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725c9874 | 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: | |
d2b0a567 | 10 | |
725c9874 | 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 | ||
16 | ||
725c9874 | 17 | # The following section of the ACL is concerned with local parts that contain |
18 | # certain non-alphanumeric characters. Dots in unusual places are | |
19 | # handled by this ACL as well. | |
20 | # | |
21 | # Non-alphanumeric characters other than dots are rarely found in genuine | |
22 | # local parts, but are often tried by people looking to circumvent | |
23 | # relaying restrictions. Therefore, although they are valid in local | |
24 | # parts, these rules disallow certain non-alphanumeric characters, as | |
25 | # a precaution. | |
26 | # | |
27 | # Empty components (two dots in a row) are not valid in RFC 2822, but Exim | |
28 | # allows them because they have been encountered. (Consider local parts | |
29 | # constructed as "firstinitial.secondinitial.familyname" when applied to | |
30 | # a name without a second initial.) However, a local part starting | |
31 | # with a dot or containing /../ can cause trouble if it is used as part of a | |
32 | # file name (e.g. for a mailing list). This is also true for local parts that | |
33 | # contain slashes. A pipe symbol can also be troublesome if the local part is | |
34 | # incorporated unthinkingly into a shell command line. | |
35 | # | |
d2b0a567 | 36 | # These ACL components will block recipient addresses that are valid |
37 | # from an RFC2822 point of view. We chose to have them blocked by | |
38 | # default for security reasons. | |
39 | # | |
40 | # If you feel that your site should have less strict recipient | |
41 | # checking, please feel free to change the default values of the macros | |
42 | # defined in main/01_exim4-config_listmacrosdefs or override them from a | |
43 | # local configuration file. | |
44 | # | |
725c9874 | 45 | # Two different rules are used. The first one has a quite strict |
46 | # default, and is applied to messages that are addressed to one of the | |
47 | # local domains handled by this host. | |
d2b0a567 | 48 | |
49 | # The default value of CHECK_RCPT_LOCAL_LOCALPARTS is defined in | |
50 | # main/01_exim4-config_listmacrosdefs: | |
51 | # CHECK_RCPT_LOCAL_LOCALPARTS = ^[.] : ^.*[@%!/|`#&?] | |
52 | # This blocks local parts that begin with a dot or contain a quite | |
53 | # broad range of non-alphanumeric characters. | |
725c9874 | 54 | .ifdef CHECK_RCPT_LOCAL_LOCALPARTS |
55 | deny | |
f6404efa | 56 | domains = +local_domains : +unix_domains |
725c9874 | 57 | local_parts = CHECK_RCPT_LOCAL_LOCALPARTS |
58 | message = restricted characters in address | |
59 | .endif | |
60 | ||
61 | ||
62 | # The second rule applies to all other domains, and its default is | |
63 | # considerably less strict. | |
d2b0a567 | 64 | |
65 | # The default value of CHECK_RCPT_REMOTE_LOCALPARTS is defined in | |
66 | # main/01_exim4-config_listmacrosdefs: | |
67 | # CHECK_RCPT_REMOTE_LOCALPARTS = ^[./|] : ^.*[@%!`#&?] : ^.*/\\.\\./ | |
68 | ||
69 | # It allows local users to send outgoing messages to sites | |
70 | # that use slashes and vertical bars in their local parts. It blocks | |
71 | # local parts that begin with a dot, slash, or vertical bar, but allows | |
72 | # these characters within the local part. However, the sequence /../ is | |
73 | # barred. The use of some other non-alphanumeric characters is blocked. | |
74 | # Single quotes might probably be dangerous as well, but they're | |
