Date: Sun, 15 Jul 2001 19:39:46 -0700 (PDT) From: jono@networkcommand.com To: FreeBSD-gnats-submit@freebsd.org Cc: jono@networkcommand.com Subject: docs/28994: New article for docproj "Checkpoint VPN-1/Firewall-1 and FreeBSD IPSEC" Message-ID: <200107160239.f6G2dk870176@biggins.securityreports.com>
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>Number: 28994
>Category: docs
>Synopsis: New article for docproj "Checkpoint VPN-1/Firewall-1 and FreeBSD IPSEC"
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-doc
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: update
>Submitter-Id: current-users
>Arrival-Date: Sun Jul 15 19:40:01 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator: Jon Orbeton
>Release: FreeBSD 4.3-STABLE i386
>Organization:
Security Reports
>Environment:
System: FreeBSD biggins.securityreports.com 4.3-STABLE FreeBSD 4.3-STABLE #8: Wed Jun 13 21:30:04 PDT 2001 root@biggins.securityreports.com:/usr/obj/usr/src/sys/BIGGINS i386
>Description:
This is just an addition of a new article to the docproj.
Please review and double-check my CVS id keywords,
I wasn't clear on this.
>How-To-Repeat:
No repeat
>Fix:
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<!DOCTYPE article PUBLIC "-//FreeBSD//DTD DocBook V4.1-Based Extension//EN" [
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<article>
<articleinfo>
<title>Integration of Checkpoint VPN-1/Firewall-1 and FreeBSD IPSEC</title>
<authorgroup>
<author>
<firstname>Jon</firstname>
<surname>Orbeton</surname>
<affiliation>
<address><email>info@networkcommand.com</email></address>
</affiliation>
</author>
<author>
<firstname>Matt</firstname>
<surname>Hite</surname>
<affiliation>
<address><email>mhite@hotmail.com</email></address>
</affiliation>
</author>
</authorgroup>
<pubdate>$Date$</pubdate>
<copyright>
<year>2001</year>
<holder role="mailto:info@networkcommand.com">Jon Orbeton</holder>
</copyright>
&legalnotice;
<abstract>
<para>This document explains how to configure a VPN tunnel
between FreeBSD and Checkpoint's VPN-1/Firewall-1.
Other documents provide similar information, but do
not contain instructions specific to VPN-1/Firewall-1
and its integration with FreeBSD. These documents are
listed at the conclusion of this paper for further reference.</para>
</abstract>
</articleinfo>
<sect1 id="prerequisites">
<title>Prerequisites</title>
<para>The following is a diagram of the machines and networks
referenced in this document.</para>
<programlisting>
External Interface External Interface
208.229.100.6 216.218.197.2
| |
+--> Firewall-1 <--> Internet <--> FreeBSD GW <--+
| |
FW-1 Protected Nets Internal Nets
199.208.192.0/24 192.168.10.0/24
</programlisting>
<para>The FreeBSD GW serves as a firewall and NAT device for
"internal nets."</para>
<para>The FreeBSD kernel must be compiled to support IPSec.
Use the following kernel options:
<programlisting>
options IPSEC
options IPSEC_ESP
options IPSEC_DEBUG
</programlisting>
<para>For instructions on building a custom kernel, refer to the
<ulink url="http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/x3663.html">;
FreeBSD handbook</ulink>. Please note that IP protocol 50 (ESP) and UDP port
500 must be open between the Firewall-1 host and the FreeBSD GW.</para>
<para>Also, racoon must be installed to support key exchange.
Racoon is part of the FreeBSD ports collection in
<filename>/usr/ports/security/racoon</filename>. The racoon
configuration file will be covered later in this document.</para>
</sect1>
<sect1 id="object">
<title>Firewall-1 Network Object Configuration</title>
<para>Begin by configuring the Firewall-1 Policy. Open the
Policy Editor on the Firewall-1 Management server and create
a new "Workstation" Network Object representing FreeBSD GW.</para>
<programlisting>
General Tab:
Set name and IP address
VPN Tab:
Encryption Schemes Defined: IKE ---> Edit
IKE Properties:
Key Negotiation Encryption Methods: 3DES
Authenication Method: Pre-Shared Secret ---> Edit
</programlisting>
<para>Select the Firewall Object and set a pre-shared secret.
