postfwd2 - postfix firewall daemon

- NAME
- SYNOPSIS
- DESCRIPTION

- INTRODUCTION
- CONFIGURATION
- ITEMS
- FILES
- ACTIONS
- MACROS/ACLS
- PLUGINS
- COMMAND LINE
- REFRESH
- EXAMPLES
- PARSER
- DEBUGGING
- INTEGRATION
- TESTING
- PERFORMANCE
- SEE ALSO

- LICENSE
- AUTHOR

# NAME

postfwd2 - postfix firewall daemon

# SYNOPSIS

postfwd2 [OPTIONS] [SOURCE1, SOURCE2, ...]

            Ruleset: (at least one, multiple use is allowed):
            -f, --file <file>               reads rules from <file>
            -r, --rule <rule>               adds <rule> to config
            -s, --scores <v>=<r>            returns <r> when score exceeds <v>

            Server:
            -i, --interface <dev>           listen on interface <dev>
            -p, --port <port>               listen on port <port>
                --proto <proto>             socket type (tcp or unix)
                --server_socket <sock>      e.g. tcp:127.0.0.1:10045
            -u, --user <name>               set uid to user <name>
            -g, --group <name>              set gid to group <name>
                --umask <mask>              umask for master filepermissions
                --server_umask <mask>       umask for server filepermissions
                --pidfile <path>            create pidfile under <path>
                --min_servers <i>           spawn at least <i> children
                --max_servers <i>           do not spawn more than <i> children
                --min_spare_servers <i>     minimum idle children
                --max_spare_servers <i>     maximum idle children

            Cache:
            -c, --cache <int>               sets the request-cache timeout to <int> seconds
                --cleanup-requests <int>    cleanup interval in seconds for request cache
                --cache_interface <dev>     listen on interface <dev>
                --cache_port <port>         listen on port <port>
                --cache_proto <proto>       socket type (tcp or unix)
                --cache_socket <sock>       e.g. tcp:127.0.0.1:10043
                --cache_umask <mask>        umask for cache filepermissions
                --cacheid <list>            list of request items for cache-id
                --cache-rdomain-only        skip recipient localpart for cache-id
                --cache-no-sender           skip sender address for cache-id
                --cache-no-size             skip size for cache-id
                --no_parent_request_cache   disable parent request cache
                --no_parent_rate_cache      disable parent rate cache
                --no_parent_dns_cache       disable parent dns cache (default)
                --no_parent_cache           disable all parent caches

            Rates:
                --cleanup-rates <int>       cleanup interval in seconds for rate cache

            Control:
            -k, --kill, --stop              terminate postfwd2
                --reload, --hup             reload postfwd2
                --watchdog <w>              watchdog timer in seconds
                --respawn <r>               respawn delay in seconds
                --failures <f>              max respawn failure counter
                --daemons <list>            list of daemons to start
                --dumpcache                 show cache contents
                --dumpstats                 show statistics
            -R, --chroot <path>             chroot to <path> before start
                --delcache <item>           removes an item from the request cache
                --delrate <item>            removes an item from the rate cache

            DNS:
            -n, --nodns                     skip any dns based test
                --dns_timeout <i>           dns query timeout in seconds
                --dns_timeout_max <i>       disable dnsbl after <i> timeouts
                --dns_timeout_interval <i>  reenable dnsbl after <i> seconds
                --cache-rbl-timeout <i>     default dns ttl if not specified in ruleset
                --cache-rbl-default <s>     default dns pattern if not specified in ruleset
                --cleanup-rbls <i>          cleanup old dns cache items every <i> seconds
                --dns_async_txt             perform dnsbl A and TXT lookups simultaneously
                --dns_max_ns_lookups        max names to look up with sender_ns_addrs
                --dns_max_mx_lookups        max names to look up with sender_mx_addrs

            Optional:
            -t, --test                      testing, always returns "dunno"
            -S, --summary <i>               show stats every <i> seconds
                --noidlestats               disables statistics when idle
                --norulestats               disables per rule statistics
            -I, --instantcfg                reloads ruleset on every new request
                --config_timeout <i>        parser timeout in seconds
                --keep_rates                do not clear rate limit counters on reload
                --save_rates <file>         save and load rate limits on disk
                --fast_limit_evaluation     evaluate rate limits before ruleset is parsed

            Plugins:
                --plugins <file>            loads postfwd plugins from file

            Logging:
            -l, --logname <label>           label for syslog messages
                --facility <s>              use syslog facility <s>
                --socktype <s>              use syslog socktype <s>
                --nodnslog                  do not log dns results
                --anydnslog                 log any dns (even cached) results
                --norulelog                 do not log rule actions
                --nolog|--perfmon           no logging at all
            -v, --verbose                   verbose logging, use twice to increase
                --debug <s>                 list of debugging classes

            Information (use only at command-line!):
            -h, --help                      display this help and exit
            -m, --manual                    shows program manual
            -V, --version                   output version information and exit
            -D, --defaults                  show postfwd2 settings and exit
            -C, --showconfig                show postfwd2 ruleset and exit (-v allowed)
            -L, --stdout                    redirect syslog messages to stdout
            -q, --quiet                     no syslogging, no stdout (-P works for compatibility)

            Obsolete (only for compatibility with postfwd v1):
            -d|--daemon, --shortlog, --dns_queuesize, --dns_retries

# DESCRIPTION

## INTRODUCTION

postfwd2 is written to combine complex postfix restrictions in a ruleset similar to those of the most firewalls. The program uses the postfix policy delegation protocol to control access to the mail system before a message has been accepted (please visit http://www.postfix.org/SMTPD_POLICY_README.html for more information).

postfwd2 allows you to choose an action (e.g. reject, dunno) for a combination of several smtp parameters (like sender and recipient address, size or the client's TLS fingerprint). Also it offers simple macros/acls which should allow straightforward and easy-to-read configurations.

Features:

* Complex combinations of smtp parameters

* Combined RBL/RHSBL lookups with arbitrary actions depending on results

* Scoring system

* Date/time based rules

* Macros/ACLs, Groups, Negation

* Compare request attributes (e.g. client_name and helo_name)

* Internal caching for requests and dns lookups

* Built in statistics for rule efficiency analysis

## CONFIGURATION

A configuration line consists of optional item=value pairs, separated by semicolons (`;`) and the appropriate desired action:

            [ <item1>=<value>; <item2>=<value>; ... ] action=<result>

Example:

            client_address=192.168.1.1 ; sender==no@bad.local ; action=REJECT

This will deny all mail from 192.168.1.1 with envelope sender no@bad.local. The order of the elements is not important. So the following would lead to the same result as the previous example:

            action=REJECT ; client_address=192.168.1.1 ; sender==no@bad.local

The way how request items are compared to the ruleset can be influenced in the following way:

            ====================================================================
             ITEM == VALUE                true if ITEM equals VALUE
             ITEM => VALUE                true if ITEM >= VALUE
             ITEM =< VALUE                true if ITEM <= VALUE
             ITEM >  VALUE                true if ITEM >  VALUE
             ITEM <  VALUE                true if ITEM <  VALUE
             ITEM =~ VALUE                true if ITEM ~= /^VALUE$/i
             ITEM != VALUE                false if ITEM equals VALUE
             ITEM !> VALUE                false if ITEM >= VALUE
             ITEM !< VALUE                false if ITEM <= VALUE
             ITEM !~ VALUE                false if ITEM ~= /^VALUE$/i
             ITEM =  VALUE                default behaviour (see ITEMS section)
            ====================================================================

To identify single rules in your log files, you may add an unique identifier for each of it:

            id=R_001 ; action=REJECT ; client_address=192.168.1.1 ; sender==no@bad.local

You may use these identifiers as target for the `jump()` command (see ACTIONS section below). Leading or trailing whitespace characters will be ignored. Use '#' to comment your configuration. Others will appreciate.

A ruleset consists of one or multiple rules, which can be loaded from files or passed as command line arguments. Please see the COMMAND LINE section below for more information on this topic.

