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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 It's the listen address of the l2tp udp protocol sent and received
 256 to LAC. This address is also assigned to the tun interface if no
 257 iftun_address is specified. Packets containing user traffic should be
 258 routed via this address if given, otherwise the primary address of the
 259 machine.
 260 </LI>
 261
 262 <LI><B>iftun_address</B> (ip address)<BR>
 263 This parameter is used when you want a tun interface address different
 264 from the address of "bind_address" (For use in cases of specific configuration).
 265 If no address is given to iftun_address and bind_address, 1.1.1.1 is used.
 266 </LI>
 267
 268 <LI><B>peer_address</B> (ip address)<BR>
 269 Address to send to clients as the default gateway.
 270 </LI>
 271
 272 <LI><B>send_garp</B> (boolean)<BR>
 273 Determines whether or not to send a gratuitous ARP for the
 274 bind_address when the server is ready to handle traffic (default:
 275 true).<BR>
 276 This value is ignored if BGP is configured.
 277 </LI>
 278
 279 <LI><B>throttle_speed</B> (int)<BR>
 280 Sets the default speed (in kbits/s) which sessions will be limited to.
 281 If this is set to 0, then throttling will not be used at all.  Note:
 282 You can set this by the CLI, but changes will not affect currently
 283 connected users.
 284 </LI>
 285
 286 <LI><B>throttle_buckets</B> (int)<BR>
 287 Number of token buckets to allocate for throttling.  Each throttled
 288 session requires two buckets (in and out).
 289 </LI>
 290
 291 <LI><B>accounting_dir</B> (string)<BR>
 292 If set to a directory, then every 5 minutes the current usage for
 293 every connected use will be dumped to a file in this directory.  Each
 294 file dumped begins with a header, where each line is prefixed by #.
 295 Following the header is a single line for every connected user, fields
 296 separated by a space.<BR> The fields are username, ip, qos,
 297 uptxoctets, downrxoctets.  The qos field is 1 if a standard user, and
 298 2 if the user is throttled.
 299 </LI>
 300
 301 <LI><B>setuid</B> (int)<BR>
 302 After starting up and binding the interface, change UID to this.  This
 303 doesn't work properly.
 304 </LI>
 305
 306 <LI><B>dump_speed</B> (boolean)<BR>
 307 If set to true, then the current bandwidth utilization will be logged every
 308 second.  Even if this is disabled, you can see this information by running
 309 the <EM>uptime</EM> command on the CLI.
 310 </LI>
 311
 312 <LI><B>multi_read_count</B> (int)<BR>
 313 Number of packets to read off each of the UDP and TUN fds when
 314 returned as readable by select (default:  10).  Avoids incurring the
 315 unnecessary system call overhead of select on busy servers.
 316 </LI>
 317
 318 <LI><B>scheduler_fifo</B> (boolean)<BR>
 319 Sets the scheduling policy for the l2tpns process to SCHED_FIFO.  This
 320 causes the kernel to immediately preempt any currently running SCHED_OTHER
 321 (normal) process in favour of l2tpns when it becomes runnable.
 322 Ignored on uniprocessor systems.
 323 </LI>
 324
 325 <LI><B>lock_pages</B> (boolean)<BR>
 326 Keep all pages mapped by the l2tpns process in memory.
 327 </LI>
 328
 329 <LI><B>icmp_rate</B> (int)<BR>
 330 Maximum number of host unreachable ICMP packets to send per second.
 331 </LI>
 332
 333 <LI><B>packet_limit</B> (int><BR>
 334 Maximum number of packets of downstream traffic to be handled each
 335 tenth of a second per session.  If zero, no limit is applied (default:
 336 0).  Intended as a DoS prevention mechanism and not a general
 337 throttling control (packets are dropped, not queued).
 338 </LI>
 339
 340 <LI><B>cluster_address</B> (ip address)<BR>
 341 Multicast cluster address (default:  239.192.13.13).  See the section
 342 on <A HREF="#Clustering">Clustering</A> for more information.
 343 </LI>
 344
 345 <LI><B>cluster_interface</B> (string)<BR>
 346 Interface for cluster packets (default: eth0).
 347 </LI>
 348
 349 <LI><B>cluster_mcast_ttl</B> (int)<BR>
 350 TTL for multicast packets (default: 1).
 351 </LI>
 352
 353 <LI><B>cluster_hb_interval</B> (int)<BR>
 354 Interval in tenths of a second between cluster heartbeat/pings.
 355 </LI>
 356
 357 <LI><B>cluster_hb_timeout</B> (int)<BR>
 358 Cluster heartbeat timeout in tenths of a second.  A new master will be
 359 elected when this interval has been passed without seeing a heartbeat
 360 from the master.
 361 </LI>
 362
 363 <LI><B>cluster_master_min_adv</B> (int)<BR>
 364 Determines the minumum number of up to date slaves required before the
 365 master will drop routes (default: 1).
 366 </LI>
 367
 368 <LI><B>echo_timeout</B> (int)<BR>
 369 Time between last packet sent and LCP ECHO generation
 370 (default: 10 (seconds)).
