2012年3月22日 星期四

IPTABLES MATCH EXTENSIONS


iptables can use extended packet matching modules.  These are loaded in
       two  ways:  implicitly, when -p or --protocol is specified, or with the
       -m or --match options, followed by  the  matching  module  name;  after
       these,  various  extra command line options become available, depending
       on the specific module.  You can specify multiple extended  match  mod-
       ules  in  one  line, and you can use the -h or --help options after the
       module has been specified to receive help specific to that module.

       The following are included in the base package, and most of  these  can
       be preceded by a !  to invert the sense of the match.

   addrtype
       This module matches packets based on their address type.  Address types
       are used within the kernel networking stack  and  categorize  addresses
       into various groups.  The exact definition of that group depends on the
       specific layer three protocol.

       The following address types are possible:

       UNSPEC an unspecified address (i.e. 0.0.0.0) UNICAST an unicast address
              LOCAL  a  local address BROADCAST a broadcast address ANYCAST an
              anycast packet MULTICAST a multicast address BLACKHOLE a  black-
              hole  address UNREACHABLE an unreachable address PROHIBIT a pro-
              hibited address THROW FIXME NAT FIXME XRESOLVE FIXME

       --src-type type
              Matches if the source address is of given type

       --dst-type type
              Matches if the destination address is of given type

   ah
       This module matches the SPIs in AH header of IPSec packets.

       --ahspi [!] spi[:spi]

   childlevel
       This is an experimental module.  It matches on whether  the  packet  is
       part  of  a master connection or one of its children (or grandchildren,
       etc).  For instance, most packets are level 0.  FTP  data  transfer  is
       level 1.

       --childlevel [!] level

   condition
       This matches if a specific /proc filename is ’0’ or ’1’.

       --condition [!] filename
              Match  on  boolean value stored in /proc/net/ipt_condition/file-
              name file

   connmark
       This module matches the netfilter mark field associated with a  connec-
       tion (which can be set using the CONNMARK target below).

       --mark value[/mask]
              Matches  packets  in connections with the given mark value (if a
              mask is specified, this is logically ANDed with the mark  before
              the comparison).

   connrate
       This module matches the current transfer rate in a connection.

       --connrate [!] [from]:[to]
              Match  against the current connection transfer rate being within
              ’from’ and ’to’ bytes per second. When the "!" argument is  used
              before the range, the sense of the match is inverted.

   conntrack
       This  module,  when combined with connection tracking, allows access to
       more connection tracking information than  the  "state"  match.   (this
       module is present only if iptables was compiled under a kernel support-
       ing this feature)

       --ctstate state
              Where state is a comma separated list of the  connection  states
              to  match.   Possible states are INVALID meaning that the packet
              is associated with no known connection, ESTABLISHED meaning that
              the  packet is associated with a connection which has seen pack-
              ets in both directions, NEW meaning that the packet has  started
              a  new  connection,  or  otherwise  associated with a connection
              which has not seen packets in both directions, and RELATED mean-
              ing that the packet is starting a new connection, but is associ-
              ated with an existing connection, such as an FTP data  transfer,
              or  an ICMP error.  SNAT A virtual state, matching if the origi-
              nal source address differs from the reply destination.   DNAT  A
              virtual state, matching if the original destination differs from
              the reply source.

       --ctproto proto
              Protocol to match (by number or name)

       --ctorigsrc [!] address[/mask]
              Match against original source address

       --ctorigdst [!] address[/mask]
              Match against original destination address

       --ctreplsrc [!] address[/mask]
              Match against reply source address

       --ctrepldst [!] address[/mask]
              Match against reply destination address

       --ctstatus [NONE|EXPECTED|SEEN_REPLY|ASSURED][,...]
              Match against internal conntrack states

       --ctexpire time[:time]
              Match remaining lifetime in seconds against given value or range
              of values (inclusive)

   dscp
       This module matches the 6 bit DSCP field within the TOS field in the IP
       header.  DSCP has superseded TOS within the IETF.

       --dscp value
              Match against a numeric (decimal or hex) value [0-32].

       --dscp-class DiffServ Class
              Match the DiffServ class. This value may be any of the  BE,  EF,
              AFxx  or  CSx  classes.   It  will  then  be converted into it’s
              according numeric value.

   dstlimit
       This module allows you to limit the packet per second (pps) rate  on  a
       per  destination  IP  or  per destination port base.  As opposed to the
       ‘limit’ match, every destination ip / destination  port  has  it’s  own
       limit.

       --dstlimit avg
              Maximum  average  match rate (packets per second unless followed
              by /sec /minute /hour /day postfixes).