Since postfwd version 1.30 rules spanning span multiple lines can be defined by prefixing the following lines with one or multiple whitespace characters (or '}' for macros):

            id=RULE001
                    client_address=192.168.1.0/24
                    sender==no@bad.local
                    action=REJECT no access

postfwd versions prior to 1.30 require trailing ';' and '\'-characters:

            id=RULE001; \
                    client_address=192.168.1.0/24; \
                    sender==no@bad.local; \
                    action=REJECT no access

## ITEMS

            id                      - a unique rule id, which can be used for log analysis
                                      ids also serve as targets for the "jump" command.

            date, time              - a time or date range within the specified rule shall hit
                                      # FORMAT:
                                      # Feb, 29th
                                      date=29.02.2008
                                      # Dec, 24th - 26th
                                      date=24.12.2008-26.12.2008
                                      # from today until Nov, 23rd
                                      date=-23.09.2008
                                      # from April, 1st until today
                                      date=01.04.2008-

            days, months            - a range of weekdays (Sun-Sat) or months (Jan-Dec)
                                      within the specified rule shall hit

            score                   - when the specified score is hit (see ACTIONS section)
                                      the specified action will be returned to postfix
                                      scores are set global until redefined!

            request_score           - this value allows to access a request's score. it
                                      may be used as variable ($$request_score).

            rbl, rhsbl,             - query the specified RBLs/RHSBLs, possible values are:
            rhsbl_client,             <name>[/<reply>/<maxcache>, <name>/<reply>/<maxcache>]
            rhsbl_sender,             (defaults: reply=^127\.0\.0\.\d+$ maxcache=3600)
            rhsbl_reverse_client      the results of all rhsbl_* queries will be combined
                                      in rhsbl_count (see below).

            rblcount, rhsblcount    - minimum RBL/RHSBL hitcounts to match. if not specified
                                      a single RBL/RHSBL hit will match the rbl/rhsbl items.
                                      you may specify 'all' to evaluate all items, and use
                                      it as variable in an action (see ACTIONS section)
                                      (default: 1)

            sender_localpart,       - the local-/domainpart of the sender address
            sender_domain

            recipient_localpart,    - the local-/domainpart of the recipient address
            recipient_domain

            helo_address            - postfwd2 tries to look up the helo_name. use
                                      helo_address=!!(0.0.0.0/0) to check for unknown.
                                      Please do not use this for positive access control
                                      (whitelisting), as it might be forged.

            sender_ns_names,        - postfwd2 tries to look up the names/ip addresses
            sender_ns_addrs           of the nameservers for the sender domain part.
                                      Please do not use this for positive access control
                                      (whitelisting), as it might be forged.

            sender_mx_names,        - postfwd2 tries to look up the names/ip addresses
            sender_mx_addrs           of the mx records for the sender domain part.
                                      Please do not use this for positive access control
                                      (whitelisting), as it might be forged.

            version                 - postfwd2 version, contains "postfwd2 n.nn"
                                      this enables version based checks in your rulesets
                                      (e.g. for migration). works with old versions too,
                                      because a non-existing item always returns false:
                                      # version >= 1.10
                                      id=R01; version~=1\.[1-9][0-9]; sender_domain==some.org \
                                            ; action=REJECT sorry no access

            ratecount               - only available for rate(), size() and rcpt() actions.
                                      contains the actual limit counter:
                                            id=R01; action=rate(sender/200/600/REJECT limit of 200 exceeded [$$ratecount hits])
                                            id=R02; action=rate(sender/100/600/WARN limit of 100 exceeded [$$ratecount hits])

Besides these you can specify any attribute of the postfix policy delegation protocol. Feel free to combine them the way you need it (have a look at the EXAMPLES section below).

Most values can be specified as regular expressions (PCRE). Please see the table below for details:

            # ==========================================================
            # ITEM=VALUE                            TYPE
            # ==========================================================
            id=something                            mask = string
            date=01.04.2007-22.04.2007              mask = date (DD.MM.YYYY-DD.MM.YYYY)
            time=08:30:00-17:00:00                  mask = time (HH:MM:SS-HH:MM:SS)
            days=Mon-Wed                            mask = weekdays (Mon-Wed) or numeric (1-3)
            months=Feb-Apr                          mask = months (Feb-Apr) or numeric (1-3)
            score=5.0                               mask = maximum floating point value
            rbl=zen.spamhaus.org                    mask = <name>/<reply>/<maxcache>[,...]
            rblcount=2                              mask = numeric, will match if rbl hits >= 2
            helo_address=<a.b.c.d/nn>               mask = CIDR[,CIDR,...]
            sender_ns_names=some.domain.tld         mask = PCRE
            sender_mx_names=some.domain.tld         mask = PCRE
            sender_ns_addrs=<a.b.c.d/nn>            mask = CIDR[,CIDR,...]
            sender_mx_addrs=<a.b.c.d/nn>            mask = CIDR[,CIDR,...]
            # ------------------------------
            # Postfix version 2.1 and later:
            # ------------------------------
            client_address=<a.b.c.d/nn>             mask = CIDR[,CIDR,...]
            client_name=another.domain.tld          mask = PCRE
            reverse_client_name=another.domain.tld  mask = PCRE
            helo_name=some.domain.tld               mask = PCRE
            sender=foo@bar.tld                      mask = PCRE
            recipient=bar@foo.tld                   mask = PCRE
            recipient_count=5                       mask = numeric, will match if recipients >= 5
            # ------------------------------
            # Postfix version 2.2 and later:
            # ------------------------------
            sasl_method=plain                       mask = PCRE
            sasl_username=you                       mask = PCRE
            sasl_sender=                            mask = PCRE
            size=12345                              mask = numeric, will match if size >= 12345
            ccert_subject=blackhole.nowhere.local   mask = PCRE (only if tls verified)
            ccert_issuer=John+20Doe                 mask = PCRE (only if tls verified)
            ccert_fingerprint=AA:BB:CC:DD:EE:...    mask = PCRE (do NOT use "..." here)
            # ------------------------------
            # Postfix version 2.3 and later:
            # ------------------------------
            encryption_protocol=TLSv1/SSLv3         mask = PCRE
            encryption_cipher=DHE-RSA-AES256-SHA    mask = PCRE
            encryption_keysize=256                  mask = numeric, will match if keysize >= 256
            ...

the current list can be found at http://www.postfix.org/SMTPD_POLICY_README.html. Please read carefully about which attribute can be used at which level of the smtp transaction (e.g. size will only work reliably at END-OF-MESSAGE level). Pattern matching is performed case insensitive.

Multiple use of the same item is allowed and will compared as logical OR, which means that this will work as expected:

            id=TRUST001; action=OK; encryption_keysize=64
                    ccert_fingerprint=11:22:33:44:55:66:77:88:99
                    ccert_fingerprint=22:33:44:55:66:77:88:99:00
                    ccert_fingerprint=33:44:55:66:77:88:99:00:11
                    sender=@domain\.local$

client_address, rbl and rhsbl items may also be specified as whitespace-or-comma-separated values:

            id=SKIP01; action=dunno
                    client_address=192.168.1.0/24, 172.16.254.23
            id=SKIP02; action=dunno
                    client_address= 10.10.3.32 10.216.222.0/27

The following items must be unique:

            id, minimum and maximum values, rblcount and rhsblcount

Any item can be negated by preceeding '!!' to it, e.g.:

            id=HOST001 ;  hostname == !!secure.trust.local ;  action=REJECT only secure.trust.local please

or using the right compare operator:

            id=HOST001 ;  hostname != secure.trust.local ;  action=REJECT only secure.trust.local please

To avoid confusion with regexps or simply for better visibility you can use '!!(...)':

            id=USER01 ;  sasl_username =~ !!( /^(bob|alice)$/ )  ;  action=REJECT who is that?

Request attributes can be compared by preceeding '$$' characters, e.g.:

            id=R-003 ;  client_name = !! $$helo_name      ;  action=WARN helo does not match DNS
            # or
            id=R-003 ;  client_name = !!($$(helo_name))   ;  action=WARN helo does not match DNS

This is only valid for PCRE values (see list above). The comparison will be performed as case insensitive exact match. Use the '-vv' option to debug.