 371 </LI>
 372
 373 <LI><B>idle_echo_timeout</B> (int)<BR>
 374 Drop sessions who have not responded within idle_echo_timeout seconds
 375 (default: 240 (seconds))
 376 </LI>
 377
 378 <LI><B>bind_address_remotelns</B> (ip address)<BR>
 379 Address of the interface to listen the remote LNS tunnels.
 380 If no address is given, all interfaces are listened (Any Address).
 381 </LI>
 382
 383 <LI><B>bind_portremotelns</B> (short)<BR>
 384 Port to bind for the Remote LNS (default: 65432).
 385 </LI>
 386
 387 </UL>
 388
 389 <P>The REMOTES LNS configuration is entered by the command:
 390 <DL> <DD><B>setforward</B> <I>MASK</I> <I>IP</I> <I>PORT</I> <I>SECRET</I> </DL>
 391
 392 where <I>MASK</I> specifies the mask of users who have forwarded to
 393 remote LNS (ex: /myISP@company.com).</BR>
 394 where <I>IP</I> specifies the IP of the  remote LNS (ex: 66.66.66.55).</BR>
 395 where <I>PORT</I> specifies the L2TP Port of the remote LNS
 396 (Normally should be 1701) (ex: 1701).</BR>
 397 where <I>SECRET</I> specifies the secret password the remote LNS (ex: mysecret).</BR>
 398
 399 <P>BGP routing configuration is entered by the command:
 400 The routing configuration section is entered by the command
 401 <DL><DD><B>router bgp</B> <I>as</I></DL>
 402 where <I>as</I> specifies the local AS number.
 403
 404 <P>Subsequent lines prefixed with
 405 <DL><DD><B>neighbour</B> <I>peer</I></DL>
 406 define the attributes of BGP neighhbours.  Valid commands are:
 407 <DL>
 408   <DD><B>neighbour</B> <I>peer</I> <B>remote-as</B> <I>as</I>
 409   <DD><B>neighbout</B> <I>peer</I> <B>timers</B> <I>keepalive hold</I>
 410 </DL>
 411
 412 Where <I>peer</I> specifies the BGP neighbour as either a hostname or
 413 IP address, <I>as</I> is the remote AS number and <I>keepalive</I>,
 414 <I>hold</I> are the timer values in seconds.
 415
 416 <P>Named access-lists are configured using one of the commands:
 417 <DL>
 418   <DD><B>ip access-list standard</B> <I>name</I>
 419   <DD><B>ip access-list extended</B> <I>name</I>
 420 </DL>
 421
 422 <P>Subsequent lines prefixed with <B>permit</B> or <B>deny</B>
 423 define the body of the access-list.  Standard access-list syntax:
 424 <DL>
 425   <DD>{<B>permit</B>|<B>deny</B>}
 426     {<I>host</I>|<I>source source-wildcard</I>|<B>any</B>}
 427     [{<I>host</I>|<I>destination destination-wildcard</I>|<B>any</B>}]
 428 </DL>
 429
 430 Extended access-lists:
 431
 432 <DIV STYLE="margin-left: 4em; text-indent: -2em">
 433   <P>{<B>permit</B>|<B>deny</B>} <B>ip</B>
 434     {<I>host</I>|<I>source source-wildcard</I>|<B>any</B>}
 435     {<I>host</I>|<I>destination destination-wildcard</I>|<B>any</B>} [<B>fragments</B>]
 436   <P>{<B>permit</B>|<B>deny</B>} <B>udp</B>
 437     {<I>host</I>|<I>source source-wildcard</I>|<B>any</B>}
 438         [{<B>eq</B>|<B>neq</B>|<B>gt</B>|<B>lt</B>} <I>port</I>|<B>range</B> <I>from</I> <I>to</I>]
 439     {<I>host</I>|<I>destination destination-wildcard</I>|<B>any</B>}
 440         [{<B>eq</B>|<B>neq</B>|<B>gt</B>|<B>lt</B>} <I>port</I>|<B>range</B> <I>from</I> <I>to</I>]
 441         [<B>fragments</B>]
 442   <P>{<B>permit</B>|<B>deny</B>} <B>tcp</B>
 443     {<I>host</I>|<I>source source-wildcard</I>|<B>any</B>}
 444         [{<B>eq</B>|<B>neq</B>|<B>gt</B>|<B>lt</B>} <I>port</I>|<B>range</B> <I>from</I> <I>to</I>]
 445     {<I>host</I>|<I>destination destination-wildcard</I>|<B>any</B>}
 446         [{<B>eq</B>|<B>neq</B>|<B>gt</B>|<B>lt</B>} <I>port</I>|<B>range</B> <I>from</I> <I>to</I>]
 447         [{<B>established</B>|{<B>match-any</B>|<B>match-all</B>}
 448             {<B>+</B>|<B>-</B>}{<B>fin</B>|<B>syn</B>|<B>rst</B>|<B>psh</B>|<B>ack</B>|<B>urg</B>}
 449             ...|<B>fragments</B>]
 450 </DIV>
 451
 452 <H3 ID="users">users</H3>
 453
 454 Usernames and passwords for the command-line interface are stored in
 455 this file.  The format is <I>username</I><B>:</B><I>password</I> where
 456 <I>password</I> may either by plain text, an MD5 digest (prefixed by
 457 <B>$1</B><I>salt</I><B>$</B>) or a DES password, distinguished from
 458 plain text by the prefix <B>{crypt}</B>.<P>
 459
 460 The username <B>enable</B> has a special meaning and is used to set
 461 the enable password.<P>
 462
 463 <B>Note:</B> If this file doesn't exist, then anyone who can get to
 464 port 23 will be allowed access without a username / password.<P>
 465
 466 <H3 ID="ip-pool">ip_pool</H3>
 467
 468 This file is used to configure the IP address pool which user
 469 addresses are assigned from.  This file should contain either an IP
 470 address or a CIDR network per line.  e.g.:<P>
 471
 472 <PRE>
 473     192.168.1.1
 474     192.168.1.2
 475     192.168.1.3
 476     192.168.4.0/24
 477     172.16.0.0/16
 478     10.0.0.0/8
 479 </PRE>
 480
 481 Keep in mind that l2tpns can only handle 65535 connections per
 482 process, so don't put more than 65535 IP addresses in the
 483 configuration file.  They will be wasted.
