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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 <LI><B>bind_portremotelns</B> (short)<BR>
 372 Port to bind for the Remote LNS (default: 65432).
 373 </LI>
 374
 375 </UL>
 376
 377 <P>The REMOTES LNS configuration is entered by the command:
 378 <DL> <DD><B>setforward</B> <I>MASK</I> <I>IP</I> <I>PORT</I> <I>SECRET</I> </DL>
 379
 380 where <I>MASK</I> specifies the mask of users who have forwarded to
 381 remote LNS (ex: /myISP@company.com).</BR>
 382 where <I>IP</I> specifies the IP of the  remote LNS (ex: 66.66.66.55).</BR>
 383 where <I>PORT</I> specifies the L2TP Port of the remote LNS
 384 (Normally should be 1701) (ex: 1701).</BR>
 385 where <I>SECRET</I> specifies the secret password the remote LNS (ex: mysecret).</BR>
 386
 387 <P>BGP routing configuration is entered by the command:
 388 The routing configuration section is entered by the command
 389 <DL><DD><B>router bgp</B> <I>as</I></DL>
 390 where <I>as</I> specifies the local AS number.
 391
 392 <P>Subsequent lines prefixed with
 393 <DL><DD><B>neighbour</B> <I>peer</I></DL>
 394 define the attributes of BGP neighhbours.  Valid commands are:
 395 <DL>
 396   <DD><B>neighbour</B> <I>peer</I> <B>remote-as</B> <I>as</I>
 397   <DD><B>neighbout</B> <I>peer</I> <B>timers</B> <I>keepalive hold</I>
 398 </DL>
 399
 400 Where <I>peer</I> specifies the BGP neighbour as either a hostname or
 401 IP address, <I>as</I> is the remote AS number and <I>keepalive</I>,
 402 <I>hold</I> are the timer values in seconds.
 403
 404 <P>Named access-lists are configured using one of the commands:
 405 <DL>
 406   <DD><B>ip access-list standard</B> <I>name</I>
 407   <DD><B>ip access-list extended</B> <I>name</I>
 408 </DL>
 409
 410 <P>Subsequent lines prefixed with <B>permit</B> or <B>deny</B>
 411 define the body of the access-list.  Standard access-list syntax:
 412 <DL>
 413   <DD>{<B>permit</B>|<B>deny</B>}
 414     {<I>host</I>|<I>source source-wildcard</I>|<B>any</B>}
 415     [{<I>host</I>|<I>destination destination-wildcard</I>|<B>any</B>}]
 416 </DL>
 417
 418 Extended access-lists:
 419
 420 <DIV STYLE="margin-left: 4em; text-indent: -2em">
 421   <P>{<B>permit</B>|<B>deny</B>} <B>ip</B>
 422     {<I>host</I>|<I>source source-wildcard</I>|<B>any</B>}
 423     {<I>host</I>|<I>destination destination-wildcard</I>|<B>any</B>} [<B>fragments</B>]
 424   <P>{<B>permit</B>|<B>deny</B>} <B>udp</B>
 425     {<I>host</I>|<I>source source-wildcard</I>|<B>any</B>}
 426         [{<B>eq</B>|<B>neq</B>|<B>gt</B>|<B>lt</B>} <I>port</I>|<B>range</B> <I>from</I> <I>to</I>]
 427     {<I>host</I>|<I>destination destination-wildcard</I>|<B>any</B>}
 428         [{<B>eq</B>|<B>neq</B>|<B>gt</B>|<B>lt</B>} <I>port</I>|<B>range</B> <I>from</I> <I>to</I>]
 429         [<B>fragments</B>]
 430   <P>{<B>permit</B>|<B>deny</B>} <B>tcp</B>
 431     {<I>host</I>|<I>source source-wildcard</I>|<B>any</B>}
 432         [{<B>eq</B>|<B>neq</B>|<B>gt</B>|<B>lt</B>} <I>port</I>|<B>range</B> <I>from</I> <I>to</I>]
