Ubuntu Manpage: greylist.conf - milter-greylist configuration file

Provided by: milter-greylist_4.6.2-1_amd64

NAME

       greylist.conf - milter-greylist configuration file

DESCRIPTION

       greylist.conf  configures  milter-greylist(8)  operation.  The format is simple: each line
       contains a keyword and optional arguments. Any line starting with a # is considered  as  a
       comment  and is ignored. Blank lines are ignored as well. Comments at the end of lines are
       accepted in some situations, but do  not  take  them  as  granted.   A  statement  can  be
       continued  on  the  next  line  by using a backslash. Anything after the backslash will be
       ignored.

WHITELIST

The primary use of greylist.conf is to setup milter-greylist(8) whitelist. It also offers
a handy blacklist feature. Access-lists (ACL) are used to do that. ACL enable the
administrator to specify complex conditions on sender IP, sender DNS address, sender e-
mail address, and recipient e-mail address. If support for DNSRBL was built-in, it is even
possible to use DNSRBL in ACL.

An access-list entry starts with the racl keyword followed by an optional id quoted
string, then the greylist, whitelist, blacklist, or continue keyword, and by any set of
the following clauses: addr, domain, from, rawfrom, rcpt, rcptcount, helo, sm_macro, time,
auth, tls, spf (if build with SPF support), geoip (if build with GeoIP support), p0f (if
build with p0f support), ldapcheck (if build with --with-openldap), urlcheck (if built
with --with-libcurl), dnsrbl (if built with --enable-dnsrbl), and nsupdate (if supported
by the DNS resolver). A message will match an ACL entry when it complies with all of its
clauses.

The greylist, whitelist, and blacklist keywords will cause the message to be respectively
greylisted, accepted or rejected if all ACL clauses match, and ACL evaluation is
terminated there. If an ACL with continue keyword does match, nothing is decided and next
ACL are evaluated.

Clauses can be negated, by prefixing them by the not keyword. Here is the detail of all
possible clauses.

addr This clause is used to specify a netblock of source IP addresses. The syntax is an
IP address followed by a slash and a CIDR netmask. Here is an example:

racl whitelist addr 127.0.0.0/8
racl whitelist addr 192.168.3.0/24
racl whitelist addr ::1

If the netmask is omitted, /32 is assumed for an IPv4 address and /128 is assumed
for an IPv6 address.

You should at least whitelist localhost (127.0.0.1/8), and if you have some user
clients connecting to the machine, you should whitelist the addresses they connect
from if you don't want them to get error messages when sending e-mail.

domain This clause selects source machines based on their DNS name, performing a suffix
search. For instance, this will whitelist any machine in the example.net domain:

racl whitelist domain example.net

Suffix search matching means, for example, that gle.com will match google.com. If
you want domain names to match on subdomain boundaries (e.g. gle.com will match
mail.gle.com and gle.com but not google.com) then enable domainexact

The name resolution is made by Sendmail, which hands it to milter-greylist(8). As a
result, it is impossible to use DNS aliases here. On the other hand, this will work even
if your DNS resolver is not thread-safe.

from This is used to select sender e-mail addresses You should not use that feature,
because sender e-mail addresses can be trivially forged.

Please note that the sender e-mail is cleared from spaces and anything leading an
equal (=) sign so that mailing-lists return-address with unique return paths can
still match. If you need unedited sender address, use a rawfrom clause.

Here is an example:

racl whitelist from postmaster@example.com

rawfrom
Same as from but the sender e-mail address is not modified to stip anything. rcpt
This is used to select recipient addresses. Example:

racl greylist rcpt John.Doe@example.net

rcptcount
Followed by an operator and a recipient count, this is used to select the amount of
recipients. Example:

racl blacklist rcptcount >= 25 msg "No more than 25 recipients, please"

helo Followed by a quoted string or a regular expression, this can be used to filter on
the HELO string.

sm_macro
This is used to select a Sendmail macro value. See the section on that topic for
more information.

time This is used to specify a time set. It should be followed by a quoted string of
crontab(5)-like time specification. Here is an example that whitelists mail
addressed to a single recipient during office hours (from 8:00 to 16:59 from monday
to friday):

racl whitelist time "* 8-16 * * 1-5" rcpt info@example.net

geoip This is used to specify a country, as reported by GeoIP. The country code must be
upper case, and is only available if milter-greylist was built with GeoIP support.
Special country code ZZ is used when the country cannot be determined (this happens
for private addresses, for instance). The geoipdb statement can be used to specify
the location of GeoIP database. geoipv6db statement can be used to specify the
location of GeoIPv6 database.

p0f This is used to match against the remote system OS fingerprint genre and
detail,obtained from p0f. It is only available if milter-greylist was built with
p0f support. p0f clauses can be used with a quoted string for case-insensitive
substring match, or against regular expressions. The p0fsock statement can be used
to specify the location of the p0f socket.