75 | # allowed by the default regexps to avoid rejecting mails to Ireland. | |
76 | # The motivation here is to prevent local users (or local users' malware) | |
77 | # from mounting certain kinds of attack on remote sites. | |
725c9874 | 78 | .ifdef CHECK_RCPT_REMOTE_LOCALPARTS |
79 | deny | |
f6404efa | 80 | domains = !+local_domains : !+unix_domains |
725c9874 | 81 | local_parts = CHECK_RCPT_REMOTE_LOCALPARTS |
82 | message = restricted characters in address | |
83 | .endif | |
84 | ||
85 | ||
86 | # Accept mail to postmaster in any local domain, regardless of the source, | |
87 | # and without verifying the sender. | |
88 | # | |
89 | accept | |
90 | .ifndef CHECK_RCPT_POSTMASTER | |
91 | local_parts = postmaster | |
92 | .else | |
93 | local_parts = CHECK_RCPT_POSTMASTER | |
94 | .endif | |
f6404efa | 95 | domains = +local_domains : +unix_domains : +relay_to_domains |
d2b0a567 | 96 | |
97 | ||
98 | # Deny unless the sender address can be verified. | |
99 | # | |
100 | # This is disabled by default so that DNSless systems don't break. If | |
101 | # your system can do DNS lookups without delay or cost, you might want | |
102 | # to enable this feature. | |
103 | # | |
104 | # This feature does not work in smarthost and satellite setups as | |
105 | # with these setups all domains pass verification. See spec.txt chapter | |
106 | # 39.31 with the added information that a smarthost/satellite setup | |
107 | # routes all non-local e-mail to the smarthost. | |
108 | .ifdef CHECK_RCPT_VERIFY_SENDER | |
109 | deny | |
110 | message = Sender verification failed | |
d38e06ff | 111 | !acl = acl_local_deny_exceptions |
d2b0a567 | 112 | !verify = sender |
113 | .endif | |
114 | ||
d0abb102 CE |
115 | # hcoop-change: Add recommended lines from |
116 | # /usr/share/doc/mailman/README.EXIM.gz so that bounce messages | |
117 | # get through, even if they are from a malformed address | |
118 | ||
119 | # Accept bounces to lists even if callbacks or other checks would fail | |
120 | warn | |
121 | message = X-WhitelistedRCPT-nohdrfromcallback: Yes | |
122 | condition = ${if and {{match{$local_part}{(.*)-bounces\+.*}} \ | |
123 | {def:domain} \ | |
124 | {eq {${lookup{$local_part@$domain}lsearch{MAILMAN_DB}}} \ | |
125 | {true}}} \ | |
126 | {yes}{no}} | |
127 | ||
128 | accept | |
129 | condition = ${if and {{match{$local_part}{(.*)-bounces\+.*}} \ | |
130 | {def:domain} \ | |
131 | {eq {${lookup{$local_part@$domain}lsearch{MAILMAN_DB}}} \ | |
132 | {true}}} \ | |
133 | {yes}{no}} | |
134 | ||
d2b0a567 | 135 | # Verify senders listed in local_sender_callout with a callout. |
136 | # | |
137 | # In smarthost and satellite setups, this causes the callout to be | |
138 | # done to the smarthost. Verification will thus only be reliable if the | |
139 | # smarthost does reject illegal addresses in the SMTP dialog. | |
140 | deny | |
d38e06ff | 141 | !acl = acl_local_deny_exceptions |
d2b0a567 | 142 | senders = ${if exists{CONFDIR/local_sender_callout}\ |
143 | {CONFDIR/local_sender_callout}\ | |
144 | {}} | |
145 | !verify = sender/callout | |
146 | ||
147 | ||
148 | # Accept if the message comes from one of the hosts for which we are an | |
149 | # outgoing relay. It is assumed that such hosts are most likely to be MUAs, | |
150 | # so we set control=submission to make Exim treat the message as a | |
151 | # submission. It will fix up various errors in the message, for example, the | |
152 | # lack of a Date: header line. If you are actually relaying out out from | |
