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1 | .\" -*-nroff-*- |
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2 | .\" |
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3 | .\" $Id: fw.1,v 1.7 1999/10/22 22:45:15 mdw Exp $ |
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4 | .\" |
5 | .\" Manual page for fw |
6 | .\" |
7 | .\" (c) 1999 Straylight/Edgeware |
8 | .\" |
9 | . |
10 | .\"----- Licensing notice --------------------------------------------------- |
11 | .\" |
12 | .\" This file is part of the `fw' port forwarder. |
13 | .\" |
14 | .\" `fw' is free software; you can redistribute it and/or modify |
15 | .\" it under the terms of the GNU General Public License as published by |
16 | .\" the Free Software Foundation; either version 2 of the License, or |
17 | .\" (at your option) any later version. |
18 | .\" |
19 | .\" `fw' is distributed in the hope that it will be useful, |
20 | .\" but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | .\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | .\" GNU General Public License for more details. |
23 | .\" |
24 | .\" You should have received a copy of the GNU General Public License |
25 | .\" along with `fw'; if not, write to the Free Software Foundation, |
26 | .\" Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
27 | . |
28 | .\" ---- Revision history --------------------------------------------------- |
29 | .\" |
30 | .\" $Log: fw.1,v $ |
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31 | .\" Revision 1.7 1999/10/22 22:45:15 mdw |
32 | .\" Describe new socket connection options. |
33 | .\" |
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34 | .\" Revision 1.6 1999/10/10 16:46:29 mdw |
35 | .\" Include grammar and options references at the end of the manual. |
36 | .\" |
cdc917d3 |
37 | .\" Revision 1.5 1999/09/26 18:18:05 mdw |
38 | .\" Remove a fixed bug from the list. Fix some nasty formatting |
39 | .\" misfeatures. |
40 | .\" |
e73034b0 |
41 | .\" Revision 1.4 1999/08/19 18:32:48 mdw |
42 | .\" Improve lexical analysis. In particular, `chmod' patterns don't have to |
43 | .\" be quoted any more. |
44 | .\" |
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45 | .\" Revision 1.3 1999/07/30 06:49:00 mdw |
46 | .\" Minor tidying and typo correction. |
47 | .\" |
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48 | .\" Revision 1.2 1999/07/26 23:31:04 mdw |
49 | .\" Document lots of new features and syntax. |
50 | .\" |
51 | . |
52 | .\"----- Various bits of fancy styling -------------------------------------- |
53 | . |
54 | .\" --- Indented paragraphs with right-aligned tags --- |
55 | . |
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56 | .de hP |
57 | .IP |
58 | \h'-\w'\fB\\$1\ \fP'u'\fB\\$1\ \fP\c |
59 | .. |
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60 | . |
61 | .\" --- Verbatim-oid typesetting --- |
62 | .de VS |
63 | .sp 1 |
64 | .RS |
65 | .nf |
66 | .ft B |
67 | .. |
68 | .de VE |
69 | .ft R |
70 | .fi |
71 | .RE |
72 | .sp 1 |
73 | .. |
74 | . |
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75 | .\" --- Grammar markup --- |
76 | .\" |
77 | .\" This is mainly for the benefit of the automatic scripts which |
78 | .\" generate the grammar summary. |
79 | . |
80 | .de GS |
81 | .PP |
82 | .. |
83 | .de GE |
84 | .PP |
85 | .. |
86 | . |
87 | .de OS |
88 | .PP |
89 | .. |
90 | .de OD |
91 | .RS |
92 | .. |
93 | .de OE |
94 | .RE |
95 | .. |
96 | . |
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97 | .\" --- Other bits of styling --- |
98 | . |
99 | .ie t \{\ |
100 | . ds o \(bu |
101 | . ds ss \s8\u |
102 | . ds se \d\s0 |
103 | . if \n(.g \{\ |
104 | . fam P |
105 | . \} |
106 | .\} |
107 | .el \{\ |
108 | . ds o o |
109 | . ds ss ^ |
110 | . ds se |
111 | .\} |
112 | . |
113 | .\"-------------------------------------------------------------------------- |
114 | . |
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115 | .TH fw 1 "1 July 1999" fw |
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116 | . |
117 | .\"-------------------------------------------------------------------------- |
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118 | .SH NAME |
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119 | . |
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120 | fw \- port forwarder |
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121 | . |
122 | .\"-------------------------------------------------------------------------- |
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123 | .SH SYNOPSIS |
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124 | . |
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125 | .B fw |
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126 | .RB [ \-dq ] |
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127 | .RB [ \-f |
128 | .IR file ] |
129 | .IR config-stmt ... |
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130 | . |
131 | .\"-------------------------------------------------------------------------- |
132 | .SH "DESCRIPTION" |
133 | . |
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134 | The |
135 | .B fw |
136 | program is a simple port forwarder. It supports a number of features |
137 | the author hasn't found in similar programs: |
138 | .TP |
139 | .I "Connection logging" |
140 | Each connection attempt to the forwarder is logged, giving the time of |
141 | the connection, the DNS-resolved hostname (if available), and the user |
142 | name resulting from an RFC931 lookup. These lookups are done |
143 | asynchronously to the main forwarder's operation. |
144 | .TP |
145 | .I "Access control" |
146 | Each forwarded port may have an access control list attached to it. |