 484
 485 <H3 ID="build-garden">build-garden</H3>
 486
 487 The garden plugin on startup creates a NAT table called "garden" then
 488 sources the <B>build-garden</B> script to populate that table.  All
 489 packets from gardened users will be sent through this table.  Example:
 490
 491 <PRE>
 492     iptables -t nat -A garden -p tcp -m tcp --dport 25 -j DNAT --to 192.168.1.1
 493     iptables -t nat -A garden -p udp -m udp --dport 53 -j DNAT --to 192.168.1.1
 494     iptables -t nat -A garden -p tcp -m tcp --dport 53 -j DNAT --to 192.168.1.1
 495     iptables -t nat -A garden -p tcp -m tcp --dport 80 -j DNAT --to 192.168.1.1
 496     iptables -t nat -A garden -p tcp -m tcp --dport 110 -j DNAT --to 192.168.1.1
 497     iptables -t nat -A garden -p tcp -m tcp --dport 443 -j DNAT --to 192.168.1.1
 498     iptables -t nat -A garden -p icmp -m icmp --icmp-type echo-request -j DNAT --to 192.168.1.1
 499     iptables -t nat -A garden -p icmp -j ACCEPT
 500     iptables -t nat -A garden -j DROP
 501 </PRE>
 502
 503 <H2 ID="ControllingtheProcess">Controlling the Process</H2>
 504
 505 A running l2tpns process can be controlled in a number of ways.  The primary
 506 method of control is by the Command-Line Interface (CLI).<P>
 507
 508 You can also remotely send commands to modules via the nsctl client
 509 provided.<P>
 510
 511 Also, there are a number of signals that l2tpns understands and takes action
 512 when it receives them.
 513
 514 <H3 ID="Command-LineInterface">Command-Line Interface</H3>
 515
 516 You can access the command line interface by telnet'ing to port 23.
 517 There is no IP address restriction, so it's a good idea to firewall
 518 this port off from anyone who doesn't need access to it.  See
 519 <A HREF="#users">users</A> for information on restricting access based
 520 on a username and password.<P>
 521
 522 The CLI gives you real-time control over almost everything in
 523 the process.  The interface is designed to look like a Cisco
 524 device, and supports things like command history, line editing and
 525 context sensitive help.  This is provided by linking with the
 526 <A HREF="http://sourceforge.net/projects/libcli">libcli</A>
 527 library.  Some general documentation of the interface is
 528 <A HREF="http://sourceforge.net/docman/display_doc.php?docid=20501&group_id=79019">
 529 here</A>.<P>
 530
 531 After you have connected to the telnet port (and perhaps logged in), you
 532 will be presented with a <I>hostname</I><B>&gt;</B> prompt.<P>
 533
 534 Enter <EM>help</EM> to get a list of possible commands.  A brief
 535 overview of the more important commands follows:
 536
 537 <UL>
 538 <LI><B>show session</B><BR>
 539 Without specifying a session ID, this will list all tunnels currently
 540 connected.  If you specify a session ID, you will be given all
 541 information on a single tunnel.  Note that the full session list can
 542 be around 185 columns wide, so you should probably use a wide terminal
 543 to see the list properly.<P>
 544 The columns listed in the overview are:
 545 <TABLE>
 546         <TR><TD><B>SID</B></TD><TD>Session ID</TD></TR>
 547         <TR><TD><B>TID</B></TD><TD>Tunnel ID - Use with <EM>show tunnel tid</EM></TD></TR>
 548         <TR><TD><B>Username</B></TD><TD>The username given in the PPP
 549         authentication.  If this is *, then LCP authentication has not
 550         completed.</TD></TR>
 551         <TR><TD><B>IP</B></TD><TD>The IP address given to the session.  If
 552         this is 0.0.0.0, LCP negotiation has not completed.</TD></TR>
 553         <TR><TD><B>I</B></TD><TD>Intercept - Y or N depending on whether the
 554         session is being snooped.  See <EM>snoop</EM>.</TD></TR>
 555         <TR><TD><B>T</B></TD><TD>Throttled - Y or N if the session is
 556         currently throttled.  See <EM>throttle</EM>.</TD></TR>
 557         <TR><TD><B>G</B></TD><TD>Walled Garden - Y or N if the user is
 558         trapped in the walled garden.  This field is present even if the
 559         garden module is not loaded.</TD></TR>
 560         <TR><TD><B>opened</B></TD><TD>The number of seconds since the
 561         session started</TD></TR>
