Makefile.in: Drop dist target
[secnet] / secnet.8
1 .\" Man page for secnet.
2 .\"
3 .\" See the secnet.git README, or the Debian copyright file, for full
4 .\" list of copyright holders.
5 .\"
6 .\" secnet is free software; you can redistribute it and/or modify it
7 .\" under the terms of the GNU General Public License as published by
8 .\" the Free Software Foundation; either version 3 of the License, or
9 .\" (at your option) any later version.
10 .\"
11 .\" secnet is distributed in the hope that it will be useful, but
12 .\" WITHOUT ANY WARRANTY; without even the implied warranty of
13 .\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 .\" General Public License for more details.
15 .\"
16 .\" You should have received a copy of the GNU General Public License
17 .\" version 3 along with secnet; if not, see
18 .\" https://www.gnu.org/licenses/gpl.html.
19 .TH secnet 8
20
21 .SH NAME
22 secnet \- VPN router daemon
23
24 .SH SYNOPSIS
25 \fBsecnet\fR [\fIOPTIONS\fR]
26
27 .SH DESCRIPTION
28 \fBsecnet\fR allows virtual private networks to be constructed
29 spanning multiple separate sites.
30
31 .SH OPTIONS
32 .TP
33 .B --verbose\fR, \fB-v
34 Enable extra diagnostics.
35 .TP
36 .B --nowarnings\fR, \fB-w
37 Suppress warnings.
38 .TP
39 .B --help
40 Display usage message.
41 .TP
42 .B --version
43 Display version string.
44 .TP
45 .B --nodetach\fR, \fB-n
46 Don't go into background.
47 The default behaviour is to become a daemon during startup.
48 .TP
49 .B --silent\fR, \fB--quiet\fR, \fB-f
50 Suppress error messages.
51 .TP
52 .B --debug\fR, \fB-d
53 Enable debug messages.
54 .TP
55 .B --config\fR, \fB-c \fIPATH
56 Specify configuration file.
57 The default is \fI/etc/secnet/secnet.conf\fR.
58 .TP
59 .B --just-check-config\fR, \fB-j
60 Check configuration and exit.
61 .TP
62 .B --sites-key\fR, \fB-s \fIKEY
63 Configuration file key defining active sites.
64 The default is \fBsites\fR.
65
66 .SH "CONFIGURATION FILE"
67 .SS Overview
68 The default configuration file is \fI/etc/secnet/secnet.conf\fR.
69 This can be overridden with the \fB--config\fR option.
70 .PP
71 The configuration file defines a dictionary (a mapping from keys to
72 values) of configuration information for secnet.
73 It is recursive in nature, i.e. values may themselves include dictionaries.
74 Any node in the nested structure thus defined can be identified by a
75 \fIpath\fR, which is the sequence of keys necessary to reach it from
76 the root, separated by "/" characters.
77 See \fBPaths\fR below for how this is used.
78 .PP
79 Furthermore, when a key is looked up in a dictionary, if it cannot be
80 found, it is sought in the parent dictionary, and so on back to the
81 root.
82 For instance, each \fIsite\fR must contain the \fBresolver\fR key, but
83 in a typical configuration there is no value in having different
84 resolvers for each site.
85 Therefore \fBresolver\fR is defined at the root and thus automatically
86 incorporated into all sites.
87 .SS Whitespace
88 Whitespace, including newlines, is ignored except to the extent that
89 it bounds other symbols.
90 .PP
91 Comment begin with "#" and continues to the end of the line.
92 Comments are ignored.
93 .SS Inclusion
94 A file may be recursively included into the configuration file using a
95 line of the form:
96 .IP
97 \fBinclude \fIPATH
98 .PP
99 This is handled at a higher level than the main parser and so
100 precludes the possibility of using the string \fBinclude\fR for any
101 other purpose.
102 .\" check if this is true. it's probably a bug!
103 .SS Assignments
104 The configuration file contains one or more assigments.
105 Each assignment is written:
106 .IP
107 \fIkey\fR [\fB=\fR] \fIlist\fR\fB;\fR
108 .PP
109 i.e. the equals sign is optional.
110 The semicolon is mandatory in all contexts.
111 .PP
112 Keys start with a letter or "_" and continue with any numbers of
113 letters, digits, "_" and "-".