These special items will be reset for any new rule:

            rblcount        - contains the number of RBL answers
            rhsblcount      - contains the number of RHSBL answers
            matches         - contains the number of matched items
            dnsbltext       - contains the dns TXT part of all RBL and RHSBL replies in the form
                              rbltype:rblname:<txt>; rbltype:rblname:<txt>; ...

These special items will be changed for any matching rule:

            request_hits    - contains ids of all matching rules

This means that it might be necessary to save them, if you plan to use these values in later rules:

            # set vals
            id=RBL01 ; rhsblcount=all; rblcount=all
                    action=set(HIT_rhls=$$rhsblcount,HIT_rbls=$$rblcount,HIT_txt=$$dnsbltext)
                    rbl=list.dsbl.org, bl.spamcop.net, dnsbl.sorbs.net, zen.spamhaus.org
                    rhsbl_client=rddn.dnsbl.net.au, rhsbl.ahbl.org, rhsbl.sorbs.net
                    rhsbl_sender=rddn.dnsbl.net.au, rhsbl.ahbl.org, rhsbl.sorbs.net

            # compare
            id=RBL02 ; HIT_rhls>=1 ; HIT_rbls>=1 ; action=554 5.7.1 blocked using $$HIT_rhls RHSBLs and $$HIT_rbls RBLs [INFO: $$HIT_txt]
            id=RBL03 ; HIT_rhls>=2               ; action=554 5.7.1 blocked using $$HIT_rhls RHSBLs [INFO: $$HIT_txt]
            id=RBL04 ; HIT_rbls>=2               ; action=554 5.7.1 blocked using $$HIT_rbls RBLs [INFO: $$HIT_txt]

## FILES

Since postfwd1 v1.15 and postfwd2 v0.18 long item lists can be stored in separate files:

            id=R001 ;  ccert_fingerprint==file:/etc/postfwd/wl_ccerts ;  action=DUNNO

postfwd2 will read a list of items (one item per line) from /etc/postfwd/wl_ccerts. comments are allowed:

            # client1
            11:22:33:44:55:66:77:88:99
            # client2
            22:33:44:55:66:77:88:99:00
            # client3
            33:44:55:66:77:88:99:00:11

To use existing tables in key=value format, you can use:

            id=R001 ;  ccert_fingerprint==table:/etc/postfwd/wl_ccerts ;  action=DUNNO

This will ignore the right-hand value. Items can be mixed:

            id=R002 ;  action=REJECT
                    client_name==unknown
                    client_name==file:/etc/postfwd/blacklisted

and for non pcre (comma separated) items:

            id=R003 ;  action=REJECT
                    client_address==10.1.1.1, file:/etc/postfwd/blacklisted

            id=R004 ;  action=REJECT
                    rbl=myrbl.home.local, zen.spamhaus.org, file:/etc/postfwd/rbls_changing

You can check your configuration with the --show_config option at the command line:

            # postfwd2 --showconfig --rule='action=DUNNO; client_address=10.1.0.0/16, file:/etc/postfwd/wl_clients, 192.168.2.1'

should give something like:

            Rule   0: id->"R-0"; action->"DUNNO"; client_address->"=;10.1.0.0/16, =;194.123.86.10, =;186.4.6.12, =;192.168.2.1"

If a file can not be read, it will be ignored:

            # postfwd2 --showconfig --rule='action=DUNNO; client_address=10.1.0.0/16, file:/etc/postfwd/wl_clients, 192.168.2.1'
            [LOG warning]: error: file /etc/postfwd/wl_clients not found - file will be ignored ?
            Rule   0: id->"R-0"; action->"DUNNO"; client_address->"=;10.1.0.0/16, =;192.168.2.1"

File items are evaluated at configuration stage. Therefore postfwd2 needs to be reloaded if a file has changed

If you want to specify a file, that will be reloaded for each request, you can use lfile: and ltable:

            id=R001; client_address=lfile:/etc/postfwd/client_whitelist; action=dunno

This will check the modification time of /etc/postfwd/client_whitelist every time the rule is evaluated and reload it as necessary. Of course this might increase the system load, so please use it with care.

The --showconfig option illustrates the difference:

            ## evaluated at configuration stage
            # postfwd2 --nodaemon -L --rule='client_address=table:/etc/postfwd/clients; action=dunno' -C
            Rule   0: id->"R-0"; action->"dunno"; client_address->"=;1.1.1.1, =;1.1.1.2, =;1.1.1.3"

            ## evaluated for any rulehit
            # postfwd2 --nodaemon -L --rule='client_address=ltable:/etc/postfwd/clients; action=dunno' -C
            Rule   0: id->"R-0"; action->"dunno"; client_address->"=;ltable:/etc/postfwd/clients"

Files can refer to other files. The following is valid.

            -- FILE /etc/postfwd/rules.cf --
            id=R01; client_address=file:/etc/postfwd/clients_master.cf; action=DUNNO

            -- FILE /etc/postfwd/clients_master.cf --
            192.168.1.0/24
            file:/etc/postfwd/clients_east.cf
            file:/etc/postfwd/clients_west.cf

            -- FILE /etc/postfwd/clients_east.cf --
            192.168.2.0/24

            -- FILE /etc/postfwd/clients_west.cf --
            192.168.3.0/24

Note that there is currently no loop detection (/a/file calls /a/file) and that this feature is only available with postfwd1 v1.15 and postfwd2 v0.18 and higher.

## ACTIONS

General

Actions will be executed, when all rule items have matched a request (or at least one of any item list). You can refer to request attributes by preceeding $$ characters, like:

            id=R-003; client_name = !!$$helo_name; action=WARN helo '$$helo_name' does not match DNS '$$client_name'
            # or
            id=R-003; client_name = !!$$helo_name; action=WARN helo '$$(helo_name)' does not match DNS '$$(client_name)'

postfix actions

Actions will be replied to postfix as result to policy delegation requests. Any action that postfix understands is allowed - see ``man 5 access'' or http://www.postfix.org/access.5.html for a description. If no action is specified, the postfix WARN action which simply logs the event will be used for the corresponding rule.

postfwd2 will return dunno if it has reached the end of the ruleset and no rule has matched. This can be changed by placing a last rule containing only an action statement:

            ...
            action=dunno ; sender=@domain.local     # sender is ok
            action=reject                           # default deny

postfwd2 actions

postfwd2 actions control the behaviour of the program. Currently you can specify the following:

            jump (<id>)
            jumps to rule with id <id>, use this to skip certain rules.
            you can jump backwards - but remember that there is no loop
            detection at the moment! jumps to non-existing ids will be skipped.

            score (<score>)
            the request's score will be modified by the specified <score>,
            which must be a floating point value. the modificator can be either
                    +n.nn   adds n.nn to current score
                    -n.nn   sustracts n.nn from the current score
                    *n.nn   multiplies the current score by n.nn
                    /n.nn   divides the current score through n.nn
                    =n.nn   sets the current score to n.nn
            if the score exceeds the maximum set by `--scores` option (see
            COMMAND LINE) or the score item (see ITEMS section), the action
            defined for this case will be returned (default: 5.0=>"REJECT postfwd2 score exceeded").

            set (<item>=<value>,<item>=<value>,...)
            this command allows you to insert or override request attributes, which then may be
            compared to your further ruleset. use this to speed up repeated comparisons to large item lists.
            please see the EXAMPLES section for more information. you may separate multiple key=value pairs
            by "," characters.