 433     {<I>host</I>|<I>destination destination-wildcard</I>|<B>any</B>}
 434         [{<B>eq</B>|<B>neq</B>|<B>gt</B>|<B>lt</B>} <I>port</I>|<B>range</B> <I>from</I> <I>to</I>]
 435         [{<B>established</B>|{<B>match-any</B>|<B>match-all</B>}
 436             {<B>+</B>|<B>-</B>}{<B>fin</B>|<B>syn</B>|<B>rst</B>|<B>psh</B>|<B>ack</B>|<B>urg</B>}
 437             ...|<B>fragments</B>]
 438 </DIV>
 439
 440 <H3 ID="users">users</H3>
 441
 442 Usernames and passwords for the command-line interface are stored in
 443 this file.  The format is <I>username</I><B>:</B><I>password</I> where
 444 <I>password</I> may either by plain text, an MD5 digest (prefixed by
 445 <B>$1</B><I>salt</I><B>$</B>) or a DES password, distinguished from
 446 plain text by the prefix <B>{crypt}</B>.<P>
 447
 448 The username <B>enable</B> has a special meaning and is used to set
 449 the enable password.<P>
 450
 451 <B>Note:</B> If this file doesn't exist, then anyone who can get to
 452 port 23 will be allowed access without a username / password.<P>
 453
 454 <H3 ID="ip-pool">ip_pool</H3>
 455
 456 This file is used to configure the IP address pool which user
 457 addresses are assigned from.  This file should contain either an IP
 458 address or a CIDR network per line.  e.g.:<P>
 459
 460 <PRE>
 461     192.168.1.1
 462     192.168.1.2
 463     192.168.1.3
 464     192.168.4.0/24
 465     172.16.0.0/16
 466     10.0.0.0/8
 467 </PRE>
 468
 469 Keep in mind that l2tpns can only handle 65535 connections per
 470 process, so don't put more than 65535 IP addresses in the
 471 configuration file.  They will be wasted.
 472
 473 <H3 ID="build-garden">build-garden</H3>
 474
 475 The garden plugin on startup creates a NAT table called "garden" then
 476 sources the <B>build-garden</B> script to populate that table.  All
 477 packets from gardened users will be sent through this table.  Example:
 478
 479 <PRE>
 480     iptables -t nat -A garden -p tcp -m tcp --dport 25 -j DNAT --to 192.168.1.1
 481     iptables -t nat -A garden -p udp -m udp --dport 53 -j DNAT --to 192.168.1.1
 482     iptables -t nat -A garden -p tcp -m tcp --dport 53 -j DNAT --to 192.168.1.1
 483     iptables -t nat -A garden -p tcp -m tcp --dport 80 -j DNAT --to 192.168.1.1
 484     iptables -t nat -A garden -p tcp -m tcp --dport 110 -j DNAT --to 192.168.1.1
 485     iptables -t nat -A garden -p tcp -m tcp --dport 443 -j DNAT --to 192.168.1.1
 486     iptables -t nat -A garden -p icmp -m icmp --icmp-type echo-request -j DNAT --to 192.168.1.1
 487     iptables -t nat -A garden -p icmp -j ACCEPT
 488     iptables -t nat -A garden -j DROP
 489 </PRE>
 490
 491 <H2 ID="ControllingtheProcess">Controlling the Process</H2>
 492
 493 A running l2tpns process can be controlled in a number of ways.  The primary
 494 method of control is by the Command-Line Interface (CLI).<P>
 495
 496 You can also remotely send commands to modules via the nsctl client
 497 provided.<P>
 498
 499 Also, there are a number of signals that l2tpns understands and takes action
 500 when it receives them.