114 .PP
115 Each \fIkey\fR is a list of one or more \fIvalues\fR, separated by commas.
116 Possible values types are \fIboolean\fR, \fIstring\fR, \fInumber\fR,
117 \fIdictionary\fR, \fIpath\fR and \fIclosure evaluation\fR.
118 .\" This man page draws a distinction between a closure (the thing
119 .\" evaluated) and a closure evaluation (the closure plus is
120 .\" arguments).
121 .SS "Strings"
122 Strings are contained within "double quotes".
123 There is (currently) no escape syntax and no way to include quotes
124 inside strings.
125 .PP
126 Example:
127 .nf
128 filename "/var/log/secnet";
129 .fi
130 .SS "Numbers"
131 Numbers are encoded in decimal and do not include a sign.
132 Numbers must lie in the range 0 to 4294967295.
133 .PP
134 Example:
135 .nf
136 mtu 1400;
137 .fi
138 .SS "Dictionaries"
139 .\" In conffile.y dictionaries can be preceded by a search path, but
140 .\" this is not implemented elsewhere, so not documented here.
141 Dictionaries consist of one or more assignments, in the same syntax as
142 given above, enclosed in "{" and "}".
143 .PP
144 Example:
145 .nf
146 system {
147 userid "secnet";
148 pidfile "/var/run/secnet.pid";
149 };
150 .fi
151 .SS "Paths"
152 Paths allow a key already defined in the configuration to be aliased.
153 .PP
154 Paths consist of a sequence of keys separated by "/".
155 If the path starts with a "/" then it is an \fIabsolute path\fR and
156 the search starts at the root of the configuration.
157 Otherwise it is a \fIrelative path\fR and starts in the containing
158 dictionary or in any of its parents, down to and including the root.
159 If there is more than one match, the one furthest from the root "wins".
160 .PP
161 The value of a path is the list assigned to the key it refers to.
162 Lists are flattened; for example if a key is defined as a list of two
163 paths, and each of those refers to a list of two integers, the
164 original key is therefore defined to be a list of four integers, not
165 a list consisting of two lists.
166 .PP
167 It is not possible to refer to a \fIlater\fR key using a path.
168 .PP
169 Example:
170 .nf
171 vpn {
172 test {
173 kakajou vpn-data/test/kakajou/kakajou;
174 araminta vpn-data/test/araminta/araminta;
175 deodand vpn-data/test/deodand/deodand;
176 all-sites kakajou,araminta,deodand;
177 };
178 };
179 all-sites vpn/test/all-sites;
180 .fi
181 .PP
182 Here, each of \fBvpn/test/kakajou\fR, \fBvpn/test/araminta\fR and
183 \fBvpn/test/deodand\fR are defined as aliases to values defined
184 elsewhere.
185 \fBvpn/tests/all-sites\fR is defined as the list of all three of those
186 values, and \fBall-sites\fR is then defined to be an alias for that.
187 .SS "Booleans"
188 The (single-element) paths \fBfalse\fR, \fBno\fR and \fBnowise\fR are
189 predefined and refer to a boolean false value.
190 Similarly \fBtrue\fR, \fByes\fR and \fBverily\fR point at a boolean
191 true value.
192 .PP
193 In all six cases, variants with just the first letter capitalized, and
194 with all letters capitalized, are also provided.
195 .PP
196 Example:
197 .nf
198 random randomfile("/dev/urandom",no);
199 .fi
200 .SS "Closure Evaluation"
201 Closure evaluation uses the following syntax:
202 .IP
203 \fICLOSURE \fB( \fIARGUMENTS \fB)
204 .PP
205 \fICLOSURE\fR may be a path referring to a closure, or may itself be a
206 closure evaluation.
207 .PP
208 \fIARGUMENTS\fR is a list of zero or more values, separated by commas.
209 As a shortcut, if the arguments consist of a single dictionary, the
210 parentheses may be ommitted:
211 .IP
212 \fICLOSURE \fB{ \fR... \fB}
213 .PP
214 Example:
215 .nf
216 sites map(site, vpn/test/all-sites);
217 .fi
218 .PP
219 When a closure is evaluated it returns a value (a list, much as above)
220 and may also have side effects (which may be immediate or may be
221 deferred to some later phase of execution).