auth This is used to select a user that succeeded SMTP AUTH. In order to select any user
that succeeds SMTP AUTH, you can use a regular expression matching, like below;

racl whitelist auth /.*/

Using such a clause automatically disable global STARTTLS and SMTP AUTH
whitelisting, like if the noauth keyword would have been used.

tls This is used to select the distinguished name (DN) of a user that succeeded
STARTTLS. Using such a clause automatically disable global STARTTLS and SMTP AUTH
whitelisting, like if the noauth keyword would have been used.

spf This is used to test SPF status. Possible values are pass, softfail, fail, neutral,
unknown, error, none, and self. The first seven values are plain SPF validation
status. The self value is a special test that checks the server's local IP address
against the sender's SPF record. If that test validates, odds are good that the
sender SPF record is wide open, and this is hint that SPF should not be trusted.

In order to use spf self, Postfix users must specify the local address in the
configuration file, using the localaddr option.

Absence of any value after the spf keyword is a synonym for spf pass. This is
present for backward compatibility.

The spf clause is only available if SPF support was compiled in. Using it will
disable global SPF whitelisting, like if the nospf keyword would have been used.

ldapcheck
This is used to query an LDAP directory. See the section on that topic for more
information.

urlcheck
This is used to query an external configuration source through an URL. See the
section on that topic for more information.

dnsrbl This is used to select a DNSRBL. See the section on that topic for more
information.

nsupdate
This always-matching clause performs a DNS update, see the section on that topic
for more information.

The domain, from, and rcpt clauses may be used with regular expressions. The regular
expressions must be enclosed by slashes (/). No escaping is available to provide a slash
inside a regular expression, so just do not use it. Regular expressions follow the format
described in re_format(7). Here is an example:

racl greylist rcpt /@example\.net$/

When regular expressions are not used, from, and rcpt perform a case insensitive substring
match with leading and trailing brackets, spaces and tabs stripped out. domain performs a
case insensitive suffix match. This means, for example, that gle.com will match
google.com. If you want domain names to match on subdomain boundaries (e.g. gle.com will
match mail.gle.com and gle.com but not google.com) then enable domainexact

An ACL entry can also hold various optional parameter used on match: delay, autowhite,
flushaddr, nolog, code, ecode, report, maxpeek, addheader, addfooter, and msg

delay Specify the greylisting delay used before the message can be accepted. This
overrides the greylist global setting, and it only makes sense on an racl greylist
entry.

autowhite
Specify the autowhitelisting duration for messages matching this ACL. This
overrides the autowhite global setting, and it only makes sense on an racl greylist
entry. Example:

racl greylist rcpt JDoe@example.net delay 15m autowhite 3d
racl greylist rcpt root@example.net delay 1h autowhite 3d

flushaddr
If a message matches the rule, any entry in the greylist or autowhite databases
matching the sender IP is removed. Used with a DNSRBL blacklist ACL, it is useful
for freeing the database from entries set up by a machine which is known to be a
spammer. Example:

racl blacklist dnsrbl "known-spammer" flushaddr

nolog Do not generate syslog message if this rule matches. Example:

racl whitelist default nolog

code

ecode

msg These 3 values can be used to choose the SMTP code, extended code and reply message
for temporary failures and rejects. Example:

racl blacklist dnsrbl "spamstomp" msg "IP caught by spamstomp"
racl greylist default code "451" ecode "4.7.1"

The msg strings accepts format string substitution as documented in the FORMAT
STRINGS section. For instance, %A gets substituted by the ACL line number.

None of the last 3 values makes sense for a whitelist entry.

report This value overrides the text displayed in the X-Greylist header, for messages that
milter-greylist(8) lets pass through, either because they are whitelisted, or
because they passed greylisting (see REPORTING). This string can be substituted as
documented in the FORMAT STRINGS section.

maxpeek
This parameter only makes sense in a RCPT-stage ACL. It overrides the global
maxpeek setting for DATA-stage handling of the message. It has no effect if global
maxpeek is set to 0.

addheader
This quoted string is a RFC822 header that gets added to the message. Format
string substitution is supported. No check is done for header length standard
compliance, so make sure the substituted string is shorter than 2048 characters.
Headers are appended to the bottom, unless an optionnal comma-separated positive
index is specified after the quoted string; in this case the header will be
inserted at this index point from the top. Here is an example:
racl continue addheader "X-Personnal-Header: Hello world!",1

addfooter
Append a footer to the message. Usual escape sequences such as \n can be used to
get special characters. The string is subject to format string expantion as
described in the FORMAT STRINGS section. The footer will not be append if milter-
greylist was not able to capture the whole message, therefore maxpeek must be set
approriately.

