1SPAMPD(8) Spam Proxy Daemon SPAMPD(8)
2
6 SpamPD - Spam Proxy Daemon (version 2.2)
7
9 spampd [--host=host[:port]] [--relayhost=hostname[:port]]
10 [--user|u=username] [--group|g=groupname] [--children|c=n]
11 #[--maxchildren|mc=n] [--maxrequests=n] [--childtimeout=n]
12 [--satimeout=n] [--pid|p=filename] [--nodetach] [--logsock=inet|unix]
13 [--maxsize=n] [--dose] [--tagall|a] [--log-rules-hit|rh]
14 [--set-envelope-headers|seh] [--set-envelope-from|sef]
15 [--auto-whitelist|aw] [--local-only|L] [--debug|d]
16 spampd --help
18
20 spampd is an SMTP/LMTP proxy that marks (or tags) spam using
21 SpamAssassin (http://www.SpamAssassin.org/). The proxy is designed to
22 be transparent to the sending and receiving mail servers and at no
23 point takes responsibility for the message itself. If a failure occurs
24 within spampd (or SpamAssassin) then the mail servers will disconnect
25 and the sending server is still responsible for retrying the message
26 for as long as it is configured to do so.
27 spampd uses SpamAssassin to modify (tag) relayed messages based on
29 their spam score, so all SA settings apply. This is described in the SA
30 documentation. spampd will by default only tell SA to tag a message if
31 it exceeds the spam threshold score, however you can have it rewrite
32 all messages passing through by adding the --tagall option (see SA for
33 how non-spam messages are tagged).
34 spampd logs all aspects of its operation to syslog(8), using the mail
36 syslog facility.
37 The latest version can be found at
39 <http://www.WorldDesign.com/index.cfm/rd/mta/spampd.htm>.
40
42 Perl modules:
43 Mail::SpamAssassin
45 Net::Server::PreForkSimple
46 IO::File
47 IO::Socket
48 Time::HiRes (not actually required but recommended)
49
51 spampd is meant to operate as an S/LMTP mail proxy which passes each
52 message through SpamAssassin for analysis. Note that spampd does not
53 do anything other than check for spam, so it is not suitable as an
54 anti-relay system. It is meant to work in conjunction with your
55 regular mail system. Typically one would pipe any messages they wanted
56 scanned through spampd after initial acceptance by your MX host. This
57 is especially useful for using Postfix's (http://www.postfix.org)
58 advanced content filtering mechanism, although certainly not limited to
59 that application.
60 Please re-read the second sentence in the above paragraph. You should
62 NOT enable spampd to listen on a public interface (IP address) unless
63 you know exactly what you're doing! It is very easy to set up an open
64 relay this way.
65 Here are some simple examples (square brackets in the "diagrams"
67 indicate physical machines):
68 Running between firewall/gateway and internal mail server
70 The firewall/gateway MTA would be configured to forward all of its
72 mail to the port that spampd listens on, and spampd would relay its
73 messages to port 25 of your internal server. spampd could either run
74 on its own host (and listen on any port) or it could run on either
75 mail server (and listen on any port except port 25).
76 Internet -> [ MX gateway (@inter.net.host:25) ->
78 spampd (@localhost:2025) ] ->
79 Internal mail (@private.host.ip:25)
80 Using Postfix advanced content filtering
82 Please see the FILTER_README that came with the Postfix
84 distribution. You need to have a version of Postfix which supports
85 this (ideally v.2 and up).
86 Internet -> [ Postfix (@inter.net.host:25) ->
88 spampd (@localhost:10025) ->
89 Postfix (@localhost:10026) ] -> final delivery
90 Note that these examples only show incoming mail delivery. Since it is
92 usually unnecessary to scan mail coming from your network (right?), it
93 may be desirable to set up a separate outbound route which bypasses
94 spampd.
95
97 If upgrading from a version prior to 2.2, please note that the
98 --add-sc-header option is no longer supported. Use SAs built-in header
99 manipulation features instead (as of SA v2.6).
100 Upgrading from version 1 simply involves replacing the spampd program
102 file with the latest one. Note that the dead-letters folder is no
103 longer being used and the --dead-letters option is no longer needed
104 (though no errors are thrown if it's present). Check the "Options"
105 list below for a full list of new and deprecated options. Also be sure
106 to check out the change log.
