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9: <A HREF="mpd.html"><EM>Mpd 5.6 User Manual</EM></A>
10: <b>:</b> <A HREF="mpd17.html"><EM>Configuring Mpd</EM></A>
11: <b>:</b> <EM>Interface layer</EM><BR>
12: <b>Previous:</b> <A HREF="mpd27.html"><EM>IPv6CP layer</EM></A><BR>
13: <b>Next:</b> <A HREF="mpd29.html"><EM>Authentication, Authorization and Accounting (AAA)</EM></A>
14:
15:
16: <HR NOSHADE>
17: <H2><A NAME="28"></A>4.9. Interface layer<A NAME="interface"></A></H2>
18:
19: <p>This chapter describes commands that configure the interface layer.
20: All of these commands apply to the currently active bundle.</p>
21: <p>Note that while most of the time mpd is used for transmitting
22: IP traffic, it is designed to support other (currently unimplemented)
23: protocols such as AppleTalk, IPX, etc. This is why the Interface
24: layer (which is protocol independent) is distinct from the
25: <A HREF="mpd26.html#ipcp">ipcp</A> which is specific to IP.</p>
26: <p>
27: <dl>
28:
29: <dt><b><code>set iface name [ <em>name</em> ]</code></b><dd><p>This command changes interface name from default ngX to specified one.
30: If name argument is not specified, original ngX name is restored.
31: Note that inside Netgraph original ngX name is always used.</p>
32:
33: <dt><b><code>set iface description [ <em>description</em> ]</code></b><dd><p>This command changes interface description.</p>
34:
35: <dt><b><code>set iface group [ <em>group</em> ]</code></b><dd><p>This command add interface to specific group.</p>
36:
37: <dt><b><code>set iface addrs [!]<em>local-ip</em> [!]<em>remote-ip</em></code></b><dd><p>This command is usually required when dial-on-demand is enabled.
38: Normally, mpd configures the interface with the IP addresses that
39: were negotiated when connecting the link. Since dial-on-demand
40: configures the interface before actually connecting, mpd has to be
41: told initial local and remote IP addresses to give the interface.
42: These addresses don't have to correspond to the ``real'' ones; in
43: fact, both addresses can be completely fictional. If and when
44: different addresses are negotiated later, mpd will automatically
45: renumber the interface and adjust the routes.</p>
46: <p>Also this command may be used to force specified addresses usage
47: instead of negotiated ones. It may be useful in some specific cases,
48: for example, to avoid routing loop with misconfigured PPTP server.
49: In such case '!' mark specifies IPs to be forced.</p>
50:
51: <dt><b><code>set iface route <em>address[/width]</em></code></b><dd><p>This command associates a route with the bundle. Whenever the
52: interface is configured up, all associated routes are added.
53: A route of <code><b>default</b></code> indicates the default route.
54: Otherwise, the route is a network address with optional netmask
55: width (e.g., <code><b>192.168.1.0/24</b></code>). If the netmask
56: width is omitted, a single host route is assumed (i.e., a width
57: of 32).</p>
58: <p>Routes are automatically removed when the interface is brought down.</p>
59:
60: <dt><b><code>set iface mtu <em>value</em></code></b><dd><p>This command sets an upper bound on the MTU that will be configured
61: on the interface when the bundle comes up.
62: This value is not used at all during link negotiation; there are
63: separate bundle and link commands for configuring that.
64: Even if a higher bundle MTU is negotiated, this limit will still apply.</p>
65: <p>This command is useful when you want to manually restrict the MTU
66: of the interface for other reasons, e.g., if you're also doing IPSec.</p>
67: <p>The default is 1500.</p>
68:
69: <dt><b><code>set iface idle <em>seconds</em></code></b><dd><p>Sets the idle timeout value for the bundle. If no incoming or
70: outgoing packets are transmitted for <code><em>seconds</em></code>
71: seconds, the connection is brought down. An idle timeout of
72: zero disables this feature.</p>
73: <p>When the idle timeout occurs, if the dial-on-demand option is
74: enabled, mpd goes back into dial-on-demand mode. Otherwise, the
75: interface is brought down and all associated routes removed.</p>
76: <p>The default is 0.</p>
77:
78: <dt><b><code>set iface session <em>seconds</em></code></b><dd><p>Sets the session timeout value for the bundle. An session timeout of
79: zero disables this feature.</p>
80: <p>The default is 0.</p>
81:
82: <dt><b><code>set iface up-script <em>script</em> </code></b><dd>
83: <dt><b><code>set iface down-script <em>script</em> </code></b><dd>
84: <p>Mpd can optionally run a user program every time one of network
85: protocols (IPCP/IPv6CP) at the interface is brought up or down.