 501
 502 <H3 ID="Command-LineInterface">Command-Line Interface</H3>
 503
 504 You can access the command line interface by telnet'ing to port 23.
 505 There is no IP address restriction, so it's a good idea to firewall
 506 this port off from anyone who doesn't need access to it.  See
 507 <A HREF="#users">users</A> for information on restricting access based
 508 on a username and password.<P>
 509
 510 The CLI gives you real-time control over almost everything in
 511 the process.  The interface is designed to look like a Cisco
 512 device, and supports things like command history, line editing and
 513 context sensitive help.  This is provided by linking with the
 514 <A HREF="http://sourceforge.net/projects/libcli">libcli</A>
 515 library.  Some general documentation of the interface is
 516 <A HREF="http://sourceforge.net/docman/display_doc.php?docid=20501&group_id=79019">
 517 here</A>.<P>
 518
 519 After you have connected to the telnet port (and perhaps logged in), you
 520 will be presented with a <I>hostname</I><B>&gt;</B> prompt.<P>
 521
 522 Enter <EM>help</EM> to get a list of possible commands.  A brief
 523 overview of the more important commands follows:
 524
 525 <UL>
 526 <LI><B>show session</B><BR>
 527 Without specifying a session ID, this will list all tunnels currently
 528 connected.  If you specify a session ID, you will be given all
 529 information on a single tunnel.  Note that the full session list can
 530 be around 185 columns wide, so you should probably use a wide terminal
 531 to see the list properly.<P>
 532 The columns listed in the overview are:
 533 <TABLE>
 534         <TR><TD><B>SID</B></TD><TD>Session ID</TD></TR>
 535         <TR><TD><B>TID</B></TD><TD>Tunnel ID - Use with <EM>show tunnel tid</EM></TD></TR>
 536         <TR><TD><B>Username</B></TD><TD>The username given in the PPP
 537         authentication.  If this is *, then LCP authentication has not
 538         completed.</TD></TR>
 539         <TR><TD><B>IP</B></TD><TD>The IP address given to the session.  If
 540         this is 0.0.0.0, LCP negotiation has not completed.</TD></TR>
 541         <TR><TD><B>I</B></TD><TD>Intercept - Y or N depending on whether the
 542         session is being snooped.  See <EM>snoop</EM>.</TD></TR>
 543         <TR><TD><B>T</B></TD><TD>Throttled - Y or N if the session is
 544         currently throttled.  See <EM>throttle</EM>.</TD></TR>
 545         <TR><TD><B>G</B></TD><TD>Walled Garden - Y or N if the user is
 546         trapped in the walled garden.  This field is present even if the
 547         garden module is not loaded.</TD></TR>
 548         <TR><TD><B>opened</B></TD><TD>The number of seconds since the
 549         session started</TD></TR>
 550         <TR><TD><B>downloaded</B></TD><TD>Number of bytes downloaded by the user</TD></TR>
 551         <TR><TD><B>uploaded</B></TD><TD>Number of bytes uploaded by the user</TD></TR>
 552         <TR><TD><B>idle</B></TD><TD>The number of seconds since traffic was
 553         detected on the session</TD></TR>
 554         <TR><TD><B>LAC</B></TD><TD>The IP address of the LAC the session is
 555         connected to.</TD></TR>
 556         <TR><TD><B>CLI</B></TD><TD>The Calling-Line-Identification field
 557         provided during the session setup.  This field is generated by the
 558         LAC.</TD></TR>
 559 </TABLE>
 560 <P>
 561 </LI>
 562
 563 <LI><B>show users</B><BR>
 564 With no arguments, display a list of currently connected users.  If an
 565 argument is given, the session details for the given username are
 566 displayed.
 567 </LI>
 568
 569 <LI><B>show tunnel</B><BR>
 570 This will show all the open tunnels in a summary, or detail on a single
 571 tunnel if you give a tunnel id.<P>
 572 The columns listed in the overview are:
 573 <TABLE>
 574         <TR><TD><B>TID</B></TD><TD>Tunnel ID</TD></TR>
 575         <TR><TD><B>Hostname</B></TD><TD>The hostname for the tunnel as
 576         provided by the LAC.  This has no relation to DNS, it is just
 577         a text field.</TD></TR>
 578         <TR><TD><B>IP</B></TD><TD>The IP address of the LAC</TD></TR>
 579         <TR><TD><B>State</B></TD><TD>Tunnel state - Free, Open, Dieing,
 580         Opening</TD></TR>
 581         <TR><TD><B>Sessions</B></TD><TD>The number of open sessions on the
 582         tunnel</TD></TR>
 583 </TABLE>
 584 <P>
 585 </LI>
 586
 587 <LI><B>show pool</B><BR>
 588 Displays the current IP address pool allocation.  This will only display
 589 addresses that are in use, or are reserved for re-allocation to a
 590 disconnected user.<P>
 591 If an address is not currently in use, but has been used, then in the User
 592 column the username will be shown in square brackets, followed by the time
 593 since the address was used:
 594 <PRE>
 595 IP Address      Used  Session User
 596 192.168.100.6     N           [joe.user] 1548s
 597 </PRE>
 598 <P>
 599 </LI>
 600
 601 <LI><B>show radius</B><BR>
 602 Show a summary of the in-use RADIUS sessions.  This list should not be very
 603 long, as RADIUS sessions should be cleaned up as soon as they are used.  The
 604 columns listed are:
 605 <TABLE>
 606         <TR><TD><B>Radius</B></TD><TD>The ID of the RADIUS request.  This is
 607         sent in the packet to the RADIUS server for identification.</TD></TR>
 608         <TR><TD><B>State</B></TD><TD>The state of the request - WAIT, CHAP,
 609         AUTH, IPCP, START, STOP, NULL.</TD></TR>
 610         <TR><TD><B>Session</B></TD><TD>The session ID that this RADIUS
 611         request is associated with</TD></TR>
 612         <TR><TD><B>Retry</B></TD><TD>If a response does not appear to the
 613         request, it will retry at this time.  This is a unix timestamp.</TD></TR>
 614         <TR><TD><B>Try</B></TD><TD>Retry count.  The RADIUS request is
 615         discarded after 3 retries.</TD></TR>
 616 </TABLE>
 617 <P>
 618 </LI>
 619
 620 <LI><B>show running-config</B><BR>
 621 This will list the current running configuration.  This is in a format that
 622 can either be pasted into the configuration file, or run directly at the
 623 command line.
