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1 | .\" -*-nroff-*- |
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2 | .\" |
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3 | .\" $Id: fw.1,v 1.8 1999/12/22 15:44:43 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 $ |
370e3c14 |
31 | .\" Revision 1.8 1999/12/22 15:44:43 mdw |
32 | .\" Fix some errors, and document new option. |
33 | .\" |
d857515e |
34 | .\" Revision 1.7 1999/10/22 22:45:15 mdw |
35 | .\" Describe new socket connection options. |
36 | .\" |
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37 | .\" Revision 1.6 1999/10/10 16:46:29 mdw |
38 | .\" Include grammar and options references at the end of the manual. |
39 | .\" |
cdc917d3 |
40 | .\" Revision 1.5 1999/09/26 18:18:05 mdw |
41 | .\" Remove a fixed bug from the list. Fix some nasty formatting |
42 | .\" misfeatures. |
43 | .\" |
e73034b0 |
44 | .\" Revision 1.4 1999/08/19 18:32:48 mdw |
45 | .\" Improve lexical analysis. In particular, `chmod' patterns don't have to |
46 | .\" be quoted any more. |
47 | .\" |
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48 | .\" Revision 1.3 1999/07/30 06:49:00 mdw |
49 | .\" Minor tidying and typo correction. |
50 | .\" |
667fb920 |
51 | .\" Revision 1.2 1999/07/26 23:31:04 mdw |
52 | .\" Document lots of new features and syntax. |
53 | .\" |
54 | . |
55 | .\"----- Various bits of fancy styling -------------------------------------- |
56 | . |
57 | .\" --- Indented paragraphs with right-aligned tags --- |
58 | . |
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59 | .de hP |
60 | .IP |
61 | \h'-\w'\fB\\$1\ \fP'u'\fB\\$1\ \fP\c |
62 | .. |
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63 | . |
64 | .\" --- Verbatim-oid typesetting --- |
65 | .de VS |
66 | .sp 1 |
67 | .RS |
68 | .nf |
69 | .ft B |
70 | .. |
71 | .de VE |
72 | .ft R |
73 | .fi |
74 | .RE |
75 | .sp 1 |
76 | .. |
77 | . |
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78 | .\" --- Grammar markup --- |
79 | .\" |
80 | .\" This is mainly for the benefit of the automatic scripts which |
81 | .\" generate the grammar summary. |
82 | . |
83 | .de GS |
84 | .PP |
85 | .. |
86 | .de GE |
87 | .PP |
88 | .. |
89 | . |
90 | .de OS |
91 | .PP |
92 | .. |
93 | .de OD |
94 | .RS |
95 | .. |
96 | .de OE |
97 | .RE |
98 | .. |
99 | . |
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100 | .\" --- Other bits of styling --- |
101 | . |
102 | .ie t \{\ |
103 | . ds o \(bu |
104 | . ds ss \s8\u |
105 | . ds se \d\s0 |
106 | . if \n(.g \{\ |
107 | . fam P |
108 | . \} |
109 | .\} |
110 | .el \{\ |
111 | . ds o o |
112 | . ds ss ^ |
113 | . ds se |
114 | .\} |
115 | . |
116 | .\"-------------------------------------------------------------------------- |
117 | . |
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118 | .TH fw 1 "1 July 1999" fw |
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119 | . |
120 | .\"-------------------------------------------------------------------------- |
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121 | .SH NAME |
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122 | . |
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123 | fw \- port forwarder |
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124 | . |
125 | .\"-------------------------------------------------------------------------- |
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126 | .SH SYNOPSIS |
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127 | . |
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128 | .B fw |
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129 | .RB [ \-dlq ] |
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130 | .RB [ \-f |
131 | .IR file ] |
132 | .IR config-stmt ... |
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133 | . |
134 | .\"-------------------------------------------------------------------------- |
135 | .SH "DESCRIPTION" |
136 | . |
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137 | The |
138 | .B fw |
139 | program is a simple port forwarder. It supports a number of features |
140 | the author hasn't found in similar programs: |
141 | .TP |
142 | .I "Connection logging" |
143 | Each connection attempt to the forwarder is logged, giving the time of |
144 | the connection, the DNS-resolved hostname (if available), and the user |
145 | name resulting from an RFC931 lookup. These lookups are done |
146 | asynchronously to the main forwarder's operation. |
147 | .TP |
148 | .I "Access control" |
149 | Each forwarded port may have an access control list attached to it. |
150 | Only authorized hosts are allowed to connect. Access control checks are |
151 | performed by quick checks on the client's IP address. |
152 | .TP |
153 | .I "Nonblocking single-process design" |
154 | The internal structure of the server is completely nonblocking. The |
155 | connections don't block; the reading and writing don't block; the name |
156 | lookups don't block. This is all done in a single process, with the |
157 | single exception of the DNS resolver. |
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158 | .TP |
159 | .I "Support for Unix-domain sockets" |
160 | Connections from and to Unix-domain sockets can be handled just as |
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161 | easily as more normal Internet sockets. Access control doesn't work on |
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162 | Unix domain sockets, though. (Yet.) |
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163 | .SS "Command line options" |
