IPsec -# -# IKE negotiations -iptables -A INPUT -p udp -i $world --sport 500 --dport 500 -j ACCEPT -iptables -A OUTPUT -p udp -o $world --sport 500 --dport 500 -j ACCEPT -# ESP encryption and authentication -iptables -A INPUT -p 50 -i $world -j ACCEPT -iptables -A OUTPUT -p 50 -o $world -j ACCEPT -# -# packet forwarding for an IPsec gateway -# simplest possible rules -$ forward everything, with no attempt to filter -# -# handle packets emerging from IPsec -# ipsec+ means any of ipsec0, ipsec1, ... -iptables -A FORWARD -d $localnet -i ipsec+ -j ACCEPT -# simple rule for outbound packets -# let local net send anything -# IPsec will encrypt some of it -iptables -A FORWARD -s $localnet -i $internal -j ACCEPT </PRE> -<P>On a production gateway, you would no doubt need tighter rules than - the above.</P> -<H2><A NAME="resources">Firewall resources</A></H2> -<P>For more information, see these handy resources:</P> -<UL> -<LI><A href="http://www.netfilter.org/documentation/">netfilter - documentation</A></LI> -<LI>books such as: -<UL> -<LI>Cheswick and Bellovin, <A href="biblio.html#firewall.book">Firewalls - and Internet Security</A></LI> -<LI>Zeigler, <A href="biblio.html#Zeigler">Linux Firewalls</A>,</LI> -</UL> -</LI> -<LI><A href="firewall.html#firewall">our firewalls document</A></LI> -<LI><A href="web.html#firewall.web">our firewall links</A></LI> -</UL> -<A HREF="quickstart.html#quick.firewall">Back to our quickstart guide.</A> -</BODY> -</HTML> - - - |