 624 <P>
 625 </LI>
 626
 627 <LI><B>show counters</B><BR>
 628 Internally, counters are kept of key values, such as bytes and packets
 629 transferred, as well as function call counters.  This function displays all
 630 these counters, and is probably only useful for debugging.<P>
 631 You can reset these counters by running <EM>clear counters</EM>.
 632 <P>
 633 </LI>
 634
 635 <LI><B>show cluster</B><BR>
 636 Show cluster status.  Shows the cluster state for this server
 637 (Master/Slave), information about known peers and (for slaves) the
 638 master IP address, last packet seen and up-to-date status.<P>
 639 See <A HREF="#Clustering">Clustering</A> for more information.
 640 <P>
 641 </LI>
 642
 643 <LI><B>write memory</B><BR>
 644 This will write the current running configuration to the config file
 645 <B>startup-config</B>, which will be run on a restart.
 646 <P>
 647 </LI>
 648
 649 <LI><B>snoop</B><BR>
 650 You must specify a username, IP address and port.  All packets for the
 651 current session for that username will be forwarded to the given
 652 host/port.  Specify <EM>no snoop username</EM> to disable interception
 653 for the session.<P>
 654
 655 If you want interception to be permanent, you will have to modify the RADIUS
 656 response for the user.  See <A HREF="#Interception">Interception</A>.
 657 <P>
 658 </LI>
 659
 660 <LI><B>throttle</B><BR>
 661 You must specify a username, which will be throttled for the current
 662 session.  Specify <EM>no throttle username</EM> to disable throttling
 663 for the current session.<P>
 664
 665 If you want throttling to be permanent, you will have to modify the
 666 RADIUS response for the user.  See <A HREF="#Throttling">Throttling</A>.
 667 <P>
 668 </LI>
 669
 670 <LI><B>drop session</B><BR>
 671 This will cleanly disconnect a session.  You must specify a session id, which
 672 you can get from <EM>show session</EM>.  This will send a disconnect message
 673 to the remote end.
 674 <P>
 675 </LI>
 676
 677 <LI><B>drop tunnel</B><BR>
 678 This will cleanly disconnect a tunnel, as well as all sessions on that
 679 tunnel.  It will send a disconnect message for each session individually, and
 680 after 10 seconds it will send a tunnel disconnect message.
 681 <P>
 682 </LI>
 683
 684 <LI><B>uptime</B><BR>
 685 This will show how long the l2tpns process has been running, and the current
 686 bandwidth utilization:
 687 <PRE>
 688 17:10:35 up 8 days, 2212 users, load average: 0.21, 0.17, 0.16
 689 Bandwidth: UDP-ETH:6/6  ETH-UDP:13/13  TOTAL:37.6   IN:3033 OUT:2569
 690 </PRE>
 691 The bandwidth line contains 4 sets of values.<BR>
 692 UDP-ETH is the current bandwidth going from the LAC to the ethernet
 693 (user uploads), in mbits/sec.<BR>
 694 ETH-UDP is the current bandwidth going from ethernet to the LAC (user
 695 downloads).<BR>
 696 TOTAL is the total aggregate bandwidth in mbits/s.<BR>
 697 IN and OUT are packets/per-second going between UDP-ETH and ETH-UDP.
 698 <P>
 699 These counters are updated every second.
 700 <P>
 701 </LI>
 702
 703 <LI><B>configure terminal</B><BR>
 704 Enter configuration mode.  Use <EM>exit</EM> or ^Z to exit this mode.
 705 The following commands are valid in this mode:<P>
 706 </LI>
 707
 708 <LI><B>load plugin</B><BR>
 709 Load a plugin.  You must specify the plugin name, and it will search in
 710 /usr/lib/l2tpns for <EM>plugin</EM>.so.  You can unload a loaded plugin with
 711 <EM>remove plugin</EM>.
