MLPPP not working in cluster mode.
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25 <H1>L2TPNS Manual</H1>
26 <OL>
27 <LI><A HREF="#Overview">Overview</A></LI>
28 <LI><A HREF="#Installation">Installation</A>
29 <OL>
30 <LI><A HREF="#Requirements">Requirements</A></LI>
31 <LI><A HREF="#Compile">Compile</A></LI>
32 <LI><A HREF="#Install">Install</A></LI>
33 <LI><A HREF="#Running">Running</A></LI>
34 </OL>
35 </LI>
36 <LI><A HREF="#Configuration">Configuration</A>
37 <OL>
38 <LI><A HREF="#startup-config">startup-config</A></LI>
39 <LI><A HREF="#users">users</A></LI>
40 <LI><A HREF="#ip-pool">ip_pool</A></LI>
41 <LI><A HREF="#build-garden">build-garden</A></LI>
42 </OL>
43 </LI>
44 <LI><A HREF="#ControllingtheProcess">Controlling the Process</A>
45 <OL>
46 <LI><A HREF="#Command-LineInterface">Command-Line Interface</A></LI>
47 <LI><A HREF="#nsctl">nsctl</A></LI>
48 <LI><A HREF="#Signals">Signals</A></LI>
49 </OL>
50 </LI>
51 <LI><A HREF="#Throttling">Throttling</A></LI>
52 <LI><A HREF="#Interception">Interception</A></LI>
53 <LI><A HREF="#Authentication">Authentication</A></LI>
54 <LI><A HREF="#Plugins">Plugins</A></LI>
55 <LI><A HREF="#WalledGarden">Walled Garden</A></LI>
56 <LI><A HREF="#Filtering">Filtering</A></LI>
57 <LI><A HREF="#Clustering">Clustering</A></LI>
58 <LI><A HREF="#Routing">Routing</A></LI>
59 <LI><A HREF="#Performance">Performance</A></LI>
60 </OL>
61
62 <H2 ID="Overview">Overview</H2>
63 l2tpns is half of a complete L2TP implementation. It supports only the
64 LNS side of the connection.<P>
65
66 L2TP (Layer 2 Tunneling Protocol) is designed to allow any layer 2
67 protocol (e.g. Ethernet, PPP) to be tunneled over an IP connection. l2tpns
68 implements PPP over L2TP only.<P>
69
70 There are a couple of other L2TP implementations, of which <A
71 HREF="http://sourceforge.net/projects/l2tpd">l2tpd</A> is probably the
72 most popular. l2tpd also will handle being either end of a tunnel, and
73 is a lot more configurable than l2tpns. However, due to the way it works,
74 it is nowhere near as scalable.<P>
75
76 l2tpns uses the TUN/TAP interface provided by the Linux kernel to receive
77 and send packets. Using some packet manipulation it doesn't require a
78 single interface per connection, as l2tpd does.<P>
79
80 This allows it to scale extremely well to very high loads and very high
81 numbers of connections.<P>
82
83 It also has a plugin architecture which allows custom code to be run
84 during processing. An example of this is in the walled garden module
85 included.<P>
86
87 <BR>
88 <EM>Documentation is not my best skill. If you find any problems
89 with this document, or if you wish to contribute, please email <A
90 HREF="mailto:l2tpns-users@lists.sourceforge.net?subject=L2TPNS+Documentation">the mailing list</A>.</EM><P>
91
92 <H2 ID="Installation">Installation</H2>
93 <H3 ID="Requirements">Requirements</H3>
94
95 <OL>
96 <LI>Linux kernel version 2.4 or above, with the Tun/Tap interface either
97 compiled in, or as a module.</LI>
98
99 <LI>libcli 1.8.0 or greater.<BR>You can get this from <A
100 HREF="http://sourceforge.net/projects/libcli">http://sourceforge.net/projects/libcli</A></LI>
101 </OL>
102
103 <H3 ID="Compile">Compile</H3>
104
105 You can generally get away with just running <B>make</B> from the source
106 directory. This will compile the daemon, associated tools and any modules
107 shipped with the distribution.<P>
108
109 <H3 ID="Install">Install</H3>
110
111 After you have successfully compiled everything, run <B>make
112 install</B> to install it. By default, the binaries are installed into
113 <EM>/usr/sbin</EM>, the configuration into <EM>/etc/l2tpns</EM>, and the
114 modules into <EM>/usr/lib/l2tpns</EM>.<P>
115
116 You will definately need to edit the configuration files before you
117 start. See the <A HREF="#Configuration">Configuration</A> section for
118 more information.<P>
119
120 <H3 ID="Running">Running</H3>
121
122 You only need to run <B>/usr/sbin/l2tpns</B> as root to start it. It does
123 not detach to a daemon process, so you should perhaps run it from init.<P>
124
125 By default there is no log destination set, so all log messages will go to
126 stdout.<P>
127
128 <H2 ID="Configuration">Configuration</H2>
129
130 All configuration of the software is done from the files installed into
131 /etc/l2tpns.
132
133 <H3 ID="startup-config">startup-config</H3>
134
135 This is the main configuration file for l2tpns. The format of the file is a
136 list of commands that can be run through the command-line interface. This
137 file can also be written directly by the l2tpns process if a user runs the
138 <EM>write memory</EM> command, so any comments will be lost. However if your
139 policy is not to write the config by the program, then feel free to comment
140 the file with a # or ! at the beginning of the line.<P>
141
142 A list of the possible configuration directives follows. Each of these
143 should be set by a line like:<P>
144 <PRE>
145 set configstring "value"
146 set ipaddress 192.168.1.1
147 set boolean true
148 </PRE>
149
150 <P>
151 <UL>
152 <LI><B>debug</B> (int)<BR>
153 Sets the level of messages that will be written to the log file. The value
154 should be between 0 and 5, with 0 being no debugging, and 5 being the
155 highest. A rough description of the levels is:
156 <OL>
157 <LI VALUE=0>Critical Errors - Things are probably broken</LI>
158 <LI>Errors - Things might have gone wrong, but probably will recover</LI>
159 <LI>Warnings - Just in case you care what is not quite perfect</LI>
160 <LI>Information - Parameters of control packets</LI>
161 <LI>Calls - For tracing the execution of the code</LI>
162 <LI>Packets - Everything, including a hex dump of all packets processed... probably twice</LI>
163 </OL><P>
164 Note that the higher you set the debugging level, the slower the program
165 will run. Also, at level 5 a LOT of information will be logged. This should
166 only ever be used for working out why it doesn't work at all.