147 | Only authorized hosts are allowed to connect. Access control checks are |
148 | performed by quick checks on the client's IP address. |
149 | .TP |
150 | .I "Nonblocking single-process design" |
151 | The internal structure of the server is completely nonblocking. The |
152 | connections don't block; the reading and writing don't block; the name |
153 | lookups don't block. This is all done in a single process, with the |
154 | single exception of the DNS resolver. |
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155 | .TP |
156 | .I "Support for Unix-domain sockets" |
157 | Connections from and to Unix-domain sockets can be handled just as |
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158 | easily as more normal Internet sockets. Access control doesn't work on |
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159 | Unix domain sockets, though. (Yet.) |
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160 | .SS "Command line options" |
161 | The |
162 | .B fw |
163 | program understands a few simple command line options: |
164 | .TP |
165 | .B "\-h, \-\-help" |
166 | Displays a screen of help text on standard output and exits |
167 | successfully. |
168 | .TP |
169 | .B "\-v, \-\-version" |
170 | Writes the version number to standard output and exits successfully. |
171 | .TP |
172 | .B "\-u, \-\-usage" |
173 | Writes a terse usage summary to standard output and exits successfully. |
174 | .TP |
175 | .BI "\-f, \-\-file=" file |
176 | Read configuration information from |
177 | .IR file . |
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178 | Equivalent to an |
179 | .RB ` include |
180 | .IR file ' |
181 | configuration file statement. |
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182 | .TP |
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183 | .B "\-d, \-\-daemon, \-\-fork" |
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184 | Forks into the background after reading the configuration and |
185 | initializing properly. |
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186 | .TP |
187 | .B "-q, \-\-quiet" |
188 | Don't output any logging information. This option is not recommended |
189 | for normal use, although it can make system call traces clearer so I use |
190 | it when debugging. |
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191 | .PP |
192 | Any further command line arguments are interpreted as configuration |
193 | lines to be read. Configuration supplied in command line arguments has |
194 | precisely the same syntax as configuration in files. If there are no |
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195 | configuration statements on the command line, and no |
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196 | .B \-f |
197 | options were supplied, configuration is read from standard input, if |
198 | stdin is not a terminal. |
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199 | . |
200 | .\"-------------------------------------------------------------------------- |
201 | .SH "CONFIGURATION LANGUAGE" |
202 | . |
203 | The |
204 | .B fw |
205 | program has a fairly sophisticated configuration language to let you |
206 | describe which things should be forwarded where and what special |
207 | features there should be. |
208 | .SS "Lexical structure" |
209 | There are four types of characters. |
210 | .TP |
211 | .I "word constituent characters" |
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212 | Word constituent characters are gathered together into words. |
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213 | Depending on its surrounding context, a word might act as a keyword or a |
214 | string. All alphanumerics are word constituents, as is the hyphen |
215 | .RB ` \- '. |
216 | Other characters may change their status in future versions. |
217 | .TP |
218 | .I "self-delimiting characters" |
219 | Self-delimiting characters always stand alone. They act as punctuation, |
220 | shaping the sequence of words into more complex grammatical forms. The |
221 | characters |
222 | .RB ` { ', |
223 | .RB ` } ', |
224 | .RB ` [ ', |
225 | .RB ` ] ', |
226 | .RB ` / ', |
227 | .RB ` , ', |
228 | .RB ` = ', |
229 | .RB ` : ', |
230 | .RB ` ; ' |
231 | and |
232 | .RB ` . ' |
233 | are self-delimiting. Note that while some characters, e.g., |
234 | .RB ` [ ' |
235 | and |
236 | .RB ` ; ', |
237 | require escaping by the shell, they are strictly optional in the grammar |
238 | and can be omitted in quick hacks at the shell prompt. |
239 | .TP |
240 | .I "whitespace characters" |
241 | Whitespace characters separate words but are otherwise ignored. All |
242 | `normal' whitespace characters (e.g., space, tab and newline) are |
243 | considered to be whitespace for these purposes. |
244 | .TP |
245 | .I "special characters" |
246 | There are three special characters. The |
247 | .RB ` # ' |
248 | character, if it appears at the start of a word, introduces a |
249 | .I comment |
250 | which extends to the end of the current line or command-line argument. |
251 | Within a word, it behaves like a normal word-constituent character. The |
252 | backslash |
253 | .RB ` \e ' |
254 | escapes the following character causing it to be interpreted as a word |
255 | constituent regardless of its normal type. The double-quote |
256 | .RB ` """" ' |
257 | escapes all characters other than backslashes up to the next |
258 | double-quote and causes them to be regarded as word constituents. Note |
259 | that you don't have to quote a whole word. The backslash can escape a |
260 | quote character allowing you to insert it into a word if really |
261 | necessary. |
