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> -u, --user <name> set uid to user <name> -g, --group <name> set gid to group <name> -R, --chroot <path> chroot the daemon to <path> -l, --logname <label> label for syslog messages --pidfile <path> create pidfile under <path> optional: -v, --verbose verbose logging, use twice (-vv) to increase level -c, --cache <int> sets the request-cache timeout to <int> seconds --cache-no-size ignores size attribute for caching --cache-rdomain-only ignores localpart of recipient address in cache -S, --summary <int> show some usage statistics every <int> seconds -L, --stdoutlog redirect syslog messages to stdout -t, --test testing, always returns "dunno" -n, --nodns disable dns -I, --instantcfg re-reads rulefiles for every new request informational (use only at command-line!): -C, --showconfig shows config, -v for verbose -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 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 score - when the specified score is hit (see ACTIONS section) the specified action will be returned to postfix scores are set global until redefined! rbl, rhsbl - query the specified RBLs/RHSBLs, possible values are: <name>[/<reply>/<maxcache>, <name>/<reply>/<maxcache>] rblcount, rhsblcount - minimum RBL/RHSBL hitcounts to match if not specified a single RBL/RHSBL hit will match the rbl/rhsbl items 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) 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 # ------------------------------ # 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_DATA 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 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=REJECT helo does not match DNS # or id=R-003 ; client_name = !!($$(helo_name)) ; action=REJECT 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.

ACTIONS
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! score (<score>) the request's score will be increased by the specified <score>, which must be a floating point value. 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=REJECT). negative values are allowed. Anything else than +/-nnnn.nn will be ignored. 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. quit (<code>) terminates the program with the given exit-code. postfix doesn`t like that too much, so use it with care.

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). -u, --user <name> Changes real and effective user to <name>. -g, --group <name> Changes real and effective group to <name>. -R, --chroot <path> Chroot the process to the specified path. Test this before using - you might need some libs there. -l, --logname <label> Labels the syslog messages. Useful when running multiple instances of postfwd. --pidfile <path> The process id will be saved in the specified file. 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> 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-rdomain-only This will strip the localpart of the recipient's address before filling the cache. This may considerably increase cache-hit rates. -S, --summary <int> Shows some usage statistics (program uptime, request counter, matching rules) every <int> seconds (default: 600). This option is included by the -v switch. 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 ... -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. -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. 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 600s) # 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; action=REJECT message too large ; size=30000000 ; client_name=\.customer1.tld$ id=SZ002; action=REJECT message too large ; size=20000000 ; sasl_username=^joejob$ id=SZ003; action=REJECT message too large ; size=10000000 ## Selective Greylisting # 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=greylisting ; rbl=dul.dnsbl.sorbs.net, zen.spamhaus.org/127.0.0.1[01]/1200 id=GR002; action=greylisting ; client_name=^unknown$ id=GR003; action=greylisting ; 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 ## 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 ; action=REJECT message too big (max. 10MB); size=10000000 id=R100 ; 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=greylisting 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(2.7) ; client_name=^unknown$ ... ## 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 ; \ }; &&DYNAMIC { \ client_name=^unknown$ ; \ client_name=(\d+[\.-_]){4} ; \ client_name=[\.-_](adsl|dynamic|ppp|)[\.-_] ; \ }; &&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

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" /root/request.small 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=!!($$heloname)" /root/request.small will give [LOGS info]: compare client_name: "unknown" -> "!!($$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-allī 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 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.small'. Simply change it to meet your requirements and use postfwd -f /etc/postfwd.cf <request.small You should get an answer like action=<whateveryouconfigured> For network tests I use netcat: nc 127.0.0.1 10040 <request.small to send a request to postfwd. If you receive nothing, make sure that postfwd is running and listening on the specified network settings.

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.