tcpflow v1.2.6

tcpflow(1)                       tcpflow 1.2.6                      tcpflow(1)



NAME
       tcpflow - TCP flow recorder

SYNOPSIS
       tcpflow [-BcCehPpsv] [-b max_bytes] [-d debug_level] [-f max_fds]
       [-i iface] [-r file] [-m minskip] [-X file.xml] [-F[outputformat]]
       [-T[filenameetemplate]] [expression]

DESCRIPTION
       tcpflow is a program that captures data transmitted as part of TCP con‐
       nections (flows), and stores the data in a way that is convenient for
       protocol analysis or debugging.  A program like tcpdump(4) shows a sum‐
       mary of packets seen on the wire, but usually doesn't store the data
       that's actually being transmitted.  In contrast, tcpflow reconstructs
       the actual data streams and stores each flow in a separate file for
       later analysis.  tcpflow understands TCP sequence numbers and will cor‐
       rectly reconstruct data streams regardless of retransmissions or out-
       of-order delivery.

       tcpflow stores all captured data in files that have names of the form
            192.168.101.102.02345-010.011.012.013.45103
       where the contents of the above file would be data transmitted from
       host 192.168.101.102 port 2345, to host 10.11.12.13 port 45103.

OPTIONS
       -B     Force binary output even when printing to console with -C or -c.

       -b     Max bytes per flow.  Capture no more than max_bytes bytes per
              flow.  Any data captured for a flow beyond max_bytes from the
              first byte captured will be discarded.  The default is to store
              an unlimited number of bytes per flow.

       -c     Console print.  Print the contents of packets to stdout as they
              are received, without storing any captured data to files
              (implies

       -C     Console print without the packet source and destination details
              being printed.  Print the contents of packets to stdout as they
              are received, without storing any captured data to files
              (implies -e When outputting to the console each flow will be
              output in different colors (blue for client to server flows, red
              for server to client flows, green for undecided flows).  -s ).

       -d     Debug level.  Set the level of debugging messages printed to
              stderr to debug_level.  Higher numbers produce more messages.
              -d 0 causes completely silent operation.  -d 1 , the default,
              produces minimal status messages.  -d 10 produces verbose output
              equivalent to -v .  Numbers higher than 10 can produce a large
              amount of debugging information useful only to developers.

       -F[format]
              Specifies format for output filenames. Format specifiers: t
              prepends each filename with a Unix timestamp.  T prepends each
              filename with an ISO-8601 timestamp.  c appends each filename
              with a connection counter.

       -FM    Include MD5 of each flow in the DFXML output.

       -FX    Suppresses file output entirely (DFXML file is still produced).

       -T[format]
              Specifies an arbitrary template for filenames.  %A expands to
              source IP address.  %a expands to source IP port.  %B expands to
              destination IP address.  %a expands to destination IP port.  %T
              expands to timestamp in ISO8601 format.  %t expands to timestamp
              in Unix time_t format.  %V expands to "--" if a VLAN is present.
              %v expands to the VLAN number if a VLAN is present.  %C expands
              to "c" if the connection count>0.  %c expands to the connection
              count if the connection count>0.  %# always expands to the con‐
              nection count.  %% prints a "%".

       -AH    Perform HTTP post-processing ("After" processing). If the output
              file is
                   208.111.153.175.00080-192.168.001.064.37314,
              Then the post-processing will create the files:
                   208.111.153.175.00080-192.168.001.064.37314-HTTP
                   208.111.153.175.00080-192.168.001.064.37314-HTTPBODY
              If the HTTPBODY was compressed with GZIP, you may get a third
              file as well:
                   208.111.153.175.00080-192.168.001.064.37314-HTTPBODY-GZIP
              Additional information about these streams, such as their MD5
              hash value, is also written to the DFXML file

       -fmax_fds
              Max file descriptors used.  Limit the number of file descriptors
              used by tcpflow to max_fds.  Higher numbers use more system
              resources, but usually perform better.  If the underlying oper‐
              ating system supports the setrlimit() system call, the OS will
              be asked to enforce the requested limit.  The default is for
              tcpflow to use the maximum number of file descriptors allowed by
              the OS.  The -v option will report how many file descriptors
              tcpflow is using.

       -h     Help.  Print usage information and exit.

       -i     Interface name.  Capture packets from the network interface
              named iface.  If no interface is specified with -i , a reason‐
              able default will be used by libpcap automatically.

       -m min_size
              Forces a new connection output file when there is a skip in the
              TCP session of min_size bytes or more.

       -P     No purge. Normally tcpflow removes connections from the hash ta‐
              ble after the connection is closed with a FIN. This conserves
              memory but takes additional CPU time. Selecting this option
              causes the std::tr1:unordered_map to grow without bounds, as
              tcpflow did prior to version 1.1. That makes tcpflow run faster
              if there are less than 10 million connections, but can lead to
              out-of-memory errors.

       -p     No promiscuous mode.  Normally, tcpflow attempts to put the net‐
              work interface into promiscuous mode before capturing packets.
              The -p option tells tcpflow not to put the interface into pro‐
              miscuous mode.  Note that it might already be in promiscuous
              mode for some other reason.

       -r     Read from file.  Read packets from file, which was created using
              the -w option of tcpdump(1).  Standard input is used if file is
              ``-''.  Note that for this option to be useful, tcpdump's -s
              option should be used to set the snaplen to the MTU of the
              interface (e.g., 1500) while capturing packets.

       -s     Strip non-printables.  Convert all non-printable characters to
              the "." character before printing packets to the console or
              storing them to a file.

