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diff --git a/doc/policygroups.html b/doc/policygroups.html new file mode 100644 index 000000000..6a507b1f6 --- /dev/null +++ b/doc/policygroups.html @@ -0,0 +1,341 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd"> +<HTML> +<HEAD> +<TITLE>Introduction to FreeS/WAN</TITLE> +<META HTTP-EQUIV="Content-Type" CONTENT="text/html; CHARSET=iso-8859-1"> +<STYLE TYPE="text/css"><!-- +BODY { font-family: serif } +H1 { font-family: sans-serif } +H2 { font-family: sans-serif } +H3 { font-family: sans-serif } +H4 { font-family: sans-serif } +H5 { font-family: sans-serif } +H6 { font-family: sans-serif } +SUB { font-size: smaller } +SUP { font-size: smaller } +PRE { font-family: monospace } +--></STYLE> +</HEAD> +<BODY> +<A HREF="toc.html">Contents</A> +<A HREF="quickstart.html">Previous</A> +<A HREF="faq.html">Next</A> +<HR> +<H1><A NAME="4">How to Configure Linux FreeS/WAN with Policy Groups</A></H1> +<A NAME="policygroups"></A> +<H2><A NAME="4_1">What are Policy Groups?</A></H2> +<P><STRONG>Policy Groups</STRONG> are an elegant general mechanism to + configure FreeS/WAN. They are useful for many FreeS/WAN users.</P> +<P>In previous FreeS/WAN versions, you needed to configure each IPsec + connection explicitly, on both local and remote hosts. This could + become complex.</P> +<P>By contrast, Policy Groups allow you to set local IPsec policy for + lists of remote hosts and networks, simply by listing the hosts and + networks which you wish to have special treatment in one of several + Policy Group files. FreeS/WAN then internally creates the connections + needed to implement each policy.</P> +<P>In the next section we describe our five Base Policy Groups, which + you can use to configure IPsec in many useful ways. Later, we will show + you how to create an IPsec VPN using one line of configuration for each + remote host or network.</P> +<A NAME="builtin_policygroups"></A> +<H3><A NAME="4_1_1">Built-In Security Options</A></H3> +<P>FreeS/WAN offers these Base Policy Groups:</P> +<DL> +<DT>private</DT> +<DD> FreeS/WAN only communicates privately with the listed<A HREF="glossary.html#CIDR"> + CIDR</A> blocks. If needed, FreeS/WAN attempts to create a connection + opportunistically. If this fails, FreeS/WAN blocks communication. + Inbound blocking is assumed to be done by the firewall. FreeS/WAN + offers firewall hooks but no modern firewall rules to help with inbound + blocking.</DD> +<DT>private-or-clear</DT> +<DD> FreeS/WAN prefers private communication with the listed CIDR + blocks. If needed, FreeS/WAN attempts to create a connection + opportunistically. If this fails, FreeS/WAN allows traffic in the + clear.</DD> +<DT>clear-or-private</DT> +<DD> FreeS/WAN communicates cleartext with the listed CIDR blocks, but + also accepts inbound OE connection requests from them. Also known as<A HREF="glossary.html#passive.OE"> + passive OE (pOE)</A>, this policy may be used to create an<A HREF="glossary.html#responder"> + opportunistic responder</A>.</DD> +<DT>clear</DT> +<DD> FreeS/WAN only communicates cleartext with the listed CIDR blocks.</DD> +<DT>block</DT> +<DD>FreeS/WAN blocks traffic to and from and the listed CIDR blocks. + Inbound blocking is assumed to be done by the firewall. FreeS/WAN + offers firewall hooks but no modern firewall rules to help with inbound + blocking. +<!-- also called "blockdrop".--> +</DD> +</DL> +<A NAME="policy.group.notes"></A> +<P>Notes:</P> +<UL> +<LI>Base Policy Groups apply to communication with this host only.</LI> +<LI>The most specific rule (whether policy or pre-configured connection) + applies. This has several practical applications: +<UL> +<LI>If CIDR blocks overlap, FreeS/WAN chooses the most specific + applicable block.