            rate (<item>/<max>/<time>/<action>)
            this command creates a counter for the given <item>, which will be increased any time a request
            containing it arrives. if it exceeds <max> within <time> seconds it will return <action> to postfix.
            rate counters are very fast as they are executed before the ruleset is parsed.
            please note that <action> was limited to postfix actions (no postfwd actions) for postfwd versions <1.33!
                # no more than 3 requests per 5 minutes
                # from the same "unknown" client
                id=RATE01 ;  client_name==unknown
                   action=rate(client_address/3/300/450 4.7.1 sorry, max 3 requests per 5 minutes)

            size (<item>/<max>/<time>/<action>)
            this command works similar to the rate() command with the difference, that the rate counter is
            increased by the request's size attribute. to do this reliably you should call postfwd2 from
            smtpd_end_of_data_restrictions. if you want to be sure, you could check it within the ruleset:
               # size limit 1.5mb per hour per client
               id=SIZE01 ;  protocol_state==END-OF-MESSAGE ;  client_address==!!(10.1.1.1)
                  action=size(client_address/1572864/3600/450 4.7.1 sorry, max 1.5mb per hour)

            rcpt (<item>/<max>/<time>/<action>)
            this command works similar to the rate() command with the difference, that the rate counter is
            increased by the request's recipient_count attribute. to do this reliably you should call postfwd
            from smtpd_data_restrictions or smtpd_end_of_data_restrictions. if you want to be sure, you could
            check it within the ruleset:
               # recipient count limit 3 per hour per client
               id=RCPT01 ;  protocol_state==END-OF-MESSAGE ;  client_address==!!(10.1.1.1)
                  action=rcpt(client_address/3/3600/450 4.7.1 sorry, max 3 recipients per hour)

            ask (<addr>:<port>[:<ignore>])
            allows to delegate the policy decision to another policy service (e.g. postgrey). the first
            and the second argument (address and port) are mandatory. a third optional argument may be
            specified to tell postfwd2 to ignore certain answers and go on parsing the ruleset:
               # example1: query postgrey and return it's answer to postfix
               id=GREY; client_address==10.1.1.1; action=ask(127.0.0.1:10031)
               # example2: query postgrey but ignore it's answer, if it matches 'DUNNO'
               # and continue parsing postfwd's ruleset
               id=GREY; client_address==10.1.1.1; action=ask(127.0.0.1:10031:^dunno$)

            mail(server/helo/from/to/subject/body)
            This command is deprecated. You should try to use the sendmail() action instead.
            Very basic mail command, that sends a message with the given arguments. LIMITATIONS:
            This basically performs a telnet. No authentication or TLS are available. Additionally it does
            not track notification state and will notify you any time, the corresponding rule hits.

            sendmail(sendmail-path::from::to::subject::body)
            Mail command, that uses an existing sendmail binary and sends a message with the given arguments.
            LIMITATIONS: The command does not track notification state and will notify you any time, the
            corresponding rule hits (which could mean 100 mails for a mail with 100 recipients at RCPT stage).

            wait (<delay>)
            pauses the program execution for <delay> seconds. use this for
            delaying or throtteling connections.

            note (<string>)
            just logs the given string and continues parsing the ruleset.
            if the string is empty, nothing will be logged (noop).

            quit (<code>)
            terminates the program with the given exit-code. postfix doesn`t
            like that too much, so use it with care.

You can reference to request attributes, like

            id=R-HELO ;  helo_name=^[^\.]+$ ;  action=REJECT invalid helo '$$helo_name'

## MACROS/ACLS

Multiple use of long items or combinations of them may be abbreviated by macros. Those must be prefixed by '&&' (two '&' characters). First the macros have to be defined as follows:

            &&RBLS { rbl=zen.spamhaus.org,list.dsbl.org,bl.spamcop.net,dnsbl.sorbs.net,ix.dnsbl.manitu.net; };

Then these may be used in your rules, like:

            &&RBLS ;  client_name=^unknown$                         ; action=REJECT
            &&RBLS ;  client_name=(\d+[\.-_]){4}                    ; action=REJECT
            &&RBLS ;  client_name=[\.-_](adsl|dynamic|ppp|)[\.-_]   ; action=REJECT

Macros can contain actions, too:

            # definition
            &&GONOW { action=REJECT your request caused our spam detection policy to reject this message. More info at http://www.domain.local; };
            # rules
            &&GONOW ;  &&RBLS ;  client_name=^unknown$
            &&GONOW ;  &&RBLS ;  client_name=(\d+[\.-_]){4}
            &&GONOW ;  &&RBLS ;  client_name=[\.-_](adsl|dynamic|ppp|)[\.-_]

Macros can contain macros, too:

            # definition
            &&RBLS{
                    rbl=zen.spamhaus.org
                    rbl=list.dsbl.org
                    rbl=bl.spamcop.net
                    rbl=dnsbl.sorbs.net
                    rbl=ix.dnsbl.manitu.net
            };
            &&DYNAMIC{
                    client_name=^unknown$
                    client_name=(\d+[\.-_]){4}
                    client_name=[\.-_](adsl|dynamic|ppp|)[\.-_]
            };
            &&GOAWAY { &&RBLS; &&DYNAMIC; };
            # rules
            &&GOAWAY ; action=REJECT dynamic client and listed on RBL

Basically macros are simple text substitutions - see the PARSER section for more information.

## PLUGINS

Description

The plugin interface allow you to define your own checks and enhance postfwd's functionality. Feel free to share useful things!

Warning

Note that the plugin interface is still at devel stage. Please test your plugins carefully, because errors may cause postfwd to break! It is also allowed to override attributes or built-in functions, but be sure that you know what you do because some of them are used internally.

Please keep security in mind, when you access sensible ressources and never, ever run postfwd as privileged user! Also never trust your input (especially hostnames, and e-mail addresses).

ITEMS

Item plugins are perl subroutines which integrate additional attributes to requests before they are evaluated against postfwd's ruleset like any other item of the policy delegation protocol. This allows you to create your own checks.

plugin-items can not be used selective. these functions will be executed for every request postfwd receives, so keep performance in mind.

            SYNOPSIS: %result = postfwd_items_plugin{<name>}(%request)

means that your subroutine, called <name>, has access to a hash called %request, which contains all request attributes, like $request{client_name} and must return a value in the following form:

            save: $result{<item>} = <value>

this creates the new item <item> containing <value>, which will be integrated in the policy delegation request and therefore may be used in postfwd's ruleset.

            # do NOT remove the next line
            %postfwd_items_plugin = (

                    # EXAMPLES - integrated in postfwd. no need to activate them here.

                            # allows to check postfwd version in ruleset
                            "version" => sub {
                                    my(%request) = @_;
                                    my(%result) = (
                                            "version" => $NAME." ".$VERSION,
                                    );
                                    return %result;
                            },

                            # sender_domain and recipient_domain
                            "address_parts" => sub {
                                    my(%request) = @_;
                                    my(%result) = ();
                                    $request{sender} =~ /@([^@]*)$/;
                                    $result{sender_domain} = ($1 || '');
                                    $request{recipient} =~ /@([^@]*)$/;
                                    $result{recipient_domain} = ($1 || '');
                                    return %result;
                            },

            # do NOT remove the next line
            );

COMPARE

Compare plugins allow you to define how your new items should be compared to the ruleset. These are optional. If you don't specify one, the default (== for exact match, =~ for PCRE, ...) will be used.

            SYNOPSIS:  <item> => sub { return &{$postfwd_compare{<type>}}(@_); },

            # do NOT remove the next line
            %postfwd_compare_plugin = (

                    EXAMPLES - integrated in postfwd. no need to activate them here.

