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