262 | . |
263 | .SS "Basic syntax" |
264 | The overall syntax looks a bit like this: |
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265 | .GS "Basic syntax" |
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266 | .I file |
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267 | ::= |
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268 | .I empty |
269 | | |
270 | .I file |
271 | .I stmt |
272 | .RB [ ; ] |
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273 | .br |
274 | .I stmt |
275 | ::= |
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276 | .I option-stmt |
277 | | |
278 | .I fw-stmt |
279 | .br |
280 | .I fw-stmt |
281 | ::= |
282 | .B fw |
283 | .I source |
284 | .I options |
285 | .RB [ to | \-> ] |
286 | .I target |
287 | .I options |
288 | .br |
289 | .I options |
290 | ::= |
291 | .B { |
292 | .I option-seq |
293 | .B } |
294 | .br |
295 | .I option-seq |
296 | ::= |
297 | .I empty |
298 | | |
299 | .I option-stmt |
300 | .RB [ ; ] |
301 | .I option-seq |
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302 | .GE |
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303 | If you prefer, the keyword |
304 | .RB ` fw ' |
305 | may be spelt |
306 | .RB ` forward ' |
307 | or |
308 | .RB ` from '. |
309 | All are equivalent. |
310 | . |
311 | .SS "Sources and targets" |
312 | Forwarding is set up by attaching |
313 | .I targets |
314 | to |
315 | .IR sources . |
316 | Sources are things which are capable of |
317 | .I initiating |
318 | one end of a data flow on their own, while targets are things which are |
319 | capable of setting up the other end on demand. In the case of a TCP |
320 | port forwarder, the part which listens for incoming client connections |
321 | is the source, while the part which sets up outgoing connections to the |
322 | destination server is the target. |
323 | .PP |
324 | Essentially, all |
325 | .B fw |
326 | does is set up a collection of sources and targets based on your |
327 | configuration file so that when a source decides to initiate a data |
328 | flow, it tells its target to set its end up, and then squirts data back |
329 | and forth between the two until there's no more. |
330 | .PP |
331 | Some sources are |
332 | .IR persistent : |
333 | they stay around indefinitely setting up multiple attachments to |
334 | targets. Others are |
335 | .IR transient : |
336 | they set up one connection and then disappear. If all the sources |
337 | defined are transient, then |
338 | .B fw |
339 | will quit when no more active sources remain and all connections have |
340 | terminated. |
341 | .PP |
342 | The |
343 | .B fw |
344 | program is fairly versatile. It allows you to attach any supported type |
345 | of source to any supported type of target. This will, I hope, be the |
346 | case in all future versions. |
347 | .PP |
348 | The syntax of a |
349 | .I source |
350 | or |
351 | .I target |
352 | depend on the source or target type, and are therefore described in the |
353 | sections specific to the various types. |
354 | . |
355 | .SS "Options structure" |
356 | Most of the objects that |
357 | .B fw |
358 | knows about (including sources and targets, but also other more specific |
359 | things such as socket address types) can have their behaviour modified |
360 | by |
361 | .IR options . |
362 | The options available at a particular point in the configuration depend |
363 | on the |
364 | .IR context . |
365 | A global option, outside of a |
366 | .I fw-stmt |
367 | has no context unless it is explicitly qualified, and affects global |
368 | behaviour. Local options, applied to a source or target in a |
369 | .I fw-stmt |
370 | has the context of the type of source or target to which it is applied, |
371 | and affects only that source or target. |
372 | .PP |
373 | Note that it's important to distinguish between an option's context |
374 | (which is affected by its qualification) and its local or global |
375 | status. No matter how qualified, a global option will always control |
376 | default options for objects, and a local option will only affect a |
377 | specific source or target. |
378 | .PP |
379 | The syntax for qualifying options is like this: |
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380 | .GS "Option syntax" |
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381 | .I option-stmt |
382 | ::= |
383 | .I q-option |
384 | .br |
385 | .I q-option |
386 | ::= |
387 | .I option |
388 | .br |
389 | | |
390 | .I prefix |
391 | .B . |
392 | .I q-option |
393 | .br |
394 | | |
395 | .I prefix |
396 | .B { |
397 | .I option-seq |
398 | .B } |
399 | .br |
400 | .I prefix |
401 | ::= |
402 | .I word |
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403 | .GE |
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404 | Thus, you may qualify either an individual option or a sequence of |
405 | options. The two are equivalent; for example, |
406 | .VS |
407 | exec.rlimit { |
408 | core = 0; |
409 | cpu = 60; |
410 | } |
411 | .VE |
412 | is equivalent to |
413 | .VS |
414 | exec.rlimit.core = 0; |
415 | exec.rlimit.cpu = 0; |
416 | .VE |
417 | For each option, there is a sequence of prefixes which maximally qualify |
418 | that option. An option prefixed with this sequence is |
419 | .IR "fully qualified" . |
420 | In actual use, some or all of those prefixes may be omitted. However, |
421 | it's possible for the option to become |
422 | .I ambiguous |
423 | if you do this. For example, the option |
424 | .B fattr.owner |
425 | may refer either to |
426 | .B file.fattr.owner |
427 | or to |
428 | .BR socket.unix.fattr.owner . |
429 | In this case, the ambiguity is benign: a local option will have as its |
