Provided by: libpcap0.8_1.0.0-2ubuntu1_i386 bug

NAME

       pcap-filter - packet filter syntax

DESCRIPTION

       pcap_compile()  is used to compile a string into a filter program.  The
       resulting filter program can then be applied to some stream of  packets
       to   determine   which   packets   will  be  supplied  to  pcap_loop(),
       pcap_dispatch(), pcap_next(), or pcap_next_ex().

       The filter expression consists of one or more  primitives.   Primitives
       usually  consist  of  an  id  (name  or number) preceded by one or more
       qualifiers.  There are three different kinds of qualifier:

       type   qualifiers say what kind of thing the id name or  number  refers
              to.   Possible  types are host, net , port and portrange.  E.g.,
              ‘host foo’, ‘net 128.3’, ‘port 20’, ‘portrange  6000-6008’.   If
              there is no type qualifier, host is assumed.

       dir    qualifiers  specify  a  particular  transfer direction to and/or
              from id.  Possible directions are src, dst, src or dst, src  and
              dst,  addr1, addr2, addr3, and addr4.  E.g., ‘src foo’, ‘dst net
              128.3’, ‘src  or  dst  port  ftp-data’.   If  there  is  no  dir
              qualifier,  src or dst is assumed.  The addr1, addr2, addr3, and
              addr4 qualifiers are only valid for  IEEE  802.11  Wireless  LAN
              link  layers.   For  some  link  layers,  such  as  SLIP and the
              ‘‘cooked’’ Linux capture mode used for the  ‘‘any’’  device  and
              for some other device types, the inbound and outbound qualifiers
              can be used to specify a desired direction.

       proto  qualifiers  restrict  the  match  to  a   particular   protocol.
              Possible  protos are: ether, fddi, tr, wlan, ip, ip6, arp, rarp,
              decnet, tcp and udp.  E.g., ‘ether src foo’,  ‘arp  net  128.3’,
              ‘tcp   port   21’,   ‘udp   portrange  7000-7009’,  ‘wlan  addr2
              0:2:3:4:5:6’.  If there is no  proto  qualifier,  all  protocols
              consistent  with  the  type  are assumed.  E.g., ‘src foo’ means
              ‘(ip or arp or rarp) src foo’ (except the latter  is  not  legal
              syntax), ‘net bar’ means ‘(ip or arp or rarp) net bar’ and ‘port
              53’ means ‘(tcp or udp) port 53’.

       [‘fddi’ is actually an  alias  for  ‘ether’;  the  parser  treats  them
       identically  as  meaning  ‘‘the  data  link level used on the specified
       network interface.’’  FDDI headers  contain  Ethernet-like  source  and
       destination addresses, and often contain Ethernet-like packet types, so
       you can filter on these FDDI fields just as with the analogous Ethernet
       fields.   FDDI  headers  also contain other fields, but you cannot name
       them explicitly in a filter expression.

       Similarly, ‘tr’ and  ‘wlan’  are  aliases  for  ‘ether’;  the  previous
       paragraph’s  statements about FDDI headers also apply to Token Ring and
       802.11 wireless LAN  headers.   For  802.11  headers,  the  destination
       address  is  the  DA  field and the source address is the SA field; the
       BSSID, RA, and TA fields aren’t tested.]

       In addition to the above, there are some special  ‘primitive’  keywords
       that  don’t  follow  the pattern: gateway, broadcast, less, greater and
       arithmetic expressions.  All of these are described below.

       More complex filter expressions are built up by using the words and, or
       and  not  to  combine primitives.  E.g., ‘host foo and not port ftp and
       not port ftp-data’.  To save typing, identical qualifier lists  can  be
       omitted.  E.g., ‘tcp dst port ftp or ftp-data or domain’ is exactly the
       same as ‘tcp dst port ftp or tcp dst port  ftp-data  or  tcp  dst  port
       domain’.

       Allowable primitives are:

       dst host host
              True  if  the  IPv4/v6  destination field of the packet is host,
              which may be either an address or a name.

       src host host
              True if the IPv4/v6 source field of the packet is host.

       host host
              True if either the IPv4/v6 source or destination of  the  packet
              is host.