164 | The |
165 | .B fw |
166 | program understands a few simple command line options: |
167 | .TP |
168 | .B "\-h, \-\-help" |
169 | Displays a screen of help text on standard output and exits |
170 | successfully. |
171 | .TP |
172 | .B "\-v, \-\-version" |
173 | Writes the version number to standard output and exits successfully. |
174 | .TP |
175 | .B "\-u, \-\-usage" |
176 | Writes a terse usage summary to standard output and exits successfully. |
177 | .TP |
178 | .BI "\-f, \-\-file=" file |
179 | Read configuration information from |
180 | .IR file . |
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181 | Equivalent to an |
182 | .RB ` include |
183 | .IR file ' |
184 | configuration file statement. |
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185 | .TP |
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186 | .B "\-d, \-\-daemon, \-\-fork" |
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187 | Forks into the background after reading the configuration and |
188 | initializing properly. |
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189 | .TP |
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190 | .B "\-l, \-\-syslog, \-\-log" |
191 | Emit logging information to the system log, rather than standard error. |
192 | .TP |
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193 | .B "-q, \-\-quiet" |
194 | Don't output any logging information. This option is not recommended |
195 | for normal use, although it can make system call traces clearer so I use |
196 | it when debugging. |
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197 | .PP |
198 | Any further command line arguments are interpreted as configuration |
199 | lines to be read. Configuration supplied in command line arguments has |
200 | precisely the same syntax as configuration in files. If there are no |
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201 | configuration statements on the command line, and no |
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202 | .B \-f |
203 | options were supplied, configuration is read from standard input, if |
204 | stdin is not a terminal. |
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205 | . |
206 | .\"-------------------------------------------------------------------------- |
207 | .SH "CONFIGURATION LANGUAGE" |
208 | . |
209 | The |
210 | .B fw |
211 | program has a fairly sophisticated configuration language to let you |
212 | describe which things should be forwarded where and what special |
213 | features there should be. |
214 | .SS "Lexical structure" |
215 | There are four types of characters. |
216 | .TP |
217 | .I "word constituent characters" |
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218 | Word constituent characters are gathered together into words. |
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219 | Depending on its surrounding context, a word might act as a keyword or a |
220 | string. All alphanumerics are word constituents, as is the hyphen |
221 | .RB ` \- '. |
222 | Other characters may change their status in future versions. |
223 | .TP |
224 | .I "self-delimiting characters" |
225 | Self-delimiting characters always stand alone. They act as punctuation, |
226 | shaping the sequence of words into more complex grammatical forms. The |
227 | characters |
228 | .RB ` { ', |
229 | .RB ` } ', |
230 | .RB ` [ ', |
231 | .RB ` ] ', |
232 | .RB ` / ', |
233 | .RB ` , ', |
234 | .RB ` = ', |
235 | .RB ` : ', |
236 | .RB ` ; ' |
237 | and |
238 | .RB ` . ' |
239 | are self-delimiting. Note that while some characters, e.g., |
240 | .RB ` [ ' |
241 | and |
242 | .RB ` ; ', |
243 | require escaping by the shell, they are strictly optional in the grammar |
244 | and can be omitted in quick hacks at the shell prompt. |
245 | .TP |
246 | .I "whitespace characters" |
247 | Whitespace characters separate words but are otherwise ignored. All |
248 | `normal' whitespace characters (e.g., space, tab and newline) are |
249 | considered to be whitespace for these purposes. |
250 | .TP |
251 | .I "special characters" |
252 | There are three special characters. The |
253 | .RB ` # ' |
254 | character, if it appears at the start of a word, introduces a |
255 | .I comment |
256 | which extends to the end of the current line or command-line argument. |
257 | Within a word, it behaves like a normal word-constituent character. The |
258 | backslash |
259 | .RB ` \e ' |
260 | escapes the following character causing it to be interpreted as a word |
261 | constituent regardless of its normal type. The double-quote |
262 | .RB ` """" ' |
263 | escapes all characters other than backslashes up to the next |
264 | double-quote and causes them to be regarded as word constituents. Note |
265 | that you don't have to quote a whole word. The backslash can escape a |
266 | quote character allowing you to insert it into a word if really |
267 | necessary. |
268 | . |
269 | .SS "Basic syntax" |
270 | The overall syntax looks a bit like this: |
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271 | .GS "Basic syntax" |
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272 | .I file |
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273 | ::= |
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274 | .I empty |
275 | | |
276 | .I file |
277 | .I stmt |
278 | .RB [ ; ] |
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279 | .br |
280 | .I stmt |
281 | ::= |
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282 | .I option-stmt |
283 | | |
284 | .I fw-stmt |
285 | .br |