222 A list of built-in closures is given below.
223 .SS "Mandatory Keys"
224 Two keys are mandatory.
225 \fBsystem\fR must be a dictionary in which the following keys can be
226 looked up:
227 .TP
228 .B log
229 A \fIlog closure\fR; see the \fBlogfile\fR documentation below.
230 The destination for log messages.
231 Mandatory.
232 .TP
233 .B userid
234 A string.
235 The userid to run as after dropping privilege.
236 Optional.
237 .TP
238 .B pidfile
239 A string.
240 The path to write a pidfile.
241 Optional.
242 .PP
243 \fBsites\fR should be a list of \fIsite closures\fR; see the \fBsite\fR documentation below.
244 This defines the collection of tunnel endpoints that \fBsecnet\fR will
245 communicate with.
246 .PP
247 Recall the recursive lookup logic described in \fBOverview\fR above:
248 if (for instance) \fBlog\fR is defined in the top level dictionary but
249 not in \fBsystem\fR, it will nevertheless be found when looked up in
250 the latter.
251
252 .SH CLOSURES
253 \fBsecnet\fR contains a collection of built-in closures
254 with names (i.e. single-element paths) given below.
255 .PP
256 Most of them return anonymous closures of various types,
257 which are described contextually.
258
259 .SS adns
260 \fBadns(\fIDICT\fB)\fR => \fIresolver closure\fR
261 .TP
262 .I DICT
263 This either be empty or contain the single key \fBconfig\fR, with a
264 string value giving configuration to supply to ADNS.
265 This might be read from a file using \fBreadfile\fR.
266 .PP
267 A \fIresolver closure\fR is a means of converting hostnames into
268 network addresses.
269
270 .SS diffie-hellman
271 .PP
272 \fBdiffie-hellman(\fIMODULUS\fB, \fIGENERATOR\fR[\fB, \fICHECK\fR]\fB)\fR => \fIdh closure\fR
273 .TP
274 .I MODULUS
275 String.
276 The prime modulus \fIp\fR in hex.
277 .TP
278 .I GENERATOR
279 String.
280 The generator \fIg\fR in hex.
281 .TP
282 .I CHECK
283 Boolean.
284 If \fBtrue\fR (the default) then check if \fIp\fR is prime.
285 .PP
286 A \fIdh closure\fR defines a group to be used for key exchange.
287
288 .SS logfile
289 \fBlogfile(\fIDICT\fB)\fR => \fIlog closure\fR
290 .PP
291 Valid keys in the \fIDICT\fR argument are:
292 .TP
293 .B filename
294 The path to log to.
295 .TP
296 .B class
297 A list of strings defining which classes of message to log.
298 The possible message classes are \fBdebug-config\fR,
299 \fBdebug-phase\fR, \fBdebug\fR, \fBinfo\fR, \fBnotice\fR,
300 \fBwarning\fR, \fBerror\fR, \fBsecurity\fR and \fBfatal\fR.
301 .IP
302 \fBall-debug\fR is the union of all the \fBdebug\fR... classes.
303 \fBdefault\fR is equivalent to \fBwarning, error, security, fatal\fR.
304 \fBverbose\fR is equivalent to \fBinfo, notice, warning, error,
305 security, fatal\fR.
306 \fBquiet\fR is equivalent to \fBfatal\fR.
307 .PP
308 A \fIlog closure\fR is a means of saving log messages.
309 See also \fBsyslog\fR below.
310
311 .SS makelist
312 \fBmakelist(\fIDICT\fB)\fR => \fILIST\fR
313 .PP
314 Returns the (flattened) list of values from the dictionary, discarding
315 the keys.
316
317 .SS map
318 \fBmap(\fICLOSURE\fB, \fIINPUT\fR...\fB)\fR => \fILIST\fR
319 .PP
320 Applies \fICLOSURE\fR to all its additional input arguments and
321 returns the resulting list.
322
323 .SS md5
324 \fBmd5\fR is a \fIhash closure\fR implementing the MD5 algorithm.