              Any  of  the  above  host  expressions can be prepended with the
              keywords, ip, arp, rarp, or ip6 as in:
                   ip host host
              which is equivalent to:
                   ether proto \ip and host host
              If host is a name with multiple IP addresses, each address  will
              be checked for a match.

       ether dst ehost
              True if the Ethernet destination address is ehost.  Ehost may be
              either a name from /etc/ethers or a number (see  ethers(3N)  for
              numeric format).

       ether src ehost
              True if the Ethernet source address is ehost.

       ether host ehost
              True  if  either  the  Ethernet source or destination address is
              ehost.

       gateway host
              True if the packet used host as a gateway.  I.e.,  the  Ethernet
              source or destination address was host but neither the IP source
              nor the IP destination was host.  Host must be a name  and  must
              be   found   both   by   the  machine’s  host-name-to-IP-address
              resolution mechanisms (host name file, DNS, NIS,  etc.)  and  by
              the machine’s host-name-to-Ethernet-address resolution mechanism
              (/etc/ethers, etc.).  (An equivalent expression is
                   ether host ehost and not host host
              which can be used with  either  names  or  numbers  for  host  /
              ehost.)  This syntax does not work in IPv6-enabled configuration
              at this moment.

       dst net net
              True if the IPv4/v6 destination address  of  the  packet  has  a
              network  number  of  net.   Net  may  be  either a name from the
              networks database (/etc/networks, etc.) or a network number.  An
              IPv4  network  number  can  be  written  as a dotted quad (e.g.,
              192.168.1.0), dotted triple (e.g., 192.168.1), dotted pair (e.g,
              172.16),   or   single   number   (e.g.,  10);  the  netmask  is
              255.255.255.255 for a dotted quad (which means that it’s  really
              a  host  match),  255.255.255.0 for a dotted triple, 255.255.0.0
              for a dotted pair, or 255.0.0.0 for a single  number.   An  IPv6
              network  number  must  be  written  out  fully;  the  netmask is
              ff:ff:ff:ff:ff:ff:ff:ff, so IPv6 "network"  matches  are  really
              always  host  matches,  and  a  network match requires a netmask
              length.

       src net net
              True if the IPv4/v6 source address of the packet has  a  network
              number of net.

       net net
              True  if either the IPv4/v6 source or destination address of the
              packet has a network number of net.

       net net mask netmask
              True if the IPv4 address matches net with the specific  netmask.
              May  be qualified with src or dst.  Note that this syntax is not
              valid for IPv6 net.

       net net/len
              True if the IPv4/v6 address matches net with a netmask len  bits
              wide.  May be qualified with src or dst.

       dst port port
              True if the packet is ip/tcp, ip/udp, ip6/tcp or ip6/udp and has
              a destination port value of port.  The port can be a number or a
              name used in /etc/services (see tcp(4P) and udp(4P)).  If a name
              is used, both the port number and protocol are  checked.   If  a
              number  or  ambiguous  name  is  used,  only  the port number is
              checked (e.g., dst port 513 will print  both  tcp/login  traffic
              and  udp/who traffic, and port domain will print both tcp/domain
              and udp/domain traffic).

       src port port
              True if the packet has a source port value of port.

       port port
              True if either the source or destination port of the  packet  is
              port.

       dst portrange port1-port2
              True if the packet is ip/tcp, ip/udp, ip6/tcp or ip6/udp and has
              a destination port value between port1  and  port2.   port1  and
              port2  are interpreted in the same fashion as the port parameter
              for port.

       src portrange port1-port2
              True if the packet has a source port  value  between  port1  and
              port2.

       portrange port1-port2
              True  if  either the source or destination port of the packet is
              between port1 and port2.