430 | context an appropriate source or target, and both global options |
431 | actually control the same default. However, the option |
432 | .B logging |
433 | may mean either |
434 | .B socket.logging |
435 | or |
436 | .BR exec.logging , |
437 | which have separate defaults, and which one you actually get depends on |
438 | the exact implementation of |
439 | .BR fw 's |
440 | option parser. (Currently this would resolve to |
441 | .BR exec.logging , |
442 | although this may change in a later version.) |
443 | .PP |
444 | In this manual, options are usually shown in their fully-qualified form. |
445 | . |
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446 | .SS "File attributes for created files: `fattr'" |
447 | Both the |
448 | .B file |
449 | and |
450 | .B socket |
451 | sources and targets can create new filesystem objects. The |
452 | .B fattr |
453 | options allow control over the attributes of the newly-created objects. |
454 | Both |
455 | .B file |
456 | and |
457 | .B socket |
458 | use the same set of defaults, so a prefix of |
459 | .B fattr |
460 | is good enough for setting global options, and the implicit context |
461 | disambiguates local options. |
462 | .PP |
463 | The following file attribute options are supported: |
464 | .OS "File attribute options (`fattr')" |
465 | .IB prefix .fattr.mode |
466 | .RB [ = ] |
467 | .I mode |
468 | .OD |
469 | Sets the permissions mode for a new file. The |
470 | .I mode |
471 | argument may be either an octal number or a |
472 | .BR chmod (1)-style |
473 | string which acts on the default permissions established by the |
474 | prevailing |
475 | .BR umask (2) |
476 | setting. The characters |
477 | .RB ` = ' |
478 | and |
479 | .RB ` , ' |
480 | do not have to be quoted within the mode string. |
481 | .OE |
482 | .OS "File attribute options (`fattr')" |
483 | .IB prefix .fattr.owner |
484 | .RB [ = ] |
485 | .I user |
486 | .OD |
487 | Sets the owner for newly created files. On non-broken systems you will |
488 | need to be the superuser to set the owner on a file. The |
489 | .I user |
490 | may either be a numeric uid or a username. The default is not to change |
491 | the owner of the file once it's created. The synonyms |
492 | .B uid |
493 | and |
494 | .B user |
495 | are accepted in place of |
496 | .BR owner . |
497 | .OE |
498 | .OS "File attribute options (`fattr')" |
499 | .IB prefix .fattr.group |
500 | .RB [ = ] |
501 | .I group |
502 | .OD |
503 | Sets the group for newly created files. You will usually need to be a |
504 | member of the group in question order to set the group of a file. The |
505 | .I group |
506 | may either be a numeric gid or a group name. The default is not to |
507 | change the group of the file once it's created. The synonym |
508 | .B gid |
509 | is accepted in place of |
510 | .BR group . |
511 | .OE |
512 | . |
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513 | .SS "The `file' source and target types" |
514 | The |
515 | .B file |
516 | source and target allow data to move to and from objects other |
517 | than sockets within the Unix filesystem. (Unix-domain sockets are |
518 | handled using the |
519 | .B socket |
520 | source and target.) |
521 | .PP |
522 | If a |
523 | .B file |
524 | is used as a source, it is set up immediately. |
525 | .PP |
526 | The syntax of |
527 | .B file |
528 | sources and targets is like this: |
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529 | .GS "File sources and targets" |
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530 | .I source |
531 | ::= |
532 | .I file |
533 | .br |
534 | .I target |
535 | ::= |
536 | .I file |
537 | .br |
538 | .I file |
539 | ::= |
540 | .B file |
541 | .RB [ . ] |
542 | .I fspec |
543 | .RB [ , |
544 | .IR fspec ] |
545 | .br |
546 | .I fspec |
547 | ::= |
548 | .I fd-spec |
549 | | |
550 | .I name-spec |
551 | | |
552 | .I null-spec |
553 | .br |
554 | .I fd-spec |
555 | ::= |
556 | .RB [[ : ] fd [ : ]] |
557 | .IR number \c |
558 | .RB | stdin | stdout |
559 | .br |
560 | .I name-spec |
561 | ::= |
562 | .RB [[ : ] file [ : ]] |
563 | .I file-name |
564 | .br |
565 | .I file-name |
566 | ::= |
567 | .I path-seq |
568 | | |
569 | .B [ |
570 | .I path-seq |
571 | .B ] |
572 | .br |
573 | .I path-seq |
574 | ::= |
575 | .I path-elt |
576 | | |
577 | .I path-seq |
578 | .I path-elt |
579 | .br |
580 | .I path-elt |
581 | ::= |
582 | .B / |
583 | | |
584 | .I word |
585 | .br |
586 | .I null-spec |
587 | ::= |
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588 | .RB [ : ] null [ : ] |
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589 | .GE |
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590 | The |
591 | .I file |
592 | specification describes two files, the first to be used as input, the |
593 | second to be used as output, each described by an |
594 | .IR fspec . |
595 | .PP |
596 | If none of the keywords |
597 | .RB ` fd ', |
598 | .RB ` name ' |
599 | or |
600 | .RB ` null ' |
601 | are given, the type of an |
602 | .I fspec |
603 | is deduced from its nature: if it matches one of the strings |
604 | .RB ` stdin ' |
605 | or |
606 | .RB ` stdout ', |
607 | or begins with a digit, it's considered to be a file descriptor; |
608 | otherwise it's interpreted as a filename. |
609 | .PP |
610 | A |
611 | .RB ` name ' |
612 | spec describes a file by its name within the filesystem. It is opened |
613 | when needed and closed again after use. For output files, the precise |
614 | behaviour is controlled by options described below. |
615 | .PP |
616 | A |
617 | .RB ` null ' |
618 | spec attaches the input or output of the source or target to |
619 | .BR /dev/null . |