286 | .I fw-stmt |
287 | ::= |
288 | .B fw |
289 | .I source |
290 | .I options |
291 | .RB [ to | \-> ] |
292 | .I target |
293 | .I options |
294 | .br |
295 | .I options |
296 | ::= |
297 | .B { |
298 | .I option-seq |
299 | .B } |
300 | .br |
301 | .I option-seq |
302 | ::= |
303 | .I empty |
304 | | |
305 | .I option-stmt |
306 | .RB [ ; ] |
307 | .I option-seq |
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308 | .GE |
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309 | If you prefer, the keyword |
310 | .RB ` fw ' |
311 | may be spelt |
312 | .RB ` forward ' |
313 | or |
314 | .RB ` from '. |
315 | All are equivalent. |
316 | . |
317 | .SS "Sources and targets" |
318 | Forwarding is set up by attaching |
319 | .I targets |
320 | to |
321 | .IR sources . |
322 | Sources are things which are capable of |
323 | .I initiating |
324 | one end of a data flow on their own, while targets are things which are |
325 | capable of setting up the other end on demand. In the case of a TCP |
326 | port forwarder, the part which listens for incoming client connections |
327 | is the source, while the part which sets up outgoing connections to the |
328 | destination server is the target. |
329 | .PP |
330 | Essentially, all |
331 | .B fw |
332 | does is set up a collection of sources and targets based on your |
333 | configuration file so that when a source decides to initiate a data |
334 | flow, it tells its target to set its end up, and then squirts data back |
335 | and forth between the two until there's no more. |
336 | .PP |
337 | Some sources are |
338 | .IR persistent : |
339 | they stay around indefinitely setting up multiple attachments to |
340 | targets. Others are |
341 | .IR transient : |
342 | they set up one connection and then disappear. If all the sources |
343 | defined are transient, then |
344 | .B fw |
345 | will quit when no more active sources remain and all connections have |
346 | terminated. |
347 | .PP |
348 | The |
349 | .B fw |
350 | program is fairly versatile. It allows you to attach any supported type |
351 | of source to any supported type of target. This will, I hope, be the |
352 | case in all future versions. |
353 | .PP |
354 | The syntax of a |
355 | .I source |
356 | or |
357 | .I target |
358 | depend on the source or target type, and are therefore described in the |
359 | sections specific to the various types. |
360 | . |
361 | .SS "Options structure" |
362 | Most of the objects that |
363 | .B fw |
364 | knows about (including sources and targets, but also other more specific |
365 | things such as socket address types) can have their behaviour modified |
366 | by |
367 | .IR options . |
368 | The options available at a particular point in the configuration depend |
369 | on the |
370 | .IR context . |
371 | A global option, outside of a |
372 | .I fw-stmt |
373 | has no context unless it is explicitly qualified, and affects global |
374 | behaviour. Local options, applied to a source or target in a |
375 | .I fw-stmt |
376 | has the context of the type of source or target to which it is applied, |
377 | and affects only that source or target. |
378 | .PP |
379 | Note that it's important to distinguish between an option's context |
380 | (which is affected by its qualification) and its local or global |
381 | status. No matter how qualified, a global option will always control |
382 | default options for objects, and a local option will only affect a |
383 | specific source or target. |
384 | .PP |
385 | The syntax for qualifying options is like this: |
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386 | .GS "Option syntax" |
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387 | .I option-stmt |
388 | ::= |
389 | .I q-option |
390 | .br |
391 | .I q-option |
392 | ::= |
393 | .I option |
394 | .br |
395 | | |
396 | .I prefix |
397 | .B . |
398 | .I q-option |
399 | .br |
400 | | |
401 | .I prefix |
402 | .B { |
403 | .I option-seq |
404 | .B } |
405 | .br |
406 | .I prefix |
407 | ::= |
408 | .I word |
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409 | .GE |
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410 | Thus, you may qualify either an individual option or a sequence of |
411 | options. The two are equivalent; for example, |
412 | .VS |
413 | exec.rlimit { |
414 | core = 0; |
415 | cpu = 60; |
416 | } |
417 | .VE |
418 | is equivalent to |
419 | .VS |
420 | exec.rlimit.core = 0; |
421 | exec.rlimit.cpu = 0; |
422 | .VE |
423 | For each option, there is a sequence of prefixes which maximally qualify |
424 | that option. An option prefixed with this sequence is |
425 | .IR "fully qualified" . |
426 | In actual use, some or all of those prefixes may be omitted. However, |
427 | it's possible for the option to become |
428 | .I ambiguous |
429 | if you do this. For example, the option |
430 | .B fattr.owner |
431 | may refer either to |
432 | .B file.fattr.owner |
433 | or to |
434 | .BR socket.unix.fattr.owner . |
435 | In this case, the ambiguity is benign: a local option will have as its |
436 | context an appropriate source or target, and both global options |
437 | actually control the same default. However, the option |
438 | .B logging |
439 | may mean either |
440 | .B socket.logging |
441 | or |
442 | .BR exec.logging , |
443 | which have separate defaults, and which one you actually get depends on |
444 | the exact implementation of |
445 | .BR fw 's |
446 | option parser. (Currently this would resolve to |
447 | .BR exec.logging , |
448 | although this may change in a later version.) |