325
326 .SS null-netlink
327 \fBnull-netlink(\fIDICT\fB)\fR => \fInetlink closure\fR
328 .br
329 \fBnull-netlink(\fIDICT\fB)\fR => \fIpure closure\fR
330 .\" TODO pure closure is what it's called internally but this is a
331 .\" very opaque name to use in docs
332 .PP
333 Valid keys in the \fIDICT\fR argument are:
334 .TP
335 .B name
336 String.
337 The name for the netlink device.
338 The default is \fBnull-netlink\fR.
339 .TP
340 .B networks
341 List of strings.
342 The networks on the host side of the netlink device.
343 .TP
344 .B remote-networks
345 List of strings.
346 Networks that may be claimed by remote sites using this netlink device.
347 .TP
348 .B secnet-address
349 String.
350 IP address of this netlink.
351 Incompatible with \fBptp-address\fR.
352 .TP
353 .B ptp-address
354 String.
355 IP address of the other end of a point-to-point link.
356 Incompatible with \fBsecnet-address\fR.
357 .TP
358 .B mtu
359 Number.
360 The MTU of the netlink device.
361 The default is 1000.
362 .PP
363 If \fBptp-address\fR is used then the result is a \fInetlink closure\fR.
364 This can be used directly with the \fBlink\fR key in the \fBsites\fR
365 closure (see below).
366 .PP
367 If \fBsecnet-address\fR is used then the result is a \fIpure
368 closure\fR.
369 This must be evaluated to yield a \fInetlink closure\fR, using a
370 dictionary argument with the following keys:
371 .TP
372 .B routes
373 String list.
374 networks reachable via this tunnel, in \fIaddress\fB/\fIbits\fR format.
375 .TP
376 .B options
377 String list.
378 A list of options:
379 .RS
380 .TP
381 .B allow-route
382 Allow packets received via this tunnel to be routed down other tunnels
383 (without this option only packets from the host will be routed).
384 .TP
385 .B soft
386 Remove these routes from the host routing table when the link quality
387 is 0.
388 .RE
389 .TP
390 .B mtu
391 Number.
392 Default MTU over this link.
393 The default is inherited from the \fIpure closure\fR.
394 .TP
395 .B priority
396 Number.
397 The priority of this link.
398 Higher values beat lower values.
399 The default is 0.
400
401 .\" TODO ptp-address turns up in sites.conf, but why? I think this
402 .\" is a bug in make-secnet-sites; it is not used by
403 \" netlink_inst_create.
404
405 .PP
406 A \fInetlink closure\fR is a virtual IP link, and is supplied to the
407 \fBlink\fR key of a \fIsite\fR closure.
408 .PP
409 The netlink created by \fBnull-netlink\fR has no connection to the
410 host.
411 See \fBtun\fR and \fBuserv-ipif\fR below for more useful alternatives.
412
413
414
415 .SS randomfile
416 \fBrandomfile(\fIFILENAME\fR[\fB, \fIBLOCKING\fR]\fB)\fR => \fIrandomsource closure\fR
417 .TP
418 .I FILENAME
419 String.
420 Path to random device, e.g. \fI/dev/urandom\fR.
421 .TP
422 .I BLOCKING
423 Boolean.
424 \fBTrue\fR if this is a blocking device and \fBfalse\fR otherwise (the default).
425 Blocking device support is not implemented so this must always be
426 \fBFalse\fR or absent.
427 .PP
428 A \fIrandomsource closure\fR is a source of random numbers.
429
430 .SS readfile
431 \fBreadfile(\fIPATH\fB)\fR => \fISTRING\fR
432 .PP
433 Read the contents of the file \fIPATH\fR (a string) and return it as a string.
434
435 .SS eax-serpent
436 \fBeax-serpent(\fIDICT\fB)\fR => \fItransform closure\fR
437 .PP
438 Valid keys in the \fIDICT\fR argument are:
439 .TP
440 .B max-sequence-skew
441 The maximum acceptable difference between the sequence number in a
442 received, decrypted message and the previous one.
443 The default is 10.
444 It may be necessary to increase this is if connectivity is poor.
445 .TP
446 .B tag-length-bytes
447 The length of the message authentication tag. The default is 16,
448 for a 128-bit tag length. It must be no longer than the Serpent
449 blocksize, 16. Must be have the same value at both ends.
450 .TP
451 .B padding-rounding
452 Messages are padded to a multiple of this many bytes. This
453 serves to obscure the exact length of messages. The default is 16,
454 .TP
455 .B capab-num
456 The transform capability number to use when advertising this
457 transform. Both ends must have the same meaning (or, at least, a
458 compatible transform) for each transform capability number they have
459 in common. The default for serpent-eax is 9.