              Any of the above port or port range expressions can be prepended
              with the keywords, tcp or udp, as in:
                   tcp src port port
              which matches only tcp packets whose source port is port.

       less length
              True  if  the  packet has a length less than or equal to length.
              This is equivalent to:
                   len <= length.

       greater length
              True if the packet has a length greater than or equal to length.
              This is equivalent to:
                   len >= length.

       ip proto protocol
              True  if  the  packet is an IPv4 packet (see ip(4P)) of protocol
              type protocol.  Protocol can be a number or  one  of  the  names
              icmp,  icmp6, igmp, igrp, pim, ah, esp, vrrp, udp, or tcp.  Note
              that the identifiers tcp, udp, and icmp are  also  keywords  and
              must  be  escaped via backslash (\), which is \\ in the C-shell.
              Note that this primitive does  not  chase  the  protocol  header
              chain.

       ip6 proto protocol
              True  if the packet is an IPv6 packet of protocol type protocol.
              Note that this primitive does  not  chase  the  protocol  header
              chain.

       ip6 protochain protocol
              True  if the packet is IPv6 packet, and contains protocol header
              with type protocol in its protocol header chain.  For example,
                   ip6 protochain 6
              matches any IPv6 packet with TCP protocol header in the protocol
              header   chain.    The   packet   may   contain,   for  example,
              authentication header,  routing  header,  or  hop-by-hop  option
              header,  between  IPv6  header  and  TCP  header.   The BPF code
              emitted by this primitive is complex and cannot be optimized  by
              the BPF optimizer code, so this can be somewhat slow.

       ip protochain protocol
              Equivalent to ip6 protochain protocol, but this is for IPv4.

       ether broadcast
              True  if  the packet is an Ethernet broadcast packet.  The ether
              keyword is optional.

       ip broadcast
              True if the packet is an IPv4 broadcast packet.  It  checks  for
              both  the  all-zeroes  and  all-ones  broadcast conventions, and
              looks up the subnet mask on the interface on which  the  capture
              is being done.

              If  the  subnet  mask  of  the interface on which the capture is
              being done is not available, either  because  the  interface  on
              which  capture  is  being  done  has  no  netmask or because the
              capture is being done on the Linux "any"  interface,  which  can
              capture  on  more  than  one interface, this check will not work
              correctly.

       ether multicast
              True if the packet is an Ethernet multicast packet.   The  ether
              keyword is optional.  This is shorthand for ‘ether[0] & 1 != 0’.

       ip multicast
              True if the packet is an IPv4 multicast packet.

       ip6 multicast
              True if the packet is an IPv6 multicast packet.

       ether proto protocol
              True if the packet is of ether type protocol.  Protocol can be a
              number  or  one  of  the  names ip, ip6, arp, rarp, atalk, aarp,
              decnet, sca, lat, mopdl, moprc, iso, stp, ipx, or netbeui.  Note
              these  identifiers  are  also  keywords  and must be escaped via
              backslash (\).

              [In the case of FDDI (e.g., ‘fddi  protocol  arp’),  Token  Ring
              (e.g.,  ‘tr protocol arp’), and IEEE 802.11 wireless LANS (e.g.,
              ‘wlan protocol arp’), for most of those protocols, the  protocol
              identification  comes  from the 802.2 Logical Link Control (LLC)
              header, which is usually layered on top of the FDDI, Token Ring,
              or 802.11 header.

              When  filtering  for  most  protocol  identifiers on FDDI, Token
              Ring, or 802.11, the filter checks only the protocol ID field of
              an  LLC  header  in so-called SNAP format with an Organizational
              Unit Identifier (OUI) of 0x000000, for encapsulated Ethernet; it
              doesn’t  check  whether the packet is in SNAP format with an OUI
              of 0x000000.  The exceptions are:

              iso    the filter checks the DSAP  (Destination  Service  Access
                     Point)  and  SSAP (Source Service Access Point) fields of
                     the LLC header;

              stp and netbeui
                     the filter checks the DSAP of the LLC header;

              atalk  the filter checks for a SNAP-format packet with an OUI of
                     0x080007 and the AppleTalk etype.

