postfwd - postfix firewall daemon postfwd [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 Scoring: -s, --scores <v>=<r> returns <r> when score exceeds <v> Networking: -d, --daemon run postfwd as daemon -i, --interface <dev> listen on interface <dev> -p, --port <port> listen on port <port> --proto <proto> socket type (tcp or unix) -u, --user <name> set uid to user <name> -g, --group <name> set gid to group <name> --umask <mask> set umask for file permissions -R, --chroot <path> chroot the daemon to <path> --pidfile <path> create pidfile under <path> --facility <f> syslog facility --socktype <s> syslog socktype -l, --logname <label> label for syslog messages --loglen <int> truncates syslogs after <int> chars Caching: -c, --cache <int> sets the request-cache timeout to <int> seconds --cache-no-size ignores size attribute for caching --cache-no-sender ignores sender address in cache --cache-rdomain-only ignores localpart of recipient address in cache --cache-rbl-timeout default rbl timeout, if not specified in ruleset --cache-rbl-default default rbl response pattern to match (regexp) --cacheid <item>, .. list of attributes for request cache identifier --cleanup-requests cleanup interval in seconds for request cache --cleanup-rbls cleanup interval in seconds for rbl cache --cleanup-rates cleanup interval in seconds for rate cache Optional: -t, --test testing, always returns "dunno" -v, --verbose verbose logging, use twice (-vv) to increase level -S, --summary <int> show some usage statistics every <int> seconds --norulelog disbles rule logging --norulestats disables per rule statistics --noidlestats disables statistics when idle -n, --nodns disable dns --nodnslog disable dns logging --dns_async_txt perform dnsbl A and TXT lookups simultaneously --dns_timeout timeout in seconds for asynchonous dns queries --dns_timeout_max maximum of dns timeouts until a dnsbl will be deactivated --dns_timeout_interval interval in seconds for dns timeout maximum counter --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 -I, --instantcfg re-reads rulefiles for every new request --config_timeout <i> parser timeout in seconds Informational (use only at command-line!): -C, --showconfig shows ruleset summary, -v for verbose -L, --stdoutlog redirect syslog messages to stdout -P, --perfmon no syslogging, no stdout -V, --version shows program version -h, --help shows usage -m, --manual shows program manual

INTRODUCTION
postfwd 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). postfwd 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$/i ITEM != VALUE false if ITEM equals VALUE ITEM !> VALUE false if ITEM >= VALUE ITEM !< VALUE false if ITEM <= VALUE ITEM !~ VALUE false if ITEM ~= /^VALUE$/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. Rules can span multiple lines by adding a trailing backslash "\" character: id=R_001 ; client_address=192.168.1.0/24; sender==no@bad.local; \ action=REJECT please use your relay from there

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 - postfwd 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, - postfwd 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, - postfwd 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 - postfwd version, contains "postfwd 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 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 currently have to be unique: id, minimum and maximum values, rblcount and rhsblcount Any item can be negated by preceeding '!!' to it, e.g.: id=TLS001 ; hostname=!!^secure\.trust\.local$ ; action=REJECT only secure.trust.local please or using the right compare operator: id=USER01 ; sasl_username !~ /^(bob|alice)$/ ; action=REJECT who is that? 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.

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 postfwd 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: # postfwd --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: # postfwd --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 postfwd 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=R001; 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 Remind 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. postfwd 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 postfwd actions postfwd 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 postfwd 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> is currently limited to postfix actions (no postfwd actions)! # 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) Please note also that the order of rate limits in your ruleset is important, which means that this: # works as expected id=R001; action=rcpt(sender/500/3600/REJECT limit of 500 recipients per hour for sender $$sender exceeded) id=R002; action=rcpt(sender/200/3600/WARN state YELLOW for sender $$sender) leads to different results than this: # rule R002 never gets executed id=R001; action=rcpt(sender/200/3600/WARN state YELLOW for sender $$sender) id=R002; action=rcpt(sender/500/3600/REJECT limit of 500 recipients per hour for sender $$sender exceeded) 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 postfwd 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 postfwd 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 the 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$) 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' These special attributes 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 attributes 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 ; \ 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 ; \ action=set(HIT_rhls=$$rhsblcount,HIT_rbls=$$rblcount,HIT_txt=$$dnsbltext) # compare id=RBL02 ; HIT_rhls>=1 ; HIT_rbls>=1 ; action=554 5.7.1 blocked using $$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]

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 (note the trailing "\" characters) &&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.