                            # Simple example
                            # SYNOPSIS:  <result> = <item> (return &{$postfwd_compare{<type>}}(@_))
                            "client_address"  => sub { return &{$postfwd_compare{cidr}}(@_); },
                            "size"            => sub { return &{$postfwd_compare{numeric}}(@_); },
                            "recipient_count" => sub { return &{$postfwd_compare{numeric}}(@_); },

                            # Complex example
                            # SYNOPSIS:  <result> = <item>(<operator>, <ruleset value>, <request value>, <request>)
                            "numeric" => sub {
                                    my($cmp,$val,$myitem,%request) = @_;
                                    my($myresult) = undef;  $myitem ||= "0"; $val ||= "0";
                                    if ($cmp eq '==') {
                                            $myresult = ($myitem == $val);
                                    } elsif ($cmp eq '=<') {
                                            $myresult = ($myitem <= $val);
                                    } elsif ($cmp eq '=>') {
                                            $myresult = ($myitem >= $val);
                                    } elsif ($cmp eq '<') {
                                            $myresult = ($myitem < $val);
                                    } elsif ($cmp eq '>') {
                                            $myresult = ($myitem > $val);
                                    } elsif ($cmp eq '!=') {
                                            $myresult = not($myitem == $val);
                                    } elsif ($cmp eq '!<') {
                                            $myresult = not($myitem <= $val);
                                    } elsif ($cmp eq '!>') {
                                            $myresult = not($myitem >= $val);
                                    } else {
                                            $myresult = ($myitem >= $val);
                                    };
                                    return $myresult;
                            },

            # do NOT remove the next line
            );

ACTIONS

Action plugins allow to define new postfwd actions. By setting the $stop-flag you can decide to continue or to stop parsing the ruleset.

            SYNOPSIS:  (<stop rule parsing>, <next rule index>, <return action>, <logprefix>, <request>) =
                            <action> (<current rule index>, <current time>, <command name>, <argument>, <logprefix>, <request>)

            # do NOT remove the next line
            %postfwd_actions_plugin = (

                    # EXAMPLES - integrated in postfwd. no need to activate them here.

                            # note(<logstring>) command
                            "note"  => sub {
                                    my($index,$now,$mycmd,$myarg,$myline,%request) = @_;
                                    my($myaction) = 'dunno'; my($stop) = 0;
                                    log_info "[RULES] ".$myline." - note: ".$myarg if $myarg;
                                    return ($stop,$index,$myaction,$myline,%request);
                            },

                            # skips next <myarg> rules
                            "skip" => sub {
                                    my($index,$now,$mycmd,$myarg,$myline,%request) = @_;
                                    my($myaction) = 'dunno'; my($stop) = 0;
                                    $index += $myarg if ( $myarg and not(($index + $myarg) > $#Rules) );
                                    return ($stop,$index,$myaction,$myline,%request);
                            },

                            # dumps current request contents to syslog
                            "dumprequest" => sub {
                                    my($index,$now,$mycmd,$myarg,$myline,%request) = @_;
                                    my($myaction) = 'dunno'; my($stop) = 0;
                                    map { log_info "[DUMP] rule=$index, Attribute: $_=$request{$_}" } (keys %request);
                                    return ($stop,$index,$myaction,$myline,%request);
                            },

            # do NOT remove the next line
            );

## COMMAND LINE

Ruleset

The following arguments are used to specify the source of the postfwd2 ruleset. This means that at least one of the following is required for postfwd2 to work.

            -f, --file <file>
            Reads rules from <file>. Please see the CONFIGURATION section
            below for more information.

            -r, --rule <rule>
            Adds <rule> to ruleset. Remember that you might have to quote
            strings that contain whitespaces or shell characters.

Scoring

            -s, --scores <val>=<action>
            Returns <action> to postfix, when the request's score exceeds <val>

Multiple usage is allowed. Just chain your arguments, like:

            postfwd2 -r "<item>=<value>;action=<result>" -f <file> -f <file> ...
              or
            postfwd2 --scores 4.5="WARN high score" --scores 5.0="REJECT postfwd2 score too high" ...

In case of multiple scores, the highest match will count. The order of the arguments will be reflected in the postfwd2 ruleset.

Networking

postfwd2 can be run as daemon so that it listens on the network for incoming requests. The following arguments will control it's behaviour in this case.

            -d, --daemon
            postfwd2 will run as daemon and listen on the network for incoming
            queries (default 127.0.0.1:10045).

            -i, --interface <dev>
            Bind postfwd2 to the specified interface (default 127.0.0.1).

            -p, --port <port>
            postfwd2 listens on the specified port (default tcp/10045).

            --proto <type>
            The protocol type for postfwd's socket. Currently you may use 'tcp' or 'unix' here.
            To use postfwd2 with a unix domain socket, run it as follows:
                postfwd2 --proto=unix --port=/somewhere/postfwd.socket

            -u, --user <name>
            Changes real and effective user to <name>.

            -g, --group <name>
            Changes real and effective group to <name>.

            --umask <mask>
            Changes the umask for filepermissions of the master process (pidfile).
            Attention: This is umask, not chmod - you have to specify the bits that
            should NOT apply. E.g.: umask 077 equals to chmod 700.

            --cache_umask <mask>
            Changes the umask for filepermissions of the cache process (unix domain socket).

            --server_umask <mask>
            Changes the umask for filepermissions of the server process (unix domain socket).

            -R, --chroot <path>
            Chroot the process to the specified path.
            Please look at http://postfwd.org/postfwd2-chroot.html before use!

            --pidfile <path>
            The process id will be saved in the specified file.

            --facility <f>
            sets the syslog facility, default is 'mail'

            --socktype <s>
            sets the Sys::Syslog socktype to 'native', 'inet' or 'unix'.
            Default is to auto-detect this depening on module version and os.

            -l, --logname <label>
            Labels the syslog messages. Useful when running multiple
            instances of postfwd.

            --loglen <int>
            Truncates any syslog message after <int> characters.

Plugins

            --plugins <file>
            Loads postfwd plugins from file. Please see http://postfwd.org/postfwd.plugins
            or the plugins.postfwd.sample that is available from the tarball for more info.

Optional arguments

These parameters influence the way postfwd2 is working. Any of them can be combined.

            -v, --verbose
            Verbose logging displays a lot of useful information but can cause
            your logfiles to grow noticeably. So use it with caution. Set the option
            twice (-vv) to get more information (logs all request attributes).

            -c, --cache <int>    (default=600)
            Timeout for request cache, results for identical requests will be
            cached until config is reloaded or this time (in seconds) expired.
            A setting of 0 disables this feature.

            --cache-no-size
            Ignores size attribute for cache comparisons which will lead to better
            cache-hit rates. You should set this option, if you don't use the size
            item in your ruleset.

            --cache-no-sender
            Ignores sender address for cache comparisons which will lead to better
            cache-hit rates. You should set this option, if you don't use the sender
            item in your ruleset.

            --cache-rdomain-only
            This will strip the localpart of the recipient's address before filling the
            cache. This may considerably increase cache-hit rates.

            --cache-rbl-timeout <timeout>     (default=3600)
            This default value will be used as timeout in seconds for rbl cache items,
            if not specified in the ruleset.

            --cache-rbl-default <pattern>    (default=^127\.0\.0\.\d+$)
            Matches <pattern> to rbl/rhsbl answers (regexp) if not specified in the ruleset.

            --cacheid <item>, <item>, ...
            This csv-separated list of request attributes will be used to construct
            the request cache identifier. Use this only, if you know exactly what you
            are doing. If you, for example, use postfwd2 only for RBL/RHSBL control,
            you may set this to
                    postfwd2 --cache=3600 --cacheid=client_name,client_address
            This increases efficiency of caching and improves postfwd's performance.
            Warning: You should list all items here, which are used in your ruleset!

            --cleanup-requests <interval>    (default=600)
            The request cache will be searched for timed out items after this <interval> in
            seconds. It is a minimum value. The cleanup process will only take place, when
            a new request arrives.

            --cleanup-rbls <interval>    (default=600)
            The rbl cache will be searched for timed out items after this <interval> in
            seconds. It is a minimum value. The cleanup process will only take place, when
            a new request arrives.

            --cleanup-rates <interval>    (default=600)
            The rate cache will be searched for timed out items after this <interval> in
            seconds. It is a minimum value. The cleanup process will only take place, when
            a new request arrives.

            -S, --summary <int>    (default=600)
            Shows some usage statistics (program uptime, request counter, matching rules)
            every <int> seconds. This option is included by the -v switch.
            This feature uses the alarm signal, so you can force postfwd2 to dump the stats
            using `kill -ALRM <pid>` (where <pid> is the process id of postfwd).