       --dstlimit-mode mode
              The limiting hashmode.  Is the specified limit per dstip, dstip-
              dstport  tuple,  srcip-dstip  tuple,  or  per srcipdstip-dstport
              tuple.

       --dstlimit-name name
              Name for /proc/net/ipt_dstlimit/* file entry

       [--dstlimit-burst burst]
              Number of packets to match in a burst.  Default: 5

       [--dstlimit-htable-size size]
              Number of buckets in the hashtable

       [--dstlimit-htable-max max]
              Maximum number of entries in the hashtable

       [--dstlimit-htable-gcinterval interval]
              Interval between garbage collection runs of  the  hashtable  (in
              miliseconds).  Default is 1000 (1 second).

       [--dstlimit-htable-expire time
              After  which  time  are  idle entries expired from hashtable (in
              miliseconds)?  Default is 10000 (10 seconds).

   ecn
       This allows you to match the ECN bits of the IPv4 and TCP header.   ECN
       is  the  Explicit  Congestion  Notification  mechanism  as specified in
       RFC3168

       --ecn-tcp-cwr
              This matches if the TCP ECN CWR (Congestion Window Received) bit
              is set.

       --ecn-tcp-ece
              This matches if the TCP ECN ECE (ECN Echo) bit is set.

       --ecn-ip-ect num
              This  matches a particular IPv4 ECT (ECN-Capable Transport). You
              have to specify a number between ‘0’ and ‘3’.

   esp
       This module matches the SPIs in ESP header of IPSec packets.

       --espspi [!] spi[:spi]

   fuzzy
       This module matches a rate limit based  on  a  fuzzy  logic  controller
       [FLC]

       --lower-limit  number"
              Specifies the lower limit (in packets per second).

       --upper-limit number
              Specifies the upper limit (in packets per second).

   helper
       This module matches packets related to a specific conntrack-helper.

       --helper string
              Matches packets related to the specified conntrack-helper.

              string  can  be  "ftp"  for  packets related to a ftp-session on
              default port.  For other ports append -portnr to the value,  ie.
              "ftp-2121".

              Same rules apply for other conntrack-helpers.

   icmp
       This  extension  is  loaded if ‘--protocol icmp’ is specified.  It pro-
       vides the following option:

       --icmp-type [!] typename
              This allows specification of the  ICMP  type,  which  can  be  a
              numeric  ICMP  type,  or one of the ICMP type names shown by the
              command
               iptables -p icmp -h

   iprange
       This matches on a given arbitrary range of IPv4 addresses

       [!]--src-range ip-ip
              Match source IP in the specified range.

       [!]--dst-range ip-ip
              Match destination IP in the specified range.

   length
       This module matches the length of a packet against a specific value  or
       range of values.

       --length length[:length]

   limit
       This  module  matches at a limited rate using a token bucket filter.  A
       rule using this extension  will  match  until  this  limit  is  reached
       (unless  the ‘!’ flag is used).  It can be used in combination with the
       LOG target to give limited logging, for example.

       --limit rate
              Maximum average matching rate: specified as a  number,  with  an
              optional  ‘/second’,  ‘/minute’,  ‘/hour’, or ‘/day’ suffix; the
              default is 3/hour.

       --limit-burst number
              Maximum initial number of packets to  match:  this  number  gets
              recharged  by  one  every  time the limit specified above is not
              reached, up to this number; the default is 5.

   mac
       --mac-source [!] address
              Match  source  MAC  address.    It   must   be   of   the   form
              XX:XX:XX:XX:XX:XX.   Note that this only makes sense for packets
              coming from an Ethernet device and entering the PREROUTING, FOR-
              WARD or INPUT chains.

   mark
       This  module  matches the netfilter mark field associated with a packet
       (which can be set using the MARK target below).

       --mark value[/mask]
              Matches packets with the given unsigned mark value (if a mask is
              specified, this is logically ANDed with the mask before the com-
              parison).

   mport
       This module matches a set of source or destination  ports.   Up  to  15
       ports can be specified.  It can only be used in conjunction with -p tcp
       or -p udp.

       --source-ports port[,port[,port...]]
              Match if the source port is one of the given  ports.   The  flag
              --sports is a convenient alias for this option.

       --destination-ports port[,port[,port...]]
              Match  if  the  destination port is one of the given ports.  The
              flag --dports is a convenient alias for this option.

       --ports port[,port[,port...]]
              Match if the both the source and destination ports are equal  to
              each other and to one of the given ports.

   multiport
       This  module  matches  a  set of source or destination ports.  Up to 15
       ports can be specified.  It can only be used in conjunction with -p tcp
       or -p udp.