(Don't use our example.)</para>
<programlisting>
Support Aggresive Mode: Checked
Supports Subnets: Checked
</programlisting>
<para>After setting the pre-shared secret in the Firewall-1 Network
Object definition, place this secret in <filename>
/usr/local/etc/racoon/psk.txt</filename> on FreeBSD GW. The format
for <filename>psk.txt</filename> is:
<programlisting>208.229.100.6 rUac0wtoo?</programlisting>
</sect1>
<sect1 id="rulecfg">
<title>Firewall-1 VPN Rule Configuration</title>
<para>Next, create a Firewall-1 rule enabling encryption between
the FreeBSD GW and the Firewall-1 protected network. In this
rule, the network services permitted through the VPN must be
defined.
<programlisting>
Source | Destination | Service | Action | Track
------------------------------------------------------------------------
FreeBSD GW | FW-1 Protected Net | VPN services | Encrypt | Long
FW-1 Protected Net| FreeBSD GW | | |
</programlisting>
<para>"VPN services" are any services (i.e. telnet, ssh, ntp, etc.)
remote hosts are permitted to access through the VPN. Use caution
when permitting services; hosts connecting through a VPN still
represent a potential security risk. Encrypting the traffic between
the two networks offers little protection if a host on either side
of the tunnel has been compromised.</para>
<para>Once the rule specifying data encryption between the FreeBSD GW
and the Firewall-1 protected network has been configured, review
the "Action Encrypt" settings.</para>
<programlisting>
Encryption Schemes Defined: IKE ---> Edit
Transform: Encryption + Data Integrity (ESP)
Encryption Algorithm: 3DES
Data Integrity: MD5
Allowed Peer Gateway: Any or Firewall Object
Use Perfect Forward Secrecy: Checked
</programlisting>
<para>The use of Perfect Forward Secrecy (PFS) is optional. Enabling PFS
will add another layer of encryption security, but does come at the
cost of increased CPU overhead. If PFS is not used, uncheck the box
above and comment out the <literal>pfs_group 1</literal> line from
<filename>racoon.conf</filename> on FreeBSD GW. An example
<filename>racoon.conf</filename> is provided later in this document.</para>
</sect1>
<sect1 id="policy">
<title>FreeBSD VPN Policy Configuration</title>
<para>At this point, the VPN policy on FreeBSD GW must be defined. The
<filename>/usr/sbin/setkey</filename> tool performs this function.</para>
<para>Below is an example shellscript which will flush setkey and add your
VPN policy rules.</para>
<programlisting>
#
# /etc/vpn1-ipsec.sh
#
# IP addresses
#
# External Interface External Interface
# 208.229.100.6 216.218.197.2
# | |
# +--> Firewall-1 <--> Internet <--> FreeBSD GW <--+
# | |
# FW-1 Protected Nets Internal Nets
# 199.208.192.0/24 192.168.10.0/24
#
# Flush the policy
#
setkey -FP
setkey -F
#
# Configure the Policy
#
setkey -c << END
spdadd 216.218.197.2/32 199.208.192.0/24 any -P out ipsec
esp/tunnel/216.218.197.2-208.229.100.6/require;
spdadd 199.208.192.0/24 216.218.197.2/32 any -P in ipsec
esp/tunnel/208.229.100.6-216.218.197.2/require;
END
#
</programlisting>
<para>Execute the setkey commands:</para>
<screen>&prompt.root; <userinput>sh /etc/vpn1-ipsec.sh</userinput></screen>
</sect1>
<sect1 id="racoon">
<title>FreeBSD Racoon Configuration</title>
<para>To facilitate the negotiation of IPSec keys on FreeBSD GW,
<filename>/usr/ports/security/racoon</filename> must be installed and
configured.</para>
<para>The following is a racoon configuration file suitable for use with
the examples outlined in this document. Please make sure you fully
understand this file before using in a production environment.</para>
<programlisting>
# racoon.conf for use with Checkpoint VPN-1/Firewall-1
#
# search this file for pre_shared_key with various ID key.
path pre_shared_key "/usr/local/etc/racoon/psk.txt" ;
#
#
log debug;
#
# "padding" defines some parameter of padding. You should not touch these.
padding
{
maximum_length 20; # maximum padding length.
randomize off; # enable randomize length.
strict_check off; # enable strict check.
exclusive_tail off; # extract last one octet.
}
#
listen
{
#isakmp ::1 [7000];
#isakmp 0.0.0.0 [500];
#admin [7002]; # administrative's port by kmpstat.
#strict_address; # required all addresses must be bound.
