Commit | Line | Data |
---|---|---|
de45f55a AM |
1 | |
2 | ### acl/30_exim4-config_check_rcpt | |
3 | ################################# | |
4 | ||
5 | # This access control list is used for every RCPT command in an incoming | |
6 | # SMTP message. The tests are run in order until the address is either | |
7 | # accepted or denied. | |
8 | # | |
9 | acl_check_rcpt: | |
10 | ||
11 | # Accept if the source is local SMTP (i.e. not over TCP/IP). We do this by | |
12 | # testing for an empty sending host field. | |
13 | accept | |
14 | hosts = : | |
15 | control = dkim_disable_verify | |
16 | ||
17 | # Do not try to verify DKIM signatures of incoming mail if DC_minimaldns | |
18 | # or DISABLE_DKIM_VERIFY are set. | |
19 | .ifdef DC_minimaldns | |
20 | warn | |
21 | control = dkim_disable_verify | |
22 | .else | |
23 | .ifdef DISABLE_DKIM_VERIFY | |
24 | warn | |
25 | control = dkim_disable_verify | |
26 | .endif | |
27 | .endif | |
28 | ||
29 | # The following section of the ACL is concerned with local parts that contain | |
30 | # certain non-alphanumeric characters. Dots in unusual places are | |
31 | # handled by this ACL as well. | |
32 | # | |
33 | # Non-alphanumeric characters other than dots are rarely found in genuine | |
34 | # local parts, but are often tried by people looking to circumvent | |
35 | # relaying restrictions. Therefore, although they are valid in local | |
36 | # parts, these rules disallow certain non-alphanumeric characters, as | |
37 | # a precaution. | |
38 | # | |
39 | # Empty components (two dots in a row) are not valid in RFC 2822, but Exim | |
40 | # allows them because they have been encountered. (Consider local parts | |
41 | # constructed as "firstinitial.secondinitial.familyname" when applied to | |
42 | # a name without a second initial.) However, a local part starting | |
43 | # with a dot or containing /../ can cause trouble if it is used as part of a | |
44 | # file name (e.g. for a mailing list). This is also true for local parts that | |
45 | # contain slashes. A pipe symbol can also be troublesome if the local part is | |
46 | # incorporated unthinkingly into a shell command line. | |
47 | # | |
48 | # These ACL components will block recipient addresses that are valid | |
49 | # from an RFC2822 point of view. We chose to have them blocked by | |
50 | # default for security reasons. | |
51 | # | |
52 | # If you feel that your site should have less strict recipient | |
53 | # checking, please feel free to change the default values of the macros | |
54 | # defined in main/01_exim4-config_listmacrosdefs or override them from a | |
55 | # local configuration file. | |
56 | # | |
57 | # Two different rules are used. The first one has a quite strict | |
58 | # default, and is applied to messages that are addressed to one of the | |
59 | # local domains handled by this host. | |
60 | ||
61 | # The default value of CHECK_RCPT_LOCAL_LOCALPARTS is defined in | |
62 | # main/01_exim4-config_listmacrosdefs: | |
63 | # CHECK_RCPT_LOCAL_LOCALPARTS = ^[.] : ^.*[@%!/|`#&?] | |
64 | # This blocks local parts that begin with a dot or contain a quite | |
65 | # broad range of non-alphanumeric characters. | |
66 | .ifdef CHECK_RCPT_LOCAL_LOCALPARTS | |
67 | deny | |
68 | domains = +local_domains | |
69 | local_parts = CHECK_RCPT_LOCAL_LOCALPARTS | |
70 | message = restricted characters in address | |
71 | .endif | |
72 | ||
73 | ||
74 | # The second rule applies to all other domains, and its default is | |
75 | # considerably less strict. | |
76 | ||
77 | # The default value of CHECK_RCPT_REMOTE_LOCALPARTS is defined in | |
78 | # main/01_exim4-config_listmacrosdefs: | |
79 | # CHECK_RCPT_REMOTE_LOCALPARTS = ^[./|] : ^.*[@%!`#&?] : ^.*/\\.\\./ | |
80 | ||
81 | # It allows local users to send outgoing messages to sites | |
82 | # that use slashes and vertical bars in their local parts. It blocks | |
83 | # local parts that begin with a dot, slash, or vertical bar, but allows | |
84 | # these characters within the local part. However, the sequence /../ is | |
85 | # barred. The use of some other non-alphanumeric characters is blocked. | |
86 | # Single quotes might probably be dangerous as well, but they're | |
87 | # allowed by the default regexps to avoid rejecting mails to Ireland. | |
88 | # The motivation here is to prevent local users (or local users' malware) | |