449 | .PP |
450 | In this manual, options are usually shown in their fully-qualified form. |
451 | . |
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452 | .SS "File attributes for created files: `fattr'" |
453 | Both the |
454 | .B file |
455 | and |
456 | .B socket |
457 | sources and targets can create new filesystem objects. The |
458 | .B fattr |
459 | options allow control over the attributes of the newly-created objects. |
460 | Both |
461 | .B file |
462 | and |
463 | .B socket |
464 | use the same set of defaults, so a prefix of |
465 | .B fattr |
466 | is good enough for setting global options, and the implicit context |
467 | disambiguates local options. |
468 | .PP |
469 | The following file attribute options are supported: |
470 | .OS "File attribute options (`fattr')" |
471 | .IB prefix .fattr.mode |
472 | .RB [ = ] |
473 | .I mode |
474 | .OD |
475 | Sets the permissions mode for a new file. The |
476 | .I mode |
477 | argument may be either an octal number or a |
478 | .BR chmod (1)-style |
479 | string which acts on the default permissions established by the |
480 | prevailing |
481 | .BR umask (2) |
482 | setting. The characters |
483 | .RB ` = ' |
484 | and |
485 | .RB ` , ' |
486 | do not have to be quoted within the mode string. |
487 | .OE |
488 | .OS "File attribute options (`fattr')" |
489 | .IB prefix .fattr.owner |
490 | .RB [ = ] |
491 | .I user |
492 | .OD |
493 | Sets the owner for newly created files. On non-broken systems you will |
494 | need to be the superuser to set the owner on a file. The |
495 | .I user |
496 | may either be a numeric uid or a username. The default is not to change |
497 | the owner of the file once it's created. The synonyms |
498 | .B uid |
499 | and |
500 | .B user |
501 | are accepted in place of |
502 | .BR owner . |
503 | .OE |
504 | .OS "File attribute options (`fattr')" |
505 | .IB prefix .fattr.group |
506 | .RB [ = ] |
507 | .I group |
508 | .OD |
509 | Sets the group for newly created files. You will usually need to be a |
510 | member of the group in question order to set the group of a file. The |
511 | .I group |
512 | may either be a numeric gid or a group name. The default is not to |
513 | change the group of the file once it's created. The synonym |
514 | .B gid |
515 | is accepted in place of |
516 | .BR group . |
517 | .OE |
518 | . |
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519 | .SS "The `file' source and target types" |
520 | The |
521 | .B file |
522 | source and target allow data to move to and from objects other |
523 | than sockets within the Unix filesystem. (Unix-domain sockets are |
524 | handled using the |
525 | .B socket |
526 | source and target.) |
527 | .PP |
528 | If a |
529 | .B file |
530 | is used as a source, it is set up immediately. |
531 | .PP |
532 | The syntax of |
533 | .B file |
534 | sources and targets is like this: |
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535 | .GS "File sources and targets" |
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536 | .I source |
537 | ::= |
538 | .I file |
539 | .br |
540 | .I target |
541 | ::= |
542 | .I file |
543 | .br |
544 | .I file |
545 | ::= |
546 | .B file |
547 | .RB [ . ] |
548 | .I fspec |
549 | .RB [ , |
550 | .IR fspec ] |
551 | .br |
552 | .I fspec |
553 | ::= |
554 | .I fd-spec |
555 | | |
556 | .I name-spec |
557 | | |
558 | .I null-spec |
559 | .br |
560 | .I fd-spec |
561 | ::= |
562 | .RB [[ : ] fd [ : ]] |
563 | .IR number \c |
564 | .RB | stdin | stdout |
565 | .br |
566 | .I name-spec |
567 | ::= |
568 | .RB [[ : ] file [ : ]] |
569 | .I file-name |
570 | .br |
571 | .I file-name |
572 | ::= |
573 | .I path-seq |
574 | | |
575 | .B [ |
576 | .I path-seq |
577 | .B ] |
578 | .br |
579 | .I path-seq |
580 | ::= |
581 | .I path-elt |
582 | | |
583 | .I path-seq |
584 | .I path-elt |
585 | .br |
586 | .I path-elt |
587 | ::= |
588 | .B / |
589 | | |
590 | .I word |
591 | .br |
592 | .I null-spec |
593 | ::= |
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594 | .RB [ : ] null [ : ] |
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595 | .GE |
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596 | The |
597 | .I file |
598 | specification describes two files, the first to be used as input, the |
599 | second to be used as output, each described by an |
600 | .IR fspec . |
601 | .PP |
602 | If none of the keywords |
603 | .RB ` fd ', |
604 | .RB ` name ' |
605 | or |
606 | .RB ` null ' |
607 | are given, the type of an |
608 | .I fspec |
609 | is deduced from its nature: if it matches one of the strings |
610 | .RB ` stdin ' |
611 | or |
612 | .RB ` stdout ', |
613 | or begins with a digit, it's considered to be a file descriptor; |
614 | otherwise it's interpreted as a filename. |
615 | .PP |
616 | A |
617 | .RB ` name ' |
618 | spec describes a file by its name within the filesystem. It is opened |
619 | when needed and closed again after use. For output files, the precise |
620 | behaviour is controlled by options described below. |
621 | .PP |
622 | A |
623 | .RB ` null ' |
624 | spec attaches the input or output of the source or target to |
625 | .BR /dev/null . |
626 | .PP |
627 | An |
628 | .RB ` fd ' |
629 | spec uses an existing open file descriptor, given either by number or a |
630 | symbolic name. The name |
631 | .RB ` stdin ' |
632 | refers to standard input (file descriptor 0 on normal systems) and |
633 | .RB ` stdout ' |
634 | refers to standard output (file descriptor 1). The names work in |
635 | exactly the same way as the equivalent file descriptor numbers. |