Entries in the access-list are evaluated sequentially, so order is very important. The
first matching entry is used to decide if a message will be whitelisted or greylisted. A
special default clause can be used in the last ACL entry as a wildcard. Here are a few
complete ACL examples:

Example 1:

racl whitelist from friend@toto.com rcpt grandma@example.com
racl whitelist from other.friend@example.net rcpt grandma@example.com
racl greylist rcpt grandma@example.com
racl whitelist default

Example 2:

racl whitelist addr 193.54.0.0/16 domain friendly.com
racl greylist rcpt user1@atmine.com
racl greylist rcpt user2@atmine.com
racl greylist rcpt user3@atmine.com
racl whitelist default

Example 3:

racl whitelist rcpt /@.*otherdomain\.org$/
racl whitelist addr 192.168.42.0/24 rcpt user1@mydomain.org
racl whitelist from friend@example.net rcpt /@.*mydomain\.org$/
racl whitelist rcpt user2@mydomain.org
racl greylist rcpt /@.*mydomain\.org$/
racl whitelist default

DATA-STAGE ACL

ACL using the racl keyword are evaluated at the RCPT stage of the SMTP transaction. It is
also possible to have ACL evaluated at the DATA stage of the SMTP transaction, using the
dacl keyword, provided the message went through RCPT-stage ACL, and possibly greylisting.
Note that you cannot use the greylist action at DATA-stage if the RCPT-stage ACL that
matched had a greylist action itself. The following clauses can be used to work on message
content:

dkim DKIM status (if build with DKIM support). Possible values are pass, fail, unknown,
error, and none,

header String or regular expression searched in message headers

body String or regular expression searched in message body

msgsize
Operator followed by a message size (k or M suffix allowed for kilobytes or
megabytes). Example:

dacl blacklist msgsize >= 4M msg "No more than 4 MB please"

spamd SpamAssassin score (if build with SpamAssassin support). If used without comparison
operator spamd is true if the score is above threshold. The spamdsock keyword can
be used to specify the location of the spamd socket.

Example 1:

spamdsock unix "/var/spamassassin/spamd.sock"
racl whitelist default
dacl greylist spamd

Example 2:

spamdsock inet "127.0.0.1:783"
racl whitelist default
dacl blacklist spamd > 15 msg "Your message is considered spam."
dacl greylist spamd > 10 delay 2h
dacl greylist spamd > 5 delay 1h

Note that if there are multiple recipient, a rcpt clause at DATA stage evaluates to true
if it matches any of them. If you want to match an exact set of recipients, you can use
multiple rcpt clauses along with a rcptcount clause.

LISTS

       It is often useful to group several users or sender IP addresses in a single ACL. This can
       be done with lists. Lists must be first defined and given a name before they can  be  used
       in ACL entries. Here is an example:

                list "my users" rcpt { user1@example.com user2@example.com }
                list "local" addr { 192.0.2.0/24 10.0.0.0/8 }

                racl whitelist list "local"
                racl greylist list "my users"
                racl whitelist default

BACKWARD COMPATIBILITY

       Previous  versions  of milter-greylist(8) used addr, domain, from, and rcpt lines, without
       the racl keyword.  Access-list management is intended to replace them.   These  lines  are
       still accepted by milter-greylist(8), but they are deprecated.  milter-greylist(8) handles
       them as access-list entries with a single clause. They  are  added  at  the  head  of  the
       access-list  so  the  use  of  these  keywords  and  access-lists  may lead to unspecified
       behaviour. Do not mix them.

       test mode (using -T) is also deprecated. Access-list semantics do not depend on this flag.

       milter-greylist(8) also used to only have a RCPT-stage ACL, which was  configured  through
       acl statements. These have been replaced by racl statements (as opposed to dacl statements
       for DATA-stage ACL).  acl statements are still accepted for backward compatibility and are
       a synonym for racl statements.

MX SYNC

       Synchronization  of  the  greylist among multiple MX is configured using the peer keyword.
       List each other MX IP addresses using the peer keyword. Here is an example:

         peer 192.0.2.18
         peer 192.0.2.17
         peer 192.0.2.22 timeout 7
         peer 192.0.2.38 timeout 5m

       You can list the local machine in the peer statements, it will be ignored.

       The timeout clause sets a peer communication timeout to have proper  retrial  in  case  of
       slow  MX  peer.  The  default  value  is  3  seconds.  The special value of 0 disables the
       connection retrials.

       By default, milter-greylist will listen on all interfaces using TCP port 5252 or the  port
       number  given  by  service  named  mxglsync if defined in /etc/services or other directory
       service. This behaviour can be changed by using the  syncaddr  keyword.  Here  are  a  few
       examples:

         syncaddr *
         syncaddr * port 7689
         syncaddr 192.0.2.2 port 9785
         syncaddr 2001:db8::1:c3b5:123
         syncaddr 2001:db8::1:c3b5:123 port 1234

       Using  '*'  as the address means to bind to all local interfaces' addresses.  Note that if
       you are not using the default port, all MXs must use the same port number.

       For outbound connections the system is selecting one of the possible  addresses.   If  you
       want to use a specific IP you can use:

         syncsrcaddr 123.456.78.9

TEXT DUMP

       milter-greylist(8) uses a text dump of its database to resume operation after a crash. The
       dump is performed at regular time interval, but as it is a heavy operation, you might want
       to configure a particular time interval, using the dumpfreq option.

