1filter-rule = [ insert ] action in-out [ options ] [ tos ] [ ttl ] 2 [ proto ] [ ip ] [ group ] [ tag ] [ pps ] . 3 4insert = "@" decnumber . 5action = block | "pass" | log | "count" | auth | call . 6in-out = "in" | "out" . 7options = [ log ] [ "quick" ] [ onif [ dup ] [ froute ] ] . 8tos = "tos" decnumber | "tos" hexnumber . 9ttl = "ttl" decnumber . 10proto = "proto" protocol . 11ip = srcdst [ flags ] [ with withopt ] [ icmp ] [ keep ] . 12group = [ "head" decnumber ] [ "group" decnumber ] . 13pps = "pps" decnumber . 14 15onif = "on" interface-name [ "out-via" interface-name ] . 16block = "block" [ return-icmp[return-code] | "return-rst" ] . 17auth = "auth" | "preauth" . 18log = "log" [ "body" ] [ "first" ] [ "or-block" ] [ "level" loglevel ] . 19tag = "tag" tagid . 20call = "call" [ "now" ] function-name "/" decnumber. 21dup = "dup-to" interface-name[":"ipaddr] . 22froute = "fastroute" | "to" interface-name . 23replyto = "reply-to" interface-name [ ":" ipaddr ] . 24protocol = "tcp/udp" | "udp" | "tcp" | "icmp" | decnumber . 25srcdst = "all" | fromto . 26fromto = "from" object "to" object . 27 28return-icmp = "return-icmp" | "return-icmp-as-dest" . 29loglevel = facility"."priority | priority . 30object = addr [ port-comp | port-range ] . 31addr = "any" | nummask | host-name [ "mask" ipaddr | "mask" hexnumber ] . 32port-comp = "port" compare port-num . 33port-range = "port" port-num range port-num . 34flags = "flags" flag { flag } [ "/" flag { flag } ] . 35with = "with" | "and" . 36icmp = "icmp-type" icmp-type [ "code" decnumber ] . 37return-code = "("icmp-code")" . 38keep = "keep" "state" [ "limit" number ] | "keep" "frags" . 39 40nummask = host-name [ "/" decnumber ] . 41host-name = ipaddr | hostname | "any" . 42ipaddr = host-num "." host-num "." host-num "." host-num . 43host-num = digit [ digit [ digit ] ] . 44port-num = service-name | decnumber . 45 46withopt = [ "not" | "no" ] opttype [ [ "," ] withopt ] . 47opttype = "ipopts" | "short" | "nat" | "bad-src" | "lowttl" | "frag" | 48 "mbcast" | "opt" ipopts . 49optname = ipopts [ "," optname ] . 50ipopts = optlist | "sec-class" [ secname ] . 51secname = seclvl [ "," secname ] . 52seclvl = "unclass" | "confid" | "reserv-1" | "reserv-2" | "reserv-3" | 53 "reserv-4" | "secret" | "topsecret" . 54icmp-type = "unreach" | "echo" | "echorep" | "squench" | "redir" | 55 "timex" | "paramprob" | "timest" | "timestrep" | "inforeq" | 56 "inforep" | "maskreq" | "maskrep" | "routerad" | 57 "routersol" | decnumber . 58icmp-code = decumber | "net-unr" | "host-unr" | "proto-unr" | "port-unr" | 59 "needfrag" | "srcfail" | "net-unk" | "host-unk" | "isolate" | 60 "net-prohib" | "host-prohib" | "net-tos" | "host-tos" | 61 "filter-prohib" | "host-preced" | "cutoff-preced" . 62optlist = "nop" | "rr" | "zsu" | "mtup" | "mtur" | "encode" | "ts" | "tr" | 63 "sec" | "lsrr" | "e-sec" | "cipso" | "satid" | "ssrr" | "addext" | 64 "visa" | "imitd" | "eip" | "finn" . 65facility = "kern" | "user" | "mail" | "daemon" | "auth" | "syslog" | 66 "lpr" | "news" | "uucp" | "cron" | "ftp" | "authpriv" | 67 "audit" | "logalert" | "local0" | "local1" | "local2" | 68 "local3" | "local4" | "local5" | "local6" | "local7" . 69priority = "emerg" | "alert" | "crit" | "err" | "warn" | "notice" | 70 "info" | "debug" . 71 72hexnumber = "0" "x" hexstring . 73hexstring = hexdigit [ hexstring ] . 74decnumber = digit [ decnumber ] . 75 76compare = "=" | "!=" | "<" | ">" | "<=" | ">=" | "eq" | "ne" | "lt" | "gt" | 77 "le" | "ge" . 78range = "<>" | "><" . 79hexdigit = digit | "a" | "b" | "c" | "d" | "e" | "f" . 80digit = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" . 81flag = "F" | "S" | "R" | "P" | "A" | "U" | "C" | "W" . 82