</LI> +<LI>This decision also takes into account any pre-configured connections + you may have.</LI> +<LI>If the most specific connection is a pre-configured connection, the + following procedure applies. If that connection is up, it will be used. + If it is routed, it will be brought up. If it is added, no action will + be taken.</LI> +</UL> +</LI> +<LI>Base Policy Groups are created using built-in connections. Details + in<A HREF="manpage.d/ipsec.conf.5.html"> man ipsec.conf</A>.</LI> +<LI>All Policy Groups are bidirectional.<A HREF="src/policy-groups-table.html"> + This chart</A> shows some technical details. FreeS/WAN does not support + one-way encryption, since it can give users a false sense of security.</LI> +</UL> +<H2><A NAME="4_2">Using Policy Groups</A></H2> +<P>The Base Policy Groups which build IPsec connections rely on + Opportunistic Encryption. To use the following examples, you must first + become OE-capable, as described in our<A HREF="quickstart.html#quickstart"> + quickstart guide</A>.<A NAME="example1"></A></P> +<H3><A NAME="4_2_1">Example 1: Using a Base Policy Group</A></H3> +<P>Simply place CIDR blocks (<A HREF="#dnswarning">names</A>, IPs or IP + ranges) in /etc/ipsec.d/policies/<VAR>[groupname]</VAR>, and reread the + policy group files.</P> +<P>For example, the<VAR> private-or-clear</VAR> policy tells FreeS/WAN + to prefer encrypted communication to the listed CIDR blocks. Failing + that, it allows talk in the clear.</P> +<P>To make this your default policy, place<A HREF="glossary.html#fullnet"> + fullnet</A> in the<VAR> private-or-clear</VAR> policy group file:</P> +<PRE> [root@xy root]# cat /etc/ipsec.d/policies/private-or-clear + # This file defines the set of CIDRs (network/mask-length) to which + # communication should be private, if possible, but in the clear otherwise. + .... + 0.0.0.0/0</PRE> +<P>and reload your policies with</P> +<PRE> ipsec auto --rereadgroups</PRE> +<P>Use<A HREF="quickstart.html#opp.test"> this test</A> to verify + opportunistic connections.</P> +<A NAME="example2"></A> +<H3><A NAME="4_2_2">Example 2: Defining IPsec Security Policy with + Groups</A></H3> +<P>Defining IPsec security policy with Base Policy Groups is like + creating a shopping list: just put CIDR blocks in the appropriate group + files. For example:</P> +<PRE> [root@xy root]# cd /etc/ipsec.d/policies + [root@xy policies]# cat private + 192.0.2.96/27 # The finance department + 192.0.2.192/29 # HR + 192.0.2.12 # HR gateway + irc.private.example.com # Private IRC server + + [root@xy policies]# cat private-or-clear + 0.0.0.0/0 # My default policy: try to encrypt. + + [root@xy policies]# cat clear + 192.0.2.18/32 # My POP3 server + 192.0.2.19/32 # My Web proxy + + [root@xy policies]# cat block + spamsource.example.com</PRE> +<P>To make these settings take effect, type:</P> +<PRE> ipsec auto --rereadgroups</PRE> +<P>Notes:</P> +<UL> +<LI>For opportunistic connection attempts to succeed, all participating + FreeS/WAN hosts and gateways must be configured for OE.</LI> +<LI>Examples 3 through 5 show how to implement a detailed<VAR> private</VAR> + policy.</LI> +<LI><A NAME="dnswarning"></A><FONT COLOR="RED"> Warning:</FONT> Using + DNS names in policy files and ipsec.conf can be tricky. If the name + does not resolve, the policy will not be implemented for that name. It + is therefore safer either to use IPs, or to put any critical names in + /etc/hosts. We plan to implement periodic DNS retry to help with this. +<BR> Names are resolved at FreeS/WAN startup, or when the policies are + reloaded. Unfortunately, name lookup can hold up the startup process. + If you have fast DNS servers, the problem may be less severe.</LI> +</UL> +<A HREF="example3"></A> +<H3><A NAME="4_2_3">Example 3: Creating a Simple IPsec VPN with the<VAR> + private</VAR> Group</A></H3> +<P>You can create an IPsec VPN between several hosts, with only one line + of configuration per host, using the<VAR> private</VAR> policy group.