            Example:
            Aug 19 12:39:45 mail1 postfwd[666]: [STATS] Counters: 213000 seconds uptime, 39 rules
            Aug 19 12:39:45 mail1 postfwd[666]: [STATS] Requests: 71643 overall, 49 last interval, 62.88% cache hits
            Aug 19 12:39:45 mail1 postfwd[666]: [STATS] Averages: 20.18 overall, 4.90 last interval, 557.30 top
            Aug 19 12:39:45 mail1 postfwd[666]: [STATS] Contents: 44 cached requests, 239 cached dnsbl results
            Aug 19 12:39:45 mail1 postfwd[666]: [STATS] Rule ID: R-001   matched: 2704 times
            Aug 19 12:39:45 mail1 postfwd[666]: [STATS] Rule ID: R-002   matched: 9351 times
            Aug 19 12:39:45 mail1 postfwd[666]: [STATS] Rule ID: R-003   matched: 3116 times
            ...

            --no-rulestats
            Disables per rule statistics. Keeps your log clean, if you do not use them.
            This option has no effect without --summary or --verbose set.

            -L, --stdout
            Redirects all syslog messages to stdout for debugging. Never use this with postfix!

            -t, --test
            In test mode postfwd2 always returns "dunno", but logs according
            to it`s ruleset. -v will be set automatically with this option.

            -n, --nodns
            Disables all DNS based checks like RBL checks. Rules containing
            such elements will be ignored.

            -n, --nodnslog
            Disables logging of dns events.

            --dns_timeout     (default: 14)
            Sets the timeout for asynchonous dns queries in seconds. This value will apply to
            all dns items in a rule.

            --dns_timeout_max    (default: 10)
            Sets the maximum timeout counter for dnsbl lookups. If the timeouts exceed this value
            the corresponding dnsbl will be deactivated for a while (see --dns_timeout_interval).

            --dns_timeout_interval    (default=1200)
            The dnsbl timeout counter will be cleaned after this interval in seconds. Use this
            in conjunction with the --dns_timeout_max parameter.

            --dns_async_txt
            Perform dnsbl A and TXT lookups simultaneously (otherwise only for listings with at
            least one A record). This needs more network bandwidth due to increased queries but
            might increase throughput because the lookups can be parallelized.

            --dns_max_ns_lookups     (default=0)
            maximum ns names to lookup up with sender_ns_addrs item. use 0 for no maximum.

            --dns_max_mx_lookups     (default=0)
            maximum mx names to lookup up with sender_mx_addrs item. use 0 for no maximum.

            -I, --instantcfg
            The config files, specified by -f will be re-read for every request
            postfwd2 receives. This enables on-the-fly configuration changes
            without restarting. Though files will be read only if necessary
            (which means their access times changed since last read) this might
            significantly increase system load.

            --config_timeout    (default=3)
            timeout in seconds to parse a single configuration line. if exceeded, the rule will
            be skipped. this is used to prevent problems due to large files or loops.

            --keep_rates    (default=0)
            With this option set postfwd2 does not clear the rate limit counters on reload. Please
            note that you have to restart (not reload) postfwd with this option if you change
            any rate limit rules.

            --save_rates    (default=none)
            With this option postfwd saves existing rate limit counters to disk and reloads them
            on program start. This allows persistent rate limits across program restarts or reboots.
            Please note that postfwd needs read and write access to the specified file.

            --fast_limit_evaluation    (default=0)
            Once a ratelimit was set by the ruleset, future requests will be evaluated against it
            before consulting the ruleset. This mode was the default behaviour until v1.30.
            With this mode rate limits will be faster, but also eventually set up
            whitelisting-rules within the ruleset might not work as expected.

Informational arguments

These arguments are for command line usage only. Never ever use them with postfix!

            -C, --showconfig
            Displays the current ruleset. Use -v for verbose output.

            -V, --version
            Displays the program version.

            -h, --help
            Shows program usage.

            -m, --manual
            Displays the program manual.

            -D, --defaults
            displays complete postfwd2 settings.

            -P, --perfmon
            This option turns of any syslogging and output. It is included
            for performance testing.

            --dumpstats
            Displays program usage statistics.

            --dumpcache
            Displays cache contents.

            --delcache <item>
            Removes an item from the request cache. Use --dumpcache to identify objects.
            E.g.:
                    # postfwd --dumpcache
                    ...
                    %rate_cache -> %sender=gmato@jqvo.org -> %RATE002+2_600 -> @count    -> '1'
                    %rate_cache -> %sender=gmato@jqvo.org -> %RATE002+2_600 -> @maxcount -> '2'
                    ...
                    # postfwd --delrate="sender=gmato@jqvo.org"
                    rate cache item 'sender=gmato@jqvo.org' removed

            --delrate <item>
            Removes an item from the rate cache. Use --dumpcache to identify objects.

## REFRESH

In daemon mode postfwd2 reloads it's ruleset after receiving a HUP signal. Please see the description of the '-I' switch to have your configuration refreshed for every request postfwd2 receives.

## EXAMPLES

            ## whitelisting
            # 1. networks 192.168.1.0/24, 192.168.2.4
            # 2. client_names *.gmx.net and *.gmx.de
            # 3. sender *@someshop.tld from 11.22.33.44
            id=WL001; action=dunno ; client_address=192.168.1.0/24, 192.168.2.4
            id=WL002; action=dunno ; client_name=\.gmx\.(net|de)$
            id=WL003; action=dunno ; sender=@someshop\.tld$ ; client_address=11.22.33.44

            ## TLS control
            # 1. *@authority.tld only with correct TLS fingerprint
            # 2. *@secret.tld only with keysizes >=64
            id=TL001; action=dunno                          ; sender=@authority\.tld$ ; ccert_fingerprint=AA:BB:CC..
            id=TL002; action=REJECT wrong TLS fingerprint   ; sender=@authority\.tld$
            id=TL003; action=REJECT tls keylength < 64      ; sender=@secret\.tld$ ; encryption_keysize=64

            ## Combined RBL checks
            # This will reject mail if
            # 1. listed on ix.dnsbl.manitu.net
            # 2. listed on zen.spamhaus.org (sbl and xbl, dns cache timeout 1200s instead of 3600s)
            # 3. listed on min 2 of bl.spamcop.net, list.dsbl.org, dnsbl.sorbs.net
            # 4. listed on bl.spamcop.net and one of rhsbl.ahbl.org, rhsbl.sorbs.net
            id=RBL01 ; action=REJECT listed on ix.dnsbl.manitu.net  ; rbl=ix.dnsbl.manitu.net
            id=RBL02 ; action=REJECT listed on zen.spamhaus.org     ; rbl=zen.spamhaus.org/127.0.0.[2-8]/1200
            id=RBL03 ; action=REJECT listed on too many RBLs        ; rblcount=2 ; rbl=bl.spamcop.net, list.dsbl.org, dnsbl.sorbs.net
            id=RBL04 ; action=REJECT combined RBL+RHSBL check       ; rbl=bl.spamcop.net ; rhsbl=rhsbl.ahbl.org, rhsbl.sorbs.net

            ## Message size (requires message_size_limit to be set to 30000000)
            # 1. 30MB for systems in *.customer1.tld
            # 2. 20MB for SASL user joejob
            # 3. 10MB default
            id=SZ001; protocol_state==END-OF-MESSAGE; action=DUNNO; size<=30000000 ; client_name=\.customer1.tld$
            id=SZ002; protocol_state==END-OF-MESSAGE; action=DUNNO; size<=20000000 ; sasl_username==joejob
            id=SZ002; protocol_state==END-OF-MESSAGE; action=DUNNO; size<=10000000
            id=SZ100; protocol_state==END-OF-MESSAGE; action=REJECT message too large