 712 <P>
 713 </LI>
 714
 715 <LI><B>set</B><BR>
 716 Set a configuration variable.  You must specify the variable name, and
 717 the value.  If the value contains any spaces, you should quote the
 718 value with double (") or single (') quotes.<P>
 719
 720 You can set any <A HREF="#startup-config">startup-config</A> value in
 721 this way, although some may require a restart to take effect.<P>
 722 </LI>
 723 </UL>
 724
 725 <H3 ID="nsctl">nsctl</H3>
 726
 727 nsctl allows messages to be passed to plugins.<P>
 728
 729 Arguments are <EM>command</EM> and optional <EM>args</EM>.  See
 730 <STRONG>nsctl</STRONG>(8) for more details.<P>
 731
 732 Built-in command are <EM>load_plugin</EM>, <EM>unload_plugin</EM> and
 733 <EM>help</EM>.  Any other commands are passed to plugins for processing.
 734
 735 <H3 ID="Signals">Signals</H3>
 736
 737 While the process is running, you can send it a few different signals, using
 738 the kill command.
 739 <PRE>
 740 killall -HUP l2tpns
 741 </PRE>
 742
 743 The signals understood are:
 744 <DL>
 745 <DT>SIGHUP</DT><DD>Reload the config from disk and re-open log file.</DD>
 746 <DT>SIGTERM, SIGINT</DT><DD>Stop process.  Tunnels and sessions are not
 747 terminated.  This signal should be used to stop l2tpns on a
 748 <A HREF="#Clustering">cluster node</A> where there are other machines to
 749 continue handling traffic.</DD>
 750 <DT>SIGQUIT</DT><DD>Shut down tunnels and sessions, exit process when
 751 complete.</DD>
 752 </DL>
 753
 754 <H2 ID="Throttling">Throttling</H2>
 755
 756 l2tpns contains support for slowing down user sessions to whatever speed you
 757 desire.  You must first enable the global setting <EM>throttle_speed</EM>
 758 before this will be activated.<P>
 759
 760 If you wish a session to be throttled permanently, you should set the
 761 Vendor-Specific RADIUS value <B>Cisco-Avpair="throttle=yes"</B>, which
 762 will be handled by the <EM>autothrottle</EM> module.<P>
 763
 764 Otherwise, you can enable and disable throttling an active session using
 765 the <EM>throttle</EM> CLI command.<P>
 766
 767 <H2 ID="Interception">Interception</H2>
 768
 769 You may have to deal with legal requirements to be able to intercept a
 770 user's traffic at any time.  l2tpns allows you to begin and end interception
 771 on the fly, as well as at authentication time.<P>
 772
 773 When a user is being intercepted, a copy of every packet they send and
 774 receive will be sent wrapped in a UDP packet to the IP address and port set
 775 in the <EM>snoop_host</EM> and <EM>snoop_port</EM> configuration
 776 variables.<P>
 777
 778 The UDP packet contains just the raw IP frame, with no extra headers.<P>
 779
 780 To enable interception on a connected user, use the <EM>snoop username</EM>
 781 and <EM>no snoop username</EM> CLI commands.  These will enable interception
 782 immediately.<P>
 783
 784 If you wish the user to be intercepted whenever they reconnect, you will
 785 need to modify the RADIUS response to include the Vendor-Specific value
 786 <B>Cisco-Avpair="intercept=yes"</B>.  For this feature to be enabled,
 787 you need to have the <EM>autosnoop</EM> module loaded.<P>
 788
 789 <H2 ID="Authentication">Authentication</H2>
 790
 791 Whenever a session connects, it is not fully set up until authentication is
 792 completed.  The remote end must send a PPP CHAP or PPP PAP authentication
 793 request to l2tpns.<P>
 794
 795 This request is sent to the RADIUS server, which will hopefully respond with
 796 Auth-Accept or Auth-Reject.<P>
 797
 798 If Auth-Accept is received, the session is set up and an IP address is
 799 assigned.  The RADIUS server can include a Framed-IP-Address field in the
 800 reply, and that address will be assigned to the client.  It can also include
 801 specific DNS servers, and a Framed-Route if that is required.<P>
 802