153 | # MTAs, you may want to disable this. If you are handling both relaying from | |
154 | # MTAs and submissions from MUAs you should probably split them into two | |
155 | # lists, and handle them differently. | |
156 | ||
157 | # Recipient verification is omitted here, because in many cases the clients | |
158 | # are dumb MUAs that don't cope well with SMTP error responses. If you are | |
159 | # actually relaying out from MTAs, you should probably add recipient | |
160 | # verification here. | |
161 | ||
162 | # Note that, by putting this test before any DNS black list checks, you will | |
163 | # always accept from these hosts, even if they end up on a black list. The | |
164 | # assumption is that they are your friends, and if they get onto black | |
165 | # list, it is a mistake. | |
166 | accept | |
167 | hosts = +relay_from_hosts | |
168 | control = submission/sender_retain | |
169 | ||
170 | ||
171 | # Accept if the message arrived over an authenticated connection, from | |
172 | # any host. Again, these messages are usually from MUAs, so recipient | |
173 | # verification is omitted, and submission mode is set. And again, we do this | |
174 | # check before any black list tests. | |
175 | accept | |
176 | authenticated = * | |
177 | control = submission/sender_retain | |
178 | ||
179 | ||
180 | # Insist that any other recipient address that we accept is either in one of | |
181 | # our local domains, or is in a domain for which we explicitly allow | |
182 | # relaying. Any other domain is rejected as being unacceptable for relaying. | |
183 | require | |
184 | message = relay not permitted | |
f6404efa | 185 | domains = +local_domains : +unix_domains : +relay_to_domains |
d2b0a567 | 186 | |
187 | ||
188 | # We also require all accepted addresses to be verifiable. This check will | |
189 | # do local part verification for local domains, but only check the domain | |
190 | # for remote domains. | |
191 | require | |
192 | verify = recipient | |
193 | ||
194 | ||
195 | # Verify recipients listed in local_rcpt_callout with a callout. | |
196 | # This is especially handy for forwarding MX hosts (secondary MX or | |
197 | # mail hubs) of domains that receive a lot of spam to non-existent | |
198 | # addresses. The only way to check local parts for remote relay | |
199 | # domains is to use a callout (add /callout), but please read the | |
200 | # documentation about callouts before doing this. | |
201 | deny | |
d38e06ff | 202 | !acl = acl_local_deny_exceptions |
d2b0a567 | 203 | recipients = ${if exists{CONFDIR/local_rcpt_callout}\ |
204 | {CONFDIR/local_rcpt_callout}\ | |
205 | {}} | |
206 | !verify = recipient/callout | |
725c9874 | 207 | |
208 | ||
725c9874 | 209 | # CONFDIR/local_sender_blacklist holds a list of envelope senders that |
210 | # should have their access denied to the local host. Incoming messages | |
211 | # with one of these senders are rejected at RCPT time. | |
212 | # | |
213 | # The explicit white lists are honored as well as negative items in | |
d2b0a567 | 214 | # the black list. See exim4-config_files(5) for details. |
725c9874 | 215 | deny |
216 | message = sender envelope address $sender_address is locally blacklisted here. If you think this is wrong, get in touch with postmaster | |
d38e06ff | 217 | !acl = acl_local_deny_exceptions |
725c9874 | 218 | senders = ${if exists{CONFDIR/local_sender_blacklist}\ |
219 | {CONFDIR/local_sender_blacklist}\ | |
220 | {}} | |
221 | ||
222 | ||
223 | # deny bad sites (IP address) | |
224 | # CONFDIR/local_host_blacklist holds a list of host names, IP addresses | |