620 | .PP |
621 | An |
622 | .RB ` fd ' |
623 | spec uses an existing open file descriptor, given either by number or a |
624 | symbolic name. The name |
625 | .RB ` stdin ' |
626 | refers to standard input (file descriptor 0 on normal systems) and |
627 | .RB ` stdout ' |
628 | refers to standard output (file descriptor 1). The names work in |
629 | exactly the same way as the equivalent file descriptor numbers. |
630 | .PP |
631 | If the output |
632 | .I fspec |
633 | is omitted, the input |
634 | .I fspec |
635 | is used for both input and output. Exception: if the input refers to |
636 | standard input then the output will refer to standard output instead. |
637 | .PP |
638 | All |
639 | .B file |
640 | options apply equally to sources and targets. The options are as |
641 | follows: |
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642 | .OS "File options" |
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643 | .B file.create |
644 | .RB [ = ] |
645 | .BR yes | no |
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646 | .OD |
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647 | Whether to create the output file if it doesn't exist. If |
648 | .B no |
649 | (the default), an error is reported if the file doesn't exist. If |
650 | .BR yes , |
651 | the file is created if it doesn't exist. |
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652 | .OE |
653 | .OS "File options" |
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654 | .B file.open |
655 | .RB [ = ] |
656 | .BR no | truncate | append |
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657 | .OD |
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658 | Controls the behaviour if the output file already exists. If |
659 | .BR no , |
660 | an error is reported. If |
661 | .B truncate |
662 | (the default), the existing file is replaced by the new data. If |
663 | .BR append , |
664 | the new data is appended to the file. |
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665 | .OE |
666 | .OS "File options" |
667 | .BR file.fattr.* |
668 | .OD |
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669 | The |
670 | .B file |
671 | source and target also accept |
672 | .B fattr |
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673 | options for controlling the attributes of the created file. |
674 | .OE |
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675 | .PP |
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676 | Under no circumstances will |
677 | .B fw |
678 | create a file through a `dangling' symbolic link. |
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679 | . |
680 | .SS "The `exec' source and target types" |
681 | The |
682 | .B exec |
683 | source and target execute programs and allow access to their standard |
684 | input and output streams. Both source and target have the same syntax, |
685 | which is as follows: |
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686 | .GS "Exec source and target" |
667fb920 |
687 | .I source |
688 | ::= |
689 | .I exec |
690 | .br |
691 | .I target |
692 | ::= |
693 | exec |
694 | .br |
695 | .I exec |
696 | ::= |
697 | .BR exec |
698 | .RB [ . ] |
699 | .I cmd-spec |
700 | .br |
701 | .I cmd-spec |
702 | ::= |
703 | .I shell-cmd |
10a454ad |
704 | | |
667fb920 |
705 | .RI [ prog-name ] |
706 | .B [ |
707 | .I argv0 |
708 | .I arg-seq |
709 | .B ] |
710 | .br |
711 | .I arg-seq |
712 | ::= |
713 | .I word |
714 | | |
715 | .I arg-seq |
716 | .I word |
717 | .br |
718 | .I shell-cmd |
719 | ::= |
720 | .I word |
721 | .br |
722 | .I argv0 |
723 | ::= |
724 | .I word |
333c51f4 |
725 | .GE |
667fb920 |
726 | If a single word is given, it is a |
727 | .I shell-cmd |
728 | and will be passed to the Bourne shell for execution. If a |
729 | bracket-enclosed sequence of words is given, it is considered to be a |
730 | list of arguments to pass to the program: if a |
731 | .I prog-name |
732 | is also supplied, it names the file containing the program to execute; |
733 | otherwise the file named by the first argument |
734 | .RI ( argv0 ) |
735 | is used. |
736 | .PP |
737 | The standard input and output of the program are forwarded to the other |
738 | end of the connection. The standard error stream is caught by |
739 | .B fw |
740 | and logged. |
741 | .PP |
742 | The |
743 | .B exec |
744 | source and target both understand the same set of options. The list of |
745 | options supported is as follows: |
333c51f4 |
746 | .OS "Exec options" |
667fb920 |
747 | .B exec.logging |
748 | .RB [ = ] |
749 | .BR yes | no |
333c51f4 |
750 | .OD |
667fb920 |
751 | Whether to log the start and end of executed programs. If |
752 | .B yes |
753 | (the default), a log message is emitted when the program is started |
754 | listing its process id, and another is emitted when the program finishes |
755 | giving its process id and exit status. If |
756 | .BR no , |
757 | these messages are not emitted. However the standard error stream is |
758 | still logged. The |
759 | .B log |
760 | abbreviation is accepted as a synonym for |
761 | .BR logging . |
333c51f4 |
762 | .OE |
763 | .OS "Exec options" |
667fb920 |
764 | .B exec.dir |
765 | .RB [ = ] |
766 | .I file-name |
333c51f4 |
767 | .OD |
667fb920 |
768 | Sets the current directory from which the the program should be run. |
769 | The default is not to change directory. The synonyms |
770 | .BR cd , |
771 | .B chdir |
772 | and |
773 | .B cwd |
774 | are accepted in place of |
775 | .BR dir . |
333c51f4 |
776 | .OE |
777 | .OS "Exec options" |
667fb920 |
778 | .B exec.root |
779 | .RB [ = ] |
780 | .I file-name |
333c51f4 |
781 | .OD |
667fb920 |
782 | Sets the root directory for the program, using the |