89 | # from mounting certain kinds of attack on remote sites. | |
90 | .ifdef CHECK_RCPT_REMOTE_LOCALPARTS | |
91 | deny | |
92 | domains = !+local_domains | |
93 | local_parts = CHECK_RCPT_REMOTE_LOCALPARTS | |
94 | message = restricted characters in address | |
95 | .endif | |
96 | ||
97 | ||
98 | # Accept mail to postmaster in any local domain, regardless of the source, | |
99 | # and without verifying the sender. | |
100 | # | |
101 | accept | |
102 | .ifndef CHECK_RCPT_POSTMASTER | |
103 | local_parts = postmaster | |
104 | .else | |
105 | local_parts = CHECK_RCPT_POSTMASTER | |
106 | .endif | |
107 | domains = +local_domains : +relay_to_domains | |
108 | ||
109 | ||
110 | # Deny unless the sender address can be verified. | |
111 | # | |
112 | # This is disabled by default so that DNSless systems don't break. If | |
113 | # your system can do DNS lookups without delay or cost, you might want | |
114 | # to enable this feature. | |
115 | # | |
116 | # This feature does not work in smarthost and satellite setups as | |
0baa7b9d SB |
117 | # with these setups all domains pass verification. See spec.txt section |
118 | # "Access control lists" subsection "Address verification" with the added | |
119 | # information that a smarthost/satellite setup routes all non-local e-mail | |
120 | # to the smarthost. | |
de45f55a AM |
121 | .ifdef CHECK_RCPT_VERIFY_SENDER |
122 | deny | |
123 | message = Sender verification failed | |
124 | !acl = acl_local_deny_exceptions | |
125 | !verify = sender | |
126 | .endif | |
127 | ||
128 | # Verify senders listed in local_sender_callout with a callout. | |
129 | # | |
130 | # In smarthost and satellite setups, this causes the callout to be | |
131 | # done to the smarthost. Verification will thus only be reliable if the | |
132 | # smarthost does reject illegal addresses in the SMTP dialog. | |
133 | deny | |
134 | !acl = acl_local_deny_exceptions | |
135 | senders = ${if exists{CONFDIR/local_sender_callout}\ | |
136 | {CONFDIR/local_sender_callout}\ | |
137 | {}} | |
138 | !verify = sender/callout | |
139 | ||
140 | ||
141 | # Accept if the message comes from one of the hosts for which we are an | |
142 | # outgoing relay. It is assumed that such hosts are most likely to be MUAs, | |
143 | # so we set control=submission to make Exim treat the message as a | |
144 | # submission. It will fix up various errors in the message, for example, the | |
145 | # lack of a Date: header line. If you are actually relaying out out from | |
146 | # MTAs, you may want to disable this. If you are handling both relaying from | |
147 | # MTAs and submissions from MUAs you should probably split them into two | |
148 | # lists, and handle them differently. | |
149 | ||
150 | # Recipient verification is omitted here, because in many cases the clients | |
151 | # are dumb MUAs that don't cope well with SMTP error responses. If you are | |
152 | # actually relaying out from MTAs, you should probably add recipient | |
153 | # verification here. | |
154 | ||
155 | # Note that, by putting this test before any DNS black list checks, you will | |
156 | # always accept from these hosts, even if they end up on a black list. The | |
157 | # assumption is that they are your friends, and if they get onto black | |
158 | # list, it is a mistake. | |
159 | accept | |
160 | hosts = +relay_from_hosts | |
161 | control = submission/sender_retain | |
162 | control = dkim_disable_verify | |
163 | ||
164 | ||
165 | # Accept if the message arrived over an authenticated connection, from | |
166 | # any host. Again, these messages are usually from MUAs, so recipient | |
167 | # verification is omitted, and submission mode is set. And again, we do this | |
168 | # check before any black list tests. | |
169 | accept | |
170 | authenticated = * | |
171 | control = submission/sender_retain | |
172 | control = dkim_disable_verify | |
173 | ||
0baa7b9d SB |
174 | # Insist that a HELO/EHLO was accepted. |
175 | ||
176 | require message = nice hosts say HELO first | |
177 | condition = ${if def:sender_helo_name} | |
de45f55a AM |
178 | |
179 | # Insist that any other recipient address that we accept is either in one of | |
180 | # our local domains, or is in a domain for which we explicitly allow | |
