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1.1.1.4 ! misho       9: <A HREF="mpd.html"><EM>Mpd 5.9 User Manual</EM></A>
1.1       misho      10:  <b>:</b> <A HREF="mpd42.html"><EM>Device Types</EM></A>
                     11:  <b>:</b> <EM>PPTP device type commands</EM><BR>
                     12: <b>Previous:</b> <A HREF="mpd46.html"><EM>UDP device type commands</EM></A><BR>
                     13: <b>Next:</b> <A HREF="mpd48.html"><EM>L2TP device type commands</EM></A>
                     14: 
                     15: 
                     16: <HR NOSHADE>
                     17:   <H2><A NAME="47"></A>5.5. PPTP device type commands<A NAME="pptp"></A></H2>
                     18: <p>This chapter describes commands that are specific to PPTP type links.
                     19: These commands apply to the currently active link, and are only
                     20: valid if the currently active link has type <b>pptp</b>.</p>
                     21: <p>The PPTP protocol can be most easily understood as just another
                     22: link layer type, where the link layer medium just happens to be
                     23: an IP connection. So, for example, instead of configuring a
                     24: telephone number to dial as you would with a modem, you configure
                     25: an IP address to connect to. Everything else that's above the
                     26: link layer functions exactly the same. Hence PPTP allows you
                     27: to ``tunnel'' PPP frames over IP.</p>
                     28: <p>Note that PPTP connections are initiated by a TCP connection from
                     29: one machine to another, and that servers usually listen to TCP
                     30: port 1723 (and this is the default for <code><em>port</em></code>
                     31: in the commands below). PPTP also uses the GRE protocol, which
                     32: has IP protocol number 47. Your firewall may need to be adjusted
                     33: to allows this type of IP packet.</p>
                     34: <p>Complete PPTP network topology looks like:
                     35: <pre>
                     36: client &lt;- some link type -&gt; PAC &lt;- PPTP tunnel -&gt; PNS
                     37: </pre>
                     38: </p>
                     39: <p>PAC is physical level repeater, which receives PPP connection of some 
                     40: type and forwards it to PNS using PPTP protocol. PNS is a PPP endpoint, 
                     41: which receives PPP frames via PPTP tunnel and processes them.</p>
                     42: <p>In simple case, when physical conversion is not required, topology 
                     43: can be simplified to:
                     44: <pre>
                     45: client (PAC emulator) &lt;- PPTP tunnel -&gt; PNS
                     46: </pre>
                     47: </p>
                     48: <p>Mpd is able to operate in both PAC and PNS modes. As PAC mpd supports 
                     49: both simple case PAC emulator and complete PAC topologies. Complete 
                     50: PAC can be configured by joining two physical devices using mpd's
                     51: repeater functionality.</p>
                     52: <p>
                     53: <dl>
                     54: 
                     55: <dt><b><code>set pptp self <em>ipaddr</em> [ <em>port</em> ]</code></b><dd><p>Sets the local IP address and port for the PPTP connection.</p>
                     56: 
                     57: <dt><b><code>set pptp peer <em>ipaddr</em> [ <em>port</em> ]</code></b><dd><p>Sets the peer IP address and port for the PPTP connection.
                     58: This command applies to both incoming and outgoing connections.
                     59: For outgoing connections, this command is required in order to
                     60: specify where to connect to. For incoming connections, this command
                     61: is optional; if not given, mpd accepts incoming connections from any
                     62: host. Otherwise, only connections from the stated IP address
                     63: (and, optionally, port) are allowed.</p>
                     64: 
                     65: <dt><b><code>set pptp callingnum <em>number</em></code></b><dd>
                     66: <dt><b><code>set pptp callednum <em>number</em></code></b><dd><p>Sets the calling and called telephone number to use when initiating a PPTP
                     67: connection. For most VPN applications this is ignored, but in certain
                     68: cases an actual phone number is required.
                     69: The default is the empty string.</p>
                     70: 
                     71: <dt><b><code>set pptp enable <em>option ...</em> </code></b><dd>
                     72: <dt><b><code>set pptp disable <em>option ...</em> </code></b><dd>
                     73: <p>Enable and disable PPTP device type options for the link.</p>
                     74: 
                     75: </dl>
                     76: </p>
                     77: 
                     78: <p>The following options are supported:</p>
                     79: <p>
                     80: <dl>
                     81: 
                     82: <dt><b><code>outcall</code></b><dd><p>In PPTP, each individual PPP connection between two IP hosts (there
                     83: may be several, and these are not to be confused with the
                     84: <em>single</em> TCP connection between any two IP hosts), is
                     85: initiated as either an incoming or an outgoing call. 
                     86: This allows to make an outgoing phone call (by PNS) via a remote access
                     87: server (PAC), as well as in more common case forward an incoming
                     88: phone call from an access server (PAC) to a remote PPTP server (PNS).</p>
                     89: <p>When this option is enabled, mpd will initiate outgoing calls (PNS);
                     90: otherwise mpd will initiate incoming calls (PAC). Although it seems that
                     91: incoming would be more correct, the default is outgoing, as this
                     92: is consistent with the behavior of the Microsoft PPTP dial-up adapter
                     93: client.</p>
                     94: <p>Mpd will accept either type of call on an incoming PPTP connection.</p>
                     95: 
                     96: <dt><b><code>delayed-ack</code></b><dd><p>Enable delayed ACK's. This can improve throughput on reliable links.</p>
                     97: <p>The default is enable.</p>
                     98: 
                     99: <dt><b><code>always-ack</code></b><dd><p>Always include ACK even if already sent. This can improve throughput
                    100: on unreliable links.</p>
                    101: <p>The default is disable.</p>
                    102: 
                    103: <dt><b><code>windowing</code></b><dd><p>Enables the windowing mechanism specified by the protocol. Disabling 
                    104: this will cause Mpd to violate the protocol, possibly confusing some 
                    105: PPTP peers, but usually results in better performance. The windowing 
                    106: mechanism is a design error in the PPTP protocol; L2TP, the successor 
                    107: to PPTP, removes it.</p>
                    108: <p>The default is disable.</p>
                    109: 
                    110: <dt><b><code>resolve-once</code></b><dd><p>Enables resolving peer address only once, on startup, or on manual
                    111: typing in CLI.</p>
                    112: <p>The default is enable.</p>
                    113: 
                    114: </dl>
                    115: </p>
                    116: <p>Note that if you are connecting to an NT server, your authentication
                    117: name must include the NT domain name. For example:</p>
                    118: <p>
                    119: <blockquote><code>
                    120: <pre>
                    121:     set auth authname "DOMAIN\\username"
                    122: </pre>
                    123: </code></blockquote>
                    124: </p>
                    125: <p>For updating Windows 95 and 98 clients so they work properly, see
1.1.1.4 ! misho     126: <A href="http://support.microsoft.com/default.aspx?scid=KB;EN-US;Q191540">VPN Update for Windows 98 and Dial-Up Networking 1.3 Available</A></p>
1.1       misho     127: 
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                    130:  <HR NOSHADE>
1.1.1.4 ! misho     131: <A HREF="mpd.html"><EM>Mpd 5.9 User Manual</EM></A>
1.1       misho     132:  <b>:</b> <A HREF="mpd42.html"><EM>Device Types</EM></A>
                    133:  <b>:</b> <EM>PPTP device type commands</EM><BR>
                    134: <b>Previous:</b> <A HREF="mpd46.html"><EM>UDP device type commands</EM></A><BR>
                    135: <b>Next:</b> <A HREF="mpd48.html"><EM>L2TP device type commands</EM></A>
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