783 | .BR chroot (2) |
784 | system call. You must be the superuser for this option to work. The |
785 | default is not to set a root directory. The synonyms |
786 | .BR cd , |
787 | .B chdir |
788 | and |
789 | .B cwd |
790 | are accepted in place of |
791 | .B dir . |
333c51f4 |
792 | .OE |
793 | .OS "Exec options" |
667fb920 |
794 | .B exec.user |
795 | .RB [ = ] |
796 | .I user |
333c51f4 |
797 | .OD |
667fb920 |
798 | Sets the user (real and effective uid) to run the program as. This will |
799 | usually require superuser privileges to work. The default is not to |
800 | change uid. The synonym |
801 | .B uid |
802 | is accepted in place of |
803 | .BR user . |
333c51f4 |
804 | .OE |
805 | .OS "Exec options" |
667fb920 |
806 | .B exec.group |
807 | .RB [ = ] |
808 | .I group |
333c51f4 |
809 | .OD |
667fb920 |
810 | Sets the group (real and effective gid) to run the program as. If |
811 | running with superuser privileges, the supplementary groups list is |
812 | cleared at the same time. The default is not to change gid (or clear |
813 | the supplementary groups list). The synonym |
814 | .B gid |
815 | is accepted in place of |
816 | .BR group . |
333c51f4 |
817 | .OE |
818 | .OS "Exec options" |
667fb920 |
819 | .BI exec.rlimit. limit \c |
820 | .RB [ .hard | .soft ] |
821 | .RB [ = ] |
822 | .I value |
333c51f4 |
823 | .OD |
667fb920 |
824 | Set resource limits for the program. The |
825 | .I limit |
826 | may be one of the resource limit names described in |
827 | .BR setrlimit (2), |
828 | in lower-case and without the |
829 | .B RLIMIT_ |
830 | prefix; for example, |
831 | .B RLIMIT_CORE |
832 | becomes simply |
833 | .BR core . |
834 | The |
835 | .I value |
836 | is a number, followed optionally by |
837 | .B k |
838 | to multiply by 1024 (2\*(ss10\*(se), |
839 | .B m |
840 | to multiply by 1048576 (2\*(ss20\*(se), or |
841 | .B g |
842 | to multiply by 1073741824 (2\*(ss30\*(se); purists can use upper-case |
843 | versions of these if they want. If |
844 | .B .hard |
845 | or |
846 | .B .soft |
847 | was specified, only the hard or soft limit is set; otherwise both are |
848 | set to the same value. Only the superuser can raise the hard limit. |
849 | The soft limit cannot be set above the hard limit. |
333c51f4 |
850 | .OE |
851 | .OS "Exec options" |
667fb920 |
852 | .B exec.env.clear |
333c51f4 |
853 | .OD |
667fb920 |
854 | Clears the program's environment. |
333c51f4 |
855 | .OE |
667fb920 |
856 | .PP |
857 | .B exec.env.unset |
858 | .I var |
333c51f4 |
859 | .OD |
667fb920 |
860 | Removes |
861 | .I var |
862 | from the program's environment. It is not an error if no variable named |
863 | .I var |
864 | exists. |
333c51f4 |
865 | .OE |
866 | .OS "Exec options" |
667fb920 |
867 | .BR exec.env. [ set ] |
868 | .I var |
869 | .RB [ = ] |
870 | .I value |
333c51f4 |
871 | .OD |
96bc31ba |
872 | Assigns the variable |
667fb920 |
873 | .I var |
874 | the value |
875 | .I value |
876 | in the program's environment, possibly replacing the existing value. |
877 | The |
878 | .B set |
879 | may be omitted if the |
880 | .B env |
881 | qualifier is present. |
333c51f4 |
882 | .OE |
667fb920 |
883 | .PP |
884 | Note that environment variable modifications are performed in order, |
885 | global modifications before local ones. |
886 | . |
887 | .SS "The `socket' source and target types" |
888 | The |
889 | .B socket |
890 | source and target provide access to network services. Support is |
891 | currently provided for TCP/IP and Unix-domain sockets, although other |
892 | address types can be added with reasonable ease. |
893 | .PP |
894 | The syntax for socket sources and targets is: |
333c51f4 |
895 | .GS "Socket source and target" |
667fb920 |
896 | .ll +8i |
897 | .I source |
898 | ::= |
899 | .I socket-source |
10a454ad |
900 | .br |
667fb920 |
901 | .I target |
902 | ::= |
903 | .I socket-target |
904 | .br |
905 | .I socket-source |
906 | ::= |
907 | .RB [ socket [ . ]] |
908 | .RB [[ : ] \c |
909 | .IR addr-type \c |
910 | .RB [ : ]] |
911 | .I source-addr |
912 | .br |
913 | .I socket-target |
914 | ::= |
915 | .RB [ socket [ . ]] |
916 | .RB [[ : ] \c |
917 | .IR addr-type \c |
918 | .RB [ : ]] |
919 | .I target-addr |
920 | .ll -8i |
333c51f4 |
921 | .GE |
667fb920 |
922 | The syntax of the source and target addresses depend on the address |
923 | types, which are described below. The default address type, if no |
924 | .I addr-type |
925 | is given, is |
926 | .BR inet . |
927 | .PP |
928 | Socket sources support options; socket targets do not. The source |
929 | options provided are: |
333c51f4 |
930 | .OS "Socket options" |
667fb920 |
931 | .B socket.conn |
932 | .RB [ = ] |
d857515e |
933 | .IR number | \c |
934 | .BR unlimited | one-shot |
333c51f4 |
935 | .OD |
d857515e |
936 | Controls the behaviour of the source when it receives connections. A |
667fb920 |
937 | .I number |
d857515e |
938 | limits the number of simultaneous connections. The value |
939 | .B unlimited |
940 | (or |
941 | .BR infinite ) |
942 | removes any limit on the number of connections possible. The value |
943 | .B one-shot |
944 | will remove the socket source after a single successful connection. |
945 | (Connections refused by access control systems don't count here.) |
946 | The default is to apply a limit of 256 concurrent connections. Use of |
947 | the |
948 | .B unlimited |
949 | option is not recommended. |
333c51f4 |
950 | .OE |
951 | .OS "Socket options" |
667fb920 |
952 | .B socket.logging |
953 | .RB [ = ] |
954 | .BR yes | no |
333c51f4 |
955 | .OD |
667fb920 |
956 | Whether to log incoming connections. If |
957 | .B yes |
