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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>PPTP - Unmaintained</title><link rel="stylesheet" href="html.css" type="text/css" /><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /><meta name="description" content="Shorewall easily supports PPTP in a number of configurations." /></head><body><div class="article" lang="en" xml:lang="en"><div class="titlepage"><div><div><h2 class="title"><a id="PPTP"></a>PPTP - Unmaintained</h2></div><div><div class="authorgroup"><div class="author"><h3 class="author"><span class="firstname">Tom</span> <span class="surname">Eastep</span></h3></div></div></div><div><p class="copyright">Copyright © 2001, 2002, 2003, 2004, 2005, 2006, 2007 Thomas M. Eastep</p></div><div><div class="legalnotice"><a id="id290194"></a><p>Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License, Version
1.2 or any later version published by the Free Software Foundation; with
no Invariant Sections, with no Front-Cover, and with no Back-Cover
Texts. A copy of the license is included in the section entitled
“<span class="quote"><a class="ulink" href="GnuCopyright.htm" target="_self">GNU Free Documentation
License</a></span>”.</p></div></div><div><p class="pubdate">2008/12/15</p></div><div><div class="abstract"><p class="title"><b>Abstract</b></p><p>Shorewall easily supports PPTP in a number of
configurations.</p></div></div></div><hr /></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#Prelim">Preliminary Reading</a></span></dt><dt><span class="section"><a href="#ServerFW">PPTP Server Running on your Firewall</a></span></dt><dd><dl><dt><span class="section"><a href="#Samba">Configuring Samba</a></span></dt><dt><span class="section"><a href="#ConfigPppd">Configuring pppd</a></span></dt><dt><span class="section"><a href="#ConfigPptpd">Configuring pptpd</a></span></dt><dt><span class="section"><a href="#ConfigFw">Configuring Shorewall</a></span></dt><dd><dl><dt><span class="section"><a href="#Basic">Basic Setup</a></span></dt><dt><span class="section"><a href="#Zones">Remote Users in a Separate Zone</a></span></dt><dt><span class="section"><a href="#Hub">Multiple Remote Networks</a></span></dt></dl></dd></dl></dd><dt><span class="section"><a href="#ServerBehind">PPTP Server Running Behind your Firewall</a></span></dt><dt><span class="section"><a href="#ClientsBehind">PPTP Clients Running Behind your Firewall</a></span></dt><dt><span class="section"><a href="#ClientFW">PPTP Client Running on your Firewall</a></span></dt><dt><span class="section"><a href="#PPTP_ADSL">PPTP Client running on your Firewall with PPTP Server in an ADSL
Modem</a></span></dt></dl></div><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>I have not used PPTP in years and as a consequence, this document is
no longer maintained (any volunteers?).</p><p>As far as I know, the information regarding Shorewall configuration
is still valid but the configurations shown for for the other components
may no longer work. For the most part, they show configuration files that
I used when I worked for <span class="trademark">Compaq</span>™ and used PPTP as my
work VPN.</p></div><div class="section" lang="en" xml:lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="Prelim"></a>Preliminary Reading</h2></div></div></div><p>I recommend reading the <a class="ulink" href="VPNBasics.html" target="_self">VPN
Basics</a> article if you plan to implement any type of VPN.</p></div><div class="section" lang="en" xml:lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ServerFW"></a>PPTP Server Running on your Firewall</h2></div></div></div><div class="section" lang="en" xml:lang="en"><div class="titlepage"><div><div><h3 class="title"><a id="Samba"></a>Configuring Samba</h3></div></div></div><p>You will need a WINS server (Samba configured to run as a WINS
server is fine). Global section from /etc/samba/smb.conf on my WINS
server (192.168.1.3) is:</p><pre class="programlisting">[global]