              In  the  case  of  Ethernet, the filter checks the Ethernet type
              field for most of those protocols.  The exceptions are:

              iso, stp, and netbeui
                     the filter checks for an 802.3 frame and then checks  the
                     LLC header as it does for FDDI, Token Ring, and 802.11;

              atalk  the  filter  checks  both  for  the AppleTalk etype in an
                     Ethernet frame and for a SNAP-format packet  as  it  does
                     for FDDI, Token Ring, and 802.11;

              aarp   the  filter  checks for the AppleTalk ARP etype in either
                     an Ethernet frame or an 802.2 SNAP frame with an  OUI  of
                     0x000000;

              ipx    the filter checks for the IPX etype in an Ethernet frame,
                     the IPX DSAP in the LLC  header,  the  802.3-with-no-LLC-
                     header  encapsulation of IPX, and the IPX etype in a SNAP
                     frame.

       decnet src host
              True if the DECNET source address  is  host,  which  may  be  an
              address  of the form ‘‘10.123’’, or a DECNET host name.  [DECNET
              host name support is only available on ULTRIX systems  that  are
              configured to run DECNET.]

       decnet dst host
              True if the DECNET destination address is host.

       decnet host host
              True if either the DECNET source or destination address is host.

       ifname interface
              True if the packet was  logged  as  coming  from  the  specified
              interface  (applies  only  to  packets  logged  by  OpenBSD’s or
              FreeBSD’s pf(4)).

       on interface
              Synonymous with the ifname modifier.

       rnr num
              True if the packet was logged as matching the specified PF  rule
              number (applies only to packets logged by OpenBSD’s or FreeBSD’s
              pf(4)).

       rulenum num
              Synonymous with the rnr modifier.

       reason code
              True if the packet was logged with the specified PF reason code.
              The   known  codes  are:  match,  bad-offset,  fragment,  short,
              normalize,  and  memory  (applies  only  to  packets  logged  by
              OpenBSD’s or FreeBSD’s pf(4)).

       rset name
              True  if  the  packet  was  logged  as matching the specified PF
              ruleset name of an anchored ruleset  (applies  only  to  packets
              logged by OpenBSD’s or FreeBSD’s pf(4)).

       ruleset name
              Synonomous with the rset modifier.

       srnr num
              True  if the packet was logged as matching the specified PF rule
              number of an anchored ruleset (applies only to packets logged by
              OpenBSD’s or FreeBSD’s pf(4)).

       subrulenum num
              Synonomous with the srnr modifier.

       action act
              True if PF took the specified action when the packet was logged.
              Known actions are: pass and block and, with  later  versions  of
              pf(4)),  nat,  rdr,  binat  and  scrub  (applies only to packets
              logged by OpenBSD’s or FreeBSD’s pf(4)).

       wlan addr1 ehost
              True if the first IEEE 802.11 address is ehost.

       wlan addr2 ehost
              True if the second IEEE 802.11 address, if  present,  is  ehost.
              The  second  address  field is used in all frames except for CTS
              (Clear To Send) and ACK (Acknowledgment) control frames.

       wlan addr3 ehost
              True if the third IEEE 802.11 address,  if  present,  is  ehost.
              The  third  address field is used in management and data frames,
              but not in control frames.

       wlan addr4 ehost
              True if the fourth IEEE 802.11 address, if  present,  is  ehost.
              The  fourth  address  field  is  only  used  for  WDS  (Wireless
              Distribution System) frames.

       ip, ip6, arp, rarp, atalk, aarp, decnet, iso, stp, ipx, netbeui
              Abbreviations for:
                   ether proto p
              where p is one of the above protocols.

       lat, moprc, mopdl
              Abbreviations for:
                   ether proto p
              where p is one of  the  above  protocols.   Note  that  not  all
              applications  using  pcap(3)  currently  know how to parse these
              protocols.

       type wlan_type
              True if  the  IEEE  802.11  frame  type  matches  the  specified
              wlan_type.  Valid wlan_types are: mgt, ctl and data.

       type wlan_type subtype wlan_subtype
              True  if  the  IEEE  802.11  frame  type  matches  the specified
              wlan_type and frame subtype matches the specified  wlan_subtype.

              If the specified wlan_type is mgt, then valid wlan_subtypes are:
              assoc-req,  assoc-resp,  reassoc-req,  reassoc-resp,  probe-req,
              probe-resp, beacon, atim, disassoc, auth and deauth.