636 | .PP |
637 | If the output |
638 | .I fspec |
639 | is omitted, the input |
640 | .I fspec |
641 | is used for both input and output. Exception: if the input refers to |
642 | standard input then the output will refer to standard output instead. |
643 | .PP |
644 | All |
645 | .B file |
646 | options apply equally to sources and targets. The options are as |
647 | follows: |
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648 | .OS "File options" |
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649 | .B file.create |
650 | .RB [ = ] |
651 | .BR yes | no |
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652 | .OD |
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653 | Whether to create the output file if it doesn't exist. If |
654 | .B no |
655 | (the default), an error is reported if the file doesn't exist. If |
656 | .BR yes , |
657 | the file is created if it doesn't exist. |
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658 | .OE |
659 | .OS "File options" |
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660 | .B file.open |
661 | .RB [ = ] |
662 | .BR no | truncate | append |
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663 | .OD |
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664 | Controls the behaviour if the output file already exists. If |
665 | .BR no , |
666 | an error is reported. If |
667 | .B truncate |
668 | (the default), the existing file is replaced by the new data. If |
669 | .BR append , |
670 | the new data is appended to the file. |
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671 | .OE |
672 | .OS "File options" |
673 | .BR file.fattr.* |
674 | .OD |
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675 | The |
676 | .B file |
677 | source and target also accept |
678 | .B fattr |
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679 | options for controlling the attributes of the created file. |
680 | .OE |
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681 | .PP |
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682 | Under no circumstances will |
683 | .B fw |
684 | create a file through a `dangling' symbolic link. |
667fb920 |
685 | . |
686 | .SS "The `exec' source and target types" |
687 | The |
688 | .B exec |
689 | source and target execute programs and allow access to their standard |
690 | input and output streams. Both source and target have the same syntax, |
691 | which is as follows: |
333c51f4 |
692 | .GS "Exec source and target" |
667fb920 |
693 | .I source |
694 | ::= |
695 | .I exec |
696 | .br |
697 | .I target |
698 | ::= |
699 | exec |
700 | .br |
701 | .I exec |
702 | ::= |
703 | .BR exec |
704 | .RB [ . ] |
705 | .I cmd-spec |
706 | .br |
707 | .I cmd-spec |
708 | ::= |
709 | .I shell-cmd |
10a454ad |
710 | | |
667fb920 |
711 | .RI [ prog-name ] |
712 | .B [ |
713 | .I argv0 |
714 | .I arg-seq |
715 | .B ] |
716 | .br |
717 | .I arg-seq |
718 | ::= |
719 | .I word |
720 | | |
721 | .I arg-seq |
722 | .I word |
723 | .br |
724 | .I shell-cmd |
725 | ::= |
726 | .I word |
727 | .br |
728 | .I argv0 |
729 | ::= |
730 | .I word |
333c51f4 |
731 | .GE |
667fb920 |
732 | If a single word is given, it is a |
733 | .I shell-cmd |
734 | and will be passed to the Bourne shell for execution. If a |
735 | bracket-enclosed sequence of words is given, it is considered to be a |
736 | list of arguments to pass to the program: if a |
737 | .I prog-name |
738 | is also supplied, it names the file containing the program to execute; |
739 | otherwise the file named by the first argument |
740 | .RI ( argv0 ) |
741 | is used. |
742 | .PP |
743 | The standard input and output of the program are forwarded to the other |
744 | end of the connection. The standard error stream is caught by |
745 | .B fw |
746 | and logged. |
747 | .PP |
748 | The |
749 | .B exec |
750 | source and target both understand the same set of options. The list of |
751 | options supported is as follows: |
333c51f4 |
752 | .OS "Exec options" |
667fb920 |
753 | .B exec.logging |
754 | .RB [ = ] |
755 | .BR yes | no |
333c51f4 |
756 | .OD |
667fb920 |
757 | Whether to log the start and end of executed programs. If |
758 | .B yes |
759 | (the default), a log message is emitted when the program is started |
760 | listing its process id, and another is emitted when the program finishes |
761 | giving its process id and exit status. If |
762 | .BR no , |
763 | these messages are not emitted. However the standard error stream is |
764 | still logged. The |
765 | .B log |
766 | abbreviation is accepted as a synonym for |
767 | .BR logging . |
333c51f4 |
768 | .OE |
769 | .OS "Exec options" |
667fb920 |
770 | .B exec.dir |
771 | .RB [ = ] |
772 | .I file-name |
333c51f4 |
773 | .OD |
667fb920 |
774 | Sets the current directory from which the the program should be run. |
775 | The default is not to change directory. The synonyms |
776 | .BR cd , |
777 | .B chdir |
778 | and |
779 | .B cwd |
780 | are accepted in place of |
781 | .BR dir . |
333c51f4 |
782 | .OE |
783 | .OS "Exec options" |
667fb920 |
784 | .B exec.root |
785 | .RB [ = ] |
786 | .I file-name |
333c51f4 |
787 | .OD |
667fb920 |
788 | Sets the root directory for the program, using the |
789 | .BR chroot (2) |
790 | system call. You must be the superuser for this option to work. The |
791 | default is not to set a root directory. The synonyms |
792 | .BR cd , |
793 | .B chdir |
794 | and |
795 | .B cwd |
796 | are accepted in place of |
797 | .B dir . |
333c51f4 |
798 | .OE |
799 | .OS "Exec options" |
667fb920 |