460 .IP
461 Transform capability numbers in the range 8..15 are intended for
462 allocation by the implementation, and may be assigned as the default
463 for new transforms in the future. Transform capability numbers in the
464 range 0..7 are reserved for definition by the user.
465 .PP
466 A \fItransform closure\fR is a reversible means of transforming
467 messages for transmission over a (presumably) insecure network.
468 It is responsible for both confidentiality and integrity.
469
470 .SS serpent256-cbc
471 \fBserpent256-cbc(\fIDICT\fB)\fR => \fItransform closure\fR
472 .PP
473 This transform
474 is deprecated as its security properties are poor; it should be
475 specified only alongside a better transform such as eax-serpent.
476 .PP
477 Valid keys in the \fIDICT\fR argument are:
478 .TP
479 .B capab-num
480 As above. The default for serpent256-cbc is 8.
481 .TP
482 .B max-sequence-skew
483 As above.
484 .PP
485 Note that this uses a big-endian variant of the Serpent block cipher
486 (which is not compatible with most other Serpent implementations).
487 .SS rsa-private
488 \fBrsa-private(\fIPATH\fB\fR[, \fICHECK\fR]\fB)\fR => \fIrsaprivkey closure\fR
489 .TP
490 .I PATH
491 String.
492 The path to a file containing an RSA private key in SSH format
493 (version 1).
494 There must be no passphrase.
495 .TP
496 .I CHECK
497 Boolean.
498 If \fBtrue\fR (the default) then check that the key is valid.
499
500 .SS rsa-public
501 \fBrsa-public(\fIKEY\fB, \fIMODULUS\fB)\fR => \fIrsapubkey closure\fR
502 .TP
503 .I KEY
504 String.
505 The public key exponent (\fIe\fR), in decimal.
506 .TP
507 .I MODULUS
508 String.
509 The modulus (\fIn\fR), in decimal.
510
511 .SS sha1
512 \fBsha1\fR is a \fIhash closure\fR implementing the SHA-1 algorithm.
513
514 .SS site
515 \fBsite(\fIDICT\fB)\fR => \fIsite closure\fR
516 .PP
517 Valid keys in the \fIDICT\fR argument are:
518 .TP
519 .B local-name
520 String.
521 The site's name for itself.
522 .TP
523 .B name
524 String.
525 The name of the site's peer.
526 .TP
527 .B link
528 A \fInetlink closure\fR.
529 .TP
530 .B comm
531 A \fIcomm closure\fR.
532 .TP
533 .B resolver
534 A \fIresolver closure\fR.
535 .TP
536 .B random
537 A \fIrandomsource closure\fR.
538 .TP
539 .B local-key
540 An \fIrsaprivkey closure\fR.
541 The key used to prove our identity to the peer.
542 .TP
543 .B address
544 String.
545 The DNS name of the peer.
546 Optional, but if it is missing then it will not be possible to
547 initiate new connections to the peer.
548 .TP
549 .B port
550 Number.
551 The port to contact the peer.
552 .TP
553 .B key
554 An \fIrsapubkey closure\fR.
555 The key used to verify the peer's identity.
556 .TP
557 .B transform
558 One or more \fItransform closures\fR.
559 Used to protect packets exchanged with the peer. These should
560 all have distinct \fBcapab-num\fR values, and the same \fBcapab-num\fR
561 value should refer to the same (or a compatible) transform at both
562 ends. The list should be in order of preference, most preferred
563 first. (The end which sends MSG1,MSG3 ends up choosing; the ordering
564 at the other end is irrelevant.)
565 .TP
566 .B dh
567 A \fIdh closure\fR.
568 The group to use in key exchange.
569 .TP
570 .B hash
571 The hash function used during setup.
572 .\" TODO clarify what we actually use it for!
573 .TP
574 .B key-lifetime
575 Number.
576 The maximum lifetime of a session key in milliseconds.
577 The default is one hour.
578 .TP
579 .B setup-retries
580 Number.
581 The maximum number of times a key negotiation packet will be
582 transmitted before giving up.