107
109 spampd can be run directly from the command prompt if desired. This is
110 useful for testing purposes, but for long term use you probably want to
111 put it somewhere like /usr/bin or /usr/local/bin and execute it at
112 system startup. For example on Red Hat-style Linux system one can use
113 a script in /etc/rc.d/init.d to start spampd (a sample script is
114 available on the spampd Web page @
115 http://www.WorldDesign.com/index.cfm/rd/mta/spampd.htm).
116 The options all have reasonable defaults, especially for a Postfix-
118 centric installation. You may want to specify the --children option if
119 you have an especially beefy or weak server box because spampd is a
120 memory-hungry program. Check the "Options" for details on this and all
121 other parameters.
122 Note that spampd replaces spamd from the SpamAssassin distribution in
124 function. You do not need to run spamd in order for spampd to work.
125 This has apparently been the source of some confusion, so now you know.
126 Postfix-specific Notes
128 Here is a typical setup for Postfix "advanced" content filtering as
129 described in the FILTER_README that came with the Postfix distribution
130 (which you really need to read):
131 /etc/postfix/master.cf:
133 smtp inet n - y - - smtpd
135 -o content_filter=smtp:localhost:10025
136 -o myhostname=mx.example.com
137 localhost:10026 inet n - n - 10 smtpd
139 -o content_filter=
140 -o myhostname=mx-int.example.com
141 The first entry is the main public-facing MTA which uses
143 localhost:10025 as the content filter for all mail. The second
144 entry receives mail from the content filter and does final delivery.
145 Both smtpd instances use the same Postfix main.cf file. spampd is the
146 process that listens on localhost:10025 and then connects to the
147 Postfix listener on localhost:10026. Note that the "myhostname"
148 options must be different between the two instances, otherwise Postfix
149 will think it's talking to itself and abort sending.
150 For the above example you can simply start spampd like this:
152 spampd --host=localhost:10025 --relayhost=localhost:10026
154 FILTER_README from the Postfix distro has more details and examples of
156 various setups, including how to skip the content filter for outbound
157 mail.
158 Another tip for Postfix when considering what timeout values to use for
160 --childtimout and --satimeout options is the following command:
161 "# postconf | grep timeout"
163 This will return a list of useful timeout settings and their values.
165 For explanations see the relevant "man" page (smtp, smtpd, lmtp). By
166 default spampd is set up for the default Postfix timeout values.
167
169 --host=ip[:port] or hostname[:port]
170 Specifies what hostname/IP and port spampd listens on. By default,
171 it listens on 127.0.0.1 (localhost) on port 10025.
172 Important! You should NOT enable spampd to listen on a public
174 interface (IP address) unless you know exactly what you're doing!
175 --port=n
177 Specifies what port spampd listens on. By default, it listens on
178 port 10025. This is an alternate to using the above --host=ip:port
179 notation.
180 --relayhost=ip[:port] or hostname[:port]
182 Specifies the hostname/IP where spampd will relay all messages.
183 Defaults to 127.0.0.1 (localhost). If the port is not provided,
184 that defaults to 25.
185 --relayport=n
187 Specifies what port spampd will relay to. Default is 25. This is
188 an alternate to using the above --relayhost=ip:port notation.
189 --user=username or --u=username
191 --group=groupname or --g=groupname
192 Specifies the user and group that the proxy will run as. Default
193 is mail/mail.
194 --children=n or --c=n
196 Number of child servers to start and maintain (where n > 0). Each
197 child will process up to --maxrequests (below) before exiting and
198 being replaced by another child. Keep this number low on systems
199 w/out a lot of memory. Default is 5 (which seems OK on a 512MB
200 lightly loaded system). Note that there is always a parent
201 process running, so if you specify 5 children you will actually
202 have 6 spampd processes running.
203 You may want to set your origination mail server to limit the
205 number of concurrent connections to spampd to match this setting
206 (for Postfix this is the "xxxx_destination_concurrency_limit"
207 setting where 'xxxx' is the transport being used, usually 'smtp',
208 and the default is 100).