COMMAND LINE
Ruleset The following arguments are used to specify the source of the postfwd ruleset. This means that at least one of the following is required for postfwd 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: postfwd -r "<item>=<value>;action=<result>" -f <file> -f <file> ... or postfwd --scores 4.5="WARN high score" --scores 5.0="REJECT postfwd score too high" ... In case of multiple scores, the highest match will count. The order of the arguments will be reflected in the postfwd ruleset. Networking postfwd 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 postfwd will run as daemon and listen on the network for incoming queries (default 127.0.0.1:10040). -i, --interface <dev> Bind postfwd to the specified interface (default 127.0.0.1). -p, --port <port> postfwd listens on the specified port (default tcp/10040). --proto <type> The protocol type for postfwd's socket. Currently you may use 'tcp' or 'unix' here. To use postfwd with a unix domain socket, run it as follows: postfwd --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 (unix domain sockets, pidfiles). Attention: This is umask, not chmod - you have to specify the bits that should NOT apply. E.g.: umask 077 equals to chmod 700. -R, --chroot <path> Chroot the process to the specified path. Test this before using - you might need some libs there. --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. Optional arguments These parameters influence the way postfwd 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 postfwd only for RBL/RHSBL control, you may set this to postfwd --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 postfwd 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, --stdoutlog Redirects all syslog messages to stdout for debugging. Never use this with postfix! -t, --test In test mode postfwd 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 postfwd 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. Informational arguments These arguments are for command line usage only. Never ever use them with postfix spawn! -C, --showconfig Displays the current ruleset. Use -v for verbose output. -P, --perfmon This option turns of any syslogging and output. It is included for performance testing. -V, --version Displays the program version. -h, --help Shows program usage. -m, --manual Displays the program manual.

REFRESH
In daemon mode postfwd 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 postfwd 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 postfwd 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: postfwd --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): postfwd --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 postfwd --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: postfwd -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: postfwd -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 postfwd 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 postfwd 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 postfwd will return dunno without logging anything unless in verbose mode. You may simply 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.

INTEGRATION
Integration via daemon mode The common way to use postfwd is to start it as daemon, listening at a specified tcp port. As postfwd will run in a single instance (multiplexing mode), it will take most benefit of it`s internal caching in that case. Start postfwd with the following parameters: postfwd -d -f /etc/postfwd.cf -i 127.0.0.1 -p 10040 -u nobody -g nobody -S For efficient caching you should check if you can use the options --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]: postfwd n.nn ready for input and use `netstat -an|grep 10040` to check for something like tcp 0 0 127.0.0.1:10040 0.0.0.0:* LISTEN If everything works, open your postfix main.cf and insert the following 127.0.0.1:10040_time_limit = 3600 <--- integration smtpd_recipient_restrictions = permit_mynetworks <--- recommended reject_unauth_destination <--- recommended check_policy_service inet:127.0.0.1:10040 <--- 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 postfwd 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:127.0.0.1:10040 <--- integration 127.0.0.1:10040_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. Integration via xinetd There might be several reasons for you to use postfwd via a tcp wrapper package like xinetd (see <http://www.xinetd.org/>). I won`t discuss that here. If you plan to do so, just add the following line to your /etc/services file: # postfwd port postfwd 10040/tcp Then create a file '/etc/xinetd.d/postfwd': { interface = 127.0.0.1 socket_type = stream protocol = tcp wait = no user = nobody server = /usr/local/bin/postfwd server_args = -f /etc/postfwd.cf disable = no } and restart the xinetd daemon (usually a SIGHUP should be fine). If you experience problems you might want to check your system's log for xinetd errors like "socket already in use". The integration with postfix is similar to the Integration via daemon mode section above. Reload postfix and watch your logs to see if everything works.

TESTING
First you have to create a ruleset (see Configuration section). Check it with postfwd -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 postfwd -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 10040 <request.sample to send a request to postfwd. If you receive nothing, make sure that postfwd 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

PLUGINS
There is a plugin interface but it still lacks documentation. Contact me if you need assistance.

SEE ALSO
See <http://www.postfix.org/SMTPD_POLICY_README.html> for a description of how Postfix policy servers work. postfwd 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) 2007, 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. Jan Peter Kessler <info (AT) postfwd (DOT) org>. Let me know, if you have any suggestions.