583 The default is 5.
584 .TP
585 .B setup-timeout
586 Number.
587 The time between retransmissions of key negotiation packets, in milliseconds.
588 The default is one second.
589 .TP
590 .B wait-time
591 Number.
592 The time to wait after a failed key setup before making another
593 attempt, in milliseconds.
594 The default is 20s.
595 .TP
596 .B renegotiate-time
597 Number.
598 The time after which a new session key will be negotiated, \fIif\fR
599 there is traffic on the link, in milliseconds.
600 It must not be greater than the \fBkey-lifetime\fR.
601 The default 5 minutes less than the key lifetime, unless the lifetime
602 is less than 10 minutes in which case the default is half the
603 lifetime.
604 .TP
605 .B keepalive
606 Boolean.
607 If \fBtrue\fR then attempt to always maintain a live session key.
608 Not implemented.
609 .TP
610 .B log-events
611 String list.
612 Types of event to log for this site.
613 .RS
614 .TP
615 .B unexpected
616 Unexpected key setup packets (including late retransmissions).
617 .TP
618 .B setup-init
619 Start of attempt to setup a session key.
620 .TP
621 .B setup-timeout
622 Failure of attempt to setup a session key, through timeout.
623 .TP
624 .B activate-key
625 Activation of a new session key.
626 .TP
627 .B timeout-key
628 Deletion of current session key through age.
629 .TP
630 .B security
631 Anything potentially suspicious.
632 .TP
633 .B state-change
634 Steps in the key setup protocol.
635 .TP
636 .B packet-drop
637 Whenever we throw away an outgoing packet.
638 .TP
639 .B dump-packets
640 Every key setup packet we see.
641 .TP
642 .B errors
643 Failure of name resolution, internal errors.
644 .TP
645 .B all
646 Everything (too much!)
647 .RE
648 .PP
649 A \fIsite closure\fR defines one site to communicate with.
650 \fBsecnet\fR expects the (root) key \fBsite\fR to be a list of site
651 closures.
652
653 .SS sysbuffer
654 \fBsysbuffer(\fR[\fISIZE\fR[\fB, \fIOPTIONS\fR]]\fB)\fR => \fIbuffer closure\fR
655 .TP
656 .I SIZE
657 Number.
658 The size of the buffer in bytes.
659 This must be between 64 and 131072.
660 The default is 4096.
661 .TP
662 .I OPTIONS
663 Dictionary.
664 Optional and presently unused.
665 .\" lockdown is accepted but ignored.
666 .PP
667 A \fIbuffer closure\fR is a means of buffering packets to send or that
668 have been received.
669
670 .SS syslog
671 \fBsyslog(\fIDICT\fB)\fR => \fIlog closure\fR
672 .PP
673 Valid keys in the \fIDICT\fR argument are:
674 .TP
675 .B ident
676 String.
677 The ident string to pass to \fBopenlog\fR(3); this value will appear
678 in each message.
679 .TP
680 .B facility
681 String.
682 The facility to log as.
683 The possible values are \fBauthpriv\fR, \fBcron\fR, \fBdaemon\fR,
684 \fBkern\fR, \fBlocal0\fR-\fB7\fR, \fBlpr\fR, \fBmail\fR, \fBnews\fR,
685 \fBsyslog\fR, \fBuser\fR and \fBuucp\fR.
686 .PP
687 See also \fBlogfile\fR above.
688
689 .SS tun
690 \fBtun(\fIDICT\fB)\fR => \fInetlink closure\fR
691 .br
692 \fBtun(\fIDICT\fB)\fR => \fIpure closure\fR
693 .PP
694 Valid keys in the \fIDICT\fR argument are those documented for
695 \fBnull-netlink\fR above, plus:
696 .TP
697 .B flavour
698 String.
699 The type of TUN interface to use.
700 Possible values are \fBlinux\fR, \fBbsd\fR, \fBstreams\fR and \fBguess\fR.
701 The default is \fBguess\fR.
702 .TP
703 .B device
704 String.
705 The path to the TUN/TAP device file.
706 The default is \fI/dev/net/tun\fR for the \fBlinux\fR flavour and
707 \fI/dev/tun\fR for the others.