167 </LI>
168
169 <LI><B>log_file</B> (string)<BR>
170 This will be where all logging and debugging information is written
171 to. This may be either a filename, such as <EM>/var/log/l2tpns</EM>, or
172 the special magic string <EM>syslog:facility</EM>, where <EM>facility</EM>
173 is any one of the syslog logging facilities, such as local5.
174 </LI>
175
176 <LI><B>pid_file</B> (string)<BR>
177 If set, the process id will be written to the specified file. The
178 value must be an absolute path.
179 </LI>
180
181 <LI><B>l2tp_secret</B> (string)<BR>
182 The secret used by l2tpns for authenticating tunnel request. Must be
183 the same as the LAC, or authentication will fail. Only actually be
184 used if the LAC requests authentication.
185 </LI>
186
187 <LI><B>l2tp_mtu</B> (int)<BR>
188 MTU of interface for L2TP traffic (default: 1500). Used to set link
189 MRU and adjust TCP MSS.
190 </LI>
191
192 <LI><B>ppp_restart_time</B> (int)<BR>
193 <B>ppp_max_configure</B> (int)<BR>
194 <B>ppp_max_failure</B> (int)<BR>
195 PPP counter and timer values, as described in &sect;4.1 of
196 <a href="ftp://ftp.rfc-editor.org/in-notes/rfc1661.txt">RFC1661</a>.
197 </LI>
198
199 <LI><B>primary_dns</B> (ip address)
200 <LI><B>secondary_dns</B> (ip address)<BR>
201 Whenever a PPP connection is established, DNS servers will be sent to the
202 user, both a primary and a secondary. If either is set to 0.0.0.0, then that
203 one will not be sent.
204 </LI>
205
206 <LI><B>primary_radius</B> (ip address)
207 <LI><B>secondary_radius</B> (ip address)<BR>
208 Sets the RADIUS servers used for both authentication and accounting.
209 If the primary server does not respond, then the secondary RADIUS
210 server will be tried.<br>
211 <strong>Note:</strong> in addition to the source IP address and
212 identifier, the RADIUS server <strong>must</strong> include the source
213 port when detecting duplicates to supress (in order to cope with a
214 large number of sessions comming on-line simultaneously l2tpns uses a
215 set of udp sockets, each with a seperate identifier).
216 </LI>
217
218 <LI><B>primary_radius_port</B> (short)
219 <LI><B>secondary_radius_port</B> (short)<BR>
220 Sets the authentication ports for the primary and secondary RADIUS
221 servers. The accounting port is one more than the authentication
222 port. If no RADIUS ports are given, the authentication port defaults
223 to 1645, and the accounting port to 1646.
224 </LI>
225
226 <LI><B>radius_accounting</B> (boolean)<BR>
227 If set to true, then RADIUS accounting packets will be sent. This
228 means that a Start record will be sent when the session is
229 successfully authenticated, and a Stop record will be sent when the
230 session is closed.
231 </LI>
232
233 <LI><B>radius_secret</B> (string)<BR>
234 This secret will be used in all RADIUS queries. If this is not set then
235 RADIUS queries will fail.
236 </LI>
237
238 <LI><B>radius_authtypes</B> (string)</BR>
239 A comma separated list of supported RADIUS authentication methods
240 (<B>pap</B> or <B>chap</B>), in order of preference (default <B>pap</B>).
241 </LI>
242
243 <LI><B>radius_dae_port</B> (short)<BR>
244 Port for DAE RADIUS (Packet of Death/Disconnect, Change of Authorization)
245 requests (default: <B>3799</B>).
246 </LI>
247
248 <LI><B>allow_duplicate_users</B> (boolean)</BR>
249 Allow multiple logins with the same username. If false (the default),
250 any prior session with the same username will be dropped when a new
251 session is established.
252 </LI>
253
254 <LI><B>bind_address</B> (ip address)<BR>
255 When the tun interface is created, it is assigned the address
256 specified here. If no address is given, 1.1.1.1 is used. Packets
257 containing user traffic should be routed via this address if given,
258 otherwise the primary address of the machine.
259 </LI>
260
261 <LI><B>peer_address</B> (ip address)<BR>
262 Address to send to clients as the default gateway.
263 </L1>
264
265 <LI><B>send_garp</B> (boolean)<BR>
266 Determines whether or not to send a gratuitous ARP for the
267 bind_address when the server is ready to handle traffic (default:
268 true).<BR>
269 This value is ignored if BGP is configured.
270 </LI>
271
272 <LI><B>throttle_speed</B> (int)<BR>
273 Sets the default speed (in kbits/s) which sessions will be limited to.
274 If this is set to 0, then throttling will not be used at all. Note:
275 You can set this by the CLI, but changes will not affect currently
276 connected users.
277 </LI>
278
279 <LI><B>throttle_buckets</B> (int)<BR>
280 Number of token buckets to allocate for throttling. Each throttled
281 session requires two buckets (in and out).
282 </LI>
283
284 <LI><B>accounting_dir</B> (string)<BR>
285 If set to a directory, then every 5 minutes the current usage for
286 every connected use will be dumped to a file in this directory. Each
287 file dumped begins with a header, where each line is prefixed by #.