958 | (the default) incoming connections are logged, together with information |
959 | about the client (where available) and whether the connection was |
960 | accepted or refused. If |
961 | .BR no , |
962 | log messages are not generated. |
333c51f4 |
963 | .OE |
667fb920 |
964 | .PP |
965 | Address types also provide their own options. |
966 | . |
967 | .SS "The `inet' socket address type" |
968 | The |
969 | .B inet |
970 | address type provides access to TCP ports. The |
971 | .B inet |
972 | source and target addresses have the following syntax: |
333c51f4 |
973 | .GS "Socket source and target" |
667fb920 |
974 | .I inet-source-addr |
10a454ad |
975 | ::= |
10a454ad |
976 | .RB [ port ] |
977 | .I port |
667fb920 |
978 | .br |
979 | .I inet-target-addr |
980 | ::= |
981 | .I address |
10a454ad |
982 | .RB [ : ] |
983 | .I port |
10a454ad |
984 | .br |
667fb920 |
985 | .I address |
10a454ad |
986 | ::= |
667fb920 |
987 | .I addr-elt |
988 | | |
989 | .I address |
990 | .I addr-elt |
10a454ad |
991 | .br |
667fb920 |
992 | .I addr-elt |
10a454ad |
993 | ::= |
667fb920 |
994 | .B . |
10a454ad |
995 | | |
667fb920 |
996 | .I word |
333c51f4 |
997 | .GE |
667fb920 |
998 | A |
999 | .I port |
1000 | may be given as a port number or a service name from the |
1001 | .B /etc/services |
1002 | file (or YP map if you do that sort of thing). A |
1003 | .B hostname |
1004 | may be a textual hostname or a numerical IP address. |
1005 | .PP |
1006 | The |
1007 | .B inet |
1008 | source address accepts the following options: |
333c51f4 |
1009 | .OS "Socket options" |
667fb920 |
1010 | .BR socket.inet. [ allow | deny ] |
10a454ad |
1011 | .RB [ from ] |
667fb920 |
1012 | .I address |
10a454ad |
1013 | .RB [ / |
667fb920 |
1014 | .IR address ] |
333c51f4 |
1015 | .OD |
667fb920 |
1016 | Adds an entry to the source's access control list. If only one |
1017 | .I address |
1018 | is given, the entry applies only to that address; if two are given, the |
1019 | first is a network address and the second is a netmask either in |
1020 | dotted-quad format or a simple number of bits (e.g., |
1021 | .B /255.255.255.192 |
1022 | and |
1023 | .B /26 |
1024 | mean the same), and the entry applies to any address which, when masked |
1025 | by the netmask, is equal to the masked network address. |
333c51f4 |
1026 | .OE |
10a454ad |
1027 | .PP |
333c51f4 |
1028 | The access control rules are examined in the order: local entries first, |
1029 | then global ones, each in the order given in the configuration file. |
1030 | The first matching entry is used. If no entries match, the behaviour is |
1031 | the |
667fb920 |
1032 | .I opposite |
1033 | of the last entry tried. If there are no entries defined, the default |
1034 | is to allow all clients. |
667fb920 |
1035 | . |
1036 | .SS "The `unix' socket address type" |
10a454ad |
1037 | The |
667fb920 |
1038 | .B unix |
1039 | address type allows access to Unix-domain sockets. The syntax for |
1040 | .B unix |
1041 | source and target addresses is like this: |
333c51f4 |
1042 | .GS "Socket source and target" |
1043 | .I unix-source-addr |
667fb920 |
1044 | ::= |
333c51f4 |
1045 | .I file-name |
667fb920 |
1046 | .br |
333c51f4 |
1047 | .I unix-target-addr |
667fb920 |
1048 | ::= |
1049 | .I file-name |
333c51f4 |
1050 | .GE |
1051 | The following options are supported by the |
1052 | .B unix |
1053 | source address type: |
1054 | .OS "Socket options" |
1055 | .BR socket.unix.fattr. * |
1056 | .OD |
667fb920 |
1057 | The |
1058 | .B unix |
1059 | source address accepts |
1060 | .B fattr |
333c51f4 |
1061 | options to control the attributes of the socket file created. |
1062 | .OE |
1063 | .PP |
1064 | Sockets are removed if |
10a454ad |
1065 | .B fw |
667fb920 |
1066 | exits normally (which it will do if it runs out of sources or |
1067 | connections, or if killed by SIGINT or SIGTERM). |
1068 | .SH "EXAMPLES" |
1069 | To forward the local port 25 to a main mail server: |
1070 | .VS |
1071 | from 25 to mailserv:25 |
1072 | .VE |
1073 | To attach a fortune server to a Unix-domain socket: |
1074 | .VS |
1075 | from unix:/tmp/fortunes |
1076 | to exec [/usr/games/fortune] { user nobody } |
1077 | .VE |
1078 | To fetch a fortune from the server: |
1079 | .VS |
1080 | from file stdin, stdout to unix:/tmp/fortunes |
1081 | .VE |
1082 | To emulate |
1083 | .BR cat (1): |
1084 | .VS |
1085 | from stdin, null to null, stdout |
1086 | .VE |
1087 | . |
1088 | .\"-------------------------------------------------------------------------- |
333c51f4 |
1089 | .SH "GRAMMAR SUMMARY" |
1090 | . |
1091 | .SS "Basic syntax" |
1092 | .I file |
1093 | ::= |
1094 | .I empty |
1095 | | |
1096 | .I file |
1097 | .I stmt |
1098 | .RB [ ; ] |
1099 | .br |
1100 | .I stmt |
1101 | ::= |
1102 | .I option-stmt |
1103 | | |
1104 | .I fw-stmt |
1105 | .br |
1106 | .I fw-stmt |
1107 | ::= |
1108 | .B fw |
1109 | .I source |
1110 | .I options |
1111 | .RB [ to | \-> ] |
1112 | .I target |
1113 | .I options |
1114 | .br |
1115 | .I options |
1116 | ::= |
1117 | .B { |
1118 | .I option-seq |
1119 | .B } |
1120 | .br |
1121 | .I option-seq |
1122 | ::= |
1123 | .I empty |
1124 | | |
1125 | .I option-stmt |
1126 | .RB [ ; ] |
1127 | .I option-seq |
1128 | . |
1129 | .SS "Option syntax" |
1130 | .I option-stmt |
1131 | ::= |
1132 | .I q-option |
1133 | .br |
1134 | .I q-option |
1135 | ::= |
1136 | .I option |
1137 | .br |
1138 | | |
1139 | .I prefix |
1140 | .B . |
1141 | .I q-option |
1142 | .br |
1143 | | |
1144 | .I prefix |
1145 | .B { |
1146 | .I option-seq |
1147 | .B } |
1148 | .br |
1149 | .I prefix |
1150 | ::= |
1151 | .I word |
1152 | . |
1153 | .SS "File source and target" |
1154 | .I source |
1155 | ::= |
1156 | .I file |