 562         <TR><TD><B>downloaded</B></TD><TD>Number of bytes downloaded by the user</TD></TR>
 563         <TR><TD><B>uploaded</B></TD><TD>Number of bytes uploaded by the user</TD></TR>
 564         <TR><TD><B>idle</B></TD><TD>The number of seconds since traffic was
 565         detected on the session</TD></TR>
 566         <TR><TD><B>LAC</B></TD><TD>The IP address of the LAC the session is
 567         connected to.</TD></TR>
 568         <TR><TD><B>CLI</B></TD><TD>The Calling-Line-Identification field
 569         provided during the session setup.  This field is generated by the
 570         LAC.</TD></TR>
 571 </TABLE>
 572 <P>
 573 </LI>
 574
 575 <LI><B>show users</B><BR>
 576 With no arguments, display a list of currently connected users.  If an
 577 argument is given, the session details for the given username are
 578 displayed.
 579 </LI>
 580
 581 <LI><B>show tunnel</B><BR>
 582 This will show all the open tunnels in a summary, or detail on a single
 583 tunnel if you give a tunnel id.<P>
 584 The columns listed in the overview are:
 585 <TABLE>
 586         <TR><TD><B>TID</B></TD><TD>Tunnel ID</TD></TR>
 587         <TR><TD><B>Hostname</B></TD><TD>The hostname for the tunnel as
 588         provided by the LAC.  This has no relation to DNS, it is just
 589         a text field.</TD></TR>
 590         <TR><TD><B>IP</B></TD><TD>The IP address of the LAC</TD></TR>
 591         <TR><TD><B>State</B></TD><TD>Tunnel state - Free, Open, Dieing,
 592         Opening</TD></TR>
 593         <TR><TD><B>Sessions</B></TD><TD>The number of open sessions on the
 594         tunnel</TD></TR>
 595 </TABLE>
 596 <P>
 597 </LI>
 598
 599 <LI><B>show pool</B><BR>
 600 Displays the current IP address pool allocation.  This will only display
 601 addresses that are in use, or are reserved for re-allocation to a
 602 disconnected user.<P>
 603 If an address is not currently in use, but has been used, then in the User
 604 column the username will be shown in square brackets, followed by the time
 605 since the address was used:
 606 <PRE>
 607 IP Address      Used  Session User
 608 192.168.100.6     N           [joe.user] 1548s
 609 </PRE>
 610 <P>
 611 </LI>
 612
 613 <LI><B>show radius</B><BR>
 614 Show a summary of the in-use RADIUS sessions.  This list should not be very
 615 long, as RADIUS sessions should be cleaned up as soon as they are used.  The
 616 columns listed are:
 617 <TABLE>
 618         <TR><TD><B>Radius</B></TD><TD>The ID of the RADIUS request.  This is
 619         sent in the packet to the RADIUS server for identification.</TD></TR>
 620         <TR><TD><B>State</B></TD><TD>The state of the request - WAIT, CHAP,
 621         AUTH, IPCP, START, STOP, NULL.</TD></TR>
 622         <TR><TD><B>Session</B></TD><TD>The session ID that this RADIUS
 623         request is associated with</TD></TR>
 624         <TR><TD><B>Retry</B></TD><TD>If a response does not appear to the
 625         request, it will retry at this time.  This is a unix timestamp.</TD></TR>
 626         <TR><TD><B>Try</B></TD><TD>Retry count.  The RADIUS request is
 627         discarded after 3 retries.</TD></TR>
 628 </TABLE>
 629 <P>
 630 </LI>
 631
 632 <LI><B>show running-config</B><BR>
 633 This will list the current running configuration.  This is in a format that
 634 can either be pasted into the configuration file, or run directly at the
 635 command line.
 636 <P>
 637 </LI>
 638
 639 <LI><B>show counters</B><BR>
 640 Internally, counters are kept of key values, such as bytes and packets
 641 transferred, as well as function call counters.  This function displays all
 642 these counters, and is probably only useful for debugging.<P>
 643 You can reset these counters by running <EM>clear counters</EM>.
 644 <P>
 645 </LI>
 646
 647 <LI><B>show cluster</B><BR>
 648 Show cluster status.  Shows the cluster state for this server
 649 (Master/Slave), information about known peers and (for slaves) the
 650 master IP address, last packet seen and up-to-date status.<P>
 651 See <A HREF="#Clustering">Clustering</A> for more information.
 652 <P>
 653 </LI>
 654
 655 <LI><B>write memory</B><BR>
 656 This will write the current running configuration to the config file
 657 <B>startup-config</B>, which will be run on a restart.