209 --maxrequests=n
211 spampd works by forking child servers to handle each message. The
212 maxrequests parameter specifies how many requests will be handled
213 before the child exits. Since a child never gives back memory, a
214 large message can cause it to become quite bloated; the only way
215 to reclaim the memory is for the child to exit. The default is 20.
216 --childtimeout=n
218 This is the number of seconds to allow each child server before it
219 times out a transaction. In an S/LMTP transaction the timer is
220 reset for every command. This timeout includes time it would take
221 to send the message data, so it should not be too short. Note
222 that it's more likely the origination or destination mail servers
223 will timeout first, which is fine. This is just a "sane"
224 failsafe. Default is 360 seconds (6 minutes).
225 --satimeout=n
227 This is the number of seconds to allow for processing a message
228 with SpamAssassin (including feeding it the message, analyzing it,
229 and adding the headers/report if necessary). This should be less
230 than your origination and destination servers' timeout settings
231 for the DATA command. For Postfix the default is 300 seconds in
232 both cases (smtp_data_done_timeout and smtpd_timeout). In the
233 event of timeout while processing the message, the problem is
234 logged and the message is passed on anyway (w/out spam tagging,
235 obviously). To fail the message with a temp 450 error, see the
236 --dose (die-on-sa-errors) option, below. Default is 285 seconds.
237 --pid=filename or --p=filename
239 Specifies a filename where spampd will write its process ID so
240 that it is easy to kill it later. The directory that will contain
241 this file must be writable by the spampd user. The default is
242 /var/run/spampd.pid.
243 --logsock=unix or inet "(new in v2.20)"
245 Syslog socket to use. May be either "unix" of "inet". Default is
246 "unix" except on HP-UX and SunOS (Solaris) systems which seem to
247 prefer "inet".
248 --nodetach "(new in v2.20)"
250 If this option is given spampd won't detach from the console and
251 fork into the background. This can be useful for running under
252 control of some daemon management tools or when configured as a
253 win32 service under cygrunsrv's control.
254 --maxsize=n
256 The maximum message size to send to SpamAssassin, in KBytes. By
257 default messages over 64KB are not scanned at all, and an
258 appropriate message is logged indicating this. The size includes
259 headers and attachments (if any).
260 --dose
262 Acronym for (d)ie (o)n (s)pamAssassin (e)rrors. By default if
263 spampd encounters a problem with processing the message through
264 Spam Assassin (timeout or other error), it will still pass the
265 mail on to the destination server. If you specify this option
266 however, the mail is instead rejected with a temporary error (code
267 450, which means the origination server should keep retrying to
268 send it). See the related --satimeout option, above.
269 --tagall or --a
271 Tells spampd to have SpamAssassin add headers to all scanned mail,
272 not just spam. By default spampd will only rewrite messages which
273 exceed the spam threshold score (as defined in the SA settings).
274 Note that for this option to work as of SA-2.50, the
275 always_add_report and/or always_add_headers settings in your
276 SpamAssassin local.cf need to be set to 1/true.
277 --log-rules-hit or --rh
279 Logs the names of each SpamAssassin rule which matched the message
280 being processed. This list is returned by SA.
281 --set-envelope-headers or --seh "(new in v2.30)"
283 Turns on addition of X-Envelope-To and X-Envelope-From headers to
284 the mail being scanned before it is passed to SpamAssassin. The
285 idea is to help SA process any blacklist/whitelist to/from
286 directives on the actual sender/recipients instead of the possibly
287 bogus envelope headers. This potentially exposes the list of all
288 recipients of that mail (even BCC'ed ones). Therefore usage of
289 this option is discouraged.
290 NOTE: Even though spampd tries to prevent this leakage by removing
292 the X-Envelope-To header after scanning, SpamAssassin itself might
293 add headers itself which report one or more of the recipients
294 which had been listed in this header.
295 --set-envelope-from or --sef "(new in v2.30)"
297 Same as above option but only enables the addition of X-Envelope-
298 From header. For those that don't feel comfortable with the
299 possible information exposure of X-Envelope-To. The above option
300 overrides this one.
301 --auto-whitelist or --aw
303 This option is no longer relevant with SA version 3.0 and above,
304 which controls auto whitelist use via local.cf settings.