800 | .B exec.user |
801 | .RB [ = ] |
802 | .I user |
333c51f4 |
803 | .OD |
667fb920 |
804 | Sets the user (real and effective uid) to run the program as. This will |
805 | usually require superuser privileges to work. The default is not to |
806 | change uid. The synonym |
807 | .B uid |
808 | is accepted in place of |
809 | .BR user . |
333c51f4 |
810 | .OE |
811 | .OS "Exec options" |
667fb920 |
812 | .B exec.group |
813 | .RB [ = ] |
814 | .I group |
333c51f4 |
815 | .OD |
667fb920 |
816 | Sets the group (real and effective gid) to run the program as. If |
817 | running with superuser privileges, the supplementary groups list is |
818 | cleared at the same time. The default is not to change gid (or clear |
819 | the supplementary groups list). The synonym |
820 | .B gid |
821 | is accepted in place of |
822 | .BR group . |
333c51f4 |
823 | .OE |
824 | .OS "Exec options" |
667fb920 |
825 | .BI exec.rlimit. limit \c |
826 | .RB [ .hard | .soft ] |
827 | .RB [ = ] |
828 | .I value |
333c51f4 |
829 | .OD |
667fb920 |
830 | Set resource limits for the program. The |
831 | .I limit |
832 | may be one of the resource limit names described in |
833 | .BR setrlimit (2), |
834 | in lower-case and without the |
835 | .B RLIMIT_ |
836 | prefix; for example, |
837 | .B RLIMIT_CORE |
838 | becomes simply |
839 | .BR core . |
840 | The |
841 | .I value |
842 | is a number, followed optionally by |
843 | .B k |
844 | to multiply by 1024 (2\*(ss10\*(se), |
845 | .B m |
846 | to multiply by 1048576 (2\*(ss20\*(se), or |
847 | .B g |
848 | to multiply by 1073741824 (2\*(ss30\*(se); purists can use upper-case |
849 | versions of these if they want. If |
850 | .B .hard |
851 | or |
852 | .B .soft |
853 | was specified, only the hard or soft limit is set; otherwise both are |
854 | set to the same value. Only the superuser can raise the hard limit. |
855 | The soft limit cannot be set above the hard limit. |
333c51f4 |
856 | .OE |
857 | .OS "Exec options" |
667fb920 |
858 | .B exec.env.clear |
333c51f4 |
859 | .OD |
667fb920 |
860 | Clears the program's environment. |
333c51f4 |
861 | .OE |
667fb920 |
862 | .PP |
863 | .B exec.env.unset |
864 | .I var |
333c51f4 |
865 | .OD |
667fb920 |
866 | Removes |
867 | .I var |
868 | from the program's environment. It is not an error if no variable named |
869 | .I var |
870 | exists. |
333c51f4 |
871 | .OE |
872 | .OS "Exec options" |
667fb920 |
873 | .BR exec.env. [ set ] |
874 | .I var |
875 | .RB [ = ] |
876 | .I value |
333c51f4 |
877 | .OD |
96bc31ba |
878 | Assigns the variable |
667fb920 |
879 | .I var |
880 | the value |
881 | .I value |
882 | in the program's environment, possibly replacing the existing value. |
883 | The |
884 | .B set |
885 | may be omitted if the |
886 | .B env |
887 | qualifier is present. |
333c51f4 |
888 | .OE |
667fb920 |
889 | .PP |
890 | Note that environment variable modifications are performed in order, |
891 | global modifications before local ones. |
892 | . |
893 | .SS "The `socket' source and target types" |
894 | The |
895 | .B socket |
896 | source and target provide access to network services. Support is |
897 | currently provided for TCP/IP and Unix-domain sockets, although other |
898 | address types can be added with reasonable ease. |
899 | .PP |
900 | The syntax for socket sources and targets is: |
333c51f4 |
901 | .GS "Socket source and target" |
667fb920 |
902 | .ll +8i |
903 | .I source |
904 | ::= |
905 | .I socket-source |
10a454ad |
906 | .br |
667fb920 |
907 | .I target |
908 | ::= |
909 | .I socket-target |
910 | .br |
911 | .I socket-source |
912 | ::= |
913 | .RB [ socket [ . ]] |
914 | .RB [[ : ] \c |
915 | .IR addr-type \c |
916 | .RB [ : ]] |
917 | .I source-addr |
918 | .br |
919 | .I socket-target |
920 | ::= |
921 | .RB [ socket [ . ]] |
922 | .RB [[ : ] \c |
923 | .IR addr-type \c |
924 | .RB [ : ]] |
925 | .I target-addr |
926 | .ll -8i |
333c51f4 |
927 | .GE |
667fb920 |
928 | The syntax of the source and target addresses depend on the address |
929 | types, which are described below. The default address type, if no |
930 | .I addr-type |
931 | is given, is |
932 | .BR inet . |
933 | .PP |
934 | Socket sources support options; socket targets do not. The source |
935 | options provided are: |
333c51f4 |
936 | .OS "Socket options" |
667fb920 |
937 | .B socket.conn |
938 | .RB [ = ] |
d857515e |
939 | .IR number | \c |
940 | .BR unlimited | one-shot |
333c51f4 |
941 | .OD |
d857515e |
942 | Controls the behaviour of the source when it receives connections. A |
667fb920 |
943 | .I number |
d857515e |
944 | limits the number of simultaneous connections. The value |
945 | .B unlimited |
946 | (or |
947 | .BR infinite ) |
948 | removes any limit on the number of connections possible. The value |
949 | .B one-shot |
950 | will remove the socket source after a single successful connection. |
951 | (Connections refused by access control systems don't count here.) |
952 | The default is to apply a limit of 256 concurrent connections. Use of |
953 | the |
954 | .B unlimited |
955 | option is not recommended. |
333c51f4 |
956 | .OE |
957 | .OS "Socket options" |
667fb920 |
958 | .B socket.logging |
959 | .RB [ = ] |
960 | .BR yes | no |
333c51f4 |
961 | .OD |
667fb920 |
962 | Whether to log incoming connections. If |
963 | .B yes |
964 | (the default) incoming connections are logged, together with information |
965 | about the client (where available) and whether the connection was |
966 | accepted or refused. If |
967 | .BR no , |
968 | log messages are not generated. |
333c51f4 |
969 | .OE |