       If  the dumpfreq value is too small, it will kill performance. If it is too high, you will
       loose a bigger part of the database on a crash.

       Set dumpfreq to 0 to get a dump on each change (kills performance), Set it to -1 to  never
       dump to a file (unsafe as you lose the whole greylist on each crash), or give a time value
       for the delay between dumps.  The time is given in seconds, except if a unit is  given:  m
       for minutes, h for hours, and d for days.

       You  may  further  improve the performance of the dump operation at the expense of humanly
       readable timestamp which by default appears as a comment at the end of each  line  in  the
       dumpfile.    You    may    disable    generation    of    this   comment   by   specifying
       dump_no_time_translation  option  in  the  configuration  file.   This   is   specifically
       recommended  if  your dumpfile grows to 100's of megabytes - it can reduce the time needed
       for the dump operation by the order of magnitude!

REPORTING

       By default, milter-greylist(8) will add a X-Greylist header to any message it handles. The
       header  shows what happened to the message: delayed or not delayed, and why. The following
       options can be used in greylist.conf to alter this behavior:

       report none
              Never add a X-Greylist header.

       report delays
              Only add a header if the message was delayed.

       report nodelays
              Add a header if the message was not delayed. The header explains  why  the  message
              was not delayed.

       report all
              Always add a header. This is the default.

SENDER CALLBACK SYSTEMS

       Sender  callback  systems are another anti-spam measure that attempts to send a DSN to the
       sender address before accepting a message. If that fails, then the sender address is wrong
       and  the  message is rejected.  Such systems usually stop their callback check at the RCPT
       stage of the SMTP transaction.

       Greylisting temporarily rejects at the RCPT stage, so sender callback and greylisting love
       to  fight  each  other.  milter-greylist(8) proposes a workaround to that problem with the
       delayedreject option. For messages coming from <> (that is, for DSN), it  will  cause  the
       temporary  reject  to happen at the DATA stage of the SMTP transaction instead of the RCPT
       stage. That way, milter-greylist(8) will cope much better with sender callback systems.

       This has a minor drawback (and this is why it is not enabled  by  default):  for  a  multi
       recipient DSN, whitelisted recipient will not be honoured: the message will be delayed for
       everyone.

SENDMAIL MACROS

       Any sendmail macro can be used as a clause in the  access  list.  You  need  to  define  a
       (macro,  value)  pair using the sm_macro keyword before using it.  Here is an example that
       uses the {client_resolve} macro to apply a larger greylisting delay to hosts that  have  a
       bogus reverse DNS:

                sm_macro "maybe_forged" "{client_resolve}" "FORGED"

                racl greylist sm_macro "maybe_forged" delay 1h
                racl greylist default delay 15m

       A  regular  expression can be used as the macro value.  It must be surrounded with slashes
       and not by quotes.  The special value unset can also be used to match an unset macro:

                sm_macro "not_foo" "{foo}" unset

       Note that any Sendmail macro that is not exported using the Milter.macros.envrcpt  setting
       of sendmail.cf will be seen as unset from milter-greylist.

DNSRBL

       DNS Reverse Black List can be used to toggle an ACL. They must be defined and named before
       they can be used. Here is an example which uses  a  bigger  greylisting  delay  for  hosts
       caught  in the SORBS dynamic pool DNRSBL (this will include DSL and cable customers pools,
       which are well known to be massively infected by spamwares):

                dnsrbl "SORBS DUN" dnsbl.sorbs.net 127.0.0.10/32

                racl greylist dnsrbl "SORBS DUN" delay 1h
                racl greylist default delay 15m

       The definition of a DNSRBL starts by the dnsrbl keyword, followed by the  quoted  name  of
       the  DNSRBL,  the  DNS  domain  on  which addresses should be looked up, and the answer we
       should consider as a positive hit.

       DNSRBL support is only available if  enabled  through  the  --enable-dnsrbl  config  flag.
       Please  make  sure  milter-greylist(8)  is  linked  against  a  thread-safe  DNS resolver,
       otherwise it shall crash.

DNS updates

ACL are able to trigger a DNS update, which can be used to feed a DNSRBL. That
functionnality is enabled at build time if the DNS resolver has DNS update support.

Configuration is done with the nsupdate statement, which may be used several times, and
the optionnal tsig statement, if you want ot use authenticated DNS update. Here is an
example syntax:

tsig "dns-update" "hmac-md5" "1B2M2Y8AsgTpgAmY7PhCfg=="
nsupdate "bl.example.net" { rname "%j.bl.example.net" rvalue "127.0.0.2" tsig
"dns-update" }

The options for nsupdate are:

rname Created record name, which uses format strings.

rvalue Created record value, which uses format strings.

servers
Quoted comma-separated list of DNS server the update should be sent to. Default is
to use the system confifugration, usualy from /etc/resolv.conf

ttl TTL of created DNS record. Default is 0 seconds.

class Created record class, as numeric value. Default is 1, for IN class.

type Created record type, as numeric value. Default is 1, for A type.

tsig The name of a tsig configuration, which must have been supplied before. If
unspecified, unauthenticated DNS updates are performed.