 658 <P>
 659 </LI>
 660
 661 <LI><B>snoop</B><BR>
 662 You must specify a username, IP address and port.  All packets for the
 663 current session for that username will be forwarded to the given
 664 host/port.  Specify <EM>no snoop username</EM> to disable interception
 665 for the session.<P>
 666
 667 If you want interception to be permanent, you will have to modify the RADIUS
 668 response for the user.  See <A HREF="#Interception">Interception</A>.
 669 <P>
 670 </LI>
 671
 672 <LI><B>throttle</B><BR>
 673 You must specify a username, which will be throttled for the current
 674 session.  Specify <EM>no throttle username</EM> to disable throttling
 675 for the current session.<P>
 676
 677 If you want throttling to be permanent, you will have to modify the
 678 RADIUS response for the user.  See <A HREF="#Throttling">Throttling</A>.
 679 <P>
 680 </LI>
 681
 682 <LI><B>drop session</B><BR>
 683 This will cleanly disconnect a session.  You must specify a session id, which
 684 you can get from <EM>show session</EM>.  This will send a disconnect message
 685 to the remote end.
 686 <P>
 687 </LI>
 688
 689 <LI><B>drop tunnel</B><BR>
 690 This will cleanly disconnect a tunnel, as well as all sessions on that
 691 tunnel.  It will send a disconnect message for each session individually, and
 692 after 10 seconds it will send a tunnel disconnect message.
 693 <P>
 694 </LI>
 695
 696 <LI><B>uptime</B><BR>
 697 This will show how long the l2tpns process has been running, and the current
 698 bandwidth utilization:
 699 <PRE>
 700 17:10:35 up 8 days, 2212 users, load average: 0.21, 0.17, 0.16
 701 Bandwidth: UDP-ETH:6/6  ETH-UDP:13/13  TOTAL:37.6   IN:3033 OUT:2569
 702 </PRE>
 703 The bandwidth line contains 4 sets of values.<BR>
 704 UDP-ETH is the current bandwidth going from the LAC to the ethernet
 705 (user uploads), in mbits/sec.<BR>
 706 ETH-UDP is the current bandwidth going from ethernet to the LAC (user
 707 downloads).<BR>
 708 TOTAL is the total aggregate bandwidth in mbits/s.<BR>
 709 IN and OUT are packets/per-second going between UDP-ETH and ETH-UDP.
 710 <P>
 711 These counters are updated every second.
 712 <P>
 713 </LI>
 714
 715 <LI><B>configure terminal</B><BR>
 716 Enter configuration mode.  Use <EM>exit</EM> or ^Z to exit this mode.
 717 The following commands are valid in this mode:<P>
 718 </LI>
 719
 720 <LI><B>load plugin</B><BR>
 721 Load a plugin.  You must specify the plugin name, and it will search in
 722 /usr/lib/l2tpns for <EM>plugin</EM>.so.  You can unload a loaded plugin with
 723 <EM>remove plugin</EM>.
 724 <P>
 725 </LI>
 726
 727 <LI><B>set</B><BR>
 728 Set a configuration variable.  You must specify the variable name, and
 729 the value.  If the value contains any spaces, you should quote the
 730 value with double (") or single (') quotes.<P>
 731
 732 You can set any <A HREF="#startup-config">startup-config</A> value in
 733 this way, although some may require a restart to take effect.<P>
 734 </LI>
 735 </UL>
 736
 737 <H3 ID="nsctl">nsctl</H3>
 738
 739 nsctl allows messages to be passed to plugins.<P>
 740
 741 Arguments are <EM>command</EM> and optional <EM>args</EM>.  See
 742 <STRONG>nsctl</STRONG>(8) for more details.<P>
 743
 744 Built-in command are <EM>load_plugin</EM>, <EM>unload_plugin</EM> and
 745 <EM>help</EM>.  Any other commands are passed to plugins for processing.
 746
 747 <H3 ID="Signals">Signals</H3>
 748
 749 While the process is running, you can send it a few different signals, using
 750 the kill command.