            ## Selective Greylisting
            ##
            ## Note that postfwd does not include greylisting. This setup requires a running postgrey service
            ## at port 10031 and the following postfix restriction class in your main.cf:
            ##
            ##      smtpd_restriction_classes = check_postgrey, ...
            ##      check_postgrey = check_policy_service inet:127.0.0.1:10031
            #
            # 1. if listed on zen.spamhaus.org with results 127.0.0.10 or .11, dns cache timeout 1200s
            # 2. Client has no rDNS
            # 3. Client comes from several dialin domains
            id=GR001; action=check_postgrey ; rbl=dul.dnsbl.sorbs.net, zen.spamhaus.org/127.0.0.1[01]/1200
            id=GR002; action=check_postgrey ; client_name=^unknown$
            id=GR003; action=check_postgrey ; client_name=\.(t-ipconnect|alicedsl|ish)\.de$

            ## Date Time
            date=24.12.2007-26.12.2007          ;  action=450 4.7.1 office closed during christmas
            time=04:00:00-05:00:00              ;  action=450 4.7.1 maintenance ongoing, try again later
            time=-07:00:00 ;  sasl_username=jim ;  action=450 4.7.1 to early for you, jim
            time=22:00:00- ;  sasl_username=jim ;  action=450 4.7.1 to late now, jim
            months=-Apr                         ;  action=450 4.7.1 see you in may
            days=!!Mon-Fri                      ;  action=check_postgrey

            ## Usage of jump
            # The following allows a message size of 30MB for different
            # users/clients while others will only have 10MB.
            id=R001 ; action=jump(R100) ; sasl_username=^(Alice|Bob|Jane)$
            id=R002 ; action=jump(R100) ; client_address=192.168.1.0/24
            id=R003 ; action=jump(R100) ; ccert_fingerprint=AA:BB:CC:DD:...
            id=R004 ; action=jump(R100) ; ccert_fingerprint=AF:BE:CD:DC:...
            id=R005 ; action=jump(R100) ; ccert_fingerprint=DD:CC:BB:DD:...
            id=R099 ; protocol_state==END-OF-MESSAGE; action=REJECT message too big (max. 10MB); size=10000000
            id=R100 ; protocol_state==END-OF-MESSAGE; action=REJECT message too big (max. 30MB); size=30000000

            ## Usage of score
            # The following rejects a mail, if the client
            # - is listed on 1 RBL and 1 RHSBL
            # - is listed in 1 RBL or 1 RHSBL and has no correct rDNS
            # - other clients without correct rDNS will be greylist-checked
            # - some whitelists are used to lower the score
            id=S01 ; score=2.6              ; action=check_postgrey
            id=S02 ; score=5.0              ; action=REJECT postfwd score too high
            id=R00 ; action=score(-1.0)     ; rbl=exemptions.ahbl.org,list.dnswl.org,query.bondedsender.org,spf.trusted-forwarder.org
            id=R01 ; action=score(2.5)      ; rbl=bl.spamcop.net, list.dsbl.org, dnsbl.sorbs.net
            id=R02 ; action=score(2.5)      ; rhsbl=rhsbl.ahbl.org, rhsbl.sorbs.net
            id=N01 ; action=score(-0.2)     ; client_name==$$helo_name
            id=N02 ; action=score(2.7)      ; client_name=^unknown$
            ...

            ## Usage of rate and size
            # The following temporary rejects requests from "unknown" clients, if they
            # 1. exceeded 30 requests per hour or
            # 2. tried to send more than 1.5mb within 10 minutes
            id=RATE01 ;  client_name==unknown ;  protocol_state==RCPT
                    action=rate(client_address/30/3600/450 4.7.1 sorry, max 30 requests per hour)
            id=SIZE01 ;  client_name==unknown ;  protocol_state==END-OF-MESSAGE
                    action=size(client_address/1572864/600/450 4.7.1 sorry, max 1.5mb per 10 minutes)

            ## Macros
            # definition
            &&RBLS { rbl=zen.spamhaus.org,list.dsbl.org,bl.spamcop.net,dnsbl.sorbs.net,ix.dnsbl.manitu.net; };
            &&GONOW { action=REJECT your request caused our spam detection policy to reject this message. More info at http://www.domain.local; };
            # rules
            &&GONOW ;  &&RBLS ;  client_name=^unknown$
            &&GONOW ;  &&RBLS ;  client_name=(\d+[\.-_]){4}
            &&GONOW ;  &&RBLS ;  client_name=[\.-_](adsl|dynamic|ppp|)[\.-_]

            ## Groups
            # definition
            &&RBLS{
                    rbl=zen.spamhaus.org
                    rbl=list.dsbl.org
                    rbl=bl.spamcop.net
                    rbl=dnsbl.sorbs.net
                    rbl=ix.dnsbl.manitu.net
            };
            &&RHSBLS{
                    ...
            };
            &&DYNAMIC{
                    client_name==unknown
                    client_name~=(\d+[\.-_]){4}
                    client_name~=[\.-_](adsl|dynamic|ppp|)[\.-_]
                    ...
            };
            &&BAD_HELO{
                    helo_name==my.name.tld
                    helo_name~=^([^\.]+)$
                    helo_name~=\.(local|lan)$
                    ...
            };
            &&MAINTENANCE{
                    date=15.01.2007
                    date=15.04.2007
                    date=15.07.2007
                    date=15.10.2007
                    time=03:00:00 - 04:00:00
            };
            # rules
            id=COMBINED    ;  &&RBLS ;  &&DYNAMIC ;  action=REJECT dynamic client and listed on RBL
            id=MAINTENANCE ;  &&MAINTENANCE       ;  action=DEFER maintenance time - please try again later

            # now with the set() command, note that long item
            # lists don't have to be compared twice
            id=RBL01    ;  &&RBLS      ;  action=set(HIT_rbls=1)
            id=HELO01   ;  &&BAD_HELO  ;  action=set(HIT_helo=1)
            id=DYNA01   ;  &&DYNAMIC   ;  action=set(HIT_dyna=1)
            id=REJECT01 ;  HIT_rbls==1 ;  HIT_helo==1  ; action=REJECT please see http://some.org/info?reject=01 for more info
            id=REJECT02 ;  HIT_rbls==1 ;  HIT_dyna==1  ; action=REJECT please see http://some.org/info?reject=02 for more info
            id=REJECT03 ;  HIT_helo==1 ;  HIT_dyna==1  ; action=REJECT please see http://some.org/info?reject=03 for more info

            ## combined with enhanced rbl features
            #
            id=RBL01 ; rhsblcount=all ; rblcount=all ; &&RBLS ; &&RHSBLS
                 action=set(HIT_dnsbls=$$rhsblcount,HIT_dnsbls+=$$rblcount,HIT_dnstxt=$$dnsbltext)
            id=RBL02 ; HIT_dnsbls>=2  ; action=554 5.7.1 blocked using $$HIT_dnsbls DNSBLs [INFO: $$HIT_dnstxt]

## PARSER

Configuration

The postfwd2 ruleset can be specified at the commandline (-r option) or be read from files (-f). The order of your arguments will be kept. You should check the parser with the -C | --showconfig switch at the command line before applying a new config. The following call:

            postfwd2 --showconfig \
                    -r "id=TEST; recipient_count=100; action=WARN mail with 100+ recipients" \
                    -f /etc/postfwd.cf \
                    -r "id=DEFAULT; action=dunno";

will produce the following output:

            Rule   0: id->"TEST" action->"WARN mail with 100+ recipients"; recipient_count->"100"
            ...
            ... <content of /etc/postfwd.cf> ...
            ...
            Rule <n>: id->"DEFAULT" action->"dunno"

Multiple items of the same type will be added to lists (see the ITEMS section for more info):

            postfwd2 --showconfig \
                    -r "client_address=192.168.1.0/24; client_address=172.16.26.32; action=dunno"

will result in:

            Rule   0: id->"R-0"; action->"dunno"; client_address->"192.168.1.0/24, 172.16.26.32"

Macros are evaluated at configuration stage, which means that

            postfwd2 --showconfig \
                    -r "&&RBLS { rbl=bl.spamcop.net; client_name=^unknown$; };" \
                    -r "id=RBL001; &&RBLS; action=REJECT listed on spamcop and bad rdns";

will result in:

            Rule   0: id->"RBL001"; action->"REJECT listed on spamcop and bad rdns"; rbl->"bl.spamcop.net"; client_name->"^unknown$"

Request processing

When a policy delegation request arrives it will be compared against postfwd`s ruleset. To inspect the processing in detail you should increase verbority using use the ``-v'' or ``-vv'' switch. ``-L'' redirects log messages to stdout.