Once configured, DNS updates can be used in any ACL:

racl blacklist rcpt spamtrap@example.net nsupdate "bl.example.net"

PROPERTIES

Properties are variables that can be set, evaluated and printed in ACL. A property may be
dropped once the current recipient is processed, or it can be retained until the message
is processed. They can be created through the following always-matching ACL clauses:

set $name="value"
This sets a property that will be retained for all next recipients. Right hand side
of the clause may be a quoted string (which will be substituted using format
strings, as described in the FORMAT STRINGS section), a number, or another property
name (which will be substituted by the property value).

rset $name="value"
Same as set clause, except that the property will be droped once the current user
will have been processed.

urlcheck
These clause will cause properties to be fetched from an external web service. See
the URL checks section below for details.

ldapcheck
These clause will cause properties to be fetched from a LDAP directory See the LDAP
CHECKS section below for details.

Properties can be used as left-hand side part of ACL clauses:

racl blacklist $name "badvalue"
racl blacklist $name /badregex/

If used left-hand side and prefixed by a star, the property will be evaluated as a glob(7)
pattern, In the example below, if sender DNS domain is test.example.net and $domain is
*.example.net, we get a match.

racl blacklist *$domain "%f"

They are also available as right-hand side of many ACL clauses:

racl continue set $badword="spam"
racl blacklist body $badword

Values of properties can be obtained in any quoted string that is subject to format string
expantion:

racl continue set $webmaster="webmaster@example.net"
racl blacklist domain evil.net msg "blacklisted, ask $P{webmaster} why"

When the property value is a number, it can be increased or decreased using this syntax:

racl continue set $score+=5
racl continue set $score-=5

Here again, right hand side may be a quoted string, a number or another property. For the
quoted string and property cases, a conversion is first made to an integer, using 0 as a
value on failure. Note that no arithmetic evaluation occurs. For instance, the quoted
string "1 + 1" will be evaluated as 0.

The log ACL clause can be helpful when one need to figure what happens to property values
during the ACL flow. See the CUSTOM REPORT section for more details.

URL checks

milter-greylist(8) is able to query external sources of information through various URL,
if it was built with --with-libcurl. Here is an example:

urlcheck "glusr" "http://www.example.net/mgl-config?rcpt=%r" 5

racl greylist urlcheck "glusr" delay 15m
racl whitelist default

The trailing 5 at the end of the urlcheck definition is the maximum number of simultaneous
connections we want to launch on this URL. For each message, the URL will be queried, with
% format tags being substituted. For instance, %r is substituted by the recipient. See the
FORMAT STRINGS section for the complete list of substitutions.

milter-greylist(8) expects an answer containing a list of \n terminated lines, with key:
value pairs. The most basic answer to get a match is:

milterGreylistStatus: Ok

TRUE can be used as an alias for Ok here.

The answer can be more complex, with keys that will overload the ACL settings:

milterGreylistDelay
The greylisting delay to use (time unit suffix allowed).

milterGreylistAutowhite
The autowhite delay to use (time unit suffix allowed).

milterGreylistFlushAddr
The value is ignored. If this key is present, then the IP address for the sender
machine will be flushed from greylist and autowhite databases.

milterGreylistCode
The SMTP code to return (e.g.: 551).

milterGreylistECode
The SMTP extended code to return (e.g.: 5.7.1)

milterGreylistMsg
The string to return with SMTP codes.

milterGreylistReport
The string to display in the X-Greylist header.

milterGreylistIgnore
This line will be ignored, without warnings in the logs.

milterGreylistAction
This feature is nifty but use it with caution, as it makes the access list a bit
difficult to understand. By specifying the values greylist, whitelist, or
blacklist, it is possible to overload the ACL action itself.

The ACL will match if any of the above key is returned: milterGreylistStatus is not
mandatory.

Optional keywords can be appended to a urlcheck definition:

postmsg
On DATA-stage ACL, This causes the message to be sent (up to maxpeek bytes) in a
POST request. Here is an example:

urlcheck "extfilter" "http://www.example.net/f.cgi" 5 postmsg

dacl blacklist urlcheck "extfilter"
dacl whitelist default

getprop
Gather the properties returned by the URL and reuse them in the ACL. The gathered
properties can be accessed in the current and following ACL by prefixing them by a
dollar ($).

clear This causes gathered properties to be cleared on each new recipient. This avoids
properties for several recipients to mix.

fork Tells milter-greylist(8) to fork a separate instance of itself for performing the
queries. Use it if you encounter thread-safety problems. fork is not compatible
with postmsg.

domatch
Cause the ldapcheck clause to be evaluated in ACL. Default behavior is to ignore
the result and just fecth properties, except if the LDAP directory is
unreachecable, in which case a temporary failure occurs. The fixldapcheck gloabal
settings may also be used to globaly cause all ldapcheck and urlcheck clauses to
match.