              If the specified wlan_type is ctl, then valid wlan_subtypes are:
              ps-poll, rts, cts, ack, cf-end and cf-end-ack.

              If the specified wlan_type is  data,  then  valid  wlan_subtypes
              are:  data,  data-cf-ack,  data-cf-poll, data-cf-ack-poll, null,
              cf-ack, cf-poll, cf-ack-poll,  qos-data,  qos-data-cf-ack,  qos-
              data-cf-poll, qos-data-cf-ack-poll, qos, qos-cf-poll and qos-cf-
              ack-poll.

       subtype wlan_subtype
              True if the IEEE 802.11  frame  subtype  matches  the  specified
              wlan_subtype  and  frame  has  the  type  to which the specified
              wlan_subtype belongs.

       dir dir
              True if the IEEE 802.11 frame direction  matches  the  specified
              dir.   Valid  directions  are:  nods, tods, fromds, dstods, or a
              numeric value.

       vlan [vlan_id]
              True if the packet is an IEEE 802.1Q VLAN packet.  If  [vlan_id]
              is specified, only true if the packet has the specified vlan_id.
              Note that the  first  vlan  keyword  encountered  in  expression
              changes  the decoding offsets for the remainder of expression on
              the assumption that the packet  is  a  VLAN  packet.   The  vlan
              [vlan_id]  expression  may  be used more than once, to filter on
              VLAN hierarchies.  Each use of that  expression  increments  the
              filter offsets by 4.

              For example:
                   vlan 100 && vlan 200
              filters on VLAN 200 encapsulated within VLAN 100, and
                   vlan && vlan 300 && ip
              filters  IPv4  protocols  encapsulated  in VLAN 300 encapsulated
              within any higher order VLAN.

       mpls [label_num]
              True if the  packet  is  an  MPLS  packet.   If  [label_num]  is
              specified,  only true is the packet has the specified label_num.
              Note that the  first  mpls  keyword  encountered  in  expression
              changes  the decoding offsets for the remainder of expression on
              the assumption that the packet is a MPLS-encapsulated IP packet.
              The  mpls  [label_num] expression may be used more than once, to
              filter  on  MPLS  hierarchies.   Each  use  of  that  expression
              increments the filter offsets by 4.

              For example:
                   mpls 100000 && mpls 1024
              filters packets with an outer label of 100000 and an inner label
              of 1024, and
                   mpls && mpls 1024 && host 192.9.200.1
              filters packets to or from 192.9.200.1 with an  inner  label  of
              1024 and any outer label.

       pppoed True  if  the  packet  is  a  PPP-over-Ethernet Discovery packet
              (Ethernet type 0x8863).

       pppoes True  if  the  packet  is  a  PPP-over-Ethernet  Session  packet
              (Ethernet  type  0x8864).   Note  that  the first pppoes keyword
              encountered in expression changes the decoding offsets  for  the
              remainder  of  expression on the assumption that the packet is a
              PPPoE session packet.

              For example:
                   pppoes && ip
              filters IPv4 protocols encapsulated in PPPoE.

       tcp, udp, icmp
              Abbreviations for:
                   ip proto p or ip6 proto p
              where p is one of the above protocols.

       iso proto protocol
              True if the packet is an OSI packet of protocol  type  protocol.
              Protocol  can  be  a  number  or one of the names clnp, esis, or
              isis.

       clnp, esis, isis
              Abbreviations for:
                   iso proto p
              where p is one of the above protocols.

       l1, l2, iih, lsp, snp, csnp, psnp
              Abbreviations for IS-IS PDU types.

       vpi n  True if the packet is an ATM packet, for SunATM on Solaris, with
              a virtual path identifier of n.

       vci n  True if the packet is an ATM packet, for SunATM on Solaris, with
              a virtual channel identifier of n.

       lane   True if the packet is an ATM packet, for SunATM on Solaris,  and
              is  an  ATM  LANE  packet.   Note  that  the  first lane keyword
              encountered  in  expression  changes  the  tests  done  in   the
              remainder  of  expression  on  the assumption that the packet is
              either a LANE emulated Ethernet packet  or  a  LANE  LE  Control
              packet.   If  lane isn’t specified, the tests are done under the
              assumption that the packet is an LLC-encapsulated packet.