288 Following the header is a single line for every connected user, fields
289 separated by a space.<BR> The fields are username, ip, qos,
290 uptxoctets, downrxoctets. The qos field is 1 if a standard user, and
291 2 if the user is throttled.
292 </LI>
293
294 <LI><B>setuid</B> (int)<BR>
295 After starting up and binding the interface, change UID to this. This
296 doesn't work properly.
297 </LI>
298
299 <LI><B>dump_speed</B> (boolean)<BR>
300 If set to true, then the current bandwidth utilization will be logged every
301 second. Even if this is disabled, you can see this information by running
302 the <EM>uptime</EM> command on the CLI.
303 </LI>
304
305 <LI><B>multi_read_count</B> (int)<BR>
306 Number of packets to read off each of the UDP and TUN fds when
307 returned as readable by select (default: 10). Avoids incurring the
308 unnecessary system call overhead of select on busy servers.
309 </LI>
310
311 <LI><B>scheduler_fifo</B> (boolean)<BR>
312 Sets the scheduling policy for the l2tpns process to SCHED_FIFO. This
313 causes the kernel to immediately preempt any currently running SCHED_OTHER
314 (normal) process in favour of l2tpns when it becomes runnable.
315 Ignored on uniprocessor systems.
316 </LI>
317
318 <LI><B>lock_pages</B> (boolean)<BR>
319 Keep all pages mapped by the l2tpns process in memory.
320 </LI>
321
322 <LI><B>icmp_rate</B> (int)<BR>
323 Maximum number of host unreachable ICMP packets to send per second.
324 </LI>
325
326 <LI><B>packet_limit</B> (int><BR>
327 Maximum number of packets of downstream traffic to be handled each
328 tenth of a second per session. If zero, no limit is applied (default:
329 0). Intended as a DoS prevention mechanism and not a general
330 throttling control (packets are dropped, not queued).
331 </LI>
332
333 <LI><B>cluster_address</B> (ip address)<BR>
334 Multicast cluster address (default: 239.192.13.13). See the section
335 on <A HREF="#Clustering">Clustering</A> for more information.
336 </LI>
337
338 <LI><B>cluster_interface</B> (string)<BR>
339 Interface for cluster packets (default: eth0).
340 </LI>
341
342 <LI><B>cluster_mcast_ttl</B> (int)<BR>
343 TTL for multicast packets (default: 1).
344 </LI>
345
346 <LI><B>cluster_hb_interval</B> (int)<BR>
347 Interval in tenths of a second between cluster heartbeat/pings.
348 </LI>
349
350 <LI><B>cluster_hb_timeout</B> (int)<BR>
351 Cluster heartbeat timeout in tenths of a second. A new master will be
352 elected when this interval has been passed without seeing a heartbeat
353 from the master.
354 </LI>
355
356 <LI><B>cluster_master_min_adv</B> (int)<BR>
357 Determines the minumum number of up to date slaves required before the
358 master will drop routes (default: 1).
359 </LI>
360
361 <LI><B>echo_timeout</B> (int)<BR>
362 Time between last packet sent and LCP ECHO generation
363 (default: 10 (seconds)).
364 </LI>
365
366 <LI><B>idle_echo_timeout</B> (int)<BR>
367 Drop sessions who have not responded within idle_echo_timeout seconds
368 (default: 240 (seconds))
369 </LI>
370
371 </UL>
372
373 <P>BGP routing configuration is entered by the command:
374 The routing configuration section is entered by the command
375 <DL><DD><B>router bgp</B> <I>as</I></DL>
376 where <I>as</I> specifies the local AS number.
377
378 <P>Subsequent lines prefixed with
379 <DL><DD><B>neighbour</B> <I>peer</I></DL>
380 define the attributes of BGP neighhbours. Valid commands are:
381 <DL>
382 <DD><B>neighbour</B> <I>peer</I> <B>remote-as</B> <I>as</I>
383 <DD><B>neighbout</B> <I>peer</I> <B>timers</B> <I>keepalive hold</I>
384 </DL>
385
386 Where <I>peer</I> specifies the BGP neighbour as either a hostname or
387 IP address, <I>as</I> is the remote AS number and <I>keepalive</I>,
388 <I>hold</I> are the timer values in seconds.