181 | # relaying. Any other domain is rejected as being unacceptable for relaying. | |
182 | require | |
183 | message = relay not permitted | |
184 | domains = +local_domains : +relay_to_domains | |
185 | ||
186 | ||
187 | # We also require all accepted addresses to be verifiable. This check will | |
188 | # do local part verification for local domains, but only check the domain | |
189 | # for remote domains. | |
190 | require | |
191 | verify = recipient | |
192 | ||
193 | ||
194 | # Verify recipients listed in local_rcpt_callout with a callout. | |
195 | # This is especially handy for forwarding MX hosts (secondary MX or | |
196 | # mail hubs) of domains that receive a lot of spam to non-existent | |
197 | # addresses. The only way to check local parts for remote relay | |
198 | # domains is to use a callout (add /callout), but please read the | |
199 | # documentation about callouts before doing this. | |
200 | deny | |
201 | !acl = acl_local_deny_exceptions | |
202 | recipients = ${if exists{CONFDIR/local_rcpt_callout}\ | |
203 | {CONFDIR/local_rcpt_callout}\ | |
204 | {}} | |
205 | !verify = recipient/callout | |
206 | ||
207 | ||
208 | # CONFDIR/local_sender_blacklist holds a list of envelope senders that | |
209 | # should have their access denied to the local host. Incoming messages | |
210 | # with one of these senders are rejected at RCPT time. | |
211 | # | |
212 | # The explicit white lists are honored as well as negative items in | |
213 | # the black list. See exim4-config_files(5) for details. | |
214 | deny | |
215 | message = sender envelope address $sender_address is locally blacklisted here. If you think this is wrong, get in touch with postmaster | |
216 | !acl = acl_local_deny_exceptions | |
217 | senders = ${if exists{CONFDIR/local_sender_blacklist}\ | |
218 | {CONFDIR/local_sender_blacklist}\ | |
219 | {}} | |
220 | ||
221 | ||
222 | # deny bad sites (IP address) | |
223 | # CONFDIR/local_host_blacklist holds a list of host names, IP addresses | |
224 | # and networks (CIDR notation) that should have their access denied to | |
225 | # The local host. Messages coming in from a listed host will have all | |
226 | # RCPT statements rejected. | |
227 | # | |
228 | # The explicit white lists are honored as well as negative items in | |
229 | # the black list. See exim4-config_files(5) for details. | |
230 | deny | |
231 | message = sender IP address $sender_host_address is locally blacklisted here. If you think this is wrong, get in touch with postmaster | |
232 | !acl = acl_local_deny_exceptions | |
233 | hosts = ${if exists{CONFDIR/local_host_blacklist}\ | |
234 | {CONFDIR/local_host_blacklist}\ | |
235 | {}} | |
236 | ||
237 | ||
238 | # Warn if the sender host does not have valid reverse DNS. | |
239 | # | |
240 | # If your system can do DNS lookups without delay or cost, you might want | |
241 | # to enable this. | |
242 | # If sender_host_address is defined, it's a remote call. If | |
243 | # sender_host_name is not defined, then reverse lookup failed. Use | |
244 | # this instead of !verify = reverse_host_lookup to catch deferrals | |
245 | # as well as outright failures. | |
246 | .ifdef CHECK_RCPT_REVERSE_DNS | |
247 | warn | |
248 | condition = ${if and{{def:sender_host_address}{!def:sender_host_name}}\ | |
249 | {yes}{no}} | |
250 | add_header = X-Host-Lookup-Failed: Reverse DNS lookup failed for $sender_host_address (${if eq{$host_lookup_failed}{1}{failed}{deferred}}) | |
251 | .endif | |
252 | ||
253 | ||
254 | # Use spfquery to perform a pair of SPF checks (for details, see | |
255 | # http://www.openspf.org/) | |
256 | # | |
257 | # This is quite costly in terms of DNS lookups (~6 lookups per mail). Do not | |
258 | # enable if that's an issue. Also note that if you enable this, you must | |
259 | # install "spf-tools-perl" which provides the spfquery command. | |
260 | # Missing spf-tools-perl will trigger the "Unexpected error in | |
261 | # SPF check" warning. | |
262 | .ifdef CHECK_RCPT_SPF | |
263 | deny | |
264 | message = [SPF] $sender_host_address is not allowed to send mail from \ | |
265 | ${if def:sender_address_domain {$sender_address_domain}{$sender_helo_name}}. \ | |
266 | Please see \ | |
267 | http://www.openspf.org/Why?scope=${if def:sender_address_domain \ | |
268 | {mfrom}{helo}};identity=${if def:sender_address_domain \ | |