305 For SA version < 3.0, turns on the SpamAssassin global whitelist
307 feature. See the SA docs. Note that per-user whitelists are not
308 available.
309 --local-only or --L
311 Turn off all SA network-based tests (DNS, Razor, etc).
312 --debug or --d
314 Turns on SpamAssassin debug messages which print to the system
315 mail log (same log as spampd will log to). Also turns on more
316 verbose logging of what spampd is doing (new in v2). Also
317 increases log level of Net::Server to 4 (debug), adding yet more
318 info (but not too much) (new in v2.2).
319 --help or --h
321 Prints usage information.
322 Deprecated Options
324 The following options are no longer used but still accepted for
325 backwards compatibility with prevoius spampd versions:
326 --dead-letters
328 --heloname
329 --stop-at-threshold
330 --add-sc-header
331 --hostname
332
334 Running between firewall/gateway and internal mail server
335 spampd listens on port 10025 on the same host as the internal mail
336 server.
337 spampd --host=192.168.1.10
339 Same as above but spampd runs on port 10025 of the same host as
341 the firewall/gateway and passes messages on to the internal mail
342 server on another host.
343 spampd --relayhost=192.168.1.10
345 Using Postfix advanced content filtering example and the SA auto-
347 whitelist feature
348 spampd --port=10025 --relayhost=127.0.0.1:10026 --auto-whitelist
349
351 spampd is written and maintained by Maxim Paperno
352 <MPaperno@WorldDesign.com>. See
353 http://www.WorldDesign.com/index.cfm/rd/mta/spampd.htm for latest info.
354 spampd v2 uses two Perl modules by Bennett Todd and Copyright (C) 2001
356 Morgan Stanley Dean Witter. These are distributed under the GNU GPL
357 (see module code for more details). Both modules have been slightly
358 modified from the originals and are included in this file under new
359 names.
360 Also thanks to Bennett Todd for the example smtpproxy script which
362 helped create this version of spampd. See
363 http://bent.latency.net/smtpprox/ .
364 spampd v1 was based on code by Dave Carrigan named assassind. Trace
366 amounts of his code or documentation may still remain. Thanks to him
367 for the original inspiration and code. See
368 http://www.rudedog.org/assassind/ .
369 Also thanks to spamd (included with SpamAssassin) and amavisd-new
371 (http://www.ijs.si/software/amavisd/) for some tricks.
372 Various people have contributed patches, bug reports, and ideas, all of
374 whom I would like to thank. I have tried to include credits in code
375 comments and in the change log, as appropriate.
376 Code Contributors (in order of appearance):
378 Kurt Andersen
379 Roland Koeckel
380 Urban Petry
381 Sven Mueller
382
384 spampd is Copyright (c) 2002 by World Design Group, Inc. and Maxim
385 Paperno.
386 Portions are Copyright (C) 2001 Morgan Stanley Dean Witter as mentioned
388 above in the Credits section.
389 This program is free software; you can redistribute it and/or modify
391 it under the terms of the GNU General Public License as published by
392 the Free Software Foundation; either version 2 of the License, or
393 (at your option) any later version.
394 This program is distributed in the hope that it will be useful,
396 but WITHOUT ANY WARRANTY; without even the implied warranty of
397 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
398 GNU General Public License for more details.
399 The GNU GPL can be found at http://www.fsf.org/copyleft/gpl.html
401
403 None known. Please report any to MPaperno@WorldDesign.com.
404
406 Figure out how to use Net::Server::PreFork because it has cool
407 potential for load management. I tried but either I'm missing
408 something or PreFork is somewhat broken in how it works. If anyone has
409 experience here, please let me know.
410 Add configurable option for rejecting mail outright based on spam
412 score. It would be nice to make this program safe enough to sit in
413 front of a mail server such as Postfix and be able to reject mail
414 before it enters our systems. The only real problem is that Postfix
415 will see localhost as the connecting client, so that disables any
416 client-based checks Postfix can do and creates a possible relay hole if
417 localhost is trusted.
418
420 perl(1), Spam::Assassin(3), <http://www.spamassassin.org/>,
421 <http://www.WorldDesign.com/index.cfm/rd/mta/spampd.htm>
422perl v5.32.0 2020-07-29 SPAMPD(8)