}
#
# Specification of default various timers.
#
timer
{
# These values can be changed per remote node.
counter 5; # maximum trying count to send.
interval 20 sec; # maximum interval to resend.
persend 1; # the number of packets per a send.
#
# timer for waiting to complete each phase.
phase1 30 sec;
phase2 15 sec;
}
remote anonymous
{
exchange_mode aggressive,main; # For Firewall-1 Aggressive mode
#my_identifier address;
#my_identifier user_fqdn "";
#my_identifier address "";
#peers_identifier address "";
#certificate_type x509 "" "";
nonce_size 16;
lifetime time 10 min; # sec,min,hour
lifetime byte 5 MB; # B,KB,GB
initial_contact on;
support_mip6 on;
proposal_check obey; # obey, strict or claim
proposal {
encryption_algorithm 3des;
hash_algorithm md5;
authentication_method pre_shared_key;
dh_group 2 ;
}
}
sainfo anonymous
{
pfs_group 1;
lifetime time 10 min;
lifetime byte 50000 KB;
encryption_algorithm 3des;
authentication_algorithm hmac_md5;
compression_algorithm deflate ;
}
</programlisting>
<para>Ensure that <filename>/usr/local/etc/racoon/psk.txt</filename>
contains the shared secret configured in the "Firewall-1 Network Object
Configuration" section of this document and has mode 600 permissions.</para>
<screen>&prompt.root; <userinput>chmod 600 /usr/local/etc/racoon/psk.txt</userinput></screen>
</sect1>
<sect1 id="startingvpn">
<title>Starting the VPN</title>
<para>You are now ready to launch racoon and test the VPN tunnel.
For debugging purposes, open the Firewall-1 Log Viewer and define
a log filter to isolate entries pertaining to FreeBSD GW. You may
also find it helpful to tail the racoon log:</para>
<screen>&prompt.root; <userinput>tail -f /var/log/racoon.log</userinput></screen>
<para>Start racoon using the following command:</para>
<screen>&prompt.root; <userinput>/usr/local/sbin/racoon -f /usr/local/etc/racoon/racoon.conf
</userinput></screen>
<para>Once racoon has been launched, telnet to a host on the Firewall-1
protected network.</para>
<screen>&prompt.root; <userinput>telnet -s 192.168.10.3 199.208.192.66 22
</userinput></screen>
<para>This command attempts to connect to the ssh port on 199.208.192.66,
a machine in the Firewall-1 protected network. The <literal>-s</literal> switch indicates
the source interface of the outbound connection. This is particularly important
when running NAT and IPFW on FreeBSD GW. Using <literal>-s</literal> and specifying an
explicit source address prevents NAT from mangling the packet prior to tunneling.</para>
<para>A successful racoon key exchange will output the following to racoon.log:</para>
<programlisting>
pfkey UPDATE succeeded: ESP/Tunnel 216.218.197.2->208.229.100.6
pk_recvupdate(): IPsec-SA established: ESP/Tunnel 216.218.197.2->208.229.100.6
get pfkey ADD message IPsec-SA established: ESP/Tunnel 208.229.100.6->216.218.197.2
</programlisting>
<para>Once key exchange completes (which takes a few seconds), an ssh banner will appear.
If all went well, two "Key Install" messages will be logged in the Firewall-1 Log Viewer.
</para>
<programlisting>
Action | Source | Dest. | Info.
Key Install | 216.218.197.2 | 208.229.100.6 | IKE Log: Phase 1 (aggressive) completion.
Key Install | 216.218.197.2 | 208.229.100.6 | scheme: IKE methods
</programlisting>
<para>Under the information column, the full log detail will read:</para>
<programlisting>
IKE Log: Phase 1 (aggressive) completion. 3DES/MD5/Pre shared secrets Negotiation Id:
scheme: IKE methods: Combined ESP: 3DES + MD5 + PFS (phase 2 completion) for host:
</programlisting>
</sect1>
<sect1 id="References">
<title>References</title>
<itemizedlist>
<listitem>
<para><ulink url="http://www.freebsd.org/handbook/ipsec.html">;
FreeBSD Handbook: IPSEC</ulink></para>
</listitem>
<listitem>
<para><ulink url="http://www.kame.net">KAME Project</ulink></para>
</listitem>
<listitem>
<para><ulink url="http://www.x-itec.de/projects/tuts/ipsec-howto.txt">;
FreeBSD IPSEC mini-HOWTO</ulink></para>
</listitem>
</itemizedlist>
</sect1>
</article>
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