389
390 <P>Named access-lists are configured using one of the commands:
391 <DL>
392 <DD><B>ip access-list standard</B> <I>name</I>
393 <DD><B>ip access-list extended</B> <I>name</I>
394 </DL>
395
396 <P>Subsequent lines prefixed with <B>permit</B> or <B>deny</B>
397 define the body of the access-list. Standard access-list syntax:
398 <DL>
399 <DD>{<B>permit</B>|<B>deny</B>}
400 {<I>host</I>|<I>source source-wildcard</I>|<B>any</B>}
401 [{<I>host</I>|<I>destination destination-wildcard</I>|<B>any</B>}]
402 </DL>
403
404 Extended access-lists:
405
406 <DIV STYLE="margin-left: 4em; text-indent: -2em">
407 <P>{<B>permit</B>|<B>deny</B>} <B>ip</B>
408 {<I>host</I>|<I>source source-wildcard</I>|<B>any</B>}
409 {<I>host</I>|<I>destination destination-wildcard</I>|<B>any</B>} [<B>fragments</B>]
410 <P>{<B>permit</B>|<B>deny</B>} <B>udp</B>
411 {<I>host</I>|<I>source source-wildcard</I>|<B>any</B>}
412 [{<B>eq</B>|<B>neq</B>|<B>gt</B>|<B>lt</B>} <I>port</I>|<B>range</B> <I>from</I> <I>to</I>]
413 {<I>host</I>|<I>destination destination-wildcard</I>|<B>any</B>}
414 [{<B>eq</B>|<B>neq</B>|<B>gt</B>|<B>lt</B>} <I>port</I>|<B>range</B> <I>from</I> <I>to</I>]
415 [<B>fragments</B>]
416 <P>{<B>permit</B>|<B>deny</B>} <B>tcp</B>
417 {<I>host</I>|<I>source source-wildcard</I>|<B>any</B>}
418 [{<B>eq</B>|<B>neq</B>|<B>gt</B>|<B>lt</B>} <I>port</I>|<B>range</B> <I>from</I> <I>to</I>]
419 {<I>host</I>|<I>destination destination-wildcard</I>|<B>any</B>}
420 [{<B>eq</B>|<B>neq</B>|<B>gt</B>|<B>lt</B>} <I>port</I>|<B>range</B> <I>from</I> <I>to</I>]
421 [{<B>established</B>|{<B>match-any</B>|<B>match-all</B>}
422 {<B>+</B>|<B>-</B>}{<B>fin</B>|<B>syn</B>|<B>rst</B>|<B>psh</B>|<B>ack</B>|<B>urg</B>}
423 ...|<B>fragments</B>]
424 </DIV>
425
426 <H3 ID="users">users</H3>
427
428 Usernames and passwords for the command-line interface are stored in
429 this file. The format is <I>username</I><B>:</B><I>password</I> where
430 <I>password</I> may either by plain text, an MD5 digest (prefixed by
431 <B>$1</B><I>salt</I><B>$</B>) or a DES password, distinguished from
432 plain text by the prefix <B>{crypt}</B>.<P>
433
434 The username <B>enable</B> has a special meaning and is used to set
435 the enable password.<P>
436
437 <B>Note:</B> If this file doesn't exist, then anyone who can get to
438 port 23 will be allowed access without a username / password.<P>
439
440 <H3 ID="ip-pool">ip_pool</H3>
441
442 This file is used to configure the IP address pool which user
443 addresses are assigned from. This file should contain either an IP
444 address or a CIDR network per line. e.g.:<P>
445
446 <PRE>
447 192.168.1.1
448 192.168.1.2
449 192.168.1.3
450 192.168.4.0/24
451 172.16.0.0/16
452 10.0.0.0/8
453 </PRE>
454
455 Keep in mind that l2tpns can only handle 65535 connections per
456 process, so don't put more than 65535 IP addresses in the
457 configuration file. They will be wasted.
458
459 <H3 ID="build-garden">build-garden</H3>
460
461 The garden plugin on startup creates a NAT table called "garden" then
462 sources the <B>build-garden</B> script to populate that table. All
463 packets from gardened users will be sent through this table. Example:
464
465 <PRE>
466 iptables -t nat -A garden -p tcp -m tcp --dport 25 -j DNAT --to 192.168.1.1
467 iptables -t nat -A garden -p udp -m udp --dport 53 -j DNAT --to 192.168.1.1
468 iptables -t nat -A garden -p tcp -m tcp --dport 53 -j DNAT --to 192.168.1.1
469 iptables -t nat -A garden -p tcp -m tcp --dport 80 -j DNAT --to 192.168.1.1
470 iptables -t nat -A garden -p tcp -m tcp --dport 110 -j DNAT --to 192.168.1.1
471 iptables -t nat -A garden -p tcp -m tcp --dport 443 -j DNAT --to 192.168.1.1
472 iptables -t nat -A garden -p icmp -m icmp --icmp-type echo-request -j DNAT --to 192.168.1.1
473 iptables -t nat -A garden -p icmp -j ACCEPT
474 iptables -t nat -A garden -j DROP
475 </PRE>
476
477 <H2 ID="ControllingtheProcess">Controlling the Process</H2>
478
479 A running l2tpns process can be controlled in a number of ways. The primary
480 method of control is by the Command-Line Interface (CLI).<P>
481
482 You can also remotely send commands to modules via the nsctl client
483 provided.<P>
484
485 Also, there are a number of signals that l2tpns understands and takes action
486 when it receives them.
487
488 <H3 ID="Command-LineInterface">Command-Line Interface</H3>
489
490 You can access the command line interface by telnet'ing to port 23.
491 There is no IP address restriction, so it's a good idea to firewall
492 this port off from anyone who doesn't need access to it. See
493 <A HREF="#users">users</A> for information on restricting access based
494 on a username and password.<P>
495
496 The CLI gives you real-time control over almost everything in
497 the process. The interface is designed to look like a Cisco
498 device, and supports things like command history, line editing and
499 context sensitive help. This is provided by linking with the
500 <A HREF="http://sourceforge.net/projects/libcli">libcli</A>
501 library. Some general documentation of the interface is
502 <A HREF="http://sourceforge.net/docman/display_doc.php?docid=20501&group_id=79019">
503 here</A>.<P>
504
505 After you have connected to the telnet port (and perhaps logged in), you
506 will be presented with a <I>hostname</I><B>&gt;</B> prompt.<P>
507
508 Enter <EM>help</EM> to get a list of possible commands. A brief
509 overview of the more important commands follows:
510
511 <UL>
512 <LI><B>show session</B><BR>
513 Without specifying a session ID, this will list all tunnels currently
514 connected. If you specify a session ID, you will be given all
515 information on a single tunnel. Note that the full session list can
516 be around 185 columns wide, so you should probably use a wide terminal
517 to see the list properly.<P>
518 The columns listed in the overview are:
519 <TABLE>
520 <TR><TD><B>SID</B></TD><TD>Session ID</TD></TR>
521 <TR><TD><B>TID</B></TD><TD>Tunnel ID - Use with <EM>show tunnel tid</EM></TD></TR>
522 <TR><TD><B>Username</B></TD><TD>The username given in the PPP
523 authentication. If this is *, then LCP authentication has not
524 completed.</TD></TR>
525 <TR><TD><B>IP</B></TD><TD>The IP address given to the session. If
526 this is 0.0.0.0, LCP negotiation has not completed.</TD></TR>
527 <TR><TD><B>I</B></TD><TD>Intercept - Y or N depending on whether the
528 session is being snooped. See <EM>snoop</EM>.</TD></TR>
529 <TR><TD><B>T</B></TD><TD>Throttled - Y or N if the session is
530 currently throttled. See <EM>throttle</EM>.</TD></TR>
531 <TR><TD><B>G</B></TD><TD>Walled Garden - Y or N if the user is
532 trapped in the walled garden. This field is present even if the
533 garden module is not loaded.</TD></TR>
534 <TR><TD><B>opened</B></TD><TD>The number of seconds since the
535 session started</TD></TR>
536 <TR><TD><B>downloaded</B></TD><TD>Number of bytes downloaded by the user</TD></TR>
537 <TR><TD><B>uploaded</B></TD><TD>Number of bytes uploaded by the user</TD></TR>
538 <TR><TD><B>idle</B></TD><TD>The number of seconds since traffic was
539 detected on the session</TD></TR>
540 <TR><TD><B>LAC</B></TD><TD>The IP address of the LAC the session is
541 connected to.</TD></TR>
542 <TR><TD><B>CLI</B></TD><TD>The Calling-Line-Identification field
543 provided during the session setup. This field is generated by the
544 LAC.</TD></TR>
545 </TABLE>
546 <P>
547 </LI>
548
549 <LI><B>show users</B><BR>
550 With no arguments, display a list of currently connected users. If an
551 argument is given, the session details for the given username are
552 displayed.
