tcpflow(1)tcpflow 1.4.5 tcpflow(1)NAMEtcpflow - TCP flow recorder
SYNOPSIStcpflow [-aBcCDhpsvVZ] [-b max_bytes] [-d debug_level] [-[eE] scanner]
[-f max_fds] [-F[ctTXMkmg]] [-i iface] [-L semlock] [-m min_bytes]
[-o outdir] [-r file1.pcap] [-R file0.pcap] [-Sname=value] [-T[file‐
name template]] [-wfile] [-x scanner] [-X file.xml] [expression]
DESCRIPTIONtcpflow 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. Rather than showing packet-by-packet
information, tcpflow reconstructs the actual data streams and stores
each flow in a separate file for later analysis. tcpflow understands
TCP sequence numbers and will correctly reconstruct data streams
regardless of retransmissions or out-of-order delivery. tcpflow pro‐
vides control over filenames for automatic binning of connections by
protocol, IP adress or connection number, and has a sophisticated plug-
in system for decompressing compressed HTTP connections, undoing MIME
encoding, or calling user-provided programs for post-processing.
By default 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.
If you want to simply process a few hundred thousand packets and see
what you have, try this:
tcpflow-a -o outdir -Fk -r packets.pcap
This will cause tcpflow to perform (-a) all processing, store the out‐
put in a directory called outdir, bin the output in directories of 1000
connections each, and read its input from the file packets.pcap. More
sophisticiated processing is possible, of course.
OPTIONS-a Enable all processing. Same as -e all.
-B Force binary output even when printing to console with -C or -c.
-b max_bytes
Specifies the maximum size of a captured flow. Any bytes beyond
max_bytes from the first byte captured will be discarded. The
default is to store an unlimited number of bytes per flow. Note:
previous versions of tcpflow could only store a maximum of 4GiB
per flow, but version 1.4 and above can really store an unlim‐
ited amount of bytes. Good thing that modern disks are so big,
eh?
-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 Console output should be in hex.
-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.
-E name
Disable all scanners and then enable scanner name
-e name
Enable scanner name.
-e all Enables all scanners. Same as -a
-e http
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
-F[format]
Specifies format for output filenames. Format specifiers: c
appends the connection counter to ALL filenames. t prepends
each filename with a Unix timestamp. T prepends each filename
with an ISO-8601 timestamp. X Do not output any files (other
than the report.xml report files).
-FM Include MD5 of each flow in the DFXML output.
-FX Suppresses file output entirely (DFXML file is still produced).
-Fk bin output in 1K directories
-Fm bin output in 1M directories (2 levels)
-Fg bin output in 1G directories (3 levels) -T[format] Specifies an
arbitrary template for filenames. %A expands to source IP
address. %a expands to source IP port. %B expands to destina‐
tion 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 "%".
-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.
-hh More help. Print more usage information and exit.
-i iface
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.
-L semlock_name
Specifies that semlock_name should be used as a Unix semaphore
to prevent two different copies of tcpflow running in two dif‐
ferent processes but outputing to the same standard output from
printing on top of each other. This is an application of Unix
named semaphores; bet you have never seen one before.
-l Treat the following arguments as filenames with an assumed -r
command before each one. This allows you to read a lot of files
at once with shell globbing. For example, to process all of the
pcap files in the current directory, use this:
tcpflow-o out -a -l *.pcap
-J Output flow information to console in multiple colors. NOTE:
This option was changed from tcpflow 1.3.
-m min_size
Forces a new connection output file when there is a skip in the
TCP session of min_size bytes or more.
-o outdir
Specifies the output directory where the transcript files will
be written.
-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.
-q Quiet mode --- don't print warnings. Currently the only warning
that tcpflow prints is a warning when more than 10,000 files are
created that the user should have provided the -Fk, -Fm, or -Fg
options. We might have other warnings in the future.
-r Read from file. Read packets from file, which was created using
the -w option of tcpdump(1). This option may be repeated any
number of times. 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.
-R Read from a file, but only to complete TCP flows. This option is
used when tcpflow is used to process a series of files that are
captured over time. For each time period n, file filen.pcap
should be processed with R -r filen.pcap, while file(n-1).pcap
should be processed with R -R file(n-1).pcap.
-Sname=value
Sets a name parameter to be equal to value for a plug-in. Use
-hh to find out all of the settable parameters.
-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 Print the version number and exit.
-v Verbose operation. Verbosely describe tcpflow's operation.
Equivalent to -d 10.
-w filename.pcap
Write packets that were not processed to filename.pcap. Typi‐
cally this will be UDP packets.
-X filename.xml
Write a DFXML report file to filename.xml. The file contains a
record of every tcp connection, how the tcpflow program was com‐
piled, and the computer on which tcpflow was run.
-Z Don't decompress gzip-compressed streams.
EXAMPLES
To record all packets arriving at or departing from sundown and extract
all of the HTTP attachments:
tcpflow-e scan_http -o outdir host sundown
To record traffic between helios and either hot or ace and bin the
results into 1000 files per directory and calculate the MD5 of each
flow:
tcpflow-X report.xml -e scan_md5 -o outdir -Fk host helios and \( hot or ace \)
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.
AUTHORS
Originally by Jeremy Elson <jelson@circlemud.org>. Substantially modi‐
fied and maintained by Simson L. Garfinkel <simsong@acm.org>. Network
visualization code by Michael Shick <mike@shick.in>
The current version of this software is available at
http://www.digitalcorpora.org/downloads/tcpflow/
An announcement mailing list for this program is at:
http://groups.google.com/group/tcpflow-users
SEE ALSOtcpdump(1), nit(4P), bpf(4), pcap(3), pcap-savefile(5), pcap-filter(7)tcpflow 1.4.5 2013-04-13 tcpflow(1)