</P> +<P>First, use our<A HREF="quickstart.html"> quickstart guide</A> to set + up each participating host with a FreeS/WAN install and OE.</P> +<P>In one host's<VAR> /etc/ipsec.d/policies/private</VAR>, list the + peers to which you wish to protect traffic. For example:</P> +<PRE> [root@xy root]# cd /etc/ipsec.d/policies + [root@xy policies]# cat private + 192.0.2.9 # several hosts at example.com + 192.0.2.11 + 192.0.2.12 + irc.private.example.com +</PRE> +<P>Copy the<VAR> private</VAR> file to each host. Remove the local host, + and add the initial host.</P> +<PRE> scp2 /etc/ipsec.d/policies/private root@192.0.2.12:/etc/ipsec.d/policies/private</PRE> +<P>On each host, reread the policy groups with</P> +<PRE> ipsec auto --rereadgroups</PRE> +<P>That's it! You're configured.</P> +<P>Test by pinging between two hosts. After a second or two, traffic + should flow, and</P> +<PRE> ipsec eroute</PRE> +<P>should yield something like</P> +<PRE> 192.0.2.11/32 -> 192.0.2.8/32 => tun0x149f@192.0.2.8</PRE> +<P>where your host IPs are substituted for 192.0.2.11 and 192.0.2.8.</P> +<P>If traffic does not flow, there may be an error in your OE setup. + Revisit our<A HREF="quickstart.html"> quickstart guide</A>.</P> +<P>Our next two examples show you how to add subnets to this IPsec VPN.</P> +<A NAME="example4"></A> +<H3><A NAME="4_2_4">Example 4: New Policy Groups to Protect a Subnet</A></H3> +<P>To protect traffic to a subnet behind your FreeS/WAN gateway, you'll + need additional DNS records, and new policy groups. To set up the DNS, + see our<A HREF="quickstart.html#opp.gate"> quickstart guide</A>. To + create five new policy groups for your subnet, copy these connections + to<VAR> /etc/ipsec.conf</VAR>. Substitute your subnet's IPs for + 192.0.2.128/29.</P> +<PRE> +conn private-net + also=private # inherits settings (eg. auto=start) from built in conn + leftsubnet=192.0.2.128/29 # your subnet's IPs here + +conn private-or-clear-net + also=private-or-clear + leftsubnet=192.0.2.128/29 + +conn clear-or-private-net + also=clear-or-private + leftsubnet=192.0.2.128/29 + +conn clear-net + also=clear + leftsubnet=192.0.2.128/29 + +conn block-net + also=block + leftsubnet=192.0.2.128/29 +</PRE> +<P>Copy the gateway's files to serve as the initial policy group files + for the new groups:</P> +<PRE> + cp -p /etc/ipsec.d/policies/private /etc/ipsec.d/policies/private-net + cp -p /etc/ipsec.d/policies/private-or-clear /etc/ipsec.d/policies/private-or-clear-net + cp -p /etc/ipsec.d/policies/clear-or-private /etc/ipsec.d/policies/clear-or-private-net + cp -p /etc/ipsec.d/policies/clear /etc/ipsec.d/policies/clear-net + cp -p /etc/ipsec.d/policies/block /etc/ipsec.d/policies/block +</PRE> +<P><STRONG>Tip: Since a missing policy group file is equivalent to a + file with no entries, you need only create files for the connections + you'll use.</STRONG></P> +<P>To test one of your new groups, place the fullnet 0.0.0.0/0 in<VAR> + private-or-clear-net</VAR>. Perform the subnet test in<A HREF="quickstart.html#opp.test"> + our quickstart guide</A>. You should see a connection, and</P> +<PRE> ipsec eroute</PRE> +<P>should include an entry which mentions the subnet node's IP and the + OE test site IP, like this:</P> +<PRE> 192.0.2.131/32 -> 192.139.46.77/32 => tun0x149f@192.0.2.11</PRE> +<A HREF="example5"></A> +<H3><A NAME="4_2_5">Example 5: Adding a Subnet to the VPN</A></H3> +<P>Suppose you wish to secure traffic to a subnet 192.0.2.192/29 behind + a FreeS/WAN box 192.0.2.12.</P> +<P>First, add DNS entries to configure 192.0.2.12 as an opportunistic + gateway for that subnet. Instructions are in our<A HREF="quickstart.html#opp.gate"> + quickstart guide</A>. Next, create a<VAR> private-net</VAR> group on + 192.0.2.12 as described in<A HREF="#example4"> Example 4</A>.