553 </LI>
554
555 <LI><B>show tunnel</B><BR>
556 This will show all the open tunnels in a summary, or detail on a single
557 tunnel if you give a tunnel id.<P>
558 The columns listed in the overview are:
559 <TABLE>
560 <TR><TD><B>TID</B></TD><TD>Tunnel ID</TD></TR>
561 <TR><TD><B>Hostname</B></TD><TD>The hostname for the tunnel as
562 provided by the LAC. This has no relation to DNS, it is just
563 a text field.</TD></TR>
564 <TR><TD><B>IP</B></TD><TD>The IP address of the LAC</TD></TR>
565 <TR><TD><B>State</B></TD><TD>Tunnel state - Free, Open, Dieing,
566 Opening</TD></TR>
567 <TR><TD><B>Sessions</B></TD><TD>The number of open sessions on the
568 tunnel</TD></TR>
569 </TABLE>
570 <P>
571 </LI>
572
573 <LI><B>show pool</B><BR>
574 Displays the current IP address pool allocation. This will only display
575 addresses that are in use, or are reserved for re-allocation to a
576 disconnected user.<P>
577 If an address is not currently in use, but has been used, then in the User
578 column the username will be shown in square brackets, followed by the time
579 since the address was used:
580 <PRE>
581 IP Address Used Session User
582 192.168.100.6 N [joe.user] 1548s
583 </PRE>
584 <P>
585 </LI>
586
587 <LI><B>show radius</B><BR>
588 Show a summary of the in-use RADIUS sessions. This list should not be very
589 long, as RADIUS sessions should be cleaned up as soon as they are used. The
590 columns listed are:
591 <TABLE>
592 <TR><TD><B>Radius</B></TD><TD>The ID of the RADIUS request. This is
593 sent in the packet to the RADIUS server for identification.</TD></TR>
594 <TR><TD><B>State</B></TD><TD>The state of the request - WAIT, CHAP,
595 AUTH, IPCP, START, STOP, NULL.</TD></TR>
596 <TR><TD><B>Session</B></TD><TD>The session ID that this RADIUS
597 request is associated with</TD></TR>
598 <TR><TD><B>Retry</B></TD><TD>If a response does not appear to the
599 request, it will retry at this time. This is a unix timestamp.</TD></TR>
600 <TR><TD><B>Try</B></TD><TD>Retry count. The RADIUS request is
601 discarded after 3 retries.</TD></TR>
602 </TABLE>
603 <P>
604 </LI>
605
606 <LI><B>show running-config</B><BR>
607 This will list the current running configuration. This is in a format that
608 can either be pasted into the configuration file, or run directly at the
609 command line.
610 <P>
611 </LI>
612
613 <LI><B>show counters</B><BR>
614 Internally, counters are kept of key values, such as bytes and packets
615 transferred, as well as function call counters. This function displays all
616 these counters, and is probably only useful for debugging.<P>
617 You can reset these counters by running <EM>clear counters</EM>.
618 <P>
619 </LI>
620
621 <LI><B>show cluster</B><BR>
622 Show cluster status. Shows the cluster state for this server
623 (Master/Slave), information about known peers and (for slaves) the
624 master IP address, last packet seen and up-to-date status.<P>
625 See <A HREF="#Clustering">Clustering</A> for more information.
626 <P>
627 </LI>
628
629 <LI><B>write memory</B><BR>
630 This will write the current running configuration to the config file
631 <B>startup-config</B>, which will be run on a restart.
632 <P>
633 </LI>
634
635 <LI><B>snoop</B><BR>
636 You must specify a username, IP address and port. All packets for the
637 current session for that username will be forwarded to the given
638 host/port. Specify <EM>no snoop username</EM> to disable interception
639 for the session.<P>
640
641 If you want interception to be permanent, you will have to modify the RADIUS
642 response for the user. See <A HREF="#Interception">Interception</A>.
643 <P>
644 </LI>
645
646 <LI><B>throttle</B><BR>
647 You must specify a username, which will be throttled for the current
648 session. Specify <EM>no throttle username</EM> to disable throttling
649 for the current session.<P>
650
651 If you want throttling to be permanent, you will have to modify the
652 RADIUS response for the user. See <A HREF="#Throttling">Throttling</A>.
653 <P>
654 </LI>
655
656 <LI><B>drop session</B><BR>
657 This will cleanly disconnect a session. You must specify a session id, which
658 you can get from <EM>show session</EM>. This will send a disconnect message
659 to the remote end.