 751 <PRE>
 752 killall -HUP l2tpns
 753 </PRE>
 754
 755 The signals understood are:
 756 <DL>
 757 <DT>SIGHUP</DT><DD>Reload the config from disk and re-open log file.</DD>
 758 <DT>SIGTERM, SIGINT</DT><DD>Stop process.  Tunnels and sessions are not
 759 terminated.  This signal should be used to stop l2tpns on a
 760 <A HREF="#Clustering">cluster node</A> where there are other machines to
 761 continue handling traffic.</DD>
 762 <DT>SIGQUIT</DT><DD>Shut down tunnels and sessions, exit process when
 763 complete.</DD>
 764 </DL>
 765
 766 <H2 ID="Throttling">Throttling</H2>
 767
 768 l2tpns contains support for slowing down user sessions to whatever speed you
 769 desire.  You must first enable the global setting <EM>throttle_speed</EM>
 770 before this will be activated.<P>
 771
 772 If you wish a session to be throttled permanently, you should set the
 773 Vendor-Specific RADIUS value <B>Cisco-Avpair="throttle=yes"</B>, which
 774 will be handled by the <EM>autothrottle</EM> module.<P>
 775
 776 Otherwise, you can enable and disable throttling an active session using
 777 the <EM>throttle</EM> CLI command.<P>
 778
 779 <H2 ID="Interception">Interception</H2>
 780
 781 You may have to deal with legal requirements to be able to intercept a
 782 user's traffic at any time.  l2tpns allows you to begin and end interception
 783 on the fly, as well as at authentication time.<P>
 784
 785 When a user is being intercepted, a copy of every packet they send and
 786 receive will be sent wrapped in a UDP packet to the IP address and port set
 787 in the <EM>snoop_host</EM> and <EM>snoop_port</EM> configuration
 788 variables.<P>
 789
 790 The UDP packet contains just the raw IP frame, with no extra headers.<P>
 791
 792 To enable interception on a connected user, use the <EM>snoop username</EM>
 793 and <EM>no snoop username</EM> CLI commands.  These will enable interception
 794 immediately.<P>
 795
 796 If you wish the user to be intercepted whenever they reconnect, you will
 797 need to modify the RADIUS response to include the Vendor-Specific value
 798 <B>Cisco-Avpair="intercept=yes"</B>.  For this feature to be enabled,
 799 you need to have the <EM>autosnoop</EM> module loaded.<P>
 800
 801 <H2 ID="Authentication">Authentication</H2>
 802
 803 Whenever a session connects, it is not fully set up until authentication is
 804 completed.  The remote end must send a PPP CHAP or PPP PAP authentication
 805 request to l2tpns.<P>
 806
 807 This request is sent to the RADIUS server, which will hopefully respond with
 808 Auth-Accept or Auth-Reject.<P>
 809
 810 If Auth-Accept is received, the session is set up and an IP address is
 811 assigned.  The RADIUS server can include a Framed-IP-Address field in the
 812 reply, and that address will be assigned to the client.  It can also include
 813 specific DNS servers, and a Framed-Route if that is required.<P>
 814
 815 If Auth-Reject is received, then the client is sent a PPP AUTHNAK packet,
 816 at which point they should disconnect.  The exception to this is when the
 817 walled garden module is loaded, in which case the user still receives the
 818 PPP AUTHACK, but their session is flagged as being a garden'd user, and they
 819 should not receive any service.<P>
 820
 821 The RADIUS reply can also contain a Vendor-Specific attribute called
 822 Cisco-Avpair.  This field is a freeform text field that most Cisco
 823 devices understand to contain configuration instructions for the session.  In
 824 the case of l2tpns it is expected to be of the form
 825 <PRE>
 826 key=value,key2=value2,key3=value3,key<EM>n</EM>=<EM>value</EM>
 827 </PRE>
 828
 829 Each key-value pair is separated and passed to any modules loaded.  The
 830 <EM>autosnoop</EM> and <EM>autothrottle</EM> understand the keys
 831 <EM>intercept</EM> and <EM>throttle</EM> respectively.  For example, to have
 832 a user who is to be throttled and intercepted, the Cisco-Avpair value should
 833 contain:
 834 <PRE>
 835 intercept=yes,throttle=yes
 836 </PRE>
 837
 838 <H2 ID="Plugins">Plugins</H2>
 839
 840 So as to make l2tpns as flexible as possible (I know the core code is pretty
 841 difficult to understand), it includes a plugin API, which you can use to
 842 hook into certain events.<P>
 843
 844 There are a few example modules included - autosnoop, autothrottle and
 845 garden.<P>
 846
 847 When an event happens that has a hook, l2tpns looks for a predefined
 848 function name in every loaded module, and runs them in the order the modules
 849 were loaded.<P>
 850
 851 The function should return <B>PLUGIN_RET_OK</B> if it is all OK.  If it returns
 852 <B>PLUGIN_RET_STOP</B>, then it is assumed to have worked, but that no further
 853 modules should be run for this event.<P>
 854 A return of <B>PLUGIN_RET_ERROR</B> means that this module failed, and
 855 no further processing should be done for this event.  <EM>Use this with care.</EM>
 856
 857 Every event function called takes a specific structure named
 858 param_<EM>event</EM>, which varies in content with each event.  The
 859 function name for each event will be <B>plugin_<EM>event</EM></B>,
 860 so for the event <EM>timer</EM>, the function declaration should look like:
 861 <PRE>
 862 int plugin_timer(struct param_timer *data);
 863 </PRE>
 864
 865 A list of the available events follows, with a list of all the fields in the
 866 supplied structure:
 867 <TABLE CELLSPACING=0 CELLPADDING=0><TR BGCOLOR=LIGHTGREEN><TD>
 868 <TABLE CELLSPACING=1 CELLPADDING=3>
 869         <TR BGCOLOR=LIGHTGREEN><TH><B>Event</B></TH><TH><B>Description</B></TH><TH><B>Parameters</B></TH></TR>
 870         <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>pre_auth</B></TD>
 871                 <TD>This is called after a RADIUS response has been
 872                 received, but before it has been processed by the
 873                 code.  This will allow you to modify the response in
 874                 some way.
