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