</P> +<P>On each other host, add the subnet 192.0.2.192/29 to<VAR> private</VAR> +, yielding for example</P> +<PRE> [root@xy root]# cd /etc/ipsec.d/policies + [root@xy policies]# cat private + 192.0.2.9 # several hosts at example.com + 192.0.2.11 + 192.0.2.12 # HR department gateway + 192.0.2.192/29 # HR subnet + irc.private.example.com +</PRE> +<P>and reread policy groups with</P> +<PRE> ipsec auto --rereadgroups</PRE> +<P>That's all the configuration you need.</P> +<P>Test your VPN by pinging from a machine on 192.0.2.192/29 to any + other host:</P> +<PRE> [root@192.0.2.194]# ping 192.0.2.11</PRE> +<P>After a second or two, traffic should flow, and</P> +<PRE> ipsec eroute</PRE> +<P>should yield something like</P> +<PRE> 192.0.2.11/32 -> 192.0.2.194/32 => tun0x149f@192.0.2.12 +</PRE> +<P>Key:</P> +<TABLE> +<TR><TD>1.</TD><TD>192.0.2.11/32</TD><TD>Local start point of the + protected traffic.</TD></TR> +<TR><TD>2.</TD><TD>192.0.2.194/32</TD><TD>Remote end point of the + protected traffic.</TD></TR> +<TR><TD>3.</TD><TD>192.0.2.12</TD><TD>Remote FreeS/WAN node (gateway or + host). May be the same as (2).</TD></TR> +<TR><TD>4.</TD><TD>[not shown]</TD><TD>Local FreeS/WAN node (gateway or + host), where you've produced the output. May be the same as (1).</TD></TR> +</TABLE> +<P>For additional assurance, you can verify with a packet sniffer that + the traffic is being encrypted.</P> +<P>Note</P> +<UL> +<LI>Because strangers may also connect via OE, this type of VPN may + require a stricter firewalling policy than a conventional VPN.</LI> +</UL> +<H2><A NAME="4_3">Appendix</A></H2> +<A NAME="hiddenconn"></A> +<H3><A NAME="4_3_1">Our Hidden Connections</A></H3> +<P>Our Base Policy Groups are created using hidden connections. These + are spelled out in<A HREF="manpage.d/ipsec.conf.5.html"> man ipsec.conf</A> + and defined in<VAR> /usr/local/lib/ipsec/_confread</VAR>.</P> +<A NAME="custom_policygroups"></A> +<H3><A NAME="4_3_2">Custom Policy Groups</A></H3> +<P>A policy group is built using a special connection description in<VAR> + ipsec.conf</VAR>, which:</P> +<UL> +<LI>is<STRONG> generic</STRONG>. It uses<VAR> + right=[%group|%opportunisticgroup]</VAR> rather than specific IPs. The + connection is cloned for every name or IP range listed in its Policy + Group file.</LI> +<LI>often has a<STRONG> failure rule</STRONG>. This rule, written<VAR> + failureshunt=[passthrough|drop|reject|none]</VAR>, tells FreeS/WAN what + to do with packets for these CIDRs if it fails to establish the + connection. Default is<VAR> none</VAR>.</LI> +</UL> +<P>To create a new group:</P> +<OL> +<LI>Create its connection definition in<VAR> ipsec.conf</VAR>.</LI> +<LI>Create a Policy Group file in<VAR> /etc/ipsec.d/policies</VAR> with + the same name as your connection.</LI> +<LI>Put a CIDR block in that file.</LI> +<LI>Reread groups with<VAR> ipsec auto --rereadgroups</VAR>.</LI> +<LI>Test:<VAR> ping</VAR> to activate any OE connection, and view + results with<VAR> ipsec eroute</VAR>.</LI> +</OL> +<A NAME="disable_oe"></A><A NAME="disable_policygroups"></A> +<H3><A NAME="4_3_3">Disabling Opportunistic Encryption</A></H3> +<P>To disable OE (eg. policy groups and packetdefault), cut and paste + the following lines to<VAR> /etc/ipsec.conf</VAR>:</P> +<PRE>conn block + auto=ignore + +conn private + auto=ignore + +conn private-or-clear + auto=ignore + +conn clear-or-private + auto=ignore + +conn clear + auto=ignore + +conn packetdefault + auto=ignore</PRE> +<P>Restart FreeS/WAN so that the changes take effect:</P> +<PRE> ipsec setup restart</PRE> +<HR> +<A HREF="toc.html">Contents</A> +<A HREF="quickstart.html">Previous</A> +<A HREF="faq.html">Next</A> +</BODY> +</HTML> |