workgroup = TDM-NSTOP
netbios name = WOOKIE
server string = GNU/Linux Box
encrypt passwords = Yes
log file = /var/log/samba/%m.log
max log size = 0
socket options = TCP_NODELAY SO_RCVBUF=8192 SO_SNDBUF=8192
os level = 65
domain master = True
preferred master = True
dns proxy = No
wins support = Yes
printing = lprng
[homes]
comment = Home Directories
valid users = %S
read only = No
create mask = 0664
directory mask = 0775
[printers]
comment = All Printers
path = /var/spool/samba
printable = Yes</pre></div><div class="section" lang="en" xml:lang="en"><div class="titlepage"><div><div><h3 class="title"><a id="ConfigPppd"></a>Configuring pppd</h3></div></div></div><p>Here is a copy of my /etc/ppp/options.poptop file:</p><pre class="programlisting">ipparam PoPToP
lock
mtu 1490
mru 1490
ms-wins 192.168.1.3
ms-dns 206.124.146.177
multilink
proxyarp
auth
+chap
+chapms
+chapms-v2
ipcp-accept-local
ipcp-accept-remote
lcp-echo-failure 30
lcp-echo-interval 5
deflate 0
mppe-128
mppe-stateless
require-mppe
require-mppe-stateless</pre><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><div class="itemizedlist"><ul type="disc"><li><p>System 192.168.1.3 acts as a WINS server so I have included
that IP as the “<span class="quote">ms-wins</span>” value.</p></li><li><p>I have pointed the remote clients at my DNS server -- it has
external address 206.124.146.177.</p></li><li><p>I am requiring 128-bit stateless compression.</p></li></ul></div></div><p>Here's my /etc/ppp/chap-secrets:</p><pre class="programlisting">Secrets for authentication using CHAP
# client server secret IP addresses
CPQTDM\\TEastep * <shhhhhh> 192.168.1.7
TEastep * <shhhhhh> 192.168.1.7</pre><p>I am the only user who connects to the server but I may connect
either with or without a domain being specified. The system I connect
from is my laptop so I give it the same IP address when tunneled in at
it has when I use its wireless LAN card around the house.</p><p>You will also want the following in /etc/modules.conf:</p><pre class="programlisting">alias ppp-compress-18 ppp_mppe
alias ppp-compress-21 bsd_comp
alias ppp-compress-24 ppp_deflate
alias ppp-compress-26 ppp_deflate</pre></div><div class="section" lang="en" xml:lang="en"><div class="titlepage"><div><div><h3 class="title"><a id="ConfigPptpd"></a>Configuring pptpd</h3></div></div></div><p>PoPTop (pptpd) is available from <a class="ulink" href="http://www.poptop.org/" target="_self">http://www.poptop.org/</a>.</p><p>Here is a copy of my /etc/pptpd.conf file:</p><pre class="programlisting">option /etc/ppp/options.poptop
speed 115200
localip 192.168.1.254
remoteip 192.168.1.33-38</pre><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><div class="itemizedlist"><ul type="disc"><li><p>I specify the /etc/ppp/options.poptop file as my ppp options
file (I have several).</p></li><li><p>The local IP is the same as my internal interface's
(192.168.1.254).</p></li><li><p>I have assigned a remote IP range that overlaps my local
network. This, together with “<span class="quote">proxyarp</span>” in my
/etc/ppp/options.poptop file make the remote hosts look like they
are part of the local subnetwork.</p></li></ul></div></div><p>I use this file to start/stop pptpd -- I have this in
/etc/init.d/pptpd:</p><pre class="programlisting">#!/bin/sh
#
# /etc/rc.d/init.d/pptpd
#
# chkconfig: 5 12 85
# description: control pptp server
#
case "$1" in
start)
echo 1 > /proc/sys/net/ipv4/ip_forward
modprobe ppp_async
modprobe ppp_generic
modprobe ppp_mppe
modprobe slhc
if /usr/local/sbin/pptpd; then
touch /var/lock/subsys/pptpd
fi
;;
stop)
killall pptpd
rm -f /var/lock/subsys/pptpd
;;
restart)
killall pptpd
if /usr/local/sbin/pptpd; then
touch /var/lock/subsys/pptpd
fi
;;
status)
ifconfig
;;
*)
echo "Usage: $0 {start|stop|restart|status}"
;;