660 <P>
661 </LI>
662
663 <LI><B>drop tunnel</B><BR>
664 This will cleanly disconnect a tunnel, as well as all sessions on that
665 tunnel. It will send a disconnect message for each session individually, and
666 after 10 seconds it will send a tunnel disconnect message.
667 <P>
668 </LI>
669
670 <LI><B>uptime</B><BR>
671 This will show how long the l2tpns process has been running, and the current
672 bandwidth utilization:
673 <PRE>
674 17:10:35 up 8 days, 2212 users, load average: 0.21, 0.17, 0.16
675 Bandwidth: UDP-ETH:6/6 ETH-UDP:13/13 TOTAL:37.6 IN:3033 OUT:2569
676 </PRE>
677 The bandwidth line contains 4 sets of values.<BR>
678 UDP-ETH is the current bandwidth going from the LAC to the ethernet
679 (user uploads), in mbits/sec.<BR>
680 ETH-UDP is the current bandwidth going from ethernet to the LAC (user
681 downloads).<BR>
682 TOTAL is the total aggregate bandwidth in mbits/s.<BR>
683 IN and OUT are packets/per-second going between UDP-ETH and ETH-UDP.
684 <P>
685 These counters are updated every second.
686 <P>
687 </LI>
688
689 <LI><B>configure terminal</B><BR>
690 Enter configuration mode. Use <EM>exit</EM> or ^Z to exit this mode.
691 The following commands are valid in this mode:<P>
692 </LI>
693
694 <LI><B>load plugin</B><BR>
695 Load a plugin. You must specify the plugin name, and it will search in
696 /usr/lib/l2tpns for <EM>plugin</EM>.so. You can unload a loaded plugin with
697 <EM>remove plugin</EM>.
698 <P>
699 </LI>
700
701 <LI><B>set</B><BR>
702 Set a configuration variable. You must specify the variable name, and
703 the value. If the value contains any spaces, you should quote the
704 value with double (") or single (') quotes.<P>
705
706 You can set any <A HREF="#startup-config">startup-config</A> value in
707 this way, although some may require a restart to take effect.<P>
708 </LI>
709 </UL>
710
711 <H3 ID="nsctl">nsctl</H3>
712
713 nsctl allows messages to be passed to plugins.<P>
714
715 Arguments are <EM>command</EM> and optional <EM>args</EM>. See
716 <STRONG>nsctl</STRONG>(8) for more details.<P>
717
718 Built-in command are <EM>load_plugin</EM>, <EM>unload_plugin</EM> and
719 <EM>help</EM>. Any other commands are passed to plugins for processing.
720
721 <H3 ID="Signals">Signals</H3>
722
723 While the process is running, you can send it a few different signals, using
724 the kill command.
725 <PRE>
726 killall -HUP l2tpns
727 </PRE>
728
729 The signals understood are:
730 <DL>
731 <DT>SIGHUP</DT><DD>Reload the config from disk and re-open log file.</DD>
732 <DT>SIGTERM, SIGINT</DT><DD>Stop process. Tunnels and sessions are not
733 terminated. This signal should be used to stop l2tpns on a
734 <A HREF="#Clustering">cluster node</A> where there are other machines to
735 continue handling traffic.</DD>
736 <DT>SIGQUIT</DT><DD>Shut down tunnels and sessions, exit process when
737 complete.</DD>
738 </DL>
739
740 <H2 ID="Throttling">Throttling</H2>
741
742 l2tpns contains support for slowing down user sessions to whatever speed you
743 desire. You must first enable the global setting <EM>throttle_speed</EM>
744 before this will be activated.<P>
745
746 If you wish a session to be throttled permanently, you should set the
747 Vendor-Specific RADIUS value <B>Cisco-Avpair="throttle=yes"</B>, which
748 will be handled by the <EM>autothrottle</EM> module.<P>
749
750 Otherwise, you can enable and disable throttling an active session using
751 the <EM>throttle</EM> CLI command.<P>
752
753 <H2 ID="Interception">Interception</H2>
754
755 You may have to deal with legal requirements to be able to intercept a
756 user's traffic at any time. l2tpns allows you to begin and end interception
757 on the fly, as well as at authentication time.<P>
758
759 When a user is being intercepted, a copy of every packet they send and
760 receive will be sent wrapped in a UDP packet to the IP address and port set
761 in the <EM>snoop_host</EM> and <EM>snoop_port</EM> configuration
762 variables.<P>
763
764 The UDP packet contains just the raw IP frame, with no extra headers.<P>
765
766 To enable interception on a connected user, use the <EM>snoop username</EM>
767 and <EM>no snoop username</EM> CLI commands. These will enable interception
768 immediately.<P>
769
770 If you wish the user to be intercepted whenever they reconnect, you will
771 need to modify the RADIUS response to include the Vendor-Specific value
772 <B>Cisco-Avpair="intercept=yes"</B>. For this feature to be enabled,
773 you need to have the <EM>autosnoop</EM> module loaded.<P>
774
775 <H2 ID="Authentication">Authentication</H2>
776
777 Whenever a session connects, it is not fully set up until authentication is
778 completed. The remote end must send a PPP CHAP or PPP PAP authentication
779 request to l2tpns.<P>
780
781 This request is sent to the RADIUS server, which will hopefully respond with
782 Auth-Accept or Auth-Reject.<P>
783
784 If Auth-Accept is received, the session is set up and an IP address is
785 assigned. The RADIUS server can include a Framed-IP-Address field in the
786 reply, and that address will be assigned to the client. It can also include
787 specific DNS servers, and a Framed-Route if that is required.<P>
788
789 If Auth-Reject is received, then the client is sent a PPP AUTHNAK packet,
790 at which point they should disconnect. The exception to this is when the
791 walled garden module is loaded, in which case the user still receives the
792 PPP AUTHACK, but their session is flagged as being a garden'd user, and they