Here is an example that will use various DNSRBL depending on a per-recipient setting
stored in the dnsrbl attribute of a LDAP directory.

dnsrbl "RBL2" "rbl.example.net" "127.0.0.2"
dnsrbl "RBL3" "rbl.example.net" "127.0.0.3"
dnsrbl "RBL4" "rbl.example.net" "127.0.0.4"
urlcheck "userconf"
"ldap://localhost/dc=example,dc=net?milterGreylistStatus,dnsrbl?one?mail=%r" 5
getprop clear

racl blacklist urlcheck "userconf" $dnsrbl "RBL2" dnsrbl "RBL2"
racl blacklist $dnsrbl "RBL3" dnsrbl "RBL3"
racl blacklist $dnsrbl "RBL4" dnsrbl "RBL4"

Note that when matching gathered properties, format strings and regex can be used.

LDAP CHECKS

       If  milter-greylist  was  built  with --with-openldap, then you can also use ldapcheck for
       pulling information from an LDAP directory. This works exactly like urlcheck, except  that
       properties are always collected: The getprop option is implicit.

       A  list of LDAP URL to use can be specified with the ldapconf keyword. The network timeout
       is optional.

                ldapconf "ldap://localhost ldaps://ldap.example.net" timeout 2s

       When ldaps:// is used, the system's ldap.conf file is used to locate x509 certificates.

       When defining LDAP queries with the ldapcheck statement, note that  the  scheme  and  host
       part of the URL are ignored.  Servers listed in ldapconf are used instead.

RATE LIMIT

       The  ratelimit  keyword specifies a ratelimit configuration to be used in access lists. It
       must be followed by the rate limit configuration name,  what  is  being  accounted  (i.e.:
       session  for  SMTP sessions, rcpt for recipients, data for bytes in body and headers), the
       actual limit, and the sampling period. Example:

                ratelimit "internalclients" rcpt 10 / 1m

                racl blacklist addr 192.0.2.0/24  ratelimit  "internalclients"  \       msg  "you
              speak too much"

       The  ratelimit  keyword  can also have an option key statement, which determine the set of
       key for message accounting. The default is %i for  per  IP  address  accounting  (see  the
       FORMAT  STRINGS  sections  for the possible syntax of this field). Here is an example that
       configures a rate limit of 100 messages per hour for each individual recipient-IP set.

                ratelimit "internalclients" rcpt 100 / 1h key "%r%i"

                racl blacklist addr 192.0.2.0/24  ratelimit  "internalclients"  \       msg  "you
              speak too much"

CUSTOM REPORTS

       The  stat keyword can be used to specify a custom report for milter-greylist activity.  It
       should be supplied with an output (either file or external command) and a  format  string.
       Here is an example:

                stat ">>/var/log/milter-greylist.log" "%T{%T},%i,%f,%r,%A\n"

       If  the  output starts by >> or > then it is a file. Use >> to append to an existing file,
       and use > to overwrite it. If the output starts by a | then the output is a shell command,
       like in the example below:

                stat "|logger -p local7.info" "%T{%T},%i,%f,%r,%A\n"

       The format string gets substituted as URL checks format string: %r gets substituted by the
       recipient, %f by the sender, and so on. See the FORMAT STRINGS section for a complete list
       of available substitutions.

       There is also an always-matching log ACL clause that can be used to send a formated string
       to syslog with LOG_INFO level.  Here is an example:

              racl continue rcpt /@example\.com$/ log "I was here"

COMMAND-LINE FLAG EQUIVALENTS

Most milter-greylist(8) command-line options have equivalent options that can be set in
the configuration file. Note that if a command line option is supplied, it will always
override the configuration file.

If a command-line equivalent keyword is used more than once, the last keyword will
override the previous ones.

verbose
Enable debug output. This is equivalent to the -v flag.

quiet Do not tell clients how much time remains before their e-mail will be accepted.
This is equivalent to the -q flag.

nodetach
Do not fork and go into the background. This is equivalent to the -D flag.

noauth Greylist clients regardless if they succeeded SMTP AUTH or STARTTLS. Equivalent to
the -A flag.

noaccessdb
Normally milter-greylist(8) will whitelist a message if sendmail(8) defines a
${greylist} macro set to WHITE. This enables complex whitelisting rules based on
the Sendmail access DB. This option inhibits this behavior.

nospf Greylist clients regardless if they are SPF-compliant. Equivalent to the -S flag.

testmode
Enable test mode. Equivalent to the -T flag. This option is deprecated.