225 | # and networks (CIDR notation) that should have their access denied to | |
226 | # The local host. Messages coming in from a listed host will have all | |
227 | # RCPT statements rejected. | |
228 | # | |
229 | # The explicit white lists are honored as well as negative items in | |
d38e06ff | 230 | # the black list. See exim4-config_files(5) for details. |
725c9874 | 231 | deny |
232 | message = sender IP address $sender_host_address is locally blacklisted here. If you think this is wrong, get in touch with postmaster | |
d38e06ff | 233 | !acl = acl_local_deny_exceptions |
725c9874 | 234 | hosts = ${if exists{CONFDIR/local_host_blacklist}\ |
235 | {CONFDIR/local_host_blacklist}\ | |
236 | {}} | |
237 | ||
238 | ||
725c9874 | 239 | # Warn if the sender host does not have valid reverse DNS. |
240 | # | |
241 | # If your system can do DNS lookups without delay or cost, you might want | |
242 | # to enable this. | |
243 | # If sender_host_address is defined, it's a remote call. If | |
244 | # sender_host_name is not defined, then reverse lookup failed. Use | |
245 | # this instead of !verify = reverse_host_lookup to catch deferrals | |
246 | # as well as outright failures. | |
247 | .ifdef CHECK_RCPT_REVERSE_DNS | |
248 | warn | |
249 | message = X-Host-Lookup-Failed: Reverse DNS lookup failed for $sender_host_address (${if eq{$host_lookup_failed}{1}{failed}{deferred}}) | |
250 | condition = ${if and{{def:sender_host_address}{!def:sender_host_name}}\ | |
251 | {yes}{no}} | |
252 | .endif | |
253 | ||
254 | ||
d2b0a567 | 255 | # Use spfquery to perform a pair of SPF checks (for details, see |
256 | # http://www.openspf.org/) | |
257 | # | |
258 | # This is quite costly in terms of DNS lookups (~6 lookups per mail). Do not | |
259 | # enable if that's an issue. Also note that if you enable this, you must | |
260 | # install "libmail-spf-query-perl" which provides the spfquery command. | |
261 | # Missing libmail-spf-query-perl will trigger the "Unexpected error in | |
262 | # SPF check" warning. | |
263 | .ifdef CHECK_RCPT_SPF | |
264 | deny | |
265 | message = [SPF] $sender_host_address is not allowed to send mail from ${if def:sender_address_domain {$sender_address_domain}{$sender_helo_name}}. \ | |
d38e06ff | 266 | Please see http://www.openspf.org/Why?scope=${if def:sender_address_domain {mfrom}{helo}};identity=${if def:sender_address_domain {$sender_address}{$sender_helo_name}};ip=$sender_host_address |
d2b0a567 | 267 | log_message = SPF check failed. |
d38e06ff | 268 | !acl = acl_local_deny_exceptions |
d2b0a567 | 269 | condition = ${run{/usr/bin/spfquery --ip \"$sender_host_address\" --mail-from \"$sender_address\" --helo \"$sender_helo_name\"}\ |
270 | {no}{${if eq {$runrc}{1}{yes}{no}}}} | |
271 | ||
272 | defer | |
273 | message = Temporary DNS error while checking SPF record. Try again later. | |
274 | condition = ${if eq {$runrc}{5}{yes}{no}} | |
275 | ||
276 | warn | |
277 | message = Received-SPF: ${if eq {$runrc}{0}{pass}{${if eq {$runrc}{2}{softfail}\ | |
278 | {${if eq {$runrc}{3}{neutral}{${if eq {$runrc}{4}{unknown}{${if eq {$runrc}{6}{none}{error}}}}}}}}}} | |
279 | condition = ${if <={$runrc}{6}{yes}{no}} | |
280 | ||
281 | warn | |
282 | log_message = Unexpected error in SPF check. | |
283 | condition = ${if >{$runrc}{6}{yes}{no}} | |
284 | ||
285 | # Support for best-guess (see http://www.openspf.org/developers-guide.html) | |
286 | warn | |
287 | message = X-SPF-Guess: ${run{/usr/bin/spfquery --ip \"$sender_host_address\" --mail-from \"$sender_address\" \ --helo \"$sender_helo_name\" --guess true}\ | |