       llc    True if the packet is an ATM packet, for SunATM on Solaris,  and
              is an LLC-encapsulated packet.

       oamf4s True  if the packet is an ATM packet, for SunATM on Solaris, and
              is a segment OAM F4 flow cell (VPI=0 & VCI=3).

       oamf4e True if the packet is an ATM packet, for SunATM on Solaris,  and
              is an end-to-end OAM F4 flow cell (VPI=0 & VCI=4).

       oamf4  True  if the packet is an ATM packet, for SunATM on Solaris, and
              is a segment or end-to-end OAM F4 flow cell (VPI=0  &  (VCI=3  |
              VCI=4)).

       oam    True  if the packet is an ATM packet, for SunATM on Solaris, and
              is a segment or end-to-end OAM F4 flow cell (VPI=0  &  (VCI=3  |
              VCI=4)).

       metac  True  if the packet is an ATM packet, for SunATM on Solaris, and
              is on a meta signaling circuit (VPI=0 & VCI=1).

       bcc    True if the packet is an ATM packet, for SunATM on Solaris,  and
              is on a broadcast signaling circuit (VPI=0 & VCI=2).

       sc     True  if the packet is an ATM packet, for SunATM on Solaris, and
              is on a signaling circuit (VPI=0 & VCI=5).

       ilmic  True if the packet is an ATM packet, for SunATM on Solaris,  and
              is on an ILMI circuit (VPI=0 & VCI=16).

       connectmsg
              True  if the packet is an ATM packet, for SunATM on Solaris, and
              is  on  a  signaling  circuit  and  is  a  Q.2931  Setup,   Call
              Proceeding,  Connect,  Connect  Ack,  Release,  or  Release Done
              message.

       metaconnect
              True if the packet is an ATM packet, for SunATM on Solaris,  and
              is  on  a  meta  signaling  circuit  and is a Q.2931 Setup, Call
              Proceeding, Connect, Release, or Release Done message.

       expr relop expr
              True if the relation holds, where relop is one of >, <, >=,  <=,
              =,  !=, and expr is an arithmetic expression composed of integer
              constants (expressed in standard C syntax),  the  normal  binary
              operators  [+,  -,  *,  /, &, |, <<, >>], a length operator, and
              special packet data accessors.  Note that  all  comparisons  are
              unsigned,  so that, for example, 0x80000000 and 0xffffffff are >
              0.  To access data inside the packet, use the following syntax:
                   proto [ expr : size ]
              Proto is one of ether, fddi, tr, wlan, ppp, slip, link, ip, arp,
              rarp,  tcp,  udp, icmp, ip6 or radio, and indicates the protocol
              layer for the index operation.  (ether,  fddi,  wlan,  tr,  ppp,
              slip  and  link all refer to the link layer. radio refers to the
              "radio header" added to some 802.11 captures.)  Note  that  tcp,
              udp and other upper-layer protocol types only apply to IPv4, not
              IPv6 (this will be fixed  in  the  future).   The  byte  offset,
              relative  to  the  indicated  protocol  layer, is given by expr.
              Size is optional and indicates the number of bytes in the  field
              of interest; it can be either one, two, or four, and defaults to
              one.  The length operator, indicated by the keyword  len,  gives
              the length of the packet.

              For  example, ‘ether[0] & 1 != 0’ catches all multicast traffic.
              The expression ‘ip[0] & 0xf != 5’ catches all IPv4 packets  with
              options.   The  expression  ‘ip[6:2]  & 0x1fff = 0’ catches only
              unfragmented IPv4 datagrams and frag  zero  of  fragmented  IPv4
              datagrams.   This check is implicitly applied to the tcp and udp
              index operations.  For instance, tcp[0] always means  the  first
              byte  of  the  TCP  header, and never means the first byte of an
              intervening fragment.

              Some offsets and field values may be expressed as  names  rather
              than  as  numeric  values.   The following protocol header field
              offsets are available:  icmptype  (ICMP  type  field),  icmpcode
              (ICMP code field), and tcpflags (TCP flags field).