       -v     Verbose operation.  Verbosely describe tcpflow's operation.
              Equivalent to -d 10 .

FILTERING EXPRESSIONS
       The expression specified on the command-line specifies which packets
       should be captured.  Because tcpflow uses the the libpcap library,
       tcpflow has the same powerful filtering language available as programs
       such as tcpdump(1).

       The following part of the man page is excerpted from the tcpdump man
       page.

       expression selects which packets will be dumped.  If no expression is
       given, all packets on the net will be dumped.  Otherwise, only packets
       for which expression is `true' will be dumped.

       The 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 and port.  E.g., `host foo',
              `net 128.3', `port 20'.  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 and src
              and dst.  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.
              For `null' link layers (i.e. point to point protocols such as
              slip) the inbound and outbound qualifiers can be used to specify
              a desired direction.

       proto  qualifiers restrict the match to a particular protocol.  Possi‐
              ble protos are: ether, fddi, ip, arp, rarp, decnet, lat, sca,
              moprc, mopdl, tcp and udp.  E.g., `ether src foo', `arp net
              128.3', `tcp port 21'.  If there is no proto qualifier, all pro‐
              tocols 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 iden‐
       tically 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.]

       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 IP destination field of the packet is host, which
              may be either an address or a name.

       src host host
              True if the IP source field of the packet is host.

       host host
              True if either the IP source or destination of the packet is
              host.  Any of the above host expressions can be prepended with
              the keywords, ip, arp, or rarp 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 in both /etc/hosts and /etc/ethers.  (An equivalent
              expression is
                   ether host ehost and not host host
              which can be used with either names or numbers for host /
              ehost.)

       dst net net
              True if the IP destination address of the packet has a network
              number of net. Net may be either a name from /etc/networks or a
              network number (see networks(5) for details).

       src net net
              True if the IP source address of the packet has a network number
              of net.

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

       net net mask mask
              True if the IP address matches net with the specific netmask.
              May be qualified with src or dst.

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

       dst port port
              True if the packet is ip/tcp or ip/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 traf‐
              fic, 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.  Any of the above port 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 ip packet (see ip(4P)) of protocol type
              protocol.  Protocol can be a number or one of the names icmp,
              igrp, udp, nd, 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.

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

       ip broadcast
              True if the packet is an IP broadcast packet.  It checks for
              both the all-zeroes and all-ones broadcast conventions, and
              looks up the local subnet mask.

       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 IP multicast packet.

       ether proto protocol
              True if the packet is of ether type protocol.  Protocol can be a
              number or a name like ip, arp, or rarp.  Note these identifiers
              are also keywords and must be escaped via backslash (\).  [In
              the case of FDDI (e.g., `fddi protocol arp'), the protocol iden‐
              tification comes from the 802.2 Logical Link Control (LLC)
              header, which is usually layered on top of the FDDI header.
              Tcpdump assumes, when filtering on the protocol identifier, that
              all FDDI packets include an LLC header, and that the LLC header
              is in so-called SNAP format.]

       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.

       ip, arp, rarp, decnet
              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 tcpdump does
              not currently know how to parse these protocols.

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

       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.  To access data inside the packet, use
              the following syntax:
                   proto [ expr : size ]
              Proto is one of ether, fddi, ip, arp, rarp, tcp, udp, or icmp,
              and indicates the protocol layer for the index operation.  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 IP packets with
              options. The expression `ip[6:2] & 0x1fff = 0' catches only
              unfragmented datagrams and frag zero of fragmented datagrams.
              This check is implicitly applied to the tcp and udp index opera‐
              tions.  For instance, tcp[0] always means the first byte of the
              TCP header, and never means the first byte of an intervening
              fragment.

       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 )

       Expression arguments can be passed to tcpdump as either a single argu‐
       ment or as multiple arguments, whichever is more convenient.  Gener‐
       ally, if the expression contains Shell metacharacters, it is easier to
       pass it as a single, quoted argument.  Multiple arguments are concate‐
       nated with spaces before being parsed.

EXAMPLES
       The following part of the man page is excerpted from the tcpdump man
       page.

       To record all packets arriving at or departing from sundown:
              tcpflow host sundown

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

       To record traffic between ace and any host except helios:
              tcpflow host ace and not helios

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

       To record all ftp traffic through internet gateway snup: (note that the
       expression is quoted to prevent the shell from (mis-)interpreting the
       parentheses):
              tcpflow 'gateway snup and (port ftp or ftp-data)'

BUGS
       Please send bug reports to simsong@acm.org.

       tcpflow currently does not understand IP fragments.  Flows containing
       IP fragments will not be recorded correctly.

       tcpflow never frees state associated with flows that it records, so
       will grow large if used to capture a very large number of flows (e.g.,
       on the order of 100,000 flows or more).

       There appears to be a bug in the way that Linux delivers packets to
       libpcap when using the loopback interface ("localhost").  When listen‐
       ing to the Linux loopback interface, selective packet filtering is not
       possible; all TCP flows on the localhost interface will be recorded.

AUTHORS
       Originally by Jeremy Elson <jelson@circlemud.org>.  Substantially modi‐
       fied and maintained by Simson L. Garfinkel <simsong@acm.org>.

       The current version of this software is available at
              http://www.afflib.org/

       An announcement mailing list for this program is at:
              http://groups.google.com/group/tcpflow-users

SEE ALSO
       tcpdump(1), nit(4P), bpf(4), pcap(3)



tcpflow 1.2.6                     15 Jan 2011                       tcpflow(1)