Have you ever wanted to inspect network TCP traffic running among containers?
Simply use TCPFLOW wrapped in a Docker container. This is a very light-weight image (~6.8MB) based on Alpine Linux 3.3. The repository is automatically published at Docker Hub as byfcz/tcpflow.
docker run --net="<see below>" byfcz/tcpflow <args>
You should choose your network settings based on your intent:
--net hostfor inspecting the traffic on your host machine--net container:<name|id>for inspecting specific container's traffic--net my-custom-netfor inspecting traffic in custom networks
Mac OSX: Since Docker runs in a VM on OSX, using host Docker networking might show you only the traffic in the VM based on its network settings.
WARNING: Not using TCPFLOW's -p option might result in computer freeze.
Following command outputs all the traffic into console for abc container.
docker run --net="container:abc" byfcz/tcpflow -p -c
Default interface TCPFLOW listens to is eth0, you might want to change it in some case using -i switch. Following command shows you all the traffic on your machine concerning port 8080 on interface eth1; it outputs only into console and different flows have different colors:
docker run --net host byfcz/tcpflow -p -c -g -i eth1 port 8080
TCPFLOW version 1.4.5
usage: tcpflow [-aBcCDhJpsvVZ] [-b max_bytes] [-d debug_level]
[-[eE] scanner] [-f max_fds] [-F[ctTXMkmg]] [-i iface] [-L semlock]
[-m min_bytes] [-o outdir] [-r file] [-R file]
[-S name=value] [-T template] [-w file] [-x scanner] [-X xmlfile]
[expression]
-a: do ALL post-processing.
-b max_bytes: max number of bytes per flow to save
-d debug_level: debug level; default is 1
-f: maximum number of file descriptors to use
-h: print this help message (-hh for more help)
-H: print detailed information about each scanner
-i: network interface on which to listen
-I: generate temporal packet-> byte index files for each flow (.findex)
-g: output each flow in alternating colors (note change!)
-l: treat non-flag arguments as input files rather than a pcap expression
-L semlock - specifies that writes are locked using a named semaphore
-p: don't use promiscuous mode
-q: quiet mode - do not print warnings
-r file: read packets from tcpdump pcap file (may be repeated)
-R file: read packets from tcpdump pcap file TO FINISH CONNECTIONS
-v: verbose operation equivalent to -d 10
-V: print version number and exit
-w file: write packets not processed to file
-o outdir : specify output directory (default '.')
-X filename : DFXML output to filename
-m bytes : specifies skip that starts a new stream (default 16777216).
-F{p} : filename prefix/suffix (-hh for options)
-T{t} : filename template (-hh for options; default %A.%a-%B.%b%V%v%C%c)
-Z: do not decompress gzip-compressed HTTP transactions
Control of Scanners:
-E scanner - turn off all scanners except scanner
-S name=value Set a configuration parameter (-hh for info)
Settable Options (and their defaults):
-S enable_report=YES Enable report.xml ()
-S http_cmd= Command to execute on each HTTP attachment (http)
-S http_alert_fd=-1 File descriptor to send information about completed HTTP attachments (http)
-S tcp_timeout=0 Timeout for TCP connections (tcpdemux)
-S check_fcs=YES Require valid Frame Check Sum (FCS) (wifiviz)
-e http - enable scanner http
-e md5 - enable scanner md5
-e netviz - enable scanner netviz
-e wifiviz - enable scanner wifiviz
-x tcpdemux - disable scanner tcpdemux
Console output options:
-B: binary output, even with -c or -C (normally -c or -C turn it off)
-c: console print only (don't create files)
-C: console print only, but without the display of source/dest header
-0: don't print newlines after packets when printing to console -s: strip non-printable characters (change to '.')
-D: output in hex (useful to combine with -c or -C)
Rendering not available because Cairo was not installed.
expression: tcpdump-like filtering expression
See the man page for additional information.