esac</pre></div><div class="section" lang="en" xml:lang="en"><div class="titlepage"><div><div><h3 class="title"><a id="ConfigFw"></a>Configuring Shorewall</h3></div></div></div><div class="section" lang="en" xml:lang="en"><div class="titlepage"><div><div><h4 class="title"><a id="Basic"></a>Basic Setup</h4></div></div></div><p>Here' a basic setup that treats your remote users as if they
were part of your <span class="bold"><strong>loc</strong></span> zone. Note that
if your primary Internet connection uses ppp0, then be sure that
<span class="bold"><strong>loc</strong></span> follows <span class="bold"><strong>net</strong></span> in /etc/shorewall/zones.</p><p><code class="filename">/etc/shorewall/tunnels</code>:</p><pre class="programlisting">#TYPE ZONE GATEWAY GATEWAY ZONE
pptpserver net 0.0.0.0/0</pre><p><code class="filename">/etc/shorewall/interfaces</code>:</p><pre class="programlisting">#ZONE INTERFACE BROADCAST OPTIONS
loc ppp+</pre></div><div class="section" lang="en" xml:lang="en"><div class="titlepage"><div><div><h4 class="title"><a id="Zones"></a>Remote Users in a Separate Zone</h4></div></div></div><p>If you want to place your remote users in their own zone so that
you can control connections between these users and the local network,
follow this example. Note that if your primary Internet connection
uses ppp0 then be sure that <span class="bold"><strong>vpn</strong></span>
follows <span class="bold"><strong>net</strong></span> in /etc/shorewall/zones
as shown below.</p><p><code class="filename">/etc/shorewall/tunnels</code>:</p><pre class="programlisting">#TYPE ZONE GATEWAY GATEWAY ZONE
pptpserver net 0.0.0.0/0</pre><p><code class="filename">/etc/shorewall/zones</code>:</p><pre class="programlisting">#ZONE TYPE
net ipv4
loc ipv4
vpn ipv4</pre><p><code class="filename">/etc/shorewall/interfaces</code>:</p><pre class="programlisting">#ZONE INTERFACE BROADCAST OPTIONS
net eth0 206.124.146.255 norfc1918
loc eth2 192.168.10.255
vpn ppp+</pre><p>Your policies and rules may now be configured for traffic
to/from the <span class="bold"><strong>vpn</strong></span> zone.</p></div><div class="section" lang="en" xml:lang="en"><div class="titlepage"><div><div><h4 class="title"><a id="Hub"></a>Multiple Remote Networks</h4></div></div></div><p>Often there will be situations where you want multiple
connections from remote networks with these networks having different
firewalling requirements.</p><div><img src="images/MultiPPTP.png" /></div><p>Here's how you configure this in Shorewall. Note that if your
primary Internet connection uses ppp0 then be sure that the <span class="bold"><strong>vpn{1-3}</strong></span> zones follows <span class="bold"><strong>net</strong></span> in /etc/shorewall/zones as shown
below.</p><p><code class="filename">/etc/shorewall/tunnels</code>:</p><pre class="programlisting">#TYPE ZONE GATEWAY GATEWAY ZONE
pptpserver net 0.0.0.0/0</pre><p><code class="filename">/etc/shorewall/zones</code>:</p><pre class="programlisting">#ZONE TYPE
fw firewall
net ipv4
loc ipv4
vpn1 ipv4
vpn2 ipv4
vpn3 ipv4</pre><p><code class="filename">/etc/shorewall/interfaces</code>:</p><pre class="programlisting">#ZONE INTERFACE BROADCAST OPTIONS
net eth0 206.124.146.255 norfc1918
loc eth2 192.168.10.255
- ppp+</pre><p><code class="filename">/etc/shorewall/hosts</code>:</p><pre class="programlisting">#ZONE HOST(S) OPTIONS
vpn1 ppp+:192.168.1.0/24
vpn2 ppp+:192.168.2.0/24
vpn3 ppp+:192.168.3.0/24</pre><p>Your policies and rules can now be configured using separate
zones (vpn1, vpn2, and vpn3) for the three remote network.</p></div></div></div><div class="section" lang="en" xml:lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ServerBehind"></a>PPTP Server Running Behind your Firewall</h2></div></div></div><p>If you have a single external IP address, add the following to your
/etc/shorewall/rules file:</p><p><code class="filename">/etc/shorewall/rules</code>:</p><pre class="programlisting">#ACTION SOURCE DEST PROTO DEST PORT(S)
DNAT net loc:<span class="emphasis"><em><server address></em></span> tcp 1723