Keeping the order of the ruleset in general, items will be compared in random order, which basically means that

            id=R001; action=dunno; client_address=192.168.1.1; sender=bob@alice.local

equals to

            id=R001; sender=bob@alice.local; client_address=192.168.1.1; action=dunno

Lists will be evaluated in the specified order. This allows to place faster expressions at first:

            postfwd2 --nodaemon -vv -L -r "id=RBL001; rbl=localrbl.local zen.spamhaus.org; action=REJECT" /some/where/request.sample

produces the following

            [LOGS info]: compare rbl: "remotehost.remote.net[68.10.1.7]"  ->  "localrbl.local"
            [LOGS info]: count1 rbl:  "2"  ->  "0"
            [LOGS info]: query rbl:   localrbl.local 7.1.10.68 (7.1.10.68.localrbl.local)
            [LOGS info]: count2 rbl:  "2"  ->  "0"
            [LOGS info]: match rbl:   FALSE
            [LOGS info]: compare rbl: "remotehost.remote.net[68.10.1.7]"  ->  "zen.spamhaus.org"
            [LOGS info]: count1 rbl:  "2"  ->  "0"
            [LOGS info]: query rbl:   zen.spamhaus.org 7.1.10.68 (7.1.10.68.zen.spamhaus.org)
            [LOGS info]: count2 rbl:  "2"  ->  "0"
            [LOGS info]: match rbl:   FALSE
            [LOGS info]: Action: dunno

The negation operator !!(<value>) has the highest priority and therefore will be evaluated first. Then variable substitutions are performed:

            postfwd2 --nodaemon -vv -L -r "id=TEST; action=REJECT; client_name=!!($$heloname)" /some/where/request.sample

will give

            [LOGS info]: compare client_name:     "unknown"  ->  "!!($$helo_name)"
            [LOGS info]: negate client_name:      "unknown"  ->  "$$helo_name"
            [LOGS info]: substitute client_name:  "unknown"  ->  "english-breakfast.cloud8.net"
            [LOGS info]: match client_name:  TRUE
            [LOGS info]: Action: REJECT

Ruleset evaluation

A rule hits when all items (or at least one element of a list for each item) have matched. As soon as one item (or all elements of a list) fails to compare against the request attribute the parser will jump to the next rule in the postfwd2 ruleset.

If a rule matches, there are two options:

* Rule returns postfix action (dunno, reject, ...) The parser stops rule processing and returns the action to postfix. Other rules will not be evaluated.

* Rule returns postfwd2 action (jump(), note(), ...) The parser evaluates the given action and continues with the next rule (except for the `jump()` or `quit()` actions - please see the ACTIONS section for more information). Nothing will be sent to postfix.

If no rule has matched and the end of the ruleset is reached postfwd2 will return dunno without logging anything unless in verbose mode. You may place a last catch-all rule to change that behaviour:

            ... <your rules> ...
            id=DEFAULT ;  action=dunno

will log any request that passes the ruleset without having hit a prior rule.

## DEBUGGING

To debug special steps of the parser the '--debug' switch takes a list of debug classes. Currently the following classes are defined:

            all cache config debugdns devel dns getcache getdns
            getdnspacket rates request setcache setdns
            parent_cache parent_dns_cache parent_rate_cache parent_request_cache
            child_cache  child_dns_cache  child_rate_cache  child_request_cache

## INTEGRATION

Integration via daemon mode

The common way to use postfwd2 is to start it as daemon, listening at a specified tcp port. postfwd2 will spawn multiple child processes which communicate with a parent cache. This is the prefered way to use postfwd2 in high volume environments. Start postfwd2 with the following parameters:

            postfwd2 -d -f /etc/postfwd.cf -i 127.0.0.1 -p 10045 -u nobody -g nobody -S

For efficient caching you should check if you can use the options --cacheid, --cache-rdomain-only, --cache-no-sender and --cache-no-size.

Now check your syslogs (default facility ``mail'') for a line like:

            Aug  9 23:00:24 mail postfwd[5158]: postfwd2 n.nn ready for input

and use `netstat -an|grep 10045` to check for something like

            tcp  0  0  127.0.0.1:10045  0.0.0.0:*  LISTEN

If everything works, open your postfix main.cf and insert the following

            127.0.0.1:10045_time_limit      = 3600                                          <--- integration
            smtpd_recipient_restrictions    = permit_mynetworks                             <--- recommended
                                              reject_unauth_destination                     <--- recommended
                                              check_policy_service inet:127.0.0.1:10045     <--- integration

Reload your configuration with `postfix reload` and watch your logs. In it works you should see lines like the following in your mail log:

            Aug  9 23:01:24 mail postfwd[5158]: rule=22, id=ML_POSTFIX, client=english-breakfast.cloud9.net[168.100.1.7], sender=owner-postfix-users@postfix.tld, recipient=someone@domain.local, helo=english-breakfast.cloud9.net, proto=ESMTP, state=RCPT, action=dunno

If you want to check for size or rcpt_count items you must integrate postfwd2 in smtp_data_restrictions or smtpd_end_of_data_restrictions. Of course you can also specify a restriction class and use it in your access tables. First create a file /etc/postfix/policy containing:

            domain1.local           postfwdcheck
            domain2.local           postfwdcheck
            ...

Then postmap that file (`postmap hash:/etc/postfix/policy`), open your main.cf and enter

            # Restriction Classes
            smtpd_restriction_classes       = postfwdcheck, <some more>...                          <--- integration
            postfwdcheck                    = check_policy_service inet:127.0.0.1:10045             <--- integration

            127.0.0.1:10045_time_limit      = 3600                                                  <--- integration
            smtpd_recipient_restrictions    = permit_mynetworks,                                    <--- recommended
                                              reject_unauth_destination,                            <--- recommended
                                              ...                                                   <--- optional
                                              check_recipient_access hash:/etc/postfix/policy,      <--- integration
                                              ...                                                   <--- optional

Reload postfix and watch your logs.

## TESTING

First you have to create a ruleset (see Configuration section). Check it with

            postfwd2 -f /etc/postfwd.cf -C

There is an example policy request distributed with postfwd, called 'request.sample'. Simply change it to meet your requirements and use

            postfwd2 -f /etc/postfwd.cf <request.sample

You should get an answer like

            action=<whateveryouconfigured>

For network tests I use netcat:

            nc 127.0.0.1 10045 <request.sample

to send a request to postfwd. If you receive nothing, make sure that postfwd2 is running and listening on the specified network settings.

## PERFORMANCE

Some of these proposals might not match your environment. Please check your requirements and test new options carefully!

            - use caching options
            - use the correct match operator ==, <=, >=
            - use ^ and/or $ in regular expressions
            - use item lists (faster than single rules)
            - use set() action on repeated item lists
            - use jumps and rate limits
            - use a pre-lookup rule for rbl/rhsbls with empty note() action

## SEE ALSO

See http://www.postfix.org/SMTPD_POLICY_README.html for a description of how Postfix policy servers work.

# LICENSE

postfwd2 is free software and released under BSD license, which basically means that you can do what you want as long as you keep the copyright notice:

Copyright (c) 2009, Jan Peter Kessler All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

     * Redistributions of source code must retain the above copyright
       notice, this list of conditions and the following disclaimer.
     * Redistributions in binary form must reproduce the above copyright
       notice, this list of conditions and the following disclaimer in
       the documentation and/or other materials provided with the
       distribution.
     * Neither the name of the authors nor the names of his contributors
       may be used to endorse or promote products derived from this
       software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY ME ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

# AUTHOR

Jan Peter Kessler <info (AT) postfwd (DOT) org>. Let me know, if you have any suggestions.