793 should not receive any service.<P>
794
795 The RADIUS reply can also contain a Vendor-Specific attribute called
796 Cisco-Avpair. This field is a freeform text field that most Cisco
797 devices understand to contain configuration instructions for the session. In
798 the case of l2tpns it is expected to be of the form
799 <PRE>
800 key=value,key2=value2,key3=value3,key<EM>n</EM>=<EM>value</EM>
801 </PRE>
802
803 Each key-value pair is separated and passed to any modules loaded. The
804 <EM>autosnoop</EM> and <EM>autothrottle</EM> understand the keys
805 <EM>intercept</EM> and <EM>throttle</EM> respectively. For example, to have
806 a user who is to be throttled and intercepted, the Cisco-Avpair value should
807 contain:
808 <PRE>
809 intercept=yes,throttle=yes
810 </PRE>
811
812 <H2 ID="Plugins">Plugins</H2>
813
814 So as to make l2tpns as flexible as possible (I know the core code is pretty
815 difficult to understand), it includes a plugin API, which you can use to
816 hook into certain events.<P>
817
818 There are a few example modules included - autosnoop, autothrottle and
819 garden.<P>
820
821 When an event happens that has a hook, l2tpns looks for a predefined
822 function name in every loaded module, and runs them in the order the modules
823 were loaded.<P>
824
825 The function should return <B>PLUGIN_RET_OK</B> if it is all OK. If it returns
826 <B>PLUGIN_RET_STOP</B>, then it is assumed to have worked, but that no further
827 modules should be run for this event.<P>
828 A return of <B>PLUGIN_RET_ERROR</B> means that this module failed, and
829 no further processing should be done for this event. <EM>Use this with care.</EM>
830
831 Every event function called takes a specific structure named
832 param_<EM>event</EM>, which varies in content with each event. The
833 function name for each event will be <B>plugin_<EM>event</EM></B>,
834 so for the event <EM>timer</EM>, the function declaration should look like:
835 <PRE>
836 int plugin_timer(struct param_timer *data);
837 </PRE>
838
839 A list of the available events follows, with a list of all the fields in the
840 supplied structure:
841 <TABLE CELLSPACING=0 CELLPADDING=0><TR BGCOLOR=LIGHTGREEN><TD>
842 <TABLE CELLSPACING=1 CELLPADDING=3>
843 <TR BGCOLOR=LIGHTGREEN><TH><B>Event</B></TH><TH><B>Description</B></TH><TH><B>Parameters</B></TH></TR>
844 <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>pre_auth</B></TD>
845 <TD>This is called after a RADIUS response has been
846 received, but before it has been processed by the
847 code. This will allow you to modify the response in
848 some way.
849 </TD>
850 <TD>
851 <DL>
852 <DT>t<DD>Tunnel
853 <DT>s<DD>Session
854 <DT>username
855 <DT>password
856 <DT>protocol<DD>0xC023 for PAP, 0xC223 for CHAP
857 <DT>continue_auth<DD>Set to 0 to stop processing authentication modules
858 </DL>
859 </TD>
860 </TR>
861 <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>post_auth</B></TD>
862 <TD>This is called after a RADIUS response has been
863 received, and the basic checks have been performed. This
864 is what the garden module uses to force authentication
865 to be accepted.
866 </TD>
867 <TD>
868 <DL>
869 <DT>t<DD>Tunnel
870 <DT>s<DD>Session
871 <DT>username
872 <DT>auth_allowed<DD>This is already set to true or
873 false depending on whether authentication has been
874 allowed so far. You can set this to 1 or 0 to force
875 allow or disallow authentication
876 <DT>protocol<DD>0xC023 for PAP, 0xC223 for CHAP
877 </DL>
878 </TD>
879 </TR>
880 <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>packet_rx</B></TD>
881 <TD>This is called whenever a session receives a
882 packet. <FONT COLOR=RED>Use this sparingly, as this will
883 seriously slow down the system.</FONT>
884 </TD>
885 <TD>
886 <DL>
887 <DT>t<DD>Tunnel
888 <DT>s<DD>Session
889 <DT>buf<DD>The raw packet data
890 <DT>len<DD>The length of buf
891 </DL>
892 </TD>
893 </TR>
894 <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>packet_tx</B></TD>
895 <TD>This is called whenever a session sends a
896 packet. <FONT COLOR=RED>Use this sparingly, as this will
897 seriously slow down the system.</FONT>
898 </TD>
899 <TD>
900 <DL>
901 <DT>t<DD>Tunnel
902 <DT>s<DD>Session
903 <DT>buf<DD>The raw packet data
904 <DT>len<DD>The length of buf
905 </DL>
906 </TD>
907 </TR>
908 <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>timer</B></TD>
909 <TD>This is run every second, no matter what is happening.
910 This is called from a signal handler, so make sure anything
911 you do is reentrant.
912 </TD>
913 <TD>
914 <DL>
915 <DT>time_now<DD>The current unix timestamp
916 </DL>
917 </TD>
918 </TR>
919 <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>new_session</B></TD>
920 <TD>This is called after a session is fully set up. The
921 session is now ready to handle traffic.
922 </TD>
923 <TD>
924 <DL>
925 <DT>t<DD>Tunnel
926 <DT>s<DD>Session
927 </DL>
928 </TD>
929 </TR>
930 <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>kill_session</B></TD>
931 <TD>This is called when a session is about to be shut down.
932 This may be called multiple times for the same session.
933 </TD>
934 <TD>
935 <DL>
936 <DT>t<DD>Tunnel
937 <DT>s<DD>Session
938 </DL>
939 </TD>
940 </TR>
941 <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>radius_response</B></TD>
942 <TD>This is called whenever a RADIUS response includes a
943 Cisco-Avpair value. The value is split up into
944 <EM>key=value</EM> pairs, and each is processed through all
945 modules.