DNAT net loc:<span class="emphasis"><em><server address></em></span> 47</pre><p>If you have multiple external IP address and you want to forward a
single <<span class="emphasis"><em>external address</em></span>>, add the following to
your /etc/shorewall/rules file:</p><p><code class="filename">/etc/shorewall/rules</code>:</p><pre class="programlisting">#ACTION SOURCE DEST PROTO DEST PORT(S) SOURCE ORIGINAL
# PORT(S) DEST
DNAT net loc:<span class="emphasis"><em><server address></em></span> tcp 1723 - <span class="emphasis"><em><external address></em></span>
DNAT net loc:<span class="emphasis"><em><server address></em></span> 47 - - <span class="emphasis"><em><external address></em></span></pre><p>You will also want to add this entry to your
<code class="filename">/etc/shorewall/masq</code> file:</p><pre class="programlisting">#INTERFACE SUBNET ADDRESS PROTO
<<span class="emphasis"><em>external interface</em></span>> <<span class="emphasis"><em>server address</em></span>> <<span class="emphasis"><em>external address</em></span>> 47</pre><div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Important</h3><p>Be sure that the above entry comes <span class="bold"><strong>before</strong></span> any other entry that might match the
server's address.</p></div></div><div class="section" lang="en" xml:lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ClientsBehind"></a>PPTP Clients Running Behind your Firewall</h2></div></div></div><p>Please see <a class="ulink" href="VPN.htm" target="_self">this article</a>.</p></div><div class="section" lang="en" xml:lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ClientFW"></a>PPTP Client Running on your Firewall</h2></div></div></div><p>The key elements of this setup are as follows:</p><div class="orderedlist"><ol type="1"><li><p>Define a zone for the remote network accessed via PPTP.</p></li><li><p>Associate that zone with a ppp interface.</p></li><li><p>Define rules for PPTP traffic to/from the firewall.</p></li><li><p>Define rules for traffic two and from the remote zone.</p></li></ol></div><p>Here are examples from one of my old setups:</p><p><code class="filename">/etc/shorewall/zones</code>:</p><pre class="programlisting">#ZONE TYPE
cpq ipv4</pre><p><code class="filename">/etc/shorewall/interfaces</code>:</p><pre class="programlisting">#ZONE INTERFACE BROADCAST OPTIONS
- ppp+</pre><p>/etc/shorewall/hosts:</p><pre class="programlisting">#ZONE HOST(S) OPTIONS
cpq ppp+:!192.168.1.0/24</pre><p><code class="filename">/etc/shorewall/tunnels</code>:</p><pre class="programlisting">#TYPE ZONE GATEWAY GATEWAY ZONE
pptpclient net 0.0.0.0/0</pre><p>I use the combination of interface and hosts file to define the
“<span class="quote">cpq</span>” zone because I also run a PPTP server on my firewall
(see above). Using this technique allows me to distinguish clients of my
own PPTP server from arbitrary hosts at Compaq; I assign addresses in
192.168.1.0/24 to my PPTP clients and Compaq doesn't use that RFC1918
Class C subnet.</p><p>I use this script in /etc/init.d to control the client. The reason
that I disable ECN when connecting is that the Compaq tunnel servers don't
do ECN yet and reject the initial TCP connection request if I enable ECN
:-(</p><pre class="programlisting">#!/bin/sh
#
# /etc/rc.d/init.d/pptp
#
# chkconfig: 5 60 85
# description: PPTP Link Control
#
NAME="Tandem"
ADDRESS=tunnel-tandem.compaq.com
USER='Tandem\tommy'
ECN=0
DEBUG=
start_pptp() {
echo $ECN > /proc/sys/net/ipv4/tcp_ecn
if /usr/sbin/pptp $ADDRESS user $USER noauth $DEBUG; then
touch /var/lock/subsys/pptp
echo "PPTP Connection to $NAME Started"
fi
}
stop_pptp() {
if killall /usr/sbin/pptp 2> /dev/null; then
echo "Stopped pptp"
else
rm -f /var/run/pptp/*
fi
# if killall pppd; then
# echo "Stopped pppd"
# fi
rm -f /var/lock/subsys/pptp
echo 1 > /proc/sys/net/ipv4/tcp_ecn
}
case "$1" in
start)
echo "Starting PPTP Connection to ${NAME}..."
start_pptp
;;
stop)
echo "Stopping $NAME PPTP Connection..."
stop_pptp
;;
restart)
echo "Restarting $NAME PPTP Connection..."