 803 If Auth-Reject is received, then the client is sent a PPP AUTHNAK packet,
 804 at which point they should disconnect.  The exception to this is when the
 805 walled garden module is loaded, in which case the user still receives the
 806 PPP AUTHACK, but their session is flagged as being a garden'd user, and they
 807 should not receive any service.<P>
 808
 809 The RADIUS reply can also contain a Vendor-Specific attribute called
 810 Cisco-Avpair.  This field is a freeform text field that most Cisco
 811 devices understand to contain configuration instructions for the session.  In
 812 the case of l2tpns it is expected to be of the form
 813 <PRE>
 814 key=value,key2=value2,key3=value3,key<EM>n</EM>=<EM>value</EM>
 815 </PRE>
 816
 817 Each key-value pair is separated and passed to any modules loaded.  The
 818 <EM>autosnoop</EM> and <EM>autothrottle</EM> understand the keys
 819 <EM>intercept</EM> and <EM>throttle</EM> respectively.  For example, to have
 820 a user who is to be throttled and intercepted, the Cisco-Avpair value should
 821 contain:
 822 <PRE>
 823 intercept=yes,throttle=yes
 824 </PRE>
 825
 826 <H2 ID="Plugins">Plugins</H2>
 827
 828 So as to make l2tpns as flexible as possible (I know the core code is pretty
 829 difficult to understand), it includes a plugin API, which you can use to
 830 hook into certain events.<P>
 831
 832 There are a few example modules included - autosnoop, autothrottle and
 833 garden.<P>
 834
 835 When an event happens that has a hook, l2tpns looks for a predefined
 836 function name in every loaded module, and runs them in the order the modules
 837 were loaded.<P>
 838
 839 The function should return <B>PLUGIN_RET_OK</B> if it is all OK.  If it returns
 840 <B>PLUGIN_RET_STOP</B>, then it is assumed to have worked, but that no further
 841 modules should be run for this event.<P>
 842 A return of <B>PLUGIN_RET_ERROR</B> means that this module failed, and
 843 no further processing should be done for this event.  <EM>Use this with care.</EM>
 844
 845 Every event function called takes a specific structure named
 846 param_<EM>event</EM>, which varies in content with each event.  The
 847 function name for each event will be <B>plugin_<EM>event</EM></B>,
 848 so for the event <EM>timer</EM>, the function declaration should look like:
 849 <PRE>
 850 int plugin_timer(struct param_timer *data);
 851 </PRE>
 852
 853 A list of the available events follows, with a list of all the fields in the
 854 supplied structure:
 855 <TABLE CELLSPACING=0 CELLPADDING=0><TR BGCOLOR=LIGHTGREEN><TD>
 856 <TABLE CELLSPACING=1 CELLPADDING=3>
 857         <TR BGCOLOR=LIGHTGREEN><TH><B>Event</B></TH><TH><B>Description</B></TH><TH><B>Parameters</B></TH></TR>
 858         <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>pre_auth</B></TD>
 859                 <TD>This is called after a RADIUS response has been
 860                 received, but before it has been processed by the
 861                 code.  This will allow you to modify the response in
 862                 some way.
 863                 </TD>
 864                 <TD>
 865                 <DL>
 866                         <DT>t<DD>Tunnel
 867                         <DT>s<DD>Session
 868                         <DT>username
 869                         <DT>password
 870                         <DT>protocol<DD>0xC023 for PAP, 0xC223 for CHAP
 871                         <DT>continue_auth<DD>Set to 0 to stop processing authentication modules
 872                 </DL>
 873                 </TD>
 874         </TR>
 875         <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>post_auth</B></TD>
 876                 <TD>This is called after a RADIUS response has been
 877                 received, and the basic checks have been performed.  This
 878                 is what the garden module uses to force authentication
 879                 to be accepted.