946 </TD>
947 <TD>
948 <DL>
949 <DT>t<DD>Tunnel
950 <DT>s<DD>Session
951 <DT>key
952 <DT>value
953 </DL>
954 </TD>
955 </TR>
956 <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>radius_reset</B></TD>
957 <TD>This is called whenever a RADIUS CoA request is
958 received to reset any options to default values before
959 the new values are applied.
960 </TD>
961 <TD>
962 <DL>
963 <DT>t<DD>Tunnel
964 <DT>s<DD>Session
965 </DL>
966 </TD>
967 </TR>
968 <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>control</B></TD>
969 <TD>This is called in whenever a nsctl packet is received.
970 This should handle the packet and form a response if
971 required.
972 </TD>
973 <TD>
974 <DL>
975 <DT>iam_master<DD>Cluster master status
976 <DT>argc<DD>The number of arguments
977 <DT>argv<DD>Arguments
978 <DT>response<DD>Return value: NSCTL_RES_OK or NSCTL_RES_ERR
979 <DT>additional<DD>Extended response text
980 </DL>
981 </TD>
982 </TR>
983 </TABLE>
984 </TD></TR></TABLE>
985
986 <H2 ID="WalledGarden">Walled Garden</H2>
987
988 Walled Garden is implemented so that you can provide perhaps limited service
989 to sessions that incorrectly authenticate.<P>
990
991 Whenever a session provides incorrect authentication, and the
992 RADIUS server responds with Auth-Reject, the walled garden module
993 (if loaded) will force authentication to succeed, but set the flag
994 <EM>garden</EM> in the session structure, and adds an iptables rule to
995 the <B>garden_users</B> chain to force all packets for the session's IP
996 address to traverse the <B>garden</B> chain.<P>
997
998 This doesn't <EM>just work</EM>. To set this all up, you will to
999 setup the <B>garden</B> nat table with the
1000 <A HREF="#build-garden">build-garden</A> script with rules to limit
1001 user's traffic. For example, to force all traffic except DNS to be
1002 forwarded to 192.168.1.1, add these entries to your
1003 <EM>build-garden</EM>:
1004 <PRE>
1005 iptables -t nat -A garden -p tcp --dport ! 53 -j DNAT --to 192.168.1.1
1006 iptables -t nat -A garden -p udp --dport ! 53 -j DNAT --to 192.168.1.1
1007 </PRE>
1008
1009 l2tpns will add entries to the garden_users chain as appropriate.<P>
1010
1011 You can check the amount of traffic being captured using the following
1012 command:
1013 <PRE>
1014 iptables -t nat -L garden -nvx
1015 </PRE>
1016
1017 <H2 ID="Filtering">Filtering</H2>
1018
1019 Sessions may be filtered by specifying <B>Filter-Id</B> attributes in
1020 the RADIUS reply. <I>filter</I>.<B>in</B> specifies that the named
1021 access-list <I>filter</I> should be applied to traffic from the
1022 customer, <I>filter</I>.<B>out</B> specifies a list for traffic to the
1023 customer.
1024
1025 <H2 ID="Clustering">Clustering</H2>
1026
1027 An l2tpns cluster consists of of one* or more servers configured with
1028 the same configuration, notably the multicast <B>cluster_address</B>.<P>
1029
1030 *A stand-alone server is simply a degraded cluster.<P>
1031
1032 Initially servers come up as cluster slaves, and periodically (every
1033 <B>cluster_hb_interval</B>/10 seconds) send out ping packets
1034 containing the start time of the process to the multicast
1035 <B>cluster_address</B>.<P>
1036
1037 A cluster master sends heartbeat rather than ping packets, which
1038 contain those session and tunnel changes since the last heartbeat.<P>
1039
1040 When a slave has not seen a heartbeat within
1041 <B>cluster_hb_timeout</B>/10 seconds it "elects" a new master by
1042 examining the list of peers it has seen pings from and determines
1043 which of these and itself is the "best" candidate to be master.
1044 "Best" in this context means the server with the highest uptime (the
1045 highest IP address is used as a tie-breaker in the case of equal
1046 uptimes).<P>
1047
1048 After discovering a master, and determining that it is up-to-date (has
1049 seen an update for all in-use sessions and tunnels from heartbeat
1050 packets) will raise a route (see <A HREF="#Routing">Routing</A>) for
1051 the <B>bind_address</B> and for all addresses/networks in
1052 <B>ip_pool</B>. Any packets recieved by the slave which would alter
1053 the session state, as well as packets for throttled or gardened
1054 sessions are forwarded to the master for handling. In addition, byte
1055 counters for session traffic are periodically forwarded.<P>
1056
1057 A master, when determining that it has at least one up-to-date slave
1058 will drop all routes (raising them again if all slaves disappear) and
1059 subsequently handle only packets forwarded to it by the slaves.<P>
1060
1061 <H2 ID="Routing">Routing</H2>
1062 If you are running a single instance, you may simply statically route
1063 the IP pools to the <B>bind_address</B> (l2tpns will send a gratuitous
1064 arp).<P>
1065
1066 For a cluster, configure the members as BGP neighbours on your router
1067 and configure multi-path load-balancing. Cisco uses "maximum-paths
1068 ibgp" for IBGP. If this is not supported by your IOS revision, you
1069 can use "maximum-paths" (which works for EBGP) and set
1070 <B>as_number</B> to a private value such as 64512.<P>
1071
1072 <H2 ID="Performance">Performance</H2>
1073
1074 Performance is great.<P>
1075
1076 I'd like to include some pretty graphs here that show a linear performance
1077 increase, with no impact by number of connected sessions.<P>
1078
1079 That's really what it looks like.<P>
1080
1081 <BR>
1082 David Parrish<BR>
1083 <A HREF="mailto:l2tpns-users@lists.sourceforge.net?subject=L2TPNS%20Documentation">l2tpns-users@lists.sourceforge.net</A>
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