288 | {pass}{${if eq {$runrc}{2}{softfail}{${if eq {$runrc}{3}{neutral}{${if eq {$runrc}{4}{unknown}\ | |
289 | {${if eq {$runrc}{6}{none}{error}}}}}}}}}} | |
290 | condition = ${if <={$runrc}{6}{yes}{no}} | |
291 | ||
292 | defer | |
293 | message = Temporary DNS error while checking SPF record. Try again later. | |
294 | condition = ${if eq {$runrc}{5}{yes}{no}} | |
295 | .endif | |
296 | ||
297 | ||
725c9874 | 298 | # Check against classic DNS "black" lists (DNSBLs) which list |
299 | # sender IP addresses | |
300 | .ifdef CHECK_RCPT_IP_DNSBLS | |
301 | warn | |
302 | message = X-Warning: $sender_host_address is listed at $dnslist_domain ($dnslist_value: $dnslist_text) | |
303 | log_message = $sender_host_address is listed at $dnslist_domain ($dnslist_value: $dnslist_text) | |
304 | dnslists = CHECK_RCPT_IP_DNSBLS | |
305 | .endif | |
306 | ||
307 | ||
308 | # Check against DNSBLs which list sender domains, with an option to locally | |
d2b0a567 | 309 | # whitelist certain domains that might be blacklisted. |
310 | # | |
311 | # Note: If you define CHECK_RCPT_DOMAIN_DNSBLS, you must append | |
312 | # "/$sender_address_domain" after each domain. For example: | |
313 | # CHECK_RCPT_DOMAIN_DNSBLS = rhsbl.foo.org/$sender_address_domain \ | |
314 | # : rhsbl.bar.org/$sender_address_domain | |
725c9874 | 315 | .ifdef CHECK_RCPT_DOMAIN_DNSBLS |
316 | warn | |
317 | message = X-Warning: $sender_address_domain is listed at $dnslist_domain ($dnslist_value: $dnslist_text) | |
318 | log_message = $sender_address_domain is listed at $dnslist_domain ($dnslist_value: $dnslist_text) | |
319 | !senders = ${if exists{CONFDIR/local_domain_dnsbl_whitelist}\ | |
320 | {CONFDIR/local_domain_dnsbl_whitelist}\ | |
321 | {}} | |
d2b0a567 | 322 | dnslists = CHECK_RCPT_DOMAIN_DNSBLS |
725c9874 | 323 | .endif |
324 | ||
325 | ||
326 | # This hook allows you to hook in your own ACLs without having to | |
327 | # modify this file. If you do it like we suggest, you'll end up with | |
328 | # a small performance penalty since there is an additional file being | |
329 | # accessed. This doesn't happen if you leave the macro unset. | |
330 | .ifdef CHECK_RCPT_LOCAL_ACL_FILE | |
331 | .include CHECK_RCPT_LOCAL_ACL_FILE | |
332 | .endif | |
333 | ||
334 | ||
d2b0a567 | 335 | ############################################################################# |
336 | # This check is commented out because it is recognized that not every | |
337 | # sysadmin will want to do it. If you enable it, the check performs | |
338 | # Client SMTP Authorization (csa) checks on the sending host. These checks | |
339 | # do DNS lookups for SRV records. The CSA proposal is currently (May 2005) | |
340 | # an Internet draft. You can, of course, add additional conditions to this | |
341 | # ACL statement to restrict the CSA checks to certain hosts only. | |
725c9874 | 342 | # |
d2b0a567 | 343 | # require verify = csa |
344 | ############################################################################# | |
725c9874 | 345 | |
346 | ||
d2b0a567 | 347 | # Accept if the address is in a domain for which we are an incoming relay, |
348 | # but again, only if the recipient can be verified. | |
349 | ||
725c9874 | 350 | accept |
351 | domains = +relay_to_domains | |
352 | endpass | |
725c9874 | 353 | verify = recipient |
354 | ||
355 | ||
d2b0a567 | 356 | # At this point, the address has passed all the checks that have been |
357 | # configured, so we accept it unconditionally. | |
725c9874 | 358 | |
725c9874 | 359 | accept |