 880                 </TD>
 881                 <TD>
 882                 <DL>
 883                         <DT>t<DD>Tunnel
 884                         <DT>s<DD>Session
 885                         <DT>username
 886                         <DT>auth_allowed<DD>This is already set to true or
 887                         false depending on whether authentication has been
 888                         allowed so far.  You can set this to 1 or 0 to force
 889                         allow or disallow authentication
 890                         <DT>protocol<DD>0xC023 for PAP, 0xC223 for CHAP
 891                 </DL>
 892                 </TD>
 893         </TR>
 894         <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>packet_rx</B></TD>
 895                 <TD>This is called whenever a session receives 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>packet_tx</B></TD>
 909                 <TD>This is called whenever a session sends a
 910                 packet.  <FONT COLOR=RED>Use this sparingly, as this will
 911                 seriously slow down the system.</FONT>
 912                 </TD>
 913                 <TD>
 914                 <DL>
 915                         <DT>t<DD>Tunnel
 916                         <DT>s<DD>Session
 917                         <DT>buf<DD>The raw packet data
 918                         <DT>len<DD>The length of buf
 919                 </DL>
 920                 </TD>
 921         </TR>
 922         <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>timer</B></TD>
 923                 <TD>This is run every second, no matter what is happening.
 924                 This is called from a signal handler, so make sure anything
 925                 you do is reentrant.
 926                 </TD>
 927                 <TD>
 928                 <DL>
 929                         <DT>time_now<DD>The current unix timestamp
 930                 </DL>
 931                 </TD>
 932         </TR>
 933         <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>new_session</B></TD>
 934                 <TD>This is called after a session is fully set up.  The
 935                 session is now ready to handle traffic.
 936                 </TD>
 937                 <TD>
 938                 <DL>
 939                         <DT>t<DD>Tunnel
 940                         <DT>s<DD>Session
 941                 </DL>
 942                 </TD>
 943         </TR>
 944         <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>kill_session</B></TD>
 945                 <TD>This is called when a session is about to be shut down.
 946                 This may be called multiple times for the same session.
 947                 </TD>
 948                 <TD>
 949                 <DL>
 950                         <DT>t<DD>Tunnel
 951                         <DT>s<DD>Session
 952                 </DL>
 953                 </TD>
 954         </TR>
 955         <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>radius_response</B></TD>
 956                 <TD>This is called whenever a RADIUS response includes a
 957                 Cisco-Avpair value.  The value is split up into
 958                 <EM>key=value</EM> pairs, and each is processed through all
 959                 modules.
 960                 </TD>
 961                 <TD>
 962                 <DL>
 963                         <DT>t<DD>Tunnel
 964                         <DT>s<DD>Session
 965                         <DT>key
 966                         <DT>value
 967                 </DL>
 968                 </TD>
 969         </TR>
 970         <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>radius_reset</B></TD>
 971                 <TD>This is called whenever a RADIUS CoA request is
 972                 received to reset any options to default values before
 973                 the new values are applied.
 974                 </TD>
 975                 <TD>
 976                 <DL>
 977                         <DT>t<DD>Tunnel
 978                         <DT>s<DD>Session
 979                 </DL>
 980                 </TD>
 981         </TR>
 982         <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>control</B></TD>
 983                 <TD>This is called in whenever a nsctl packet is received.
 984                 This should handle the packet and form a response if
 985                 required.