       --source-ports port[,port[,port...]]
              Match  if  the  source port is one of the given ports.  The flag
              --sports is a convenient alias for this option.

       --destination-ports port[,port[,port...]]
              Match if the destination port is one of the  given  ports.   The
              flag --dports is a convenient alias for this option.

       --ports port[,port[,port...]]
              Match  if the both the source and destination ports are equal to
              each other and to one of the given ports.

   nth
       This module matches every ‘n’th packet

       --every value
              Match every ‘value’ packet

       [--counter num]
              Use internal counter number ‘num’.  Default is ‘0’.

       [--start num]
              Initialize the counter at the number ‘num’ insetad of ‘0’.  Most
              between ‘0’ and ‘value’-1.

       [--packet num]
              Match on ‘num’ packet.  Most be between ‘0’ and ‘value’-1.

   owner
       This  module  attempts  to  match various characteristics of the packet
       creator, for locally-generated packets.  It is only valid in the OUTPUT
       chain,  and  even  this  some packets (such as ICMP ping responses) may
       have no owner, and hence never match.

       --uid-owner userid
              Matches if the packet was created by a process  with  the  given
              effective user id.

       --gid-owner groupid
              Matches  if  the  packet was created by a process with the given
              effective group id.

       --pid-owner processid
              Matches if the packet was created by a process  with  the  given
              process id.

       --sid-owner sessionid
              Matches if the packet was created by a process in the given ses-
              sion group.

       --cmd-owner name
              Matches if the packet was created by a process  with  the  given
              command name.  (this option is present only if iptables was com-
              piled under a kernel supporting this feature)

       NOTE: pid, sid and command matching are broken on SMP

   physdev
       This module matches  on  the  bridge  port  input  and  output  devices
       enslaved  to  a bridge device. This module is a part of the infrastruc-
       ture that enables a transparent bridging IP firewall and is only useful
       for kernel versions above version 2.5.44.

       --physdev-in name
              Name  of  a bridge port via which a packet is received (only for
              packets entering the INPUT, FORWARD and PREROUTING  chains).  If
              the  interface  name  ends  in  a  "+", then any interface which
              begins with this name will match. If the  packet  didn’t  arrive
              through  a  bridge  device, this packet won’t match this option,
              unless ’!’ is used.

       --physdev-out name
              Name of a bridge port via which a packet is  going  to  be  sent
              (for  packets  entering  the  FORWARD,  OUTPUT  and  POSTROUTING
              chains).  If the interface name ends in a "+", then  any  inter-
              face  which  begins  with this name will match. Note that in the
              nat and mangle OUTPUT chains one cannot match on the bridge out-
              put  port,  however  one  can in the filter OUTPUT chain. If the
              packet won’t leave by a bridge device or it is yet unknown  what
              the  output  device  will  be,  then the packet won’t match this
              option, unless

       --physdev-is-in
              Matches if the packet has entered through a bridge interface.

       --physdev-is-out
              Matches if the packet will leave through a bridge interface.

       --physdev-is-bridged
              Matches if the packet is being  bridged  and  therefore  is  not
              being  routed.  This is only useful in the FORWARD and POSTROUT-
              ING chains.

   pkttype
       This module matches the link-layer packet type.

       --pkt-type [unicast|broadcast|multicast]

   random
       This module randomly matches a certain percentage of all packets.

       --average percent
              Matches the given percentage.  If omitted, a probability of  50%
              is set.

   realm
       This  matches  the  routing  realm.  Routing realms are used in complex
       routing setups involving dynamic routing protocols like BGP.

       --realm [!]value[/mask]
              Matches a given realm number (and optionally mask).

   set
       This modules macthes IP sets which can be defined by ipset(8).

       --set setname flag[,flag...]
              where flags are src and/or dst and there can be no more than six
              of them. Hence the command
               iptables -A FORWARD -m set --set test src,dst
              will match packets, for which (depending on the type of the set)
              the source address or port number of the packet can be found  in
              the specified set. If there is a binding belonging to the mached
              set element or there is a default binding  for  the  given  set,
              then  the  rule  will  match  the  packet  only  if additionally
              (depending on the type of the set) the  destination  address  or
              port  number  of the packet can be found in the set according to
              the binding.

   state
       This module, when combined with connection tracking, allows  access  to
       the connection tracking state for this packet.

