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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 <- some link type -> PAC <- PPTP tunnel -> 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) <- PPTP tunnel -> 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:
128:
129:
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>
136:
137:
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139: </BODY>
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