              The  following  ICMP  type  field  values  are  available: icmp-
              echoreply, icmp-unreach, icmp-sourcequench, icmp-redirect, icmp-
              echo,   icmp-routeradvert,   icmp-routersolicit,  icmp-timxceed,
              icmp-paramprob, icmp-tstamp, icmp-tstampreply, icmp-ireq,  icmp-
              ireqreply, icmp-maskreq, icmp-maskreply.

              The  following  TCP  flags  field values are available: tcp-fin,
              tcp-syn, tcp-rst, tcp-push, tcp-ack, tcp-urg.

       Primitives may be combined using:

              A parenthesized group of primitives and  operators  (parentheses
              are special to the Shell and must be escaped).

              Negation (‘!’ or ‘not’).

              Concatenation (‘&&’ or ‘and’).

              Alternation (‘||’ or ‘or’).

       Negation  has  highest  precedence.  Alternation and concatenation have
       equal precedence and associate left to right.  Note that  explicit  and
       tokens, not juxtaposition, are now required for concatenation.

       If an identifier is given without a keyword, the most recent keyword is
       assumed.  For example,
            not host vs and ace
       is short for
            not host vs and host ace
       which should not be confused with
            not ( host vs or ace )

EXAMPLES

       To select all packets arriving at or departing from sundown:
              host sundown

       To select traffic between helios and either hot or ace:
              host helios and \( hot or ace \)

       To select all IP packets between ace and any host except helios:
              ip host ace and not helios

       To select all traffic between local hosts and hosts at Berkeley:
              net ucb-ether

       To select all ftp traffic through internet gateway snup:
              gateway snup and (port ftp or ftp-data)

       To select traffic neither sourced from nor destined for local hosts (if
       you gateway to one other net, this stuff should never make it onto your
       local net).
              ip and not net localnet

       To select the start and end packets (the SYN and FIN packets)  of  each
       TCP conversation that involves a non-local host.
              tcp[tcpflags] & (tcp-syn|tcp-fin) != 0 and not src and dst net localnet

       To  select  all  IPv4 HTTP packets to and from port 80, i.e. print only
       packets that contain data, not, for example, SYN and  FIN  packets  and
       ACK-only packets.  (IPv6 is left as an exercise for the reader.)
              tcp port 80 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - ((tcp[12]&0xf0)>>2)) != 0)

       To select IP packets longer than 576 bytes sent through gateway snup:
              gateway snup and ip[2:2] > 576

       To  select  IP  broadcast  or  multicast packets that were not sent via
       Ethernet broadcast or multicast:
              ether[0] & 1 = 0 and ip[16] >= 224

       To select all ICMP packets that are not  echo  requests/replies  (i.e.,
       not ping packets):
              icmp[icmptype] != icmp-echo and icmp[icmptype] != icmp-echoreply

SEE ALSO

       pcap(3PCAP)

AUTHORS

       The original authors are:

       Van  Jacobson,  Craig  Leres  and  Steven  McCanne, all of the Lawrence
       Berkeley National Laboratory, University of California, Berkeley, CA.

       It is currently being maintained by tcpdump.org.

       The current version of libpcap is available via http:

              http://www.tcpdump.org/

       The original distribution is available via anonymous ftp:

              ftp://ftp.ee.lbl.gov/tcpdump.tar.Z

BUGS

       Please send problems, bugs, questions, desirable enhancements, etc. to:

              tcpdump-workers@lists.tcpdump.org

       Filter  expressions  on  fields  other than those in Token Ring headers
       will not correctly handle source-routed Token Ring packets.

       Filter expressions on fields other than those in  802.11  headers  will
       not  correctly  handle  802.11 data packets with both To DS and From DS
       set.

       ip6 proto should chase header chain, but at this moment  it  does  not.
       ip6 protochain is supplied for this behavior.

       Arithmetic  expression  against  transport  layer headers, like tcp[0],
       does not work against IPv6 packets.  It only looks at IPv4 packets.

                                6 January 2008                  PCAP-FILTER(7)