stop_pptp
start_pptp
;;
status)
ifconfig
;;
*)
echo "Usage: $0 {start|stop|restart|status}"
;;
esac</pre><p>Here's my /etc/ppp/options file:</p><pre class="programlisting">#
# Identify this connection
#
ipparam Compaq
#
# Lock the port
#
lock
#
# We don't need the tunnel server to authenticate itself
#
noauth
+chap
+chapms
+chapms-v2
multilink
mrru 1614
#
# Turn off transmission protocols we know won't be used
#
nobsdcomp
nodeflate
#
# We want MPPE
#
mppe-128
mppe-stateless
#
# We want a sane mtu/mru
#
mtu 1000
mru 1000
#
# Time this thing out of it goes poof
#
lcp-echo-failure 10
lcp-echo-interval 10</pre><p>My /etc/ppp/ip-up.local file sets up the routes that I need to route
Compaq traffic through the PPTP tunnel:</p><pre class="programlisting">#/bin/sh
case $6 in
Compaq)
route add -net 16.0.0.0 netmask 255.0.0.0 gw $5 $1
route add -net 130.252.0.0 netmask 255.255.0.0 gw $5 $1
route add -net 131.124.0.0 netmask 255.255.0.0 gw $5 $1
...
;;
esac</pre><p>Finally, I run the following script every five minutes under crond
to restart the tunnel if it fails:</p><pre class="programlisting">#!/bin/sh
restart_pptp() {
/sbin/service pptp stop
sleep 10
if /sbin/service pptp start; then
/usr/bin/logger "PPTP Restarted"
fi
}
if [ -n "`ps ax | grep /usr/sbin/pptp | grep -v grep`" ]; then
exit 0
fi
echo "Attempting to restart PPTP"
restart_pptp > /dev/null 2>&1 &</pre><p><a class="ulink" href="ftp://ftp.shorewall.net/pub/shorewall/misc/Vonau" target="_self">Here's
a script and corresponding ip-up.local</a> from Jerry Vonau
<code class="email"><<a class="email" href="mailto:jvonau@home.com">jvonau@home.com</a>></code> that controls two PPTP connections.</p></div><div class="section" lang="en" xml:lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="PPTP_ADSL"></a>PPTP Client running on your Firewall with PPTP Server in an ADSL
Modem</h2></div></div></div><p>Some ADSL systems in Europe (most notably in Austria and the
Netherlands) feature a PPTP server builtinto an ADSL “<span class="quote">Modem</span>”.
In this setup, an Ethernet interface is dedicated to supporting the PPTP
tunnel between the firewall and the “<span class="quote">Modem</span>” while the actual
Internet access is through PPTP (interface ppp0). If you have this type of
setup, you need to modify the sample configuration that you downloaded as
described in this section. <span class="bold"><strong>These changes are in
addition to those described in the <a class="ulink" href="shorewall_quickstart_guide.htm" target="_self">QuickStart
Guides</a>.</strong></span></p><p>Lets assume the following:</p><div class="itemizedlist"><ul type="disc"><li><p>ADSL Modem connected through eth0</p></li><li><p>Modem IP address = 192.168.1.1</p></li><li><p>eth0 IP address = 192.168.1.2</p></li></ul></div><p>The changes you need to make are as follows:</p><div class="orderedlist"><ol type="1"><li><p>Add this entry to /etc/shorewall/zones:</p><pre class="programlisting">#ZONE TYPE
modem ipv4</pre><p>That entry defines a new zone called “<span class="quote">modem</span>” which
will contain only your ADSL modem.</p></li><li><p>Add the following entry to /etc/shorewall/interfaces:</p><pre class="programlisting">#ZONE INTERFACE BROADCAST OPTIONS
modem eth0 192.168.1.255 dhcp</pre><p>You will of course modify the “<span class="quote">net</span>” entry in
/etc/shorewall/interfaces to specify “<span class="quote">ppp0</span>” as the
interface as described in the QuickStart Guide corresponding to your
setup.</p></li><li><p>Add the following to /etc/shorewall/tunnels:</p><pre class="programlisting">#TYPE ZONE GATEWAY GATEWAY ZONE
pptpclient modem 192.168.1.1</pre><p>That entry allows a PPTP tunnel to be established between your
Shorewall system and the PPTP server in the modem.</p></li></ol></div></div></div></body></html>
