Tcpdump

Applicable for

STM32MP13x lines, STM32MP15x lines, Unknown MPU, Unknown MPU, Unknown MPU

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1. Article purpose

This article provides the basic information needed to start using the Linux tool: tcpdump.

2. Introduction

The following table provides a brief description of the tool, as well as its availability depending on the software packages:

: this tool is either present (ready to use or to be activated), or can be integrated and activated on the software package.

: this tool is not present and cannot be integrated, or it is present but cannot be activated on the software package.

Tool			STM32MPU Embedded Software distribution			STM32MPU Embedded Software distribution for Android™ Only supported for STM32MP15x lines  Warning The STM32MPU distribution for Android™ is not available in the v4 ecosystem releases: refer to the Tcpdump page for the v2 ecosystem releases (in archived wiki).
Name	Category	Purpose	Starter Package	Developer Package	Distribution Package	Starter Package	Developer Package	Distribution Package
tcpdump	Monitoring tools	tcpdump is a common packet analyzer that runs under the command line. It allows the user to display TCP/IP and other packets being transmitted or received over a network to which the computer is connected.

3. Installing the trace and debug tool on your target board

3.1. Using the STM32MPU Embedded Software distribution

tcpdump is installed by default and ready to be used with all STM32MPU Embedded Software Packages.

which tcpdump
/usr/bin/tcpdump

tcpdump is integrated in weston image distribution through meta-st package: meta-st/meta-st-openstlinux/recipes-st/packagegroups/packagegroup-framework-tools.bb.

RDEPENDS_packagegroup-framework-tools-network = "\
   tcpdump         \
   iptables        \
   ...
RDEPENDS:packagegroup-framework-tools-network = "\
    tcpdump         \
    packagegroup-core-full-cmdline-extended \
    ...
    "

3.2. Using the STM32MPU Embedded Software distribution for Android™

tcpdump is installed by default (/system/bin/tcpdump) and is ready to be used with all STM32MPU software packages for Android™, as soon as debug mode is enable (eng or userdebug build variants). Please see external/tcpdump/Android.mk.

which tcpdump
/system/bin/tcpdump

4. Getting started

• Command line description

tcpdump --help
Usage: tcpdump [-aAbdDefhHIJKlLnNOpqStuUvxX#] [ -B size ] [ -c count ]
               [ -C file_size ] [ -E algo:secret ] [ -F file ] [ -G seconds ]
               [ -i interface ] [ -j tstamptype ] [ -M secret ] [ --number ]
               [ -Q in|out|inout ]
               [ -r file ] [ -s snaplen ] [ --time-stamp-precision precision ]
               [ --immediate-mode ] [ -T type ] [ --version ] [ -V file ]
               [ -w file ] [ -W filecount ] [ -y datalinktype ] [ -z postrotate-command ]
               [ -Z user ] [ expression ]

• Dump tcp traffic on end0 interface (you can use ip addr show command to know the list of network interface available)

tcpdump -i end0
tcpdump: verbose output suppressed, use -v or -v[v] for full protocol decode
listening on end0, link-type EN10MB (Ethernet), capture size 262144 bytes
10:55:33.107716 IP 10.48.2.165.ssh > 10.201.23.91.52308: Flags [P.], seq 4266254400:4266254528, ack 3520172211, win 333, options [nop,nop,TS val 57572827 ecr 260374058], length 128
10:55:33.108933 IP 10.201.23.91.52308 > 10.48.2.165.ssh: Flags [.], ack 128, win 1444, options [nop,nop,TS val 260374095 ecr 57572827], length 0
...

5. To go further

Some usage examples.

6. References

• Useful external links

Document link	Document Type	Description
tcpdump manpage	Standard	linux.die.net
tcpdump (wikipedia.org)	Standard	wikipedia.org

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