667fb920 |
970 | .PP |
971 | Address types also provide their own options. |
972 | . |
973 | .SS "The `inet' socket address type" |
974 | The |
975 | .B inet |
976 | address type provides access to TCP ports. The |
977 | .B inet |
978 | source and target addresses have the following syntax: |
333c51f4 |
979 | .GS "Socket source and target" |
667fb920 |
980 | .I inet-source-addr |
10a454ad |
981 | ::= |
10a454ad |
982 | .RB [ port ] |
983 | .I port |
667fb920 |
984 | .br |
985 | .I inet-target-addr |
986 | ::= |
987 | .I address |
10a454ad |
988 | .RB [ : ] |
989 | .I port |
10a454ad |
990 | .br |
667fb920 |
991 | .I address |
10a454ad |
992 | ::= |
667fb920 |
993 | .I addr-elt |
994 | | |
995 | .I address |
996 | .I addr-elt |
10a454ad |
997 | .br |
667fb920 |
998 | .I addr-elt |
10a454ad |
999 | ::= |
667fb920 |
1000 | .B . |
10a454ad |
1001 | | |
667fb920 |
1002 | .I word |
333c51f4 |
1003 | .GE |
667fb920 |
1004 | A |
1005 | .I port |
1006 | may be given as a port number or a service name from the |
1007 | .B /etc/services |
1008 | file (or YP map if you do that sort of thing). A |
1009 | .B hostname |
1010 | may be a textual hostname or a numerical IP address. |
1011 | .PP |
1012 | The |
1013 | .B inet |
1014 | source address accepts the following options: |
333c51f4 |
1015 | .OS "Socket options" |
667fb920 |
1016 | .BR socket.inet. [ allow | deny ] |
10a454ad |
1017 | .RB [ from ] |
667fb920 |
1018 | .I address |
10a454ad |
1019 | .RB [ / |
667fb920 |
1020 | .IR address ] |
333c51f4 |
1021 | .OD |
667fb920 |
1022 | Adds an entry to the source's access control list. If only one |
1023 | .I address |
1024 | is given, the entry applies only to that address; if two are given, the |
1025 | first is a network address and the second is a netmask either in |
1026 | dotted-quad format or a simple number of bits (e.g., |
1027 | .B /255.255.255.192 |
1028 | and |
1029 | .B /26 |
1030 | mean the same), and the entry applies to any address which, when masked |
1031 | by the netmask, is equal to the masked network address. |
333c51f4 |
1032 | .OE |
10a454ad |
1033 | .PP |
333c51f4 |
1034 | The access control rules are examined in the order: local entries first, |
1035 | then global ones, each in the order given in the configuration file. |
1036 | The first matching entry is used. If no entries match, the behaviour is |
1037 | the |
667fb920 |
1038 | .I opposite |
1039 | of the last entry tried. If there are no entries defined, the default |
1040 | is to allow all clients. |
667fb920 |
1041 | . |
1042 | .SS "The `unix' socket address type" |
10a454ad |
1043 | The |
667fb920 |
1044 | .B unix |
1045 | address type allows access to Unix-domain sockets. The syntax for |
1046 | .B unix |
1047 | source and target addresses is like this: |
333c51f4 |
1048 | .GS "Socket source and target" |
1049 | .I unix-source-addr |
667fb920 |
1050 | ::= |
333c51f4 |
1051 | .I file-name |
667fb920 |
1052 | .br |
333c51f4 |
1053 | .I unix-target-addr |
667fb920 |
1054 | ::= |
1055 | .I file-name |
333c51f4 |
1056 | .GE |
1057 | The following options are supported by the |
1058 | .B unix |
1059 | source address type: |
1060 | .OS "Socket options" |
1061 | .BR socket.unix.fattr. * |
1062 | .OD |
667fb920 |
1063 | The |
1064 | .B unix |
1065 | source address accepts |
1066 | .B fattr |
333c51f4 |
1067 | options to control the attributes of the socket file created. |
1068 | .OE |
1069 | .PP |
1070 | Sockets are removed if |
10a454ad |
1071 | .B fw |
667fb920 |
1072 | exits normally (which it will do if it runs out of sources or |
1073 | connections, or if killed by SIGINT or SIGTERM). |
1074 | .SH "EXAMPLES" |
1075 | To forward the local port 25 to a main mail server: |
1076 | .VS |
1077 | from 25 to mailserv:25 |
1078 | .VE |
1079 | To attach a fortune server to a Unix-domain socket: |
1080 | .VS |
1081 | from unix:/tmp/fortunes |
1082 | to exec [/usr/games/fortune] { user nobody } |
1083 | .VE |
1084 | To fetch a fortune from the server: |
1085 | .VS |
1086 | from file stdin, stdout to unix:/tmp/fortunes |
1087 | .VE |
1088 | To emulate |
1089 | .BR cat (1): |
1090 | .VS |
1091 | from stdin, null to null, stdout |
1092 | .VE |
1093 | . |
1094 | .\"-------------------------------------------------------------------------- |
333c51f4 |
1095 | .SH "GRAMMAR SUMMARY" |
1096 | . |
1097 | .SS "Basic syntax" |
1098 | .I file |
1099 | ::= |
1100 | .I empty |
1101 | | |
1102 | .I file |
1103 | .I stmt |
1104 | .RB [ ; ] |
1105 | .br |
1106 | .I stmt |
1107 | ::= |
1108 | .I option-stmt |
1109 | | |
1110 | .I fw-stmt |
1111 | .br |
1112 | .I fw-stmt |
1113 | ::= |
1114 | .B fw |
1115 | .I source |
1116 | .I options |
1117 | .RB [ to | \-> ] |
1118 | .I target |
1119 | .I options |
1120 | .br |
1121 | .I options |
1122 | ::= |
1123 | .B { |
1124 | .I option-seq |
1125 | .B } |
1126 | .br |
1127 | .I option-seq |
1128 | ::= |
1129 | .I empty |
1130 | | |
1131 | .I option-stmt |
1132 | .RB [ ; ] |
1133 | .I option-seq |
1134 | . |
1135 | .SS "Option syntax" |
1136 | .I option-stmt |
1137 | ::= |
1138 | .I q-option |
1139 | .br |
1140 | .I q-option |
1141 | ::= |
1142 | .I option |
1143 | .br |
1144 | | |
1145 | .I prefix |
1146 | .B . |
1147 | .I q-option |
1148 | .br |
1149 | | |
1150 | .I prefix |
1151 | .B { |
1152 | .I option-seq |
1153 | .B } |
1154 | .br |
1155 | .I prefix |
1156 | ::= |
1157 | .I word |
1158 | . |
1159 | .SS "File source and target" |
1160 | .I source |
1161 | ::= |
1162 | .I file |
1163 | .br |
1164 | .I target |
1165 | ::= |
1166 | .I file |
1167 | .br |
1168 | .I file |
1169 | ::= |