greylist
The argument sets how much time milter-greylist(8) will want the client to wait
between the first attempt and the time the message is accepted. The time is given
in seconds, except if a unit is given: m for minutes, h for hours, and d for days.
The greylist keyword is equivalent to the -w option. Here is an example that sets
the delay to 45 minutes:

greylist 45m

autowhite
This sets the auto-whitelisting duration, equivalent to the -a command-line option.
As for the greylist keyword, units can be supplied. Here is an example for a 3 day
long auto-whitelisting:

autowhite 3d

pidfile
This causes milter-greylist(8) to write its PID into the file given as argument,
like the -P command line argument does. The path to the file must be absolute and
it must be enclosed in quotes. Here is an example:

pidfile "/var/run/greylist.pid"

dumpfile
This chooses the location of the greylist dump file, like the -d command line
option does. The path must be absolute and enclosed in quotes. It can optionally
be followed by an octal permission mode. Example:

dumpfile "/var/milter-greylist/greylist.db" 640

subnetmatch
This is equivalent to the -L command line option. It takes a slash followed by a
CIDR mask as argument, and it commands the subnet matching feature. Example, for a
class C wide matching:

subnetmatch /24

subnetmatch6
This is equivalent to the -M command line option. It takes a slash followed by a
prefixlen as argument, and it commands the subnet matching feature. Example, for a
subnet wide matching:

subnetmatch6 /64

socket Like the -p command line option, this keyword is used to specify the socket used to
communicate with sendmail(8). It must be enclosed in quotes and can optionally be
followed by an octal permission mode (valid values are 666, 660 or 600, other
values cause an error):

socket "/var/milter-greylist/milter-greylist.sock" 660

user This keyword should be followed by a quoted user login and optionally a colon
followed by a groupname. Like the -u option, this is used to run milter-
greylist(8) as a non root user. Here is an example:

user "smmsp"

MISCELLANEOUS

These options have no command line equivalent:

logfac Sets the syslog facility for messages. Can be set to any of the standard
facilities: kern, user, mail, daemon, auth, syslog, lpr, news, uucp, cron,
authpriv, ftp, local0, local1, local2, local3, local4, local5, local6, local7. Can
also be set to none to disable syslog output completely.

timeout
is used to control how long greylist tuples are retained in the database. Value is
in seconds, except if a suffix is given (m for minutes, h for hours, d for days).
Default is 5 days.

extendedregex
Use extended regular expressions instead of basic regular expressions.

unbracket
Attempt to resolve sender address when the MTA handed it as bracketed IP address
(e.g.: [192.0.2.18] ). Default is to leave it as is.

maxpeek
Limit (in bytes) how much of messages are examined for header and body searches.

lazyaw Make auto-whitelist look at just the IP instead of the (sender IP, sender e-mail
address, recipient e-mail address) tuple.

domainexact
match on subdomain boundaries instead of the default suffix matching. E.g. if
domainexact is not enabled (the default) then gle.com will match google.com in
addition to gle.com. If domainexact is enabled then, domain names will match on
subdomain boundaries (e.g. gle.com will match mail.gle.com and gle.com but not
google.com)

drac db
Tell where the DRAC DB file is. This is only available if DRAC support was compiled
in. Here is an example:

drac db "/usr/local/etc/drac.db"

nodrac Disable DRAC.

logexpired
This option causes greylist entries that expire to be logged via syslog. This
allows you to easily collect the IP addresses and sender names and use them for
blacklisting, SPAM scoring, etc. Normally, expiration's are only logged if the
debug option is set, but that generates a lot of extra messages.

localaddr
This keyword can be used to manually define the local MTA's IP address for such
uses as spf self and p0f in absence of the milter-API {if_addr} macro support in
your MTA (Postfix, Sun/Oracle CommSuite Messaging Server). This is not so useful
when using Sendmail, since it serves the macro and the local address can be
detected automatically.

The configuration file is reloaded automatically once it is modified when new e-mail
arrives. Most configuration keywords will take effect immediately, except the following,
which will only take effect after a restart of milter-greylist(8): nodetach, pidfile,
socket, and user.

The dumpfreq option can be changed dynamically, but the change will only take effect after
the next dump.

multiracl
By default, once a RCPT-stage ACL whitelists a recipient, next recipient gets
automatically whitelisted. This historical behavior can be considered a bug, and
this option disables it.

FORMAT STRINGS

Various statements in the configuration file accept format strings, where the following %
prefixed tokens are substituted. Here is the complete list of available substitutions
(Note that some substitutions are not relevant in any context).

%r the message recipient e-mail address. This is not substituted for DATA stage ACL
since there can be multiple recipients for the message.

%f the message sender e-mail address

%i the sender machine IP address

%j the reversed sender machine IP address. For instance, 192.0.2.12 becomes
12.2.0.192.

%I the sender machine IP address masked by a CIDR. Example: %I{/24}

%d the sender machine DNS address

%h the SMTP transaction HELO string

%mr the mailbox part of %r (before the @ sign). This is not substituted for DATA stage
ACL since there can be multiple recipients for the message.

%sr the site part of %r (after the @ sign). This is not substituted for DATA stage ACL
since there can be multiple recipients for the message.