708 .TP
709 .B interface
710 String.
711 The interface to use.
712 The default is to pick one automatically.
713 This cannot be used with the \fBstreams\fR flavour.
714 .TP
715 .B local-address
716 String.
717 IP address of the host's tunnel interface.
718 .\" README says this belongs to netlink-null but actually it's
719 \" duplicated between slip & tun
720 .TP
721 .B ifconfig-path
722 String.
723 The name of the \fBifconfig\fR command.
724 The default is simply "ifconfig".
725 .TP
726 .B route-path
727 String.
728 The name of the \fBroute\fR command.
729 The default is simply "route".
730 .TP
731 .B ifconfig-type
732 String.
733 The syntax expected by the \fBifconfig\fR command.
734 Possible values are \fBlinux\fR, \fBbsd\fR, \fBioctl\fR,
735 \fBsolaris-2.5\fR and \fBguess\fR.
736 The default is \fBguess\fR.
737 .TP
738 .B route-type
739 String.
740 The syntax expected by the \fBifconfig\fR command.
741 Possible values are \fBlinux\fR, \fBbsd\fR, \fBioctl\fR,
742 \fBsolaris-2.5\fR and \fBguess\fR.
743 The default is \fBguess\fR.
744 .TP
745 .B buffer
746 A \fIbuffer closure\fR to use for packets transferred from the host to secnet.
747 The buffer size must be at least 60 greater than the MTU.
748 .\" TODO rumour has is that buffers are sometimes shareable between
749 .\" netlink devices - document that if the conditions are reasonable
750 .\" ones.
751 .PP
752 The \fBifconfig-type\fR and \fBroute-type\fR values determine how
753 those commands are executed.
754 If they are set to \fBioctl\fR then low-level system calls are used
755 directly instead of invoking the commands.
756 .PP
757 The netlink created by \fBtun\fR uses the \fBtun\fR device to
758 communicate with the host kernel.
759
760 .SS udp
761 \fBudp(\fIDICT\fB)\fR => \fIcomm closure\fR
762 .PP
763 Valid keys in the \fIDICT\fR argument are:
764 .TP
765 .B address
766 String.
767 The IP address to bind on.
768 The default is 0.0.0.0, i.e. "any".
769 .TP
770 .B port
771 Number.
772 The port number to bind to.
773 The default is 0, i.e. the OS will choose one.
774 It is suggested that any given VPN agree a common port number.
775 .TP
776 .B buffer
777 A \fIbuffer closure\fR.
778 See the \fBsysbuffer\fR closure above.
779 .TP
780 .B authbind
781 String.
782 The path to a helper program to bind the socket.
783 Optional.
784 .IP
785 The program will be invoked with the address and port number as its
786 arguments, and with the socket to bind as file descriptor 0.
787 It should either bind the socket as requested, or exit with nonzero
788 status.
789 .PP
790 A \fIcomm closure\fR is a means of sending and receiving messages via
791 a network.
792 It does not provide confidentiality, reliablity or availability.
793
794 .SS userv-ipif
795 \fBuserv-ipif(\fIDICT\fB)\fR => \fInetlink closure\fR
796 .br
797 \fBuserv-ipif(\fIDICT\fB)\fR => \fIpure closure\fR
798 .PP
799 Valid keys in the \fIDICT\fR argument are those documented for
800 \fBnull-netlink\fR above, plus:
801 .TP
802 .B local-address
803 String.
804 IP address of the host's SLIP interface.
805 .\" README says this belongs to netlink-null but actually it's
806 \" duplicated between SLIP & tun
807 .TP
808 .B userv-path
809 String.
810 Where to find \fBuserv\fR(1).
811 The default is \fB"userv"\fR.
812 .TP
813 .B service-user
814 String.
815 The name of the user that owns the service.
816 The default is \fB"root"\fR.
817 .TP
818 .B service-name
819 String.
820 The name of the service to request.
821 The default is \fB"ipif"\fR.
822 .TP
823 .B buffer
824 A \fIbuffer closure\fR to use for packets transferred from the host to secnet.
825 .PP
826 The netlink created by \fBuserv-ipif\fR invokes the specified \fBuserv\fR service with pipes connected to its standard input and output.
827 It uses SLIP to communicate with the host kernel via these pipes.
828
829 .SH FILES
830 .TP
831 .I /etc/secnet/secnet.conf
832 Configuration file.
833
834 .SH "SEE ALSO"
835 \fBuserv\fR(1)