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-<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>
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