 875                 </TD>
 876                 <TD>
 877                 <DL>
 878                         <DT>t<DD>Tunnel
 879                         <DT>s<DD>Session
 880                         <DT>username
 881                         <DT>password
 882                         <DT>protocol<DD>0xC023 for PAP, 0xC223 for CHAP
 883                         <DT>continue_auth<DD>Set to 0 to stop processing authentication modules
 884                 </DL>
 885                 </TD>
 886         </TR>
 887         <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>post_auth</B></TD>
 888                 <TD>This is called after a RADIUS response has been
 889                 received, and the basic checks have been performed.  This
 890                 is what the garden module uses to force authentication
 891                 to be accepted.
 892                 </TD>
 893                 <TD>
 894                 <DL>
 895                         <DT>t<DD>Tunnel
 896                         <DT>s<DD>Session
 897                         <DT>username
 898                         <DT>auth_allowed<DD>This is already set to true or
 899                         false depending on whether authentication has been
 900                         allowed so far.  You can set this to 1 or 0 to force
 901                         allow or disallow authentication
 902                         <DT>protocol<DD>0xC023 for PAP, 0xC223 for CHAP
 903                 </DL>
 904                 </TD>
 905         </TR>
 906         <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>packet_rx</B></TD>
 907                 <TD>This is called whenever a session receives a
 908                 packet.  <FONT COLOR=RED>Use this sparingly, as this will
 909                 seriously slow down the system.</FONT>
 910                 </TD>
 911                 <TD>
 912                 <DL>
 913                         <DT>t<DD>Tunnel
 914                         <DT>s<DD>Session
 915                         <DT>buf<DD>The raw packet data
 916                         <DT>len<DD>The length of buf
 917                 </DL>
 918                 </TD>
 919         </TR>
 920         <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>packet_tx</B></TD>
 921                 <TD>This is called whenever a session sends a
 922                 packet.  <FONT COLOR=RED>Use this sparingly, as this will
 923                 seriously slow down the system.</FONT>
 924                 </TD>
 925                 <TD>
 926                 <DL>
 927                         <DT>t<DD>Tunnel
 928                         <DT>s<DD>Session
 929                         <DT>buf<DD>The raw packet data
 930                         <DT>len<DD>The length of buf
 931                 </DL>
 932                 </TD>
 933         </TR>
 934         <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>timer</B></TD>
 935                 <TD>This is run every second, no matter what is happening.
 936                 This is called from a signal handler, so make sure anything
 937                 you do is reentrant.
 938                 </TD>
 939                 <TD>
 940                 <DL>
 941                         <DT>time_now<DD>The current unix timestamp
 942                 </DL>
 943                 </TD>
 944         </TR>
 945         <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>new_session</B></TD>
 946                 <TD>This is called after a session is fully set up.  The
 947                 session is now ready to handle traffic.
 948                 </TD>
 949                 <TD>
 950                 <DL>
 951                         <DT>t<DD>Tunnel
 952                         <DT>s<DD>Session
 953                 </DL>
 954                 </TD>
 955         </TR>
 956         <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>kill_session</B></TD>
 957                 <TD>This is called when a session is about to be shut down.
 958                 This may be called multiple times for the same session.
 959                 </TD>
 960                 <TD>
 961                 <DL>
 962                         <DT>t<DD>Tunnel
 963                         <DT>s<DD>Session
 964                 </DL>
 965                 </TD>
 966         </TR>
 967         <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>radius_response</B></TD>
 968                 <TD>This is called whenever a RADIUS response includes a
 969                 Cisco-Avpair value.  The value is split up into
 970                 <EM>key=value</EM> pairs, and each is processed through all
 971                 modules.
 972                 </TD>
 973                 <TD>
 974                 <DL>
 975                         <DT>t<DD>Tunnel
 976                         <DT>s<DD>Session
 977                         <DT>key
 978                         <DT>value
 979                 </DL>
 980                 </TD>
 981         </TR>
 982         <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>radius_reset</B></TD>
 983                 <TD>This is called whenever a RADIUS CoA request is
 984                 received to reset any options to default values before
 985                 the new values are applied.
 986                 </TD>
 987                 <TD>
 988                 <DL>
 989                         <DT>t<DD>Tunnel
 990                         <DT>s<DD>Session
 991                 </DL>
 992                 </TD>
 993         </TR>
 994         <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>control</B></TD>
 995                 <TD>This is called in whenever a nsctl packet is received.
 996                 This should handle the packet and form a response if
 997                 required.