1170 | .B file |
1171 | .RB [ . ] |
1172 | .I fspec |
1173 | .RB [ , |
1174 | .IR fspec ] |
1175 | .br |
1176 | .I fspec |
1177 | ::= |
1178 | .I fd-spec |
1179 | | |
1180 | .I name-spec |
1181 | | |
1182 | .I null-spec |
1183 | .br |
1184 | .I fd-spec |
1185 | ::= |
1186 | .RB [[ : ] fd [ : ]] |
1187 | .IR number \c |
1188 | .RB | stdin | stdout |
1189 | .br |
1190 | .I name-spec |
1191 | ::= |
1192 | .RB [[ : ] file [ : ]] |
1193 | .I file-name |
1194 | .br |
1195 | .I file-name |
1196 | ::= |
1197 | .I path-seq |
1198 | | |
1199 | .B [ |
1200 | .I path-seq |
1201 | .B ] |
1202 | .br |
1203 | .I path-seq |
1204 | ::= |
1205 | .I path-elt |
1206 | | |
1207 | .I path-seq |
1208 | .I path-elt |
1209 | .br |
1210 | .I path-elt |
1211 | ::= |
1212 | .B / |
1213 | | |
1214 | .I word |
1215 | .br |
1216 | .I null-spec |
1217 | ::= |
1218 | .RB [ : ] null [ : ] |
1219 | . |
1220 | .SS "Exec source and target" |
1221 | .I source |
1222 | ::= |
1223 | .I exec |
1224 | .br |
1225 | .I target |
1226 | ::= |
1227 | exec |
1228 | .br |
1229 | .I exec |
1230 | ::= |
1231 | .BR exec |
1232 | .RB [ . ] |
1233 | .I cmd-spec |
1234 | .br |
1235 | .I cmd-spec |
1236 | ::= |
1237 | .I shell-cmd |
1238 | | |
1239 | .RI [ prog-name ] |
1240 | .B [ |
1241 | .I argv0 |
1242 | .I arg-seq |
1243 | .B ] |
1244 | .br |
1245 | .I arg-seq |
1246 | ::= |
1247 | .I word |
1248 | | |
1249 | .I arg-seq |
1250 | .I word |
1251 | .br |
1252 | .I shell-cmd |
1253 | ::= |
1254 | .I word |
1255 | .br |
1256 | .I argv0 |
1257 | ::= |
1258 | .I word |
1259 | . |
1260 | .SS "Socket source and target" |
1261 | .ll +8i |
1262 | .I source |
1263 | ::= |
1264 | .I socket-source |
1265 | .br |
1266 | .I target |
1267 | ::= |
1268 | .I socket-target |
1269 | .br |
1270 | .I socket-source |
1271 | ::= |
1272 | .RB [ socket [ . ]] |
1273 | .RB [[ : ] \c |
1274 | .IR addr-type \c |
1275 | .RB [ : ]] |
1276 | .I source-addr |
1277 | .br |
1278 | .I socket-target |
1279 | ::= |
1280 | .RB [ socket [ . ]] |
1281 | .RB [[ : ] \c |
1282 | .IR addr-type \c |
1283 | .RB [ : ]] |
1284 | .I target-addr |
1285 | .ll -8i |
1286 | .PP |
1287 | .I inet-source-addr |
1288 | ::= |
1289 | .RB [ port ] |
1290 | .I port |
1291 | .br |
1292 | .I inet-target-addr |
1293 | ::= |
1294 | .I address |
1295 | .RB [ : ] |
1296 | .I port |
1297 | .br |
1298 | .I address |
1299 | ::= |
1300 | .I addr-elt |
1301 | | |
1302 | .I address |
1303 | .I addr-elt |
1304 | .br |
1305 | .I addr-elt |
1306 | ::= |
1307 | .B . |
1308 | | |
1309 | .I word |
1310 | .PP |
1311 | .I unix-source-addr |
1312 | ::= |
1313 | .I file-name |
1314 | .br |
1315 | .I unix-target-addr |
1316 | ::= |
1317 | .I file-name |
1318 | . |
1319 | .\"-------------------------------------------------------------------------- |
1320 | .SH "OPTION SUMMARY" |
1321 | . |
1322 | .SS "File attributes (`fattr')" |
1323 | .IB prefix .fattr.mode |
1324 | .RB [ = ] |
1325 | .I mode |
1326 | .br |
1327 | .IB prefix .fattr.owner |
1328 | .RB [ = ] |
1329 | .I user |
1330 | .br |
1331 | .IB prefix .fattr.group |
1332 | .RB [ = ] |
1333 | .I group |
1334 | . |
1335 | .SS "File options" |
1336 | .B file.create |
1337 | .RB [ = ] |
1338 | .BR yes | no |
1339 | .br |
1340 | .B file.open |
1341 | .RB [ = ] |
1342 | .BR no | truncate | append |
1343 | .br |
1344 | .BR file.fattr. * |
1345 | . |
1346 | .SS "Exec options" |
1347 | .B exec.logging |
1348 | .RB [ = ] |
1349 | .BR yes | no |
1350 | .br |
1351 | .B exec.dir |
1352 | .RB [ = ] |
1353 | .I file-name |
1354 | .br |
1355 | .B exec.root |
1356 | .RB [ = ] |
1357 | .I file-name |
1358 | .br |
1359 | .B exec.user |
1360 | .RB [ = ] |
1361 | .I user |
1362 | .br |
1363 | .B exec.group |
1364 | .RB [ = ] |
1365 | .I group |
1366 | .br |
1367 | .BI exec.rlimit. limit \c |
1368 | .RB [ .hard | .soft ] |
1369 | .RB [ = ] |
1370 | .I value |
1371 | .br |
1372 | .B exec.env.clear |
1373 | .br |
1374 | .B exec.env.unset |
1375 | .I var |
1376 | .br |
1377 | .BR exec.env. [ set ] |
1378 | .I var |
1379 | .RB [ = ] |
1380 | .I value |
1381 | . |
1382 | .SS "Socket options" |
1383 | .B socket.conn |
1384 | .RB [ = ] |
d857515e |
1385 | .IR number | \c |
1386 | .BR unlimited | one-shot |
333c51f4 |
1387 | .br |
1388 | .B socket.logging |
1389 | .RB [ = ] |
1390 | .BR yes | no |
1391 | .PP |
1392 | .BR socket.inet. [ allow | deny ] |
1393 | .RB [ from ] |
1394 | .I address |
1395 | .RB [ / |
1396 | .IR address ] |
1397 | .PP |
1398 | .BR socket.unix.fattr. * |
1399 | . |
1400 | .\"-------------------------------------------------------------------------- |
10a454ad |
1401 | .SH "BUGS" |
667fb920 |
1402 | . |
cdc917d3 |
1403 | The syntax for IP addresses and filenames is nasty. |
10a454ad |
1404 | .PP |
d857515e |
1405 | IPv6 is not supported yet. Because of |
1406 | .BR fw 's |
1407 | socket address architecture, it's probably not a major piece of work to |
667fb920 |
1408 | add. |
10a454ad |
1409 | .PP |
667fb920 |
1410 | Please inform me of any security problems you think you've identified in |
1411 | this program. I take security very seriously, and I will fix security |
1412 | holes as a matter of priority when I find out about them. I will be |
1413 | annoyed if I have to read about problems on Bugtraq because they weren't |
1414 | mailed to me first. |
1415 | . |
1416 | .\"-------------------------------------------------------------------------- |
10a454ad |
1417 | .SH "AUTHOR" |
667fb920 |
1418 | . |
10a454ad |
1419 | Mark Wooding, <mdw@nsict.org> |
667fb920 |
1420 | . |
1421 | .\"----- That's all, folks -------------------------------------------------- |