1157 | .br |
1158 | .I target |
1159 | ::= |
1160 | .I file |
1161 | .br |
1162 | .I file |
1163 | ::= |
1164 | .B file |
1165 | .RB [ . ] |
1166 | .I fspec |
1167 | .RB [ , |
1168 | .IR fspec ] |
1169 | .br |
1170 | .I fspec |
1171 | ::= |
1172 | .I fd-spec |
1173 | | |
1174 | .I name-spec |
1175 | | |
1176 | .I null-spec |
1177 | .br |
1178 | .I fd-spec |
1179 | ::= |
1180 | .RB [[ : ] fd [ : ]] |
1181 | .IR number \c |
1182 | .RB | stdin | stdout |
1183 | .br |
1184 | .I name-spec |
1185 | ::= |
1186 | .RB [[ : ] file [ : ]] |
1187 | .I file-name |
1188 | .br |
1189 | .I file-name |
1190 | ::= |
1191 | .I path-seq |
1192 | | |
1193 | .B [ |
1194 | .I path-seq |
1195 | .B ] |
1196 | .br |
1197 | .I path-seq |
1198 | ::= |
1199 | .I path-elt |
1200 | | |
1201 | .I path-seq |
1202 | .I path-elt |
1203 | .br |
1204 | .I path-elt |
1205 | ::= |
1206 | .B / |
1207 | | |
1208 | .I word |
1209 | .br |
1210 | .I null-spec |
1211 | ::= |
1212 | .RB [ : ] null [ : ] |
1213 | . |
1214 | .SS "Exec source and target" |
1215 | .I source |
1216 | ::= |
1217 | .I exec |
1218 | .br |
1219 | .I target |
1220 | ::= |
1221 | exec |
1222 | .br |
1223 | .I exec |
1224 | ::= |
1225 | .BR exec |
1226 | .RB [ . ] |
1227 | .I cmd-spec |
1228 | .br |
1229 | .I cmd-spec |
1230 | ::= |
1231 | .I shell-cmd |
1232 | | |
1233 | .RI [ prog-name ] |
1234 | .B [ |
1235 | .I argv0 |
1236 | .I arg-seq |
1237 | .B ] |
1238 | .br |
1239 | .I arg-seq |
1240 | ::= |
1241 | .I word |
1242 | | |
1243 | .I arg-seq |
1244 | .I word |
1245 | .br |
1246 | .I shell-cmd |
1247 | ::= |
1248 | .I word |
1249 | .br |
1250 | .I argv0 |
1251 | ::= |
1252 | .I word |
1253 | . |
1254 | .SS "Socket source and target" |
1255 | .ll +8i |
1256 | .I source |
1257 | ::= |
1258 | .I socket-source |
1259 | .br |
1260 | .I target |
1261 | ::= |
1262 | .I socket-target |
1263 | .br |
1264 | .I socket-source |
1265 | ::= |
1266 | .RB [ socket [ . ]] |
1267 | .RB [[ : ] \c |
1268 | .IR addr-type \c |
1269 | .RB [ : ]] |
1270 | .I source-addr |
1271 | .br |
1272 | .I socket-target |
1273 | ::= |
1274 | .RB [ socket [ . ]] |
1275 | .RB [[ : ] \c |
1276 | .IR addr-type \c |
1277 | .RB [ : ]] |
1278 | .I target-addr |
1279 | .ll -8i |
1280 | .PP |
1281 | .I inet-source-addr |
1282 | ::= |
1283 | .RB [ port ] |
1284 | .I port |
1285 | .br |
1286 | .I inet-target-addr |
1287 | ::= |
1288 | .I address |
1289 | .RB [ : ] |
1290 | .I port |
1291 | .br |
1292 | .I address |
1293 | ::= |
1294 | .I addr-elt |
1295 | | |
1296 | .I address |
1297 | .I addr-elt |
1298 | .br |
1299 | .I addr-elt |
1300 | ::= |
1301 | .B . |
1302 | | |
1303 | .I word |
1304 | .PP |
1305 | .I unix-source-addr |
1306 | ::= |
1307 | .I file-name |
1308 | .br |
1309 | .I unix-target-addr |
1310 | ::= |
1311 | .I file-name |
1312 | . |
1313 | .\"-------------------------------------------------------------------------- |
1314 | .SH "OPTION SUMMARY" |
1315 | . |
1316 | .SS "File attributes (`fattr')" |
1317 | .IB prefix .fattr.mode |
1318 | .RB [ = ] |
1319 | .I mode |
1320 | .br |
1321 | .IB prefix .fattr.owner |
1322 | .RB [ = ] |
1323 | .I user |
1324 | .br |
1325 | .IB prefix .fattr.group |
1326 | .RB [ = ] |
1327 | .I group |
1328 | . |
1329 | .SS "File options" |
1330 | .B file.create |
1331 | .RB [ = ] |
1332 | .BR yes | no |
1333 | .br |
1334 | .B file.open |
1335 | .RB [ = ] |
1336 | .BR no | truncate | append |
1337 | .br |
1338 | .BR file.fattr. * |
1339 | . |
1340 | .SS "Exec options" |
1341 | .B exec.logging |
1342 | .RB [ = ] |
1343 | .BR yes | no |
1344 | .br |
1345 | .B exec.dir |
1346 | .RB [ = ] |
1347 | .I file-name |
1348 | .br |
1349 | .B exec.root |
1350 | .RB [ = ] |
1351 | .I file-name |
1352 | .br |
1353 | .B exec.user |
1354 | .RB [ = ] |
1355 | .I user |
1356 | .br |
1357 | .B exec.group |
1358 | .RB [ = ] |
1359 | .I group |
1360 | .br |
1361 | .BI exec.rlimit. limit \c |
1362 | .RB [ .hard | .soft ] |
1363 | .RB [ = ] |
1364 | .I value |
1365 | .br |
1366 | .B exec.env.clear |
1367 | .br |
1368 | .B exec.env.unset |
1369 | .I var |
1370 | .br |
1371 | .BR exec.env. [ set ] |
1372 | .I var |
1373 | .RB [ = ] |
1374 | .I value |
1375 | . |
1376 | .SS "Socket options" |
1377 | .B socket.conn |
1378 | .RB [ = ] |
d857515e |
1379 | .IR number | \c |
1380 | .BR unlimited | one-shot |
333c51f4 |
1381 | .br |
1382 | .B socket.logging |
1383 | .RB [ = ] |
1384 | .BR yes | no |
1385 | .PP |
1386 | .BR socket.inet. [ allow | deny ] |
1387 | .RB [ from ] |
1388 | .I address |
1389 | .RB [ / |
1390 | .IR address ] |
1391 | .PP |
1392 | .BR socket.unix.fattr. * |
1393 | . |
1394 | .\"-------------------------------------------------------------------------- |
10a454ad |
1395 | .SH "BUGS" |
667fb920 |
1396 | . |
cdc917d3 |
1397 | The syntax for IP addresses and filenames is nasty. |
10a454ad |
1398 | .PP |
d857515e |
1399 | IPv6 is not supported yet. Because of |
1400 | .BR fw 's |
1401 | socket address architecture, it's probably not a major piece of work to |
667fb920 |
1402 | add. |
10a454ad |
1403 | .PP |
667fb920 |
1404 | Please inform me of any security problems you think you've identified in |
1405 | this program. I take security very seriously, and I will fix security |
1406 | holes as a matter of priority when I find out about them. I will be |
1407 | annoyed if I have to read about problems on Bugtraq because they weren't |
1408 | mailed to me first. |
1409 | . |
1410 | .\"-------------------------------------------------------------------------- |
10a454ad |
1411 | .SH "AUTHOR" |
667fb920 |
1412 | . |
10a454ad |
1413 | Mark Wooding, <mdw@nsict.org> |
667fb920 |
1414 | . |
1415 | .\"----- That's all, folks -------------------------------------------------- |