269 | {$sender_address}{$sender_helo_name}};ip=$sender_host_address | |
270 | log_message = SPF check failed. | |
271 | !acl = acl_local_deny_exceptions | |
272 | condition = ${run{/usr/bin/spfquery.mail-spf-perl --ip \ | |
273 | ${quote:$sender_host_address} --identity \ | |
274 | ${if def:sender_address_domain \ | |
275 | {--scope mfrom --identity ${quote:$sender_address}}\ | |
276 | {--scope helo --identity ${quote:$sender_helo_name}}}}\ | |
277 | {no}{${if eq {$runrc}{1}{yes}{no}}}} | |
278 | ||
279 | defer | |
280 | message = Temporary DNS error while checking SPF record. Try again later. | |
281 | !acl = acl_local_deny_exceptions | |
282 | condition = ${if eq {$runrc}{5}{yes}{no}} | |
283 | ||
284 | warn | |
285 | condition = ${if <={$runrc}{6}{yes}{no}} | |
286 | add_header = Received-SPF: ${if eq {$runrc}{0}{pass}\ | |
287 | {${if eq {$runrc}{2}{softfail}\ | |
288 | {${if eq {$runrc}{3}{neutral}\ | |
289 | {${if eq {$runrc}{4}{permerror}\ | |
290 | {${if eq {$runrc}{6}{none}{error}}}}}}}}}\ | |
291 | } client-ip=$sender_host_address; \ | |
292 | ${if def:sender_address_domain \ | |
293 | {envelope-from=${sender_address}; }{}}\ | |
294 | helo=$sender_helo_name | |
295 | ||
296 | warn | |
297 | log_message = Unexpected error in SPF check. | |
298 | condition = ${if >{$runrc}{6}{yes}{no}} | |
299 | .endif | |
300 | ||
301 | ||
302 | # Check against classic DNS "black" lists (DNSBLs) which list | |
303 | # sender IP addresses | |
304 | .ifdef CHECK_RCPT_IP_DNSBLS | |
305 | warn | |
306 | dnslists = CHECK_RCPT_IP_DNSBLS | |
307 | add_header = X-Warning: $sender_host_address is listed at $dnslist_domain ($dnslist_value: $dnslist_text) | |
308 | log_message = $sender_host_address is listed at $dnslist_domain ($dnslist_value: $dnslist_text) | |
309 | .endif | |
310 | ||
311 | ||
312 | # Check against DNSBLs which list sender domains, with an option to locally | |
313 | # whitelist certain domains that might be blacklisted. | |
314 | # | |
315 | # Note: If you define CHECK_RCPT_DOMAIN_DNSBLS, you must append | |
316 | # "/$sender_address_domain" after each domain. For example: | |
317 | # CHECK_RCPT_DOMAIN_DNSBLS = rhsbl.foo.org/$sender_address_domain \ | |
318 | # : rhsbl.bar.org/$sender_address_domain | |
319 | .ifdef CHECK_RCPT_DOMAIN_DNSBLS | |
320 | warn | |
321 | !senders = ${if exists{CONFDIR/local_domain_dnsbl_whitelist}\ | |
322 | {CONFDIR/local_domain_dnsbl_whitelist}\ | |
323 | {}} | |
324 | dnslists = CHECK_RCPT_DOMAIN_DNSBLS | |
325 | add_header = X-Warning: $sender_address_domain is listed at $dnslist_domain ($dnslist_value: $dnslist_text) | |
326 | log_message = $sender_address_domain is listed at $dnslist_domain ($dnslist_value: $dnslist_text) | |
327 | .endif | |
328 | ||
329 | ||
330 | # This hook allows you to hook in your own ACLs without having to | |
331 | # modify this file. If you do it like we suggest, you'll end up with | |
332 | # a small performance penalty since there is an additional file being | |
333 | # accessed. This doesn't happen if you leave the macro unset. | |
334 | .ifdef CHECK_RCPT_LOCAL_ACL_FILE | |
335 | .include CHECK_RCPT_LOCAL_ACL_FILE | |
336 | .endif | |
337 | ||
338 | ||
339 | ############################################################################# | |
340 | # This check is commented out because it is recognized that not every | |
341 | # sysadmin will want to do it. If you enable it, the check performs | |
342 | # Client SMTP Authorization (csa) checks on the sending host. These checks | |
343 | # do DNS lookups for SRV records. The CSA proposal is currently (May 2005) | |
344 | # an Internet draft. You can, of course, add additional conditions to this | |
345 | # ACL statement to restrict the CSA checks to certain hosts only. | |
346 | # | |
347 | # require verify = csa | |
348 | ############################################################################# | |
349 | ||
350 | ||
351 | # Accept if the address is in a domain for which we are an incoming relay, | |
352 | # but again, only if the recipient can be verified. | |
353 | ||
354 | accept | |
355 | domains = +relay_to_domains | |
356 | endpass | |
357 | verify = recipient | |
358 | ||
359 | ||
360 | # At this point, the address has passed all the checks that have been | |
361 | # configured, so we accept it unconditionally. | |
362 | ||
363 | accept |