86: The <code><b>up-script</b></code> is called like this:
87: <blockquote><code>
88: <code><em>script</em> <em>interface</em> <em>proto</em> <em>local-ip</em> <em>remote-ip</em> <em>authname</em> [ dns1 <em>server-ip</em> ] [ dns2 <em>server-ip</em> ]
89: <em>peer-address</em></code>
90: </code></blockquote>
91: </p>
92: <p>If up-script exit status is not 0, mpd will kill respective protocol.</p>
93: <p>The <code><b>down-script</b></code> is called like this:
94: <blockquote><code>
95: <code><em>script</em> <em>interface</em> <em>proto</em> <em>local-ip</em> <em>remote-ip</em> <em>authname</em> <em>peer-address</em></code>
96: </code></blockquote>
97: </p>
98:
99: <dt><b><code>set iface enable <em>option ...</em><br>
100: set iface disable <em>option ...</em></code></b><dd><p>Enable and disable the various interface layer options for the bundle.</p>
101:
102: </dl>
103: </p>
104:
105: <p>The options available at the interface layer are:</p>
106: <p>
107: <dl>
108:
109: <dt><b><code>on-demand</code></b><dd><p>This option causes the interface to operate in dial-on-demand mode,
110: allowing you to have a ``virtual full time'' connection.
111: An OPEN event causes the interface to be configured, but the actual
112: connection of the link is delayed until qualifying outgoing traffic
113: is detected. Moreover, after an idle timeout, the interface is not
114: brought down; further traffic will bring the link back up again.</p>
115: <p>The default is disable.</p>
116:
117: <dt><b><code>proxy-arp</code></b><dd><p>When this option is enabled, if after link negotiation the peer's
118: IP address is determined to lie on a local subnet, then mpd will
119: arrange for the local machine to install a proxy ARP entry for
120: the remote machine's IP address.</p>
121: <p>For example, suppose the local machine lies on a LAN with address
122: 192.168.1.10, and another machine will be connecting via mpd
123: and using the LAN address 192.168.1.20. Then these commands would
124: set up proxy ARP for the remote machine:
125: <blockquote><code>
126: <code>set iface enable proxy-arp<br>
127: set ipcp ranges 192.168.1.10/32 192.168.1.20/32</code>
128: </code></blockquote>
129: </p>
130: <p>The default is disable.</p>
131:
132: <dt><b><code>tcpmssfix</code></b><dd><p>This option causes mpd to adjust incoming and outgoing TCP SYN
133: segments so that the requested maximum segment size is not greater
134: than the amount allowed by the interface MTU.</p>
135: <p>This is necessary in many setups to avoid problems caused by routers
136: that drop ICMP Datagram Too Big messages. Without these messages,
137: the originating machine sends data, it passes the rogue router then
138: hits a machine that has an MTU that is not big enough for the data.
139: Because the IP Don't Fragment option is set, this machine sends an
140: ICMP Datagram Too Big message back to the originator and drops the
141: packet. The rogue router drops the ICMP message and the originator
142: never gets to discover that it must reduce the fragment size or drop
143: the IP Don't Fragment option from its outgoing data.</p>
144: <p>The code is based on tcpmssd wich was written by Ruslan Ermilov
145: <A href="mailto:<ru@FreeBSD.org>">mailto:<ru@FreeBSD.org></A>
146: based on work done by Patrick Bihan-Faou
147: <A href="mailto:<patrick@mindstep.com>">mailto:<patrick@mindstep.com></A>.</p>
148: <p>The default is disable.</p>
149:
150: <dt><b><code>tee</code></b><dd><p>If enabled, a ng_tee(4) node will be inserted
151: into the bundle graph, right after the interface node. The tee node
152: can be useful for debugging or traffic accounting.</p>
153: <p>The default is disable.</p>
154:
155: <dt><b><code>nat</code></b><dd><p>Enable NAT for this bundle.
156: See
157: <A HREF="mpd39.html#nat">nat</A> for more information.</p>
158: <p>The default is disable.</p>
159:
160: <dt><b><code>netflow-in</code></b><dd>
161: <dt><b><code>netflow-out</code></b><dd>
162: <dt><b><code>netflow-once</code></b><dd><p>If enabled, the bundle will participate in
163: NetFlow generation. See
164: <A HREF="mpd34.html#netflow">netflow</A>
165: for more information. The netflow-out option is like netflow-in, but
166: generates NetFlow data for outgoing packets instead of incoming.
167: If netflow-once enabled - packet will be accounted only once while
168: in kernel.</p>
169: <p>The default is disable.</p>
170:
171: <dt><b><code>ipacct</code></b><dd><p>If enabled, the bundle will participate in IP accounting with ng_ipacct node.
172: See
173: <A HREF="mpd35.html#ipacct">ipacct</A> for more information.</p>
174: <p>The default is disable.</p>
175:
176: </dl>
177: </p>
178: <HR NOSHADE>
179: <A HREF="mpd.html"><EM>Mpd 5.6 User Manual</EM></A>
180: <b>:</b> <A HREF="mpd17.html"><EM>Configuring Mpd</EM></A>
181: <b>:</b> <EM>Interface layer</EM><BR>
182: <b>Previous:</b> <A HREF="mpd27.html"><EM>IPv6CP layer</EM></A><BR>
183: <b>Next:</b> <A HREF="mpd29.html"><EM>Authentication, Authorization and Accounting (AAA)</EM></A>
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