%mf the mailbox part of %f (before the @ sign)

%sf the site part of %f (after the @ sign)

%md the machine part of %d (before the first . sign)

%sd the site part of %d (after the first . sign)

%Xc the SMTP code returned

%Xe the SMTP extended code returned

%Xm the SMTP message returned

%Xh the message displayed in the X-Greylist header

%D Comma-separated list of DNSRBL for which the sender host matched

%M a sendmail macro value. Examples: %Mj or %M{if_addr}

%g a regex back reference. For instance, %g{\2} is substituted by the string matching
the second parenthesis group in all ACL regex clauses

%T a brace-enclosed strftime(3) format string that will be substituted by the system
time. Example: %T{%Y%m%d:%H%M%S}

%v milter-greylist's version

%G Offset to GMT (e.g.: -0100)

%C Sender IP country code, as reported by GeoIP. This is only available if milter-
greylist was built with GeoIP support

%Fx p0f OS fingerprint genre and detail. This is only available if milter-greylist was
built with p0f support.

%V Shortcut to "milter-greylist-%v (%Mj [%M{if_addr}]); %T{%a, %d %b %Y %T} %G
(%T{%Z})"

%S the action performed: accept, tempfail, or reject.

%A the line number of the ACL that caused the action.

%a the id string of the ACL that caused the action. If no id was given, the line
number is used instead.

%cA the line number of the ACL being evaluated, whether it matches or not.

%ca the id string of the ACL being avaluated, whether it matches or not. If no id was
given, the line number is used instead.

%Et total elapsed time in seconds before a greylisted message has been accepted

%Eh hours elapsed

%Em minutes elapsed (modulo one hour)

%Es seconds elapsed (modulo one minute)

%E shortcut to %Eh:%Em:Es

%Rt total remaining time in seconds before a greylisted message will be accepted

%Rh hours remaining

%Rm minutes remaining (modulo one hour)

%Rs seconds remaining (modulo one minute)

%R shortcut to %Rh:%Rm:Rs

%Hs SpamAssassin score (if build with SpamAssassin support)

%pn Name of last LDAP or CURL gathered property that matched an ACL.

%pv Value of last LDAP or CURL gathered property that matched an ACL.

%pr Recipient that caused storage of the last matching LDAP or CURL gathered property.
%P a LDAP or CURL gathered propery. Example: %P{mail} Note that this copes very
badly with multivalued properties.

%Qd DKIM query result (pass, fail, etc.), if built with DKIM support.

%Qs SPF query result (pass, (soft)fail, etc.), if built with SPF support.

%QA Authentication results summary, suitable for Authentication-Results header. Will
included formatted query results from DKIM and SPF if checked.

%QS SPF result, suitable for Received-SPF header. Available when compiled with libspf2.

%% a single % character

AUTHORS

       Emmanuel Dreyfus <manu@netbsd.org>

       milter-greylist   received   many  contributions  from  (in  alphabetical  order):  Adrian
       Dabrowski, Aida Shinra, Adam Katz, Alexander Lobodzinski, Alexandre Cherif, Alexey  Popov,
       Andrew   McGill,  Attila  Bruncsak,  Benoit  Branciard,  Bernhard  Schneider,  Bob  Smith,
       Constantine A. Murenin, Chris Bennett, Christian Pelissier, Cyril  Guibourg,  Dan  Hollis,
       David  Binderman,  Denis  Solovyov,  Elrond, Enrico Scholz, Eugene Crosser, Fabien Tassin,
       Fredrik Pettai, Gary Aitken, Georg Horn,  Gert  Doering,  Greg  Troxel,  Guido  Kerkewitz,
       Hajimu Umemoto, Hideki ONO, Ivan F. Martinez, Jacques Beigbeder, Jean Benoit, Jean-Jacques
       Puig, Jeff Rife, Jim Klimov, Jobst Schmalenbach, Joe  Pruett,  Joel  Bertrand,  Johann  E.
       Klasek,  Johann  Klasek,  John Thiltges, John Wood, Jorgen Lundman, Kazuyuki Yoshida, Klas
       Heggemann, Kouhei Sutou, Laurence Moindrot,  Lev  Walkin,  Manuel  Badzong,  Mart  Pirita,
       Martin  Paul,  Matt  Kettler,  Mattheu  Herrb,  Matthias  Scheler, Matthieu Herrb, Michael
       Fromme, Moritz Both, Nerijus Baliunas, Ole Hansen, Pavel Cahyna, Pascal Lalonde, Per Holm,
       Petar  Bogdanovic,  Petr  Kristof,  Piotr  Wadas,  R P Herrold, Ralf S. Engelschall, Ranko
       Zivojnovic, Remy Card, Rick Adams, Rogier Maas, Romain  Kang,  Rudy  Eschauzier,  Stephane
       Lentz,  Steven  Hiscocks,  Thomas  Scheunemann,  Tim  Mooney,  Vincent  Dufresne, Wolfgang
       Solfrank, and Yaroslav Boychuk.

       Thanks to Helmut Messerer and Thomas Pfau for their feedback on the first releases of this
       software.