 986                 </TD>
 987                 <TD>
 988                 <DL>
 989                         <DT>iam_master<DD>Cluster master status
 990                         <DT>argc<DD>The number of arguments
 991                         <DT>argv<DD>Arguments
 992                         <DT>response<DD>Return value: NSCTL_RES_OK or NSCTL_RES_ERR
 993                         <DT>additional<DD>Extended response text
 994                 </DL>
 995                 </TD>
 996         </TR>
 997 </TABLE>
 998 </TD></TR></TABLE>
 999
1000 <H2 ID="WalledGarden">Walled Garden</H2>
1001
1002 Walled Garden is implemented so that you can provide perhaps limited service
1003 to sessions that incorrectly authenticate.<P>
1004
1005 Whenever a session provides incorrect authentication, and the
1006 RADIUS server responds with Auth-Reject, the walled garden module
1007 (if loaded) will force authentication to succeed, but set the flag
1008 <EM>garden</EM> in the session structure, and adds an iptables rule to
1009 the <B>garden_users</B> chain to force all packets for the session's IP
1010 address to traverse the <B>garden</B> chain.<P>
1011
1012 This doesn't <EM>just work</EM>.  To set this all up, you will to
1013 setup the <B>garden</B> nat table with the
1014 <A HREF="#build-garden">build-garden</A> script with rules to limit
1015 user's traffic.  For example, to force all traffic except DNS to be
1016 forwarded to 192.168.1.1, add these entries to your
1017 <EM>build-garden</EM>:
1018 <PRE>
1019 iptables -t nat -A garden -p tcp --dport ! 53 -j DNAT --to 192.168.1.1
1020 iptables -t nat -A garden -p udp --dport ! 53 -j DNAT --to 192.168.1.1
1021 </PRE>
1022
1023 l2tpns will add entries to the garden_users chain as appropriate.<P>
1024
1025 You can check the amount of traffic being captured using the following
1026 command:
1027 <PRE>
1028 iptables -t nat -L garden -nvx
1029 </PRE>
1030
1031 <H2 ID="Filtering">Filtering</H2>
1032
1033 Sessions may be filtered by specifying <B>Filter-Id</B> attributes in
1034 the RADIUS reply.  <I>filter</I>.<B>in</B> specifies that the named
1035 access-list <I>filter</I> should be applied to traffic from the
1036 customer, <I>filter</I>.<B>out</B> specifies a list for traffic to the
1037 customer.
1038
1039 <H2 ID="Clustering">Clustering</H2>
1040
1041 An l2tpns cluster consists of of one* or more servers configured with
1042 the same configuration, notably the multicast <B>cluster_address</B>.<P>
1043
1044 *A stand-alone server is simply a degraded cluster.<P>
1045
1046 Initially servers come up as cluster slaves, and periodically (every
1047 <B>cluster_hb_interval</B>/10 seconds) send out ping packets
1048 containing the start time of the process to the multicast
1049 <B>cluster_address</B>.<P>
1050
1051 A cluster master sends heartbeat rather than ping packets, which
1052 contain those session and tunnel changes since the last heartbeat.<P>
1053
1054 When a slave has not seen a heartbeat within
1055 <B>cluster_hb_timeout</B>/10 seconds it "elects" a new master by
1056 examining the list of peers it has seen pings from and determines
1057 which of these and itself is the "best" candidate to be master.
1058 "Best" in this context means the server with the highest uptime (the
1059 highest IP address is used as a tie-breaker in the case of equal
1060 uptimes).<P>
1061
1062 After discovering a master, and determining that it is up-to-date (has
1063 seen an update for all in-use sessions and tunnels from heartbeat
1064 packets) will raise a route (see <A HREF="#Routing">Routing</A>) for
1065 the <B>bind_address</B> and for all addresses/networks in
1066 <B>ip_pool</B>.  Any packets recieved by the slave which would alter
1067 the session state, as well as packets for throttled or gardened
1068 sessions are forwarded to the master for handling.  In addition, byte
1069 counters for session traffic are periodically forwarded.<P>
1070
1071 A master, when determining that it has at least one up-to-date slave
1072 will drop all routes (raising them again if all slaves disappear) and
1073 subsequently handle only packets forwarded to it by the slaves.<P>
1074
1075 <H2 ID="Routing">Routing</H2>
1076 If you are running a single instance, you may simply statically route
1077 the IP pools to the <B>bind_address</B> (l2tpns will send a gratuitous
1078 arp).<P>
1079
1080 For a cluster, configure the members as BGP neighbours on your router
1081 and configure multi-path load-balancing.  Cisco uses "maximum-paths
1082 ibgp" for IBGP.  If this is not supported by your IOS revision, you
1083 can use "maximum-paths" (which works for EBGP) and set
1084 <B>as_number</B> to a private value such as 64512.<P>
1085
1086 <H2 ID="Performance">Performance</H2>
1087
1088 Performance is great.<P>
1089
1090 I'd like to include some pretty graphs here that show a linear performance
1091 increase, with no impact by number of connected sessions.<P>
1092
1093 That's really what it looks like.<P>
1094
1095 <BR>
1096 David Parrish<BR>
1097 <A HREF="mailto:l2tpns-users@lists.sourceforge.net?subject=L2TPNS%20Documentation">l2tpns-users@lists.sourceforge.net</A>
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