       --state state
              Where  state  is a comma separated list of the connection states
              to match.  Possible states are INVALID meaning that  the  packet
              could  not  be identified for some reason which includes running
              out of memory and ICMP errors  which  don’t  correspond  to  any
              known   connection,  ESTABLISHED  meaning  that  the  packet  is
              associated with a connection which  has  seen  packets  in  both
              directions,  NEW  meaning that the packet has started a new con-
              nection, or otherwise associated with a connection which has not
              seen  packets  in  both directions, and RELATED meaning that the
              packet is starting a new connection, but is associated  with  an
              existing  connection,  such  as an FTP data transfer, or an ICMP
              error.

   tcp
       These extensions are loaded if ‘--protocol tcp’ is specified.  It  pro-
       vides the following options:

       --source-port [!] port[:port]
              Source  port  or  port range specification. This can either be a
              service name or a port number. An inclusive range  can  also  be
              specified,  using  the  format  port:port.  If the first port is
              omitted, "0" is assumed; if the  last  is  omitted,  "65535"  is
              assumed.  If the second port greater then the first they will be
              swapped.  The flag  --sport  is  a  convenient  alias  for  this
              option.

       --destination-port [!] port[:port]
              Destination  port or port range specification.  The flag --dport
              is a convenient alias for this option.

       --tcp-flags [!] mask comp
              Match when the TCP flags are as specified.  The  first  argument
              is  the  flags which we should examine, written as a comma-sepa-
              rated list, and the second argument is a comma-separated list of
              flags which must be set.  Flags are: SYN ACK FIN RST URG PSH ALL
              NONE.  Hence the command
               iptables -A FORWARD -p tcp --tcp-flags SYN,ACK,FIN,RST SYN
              will only match packets with the SYN flag set, and the ACK,  FIN
              and RST flags unset.

       [!] --syn
              Only  match TCP packets with the SYN bit set and the ACK and RST
              bits cleared.  Such packets are used to request  TCP  connection
              initiation;  for  example,  blocking  such  packets coming in an
              interface will prevent incoming TCP  connections,  but  outgoing
              TCP  connections will be unaffected.  It is equivalent to --tcp-
              flags SYN,RST,ACK SYN.  If the "!" flag  precedes  the  "--syn",
              the sense of the option is inverted.

       --tcp-option [!] number
              Match if TCP option set.

       --mss value[:value]
              Match  TCP  SYN  or SYN/ACK packets with the specified MSS value
              (or range), which control the maximum packet size for that  con-
              nection.

   tcpmss
       This  matches  the  TCP  MSS  (maximum  segment  size) field of the TCP
       header.  You can only use this on TCP SYN or SYN/ACK packets, since the
       MSS  is  only negotiated during the TCP handshake at connection startup
       time.

       [!] --mss value[:value]"
              Match a given TCP MSS value or range.

   time
       This matches if the packet arrival time/date is within a  given  range.
       All options are facultative.

        --timestart value
              Match  only  if  it is after ‘value’ (Inclusive, format: HH:MM ;
              default 00:00).

       --timestop  value
              Match only if it is before ‘value’ (Inclusive, format:  HH:MM  ;
              default 23:59).

       --days listofdays
              Match  only  if  today  is  one  of  the  given  days.  (format:
              Mon,Tue,Wed,Thu,Fri,Sat,Sun ; default everyday)

       --datestart date
              Match  only  if  it  is   after   ‘date’   (Inclusive,   format:
              YYYY[:MM[:DD[:hh[:mm[:ss]]]]]  ; h,m,s start from 0 ; default to
              1970)

       --datestop date
              Match  only  if  it  is  before   ‘date’   (Inclusive,   format:
              YYYY[:MM[:DD[:hh[:mm[:ss]]]]]  ; h,m,s start from 0 ; default to
              2037)

   tos
       This module matches the 8 bits of Type  of  Service  field  in  the  IP
       header (ie. including the precedence bits).

       --tos tos
              The argument is either a standard name, (use
               iptables -m tos -h
              to see the list), or a numeric value to match.

   ttl
       This module matches the time to live field in the IP header.

       --ttl-eq ttl
              Matches the given TTL value.

       --ttl-gt ttl
              Matches if TTL is greater than the given TTL value.

       --ttl-lt ttl
              Matches if TTL is less than the given TTL value.

   udp
       These  extensions are loaded if ‘--protocol udp’ is specified.  It pro-
       vides the following options:

       --source-port [!] port[:port]
              Source port or port range specification.  See the description of
              the --source-port option of the TCP extension for details.

       --destination-port [!] port[:port]
              Destination  port or port range specification.  See the descrip-
              tion of the --destination-port option of the TCP  extension  for
              details.

   unclean
       This  module takes no options, but attempts to match packets which seem
       malformed or unusual.  This is regarded as experimental.

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