 998                 </TD>
 999                 <TD>
1000                 <DL>
1001                         <DT>iam_master<DD>Cluster master status
1002                         <DT>argc<DD>The number of arguments
1003                         <DT>argv<DD>Arguments
1004                         <DT>response<DD>Return value: NSCTL_RES_OK or NSCTL_RES_ERR
1005                         <DT>additional<DD>Extended response text
1006                 </DL>
1007                 </TD>
1008         </TR>
1009 </TABLE>
1010 </TD></TR></TABLE>
1011
1012 <H2 ID="WalledGarden">Walled Garden</H2>
1013
1014 Walled Garden is implemented so that you can provide perhaps limited service
1015 to sessions that incorrectly authenticate.<P>
1016
1017 Whenever a session provides incorrect authentication, and the
1018 RADIUS server responds with Auth-Reject, the walled garden module
1019 (if loaded) will force authentication to succeed, but set the flag
1020 <EM>garden</EM> in the session structure, and adds an iptables rule to
1021 the <B>garden_users</B> chain to force all packets for the session's IP
1022 address to traverse the <B>garden</B> chain.<P>
1023
1024 This doesn't <EM>just work</EM>.  To set this all up, you will to
1025 setup the <B>garden</B> nat table with the
1026 <A HREF="#build-garden">build-garden</A> script with rules to limit
1027 user's traffic.  For example, to force all traffic except DNS to be
1028 forwarded to 192.168.1.1, add these entries to your
1029 <EM>build-garden</EM>:
1030 <PRE>
1031 iptables -t nat -A garden -p tcp --dport ! 53 -j DNAT --to 192.168.1.1
1032 iptables -t nat -A garden -p udp --dport ! 53 -j DNAT --to 192.168.1.1
1033 </PRE>
1034
1035 l2tpns will add entries to the garden_users chain as appropriate.<P>
1036
1037 You can check the amount of traffic being captured using the following
1038 command:
1039 <PRE>
1040 iptables -t nat -L garden -nvx
1041 </PRE>
1042
1043 <H2 ID="Filtering">Filtering</H2>
1044
1045 Sessions may be filtered by specifying <B>Filter-Id</B> attributes in
1046 the RADIUS reply.  <I>filter</I>.<B>in</B> specifies that the named
1047 access-list <I>filter</I> should be applied to traffic from the
1048 customer, <I>filter</I>.<B>out</B> specifies a list for traffic to the
1049 customer.
1050
1051 <H2 ID="Clustering">Clustering</H2>
1052
1053 An l2tpns cluster consists of of one* or more servers configured with
1054 the same configuration, notably the multicast <B>cluster_address</B>.<P>
1055
1056 *A stand-alone server is simply a degraded cluster.<P>
1057
1058 Initially servers come up as cluster slaves, and periodically (every
1059 <B>cluster_hb_interval</B>/10 seconds) send out ping packets
1060 containing the start time of the process to the multicast
1061 <B>cluster_address</B>.<P>
1062
1063 A cluster master sends heartbeat rather than ping packets, which
1064 contain those session and tunnel changes since the last heartbeat.<P>
1065
1066 When a slave has not seen a heartbeat within
1067 <B>cluster_hb_timeout</B>/10 seconds it "elects" a new master by
1068 examining the list of peers it has seen pings from and determines
1069 which of these and itself is the "best" candidate to be master.
1070 "Best" in this context means the server with the highest uptime (the
1071 highest IP address is used as a tie-breaker in the case of equal
1072 uptimes).<P>
1073
1074 After discovering a master, and determining that it is up-to-date (has
1075 seen an update for all in-use sessions and tunnels from heartbeat
1076 packets) will raise a route (see <A HREF="#Routing">Routing</A>) for
1077 the <B>bind_address</B> and for all addresses/networks in
1078 <B>ip_pool</B>.  Any packets recieved by the slave which would alter
1079 the session state, as well as packets for throttled or gardened
1080 sessions are forwarded to the master for handling.  In addition, byte
1081 counters for session traffic are periodically forwarded.<P>
1082
1083 A master, when determining that it has at least one up-to-date slave
1084 will drop all routes (raising them again if all slaves disappear) and
1085 subsequently handle only packets forwarded to it by the slaves.<P>
1086
1087 <H2 ID="Routing">Routing</H2>
1088 If you are running a single instance, you may simply statically route
1089 the IP pools to the <B>bind_address</B> (l2tpns will send a gratuitous
1090 arp).<P>
1091
1092 For a cluster, configure the members as BGP neighbours on your router
1093 and configure multi-path load-balancing.  Cisco uses "maximum-paths
1094 ibgp" for IBGP.  If this is not supported by your IOS revision, you
1095 can use "maximum-paths" (which works for EBGP) and set
1096 <B>as_number</B> to a private value such as 64512.<P>
1097
1098 <H2 ID="Performance">Performance</H2>
1099
1100 Performance is great.<P>
1101
1102 I'd like to include some pretty graphs here that show a linear performance
1103 increase, with no impact by number of connected sessions.<P>
1104
1105 That's really what it looks like.<P>
1106
1107 <BR>
1108 David Parrish<BR>
1109 <A HREF="mailto:l2tpns-users@lists.sourceforge.net?subject=L2TPNS%20Documentation">l2tpns-users@lists.sourceforge.net</A>
1110 </BODY>
1111 </HTML>