cincan-command 0.2.9

Cincan wrapper for dockerized command-line tools

CinCan command

The tool cincan command provide for a convenient use of the native command-line tools provided as docker images.

Supported platforms

The cincan tool should run on fairly modern Linux distributions. Partial support for macOS is available - tested to work with macOS Catalina.

On Windows cincan does not work, unfortunately.

Installation

As prerequisite you must have installed Docker for running the tools, and Python 3 and pip Python package management program for the command program. Consult your system documentation how to install them.

The command program is then installed using pip for Python 3:

% pip install cincan-command --user

This will install package for current user. However, it is possible that these packages are not in path. You can add user-specific binaries into path for current session with:

export PATH=$PATH:$HOME/.local/bin

To add it permanently, append it into ~/.bashrc file with your favorite text editor. Note that this can depend on what kind of shell you are using.

To activate changes:

source ~/.bashrc

If you invoke the pip installation with sudo and without --user flag (if you are OK with that) the command cincan should be added to your path automatically and installed in system wide.

NOTE: You may want to install the tool into virtualenv to avoid conflicts with other Python applications you may have. Please consult appropriate documentation.

You can check that all works as follows:

% cincan list

If all goes well you get a list of the latest stable tools dockerized in the 'CinCan' project. First time running this might take a while as it must fetch information of the tools and cache it locally.

cincan list is using list command from module cincan-registry Please, consult documentation in there for all available options.

Running tools with cincan

Invoking tools

A tool can be invoked with cincan using 'run' sub-command like this:

% cincan run <tool> <parameters..>

As you may remember you get the list of tools dockerized in 'CinCan' project with cincan list. For example the tool cincan/pywhois:

% cincan run cincan/pywhois 127.0.0.1

Many tools give you help information, if you invoke them without arguments, for example:

% cincan run cincan/tshark

More help is available with options like -h or --help, depending on the tool.

Version checks of tools

By default, every time tool is used, it's version status is showed. Is it up-to-date compared to Docker Hub, or maybe upstream has later version which is not ended up into our Docker Hub yet? This feature is available only for cincan tools, for those which are configured correctly.

If you want to disable it, modify/add file ~/.cincan/config.json to contain attribute show_updates and set it as false.

Input and output files

As the tools are actually ran on docker container, possible input and output files must be transferred into and out from the container. As default, this happens transparently as running the tools without docker. For example, if you have file myfile.pcap, the following command should give you JSON-formatted output from 'tshark':

% cincan run cincan/tshark -r myfile.pcap
cincan/tshark: <= myfile.pcap in
...

If you redirect output to a file, the file should be downloaded from the container as you would expect, for example:

% cincan run cincan/tshark -r myfile.pcap -w result.pcap
cincan/tshark: <= myfile.pcap in
cincan/tshark: => result.pcap

Use argument -q to get rid of the log indicating which files are copied in or out, e.g.

% cincan -q run cincan/tshark -r myfile.pcap -w result.pcap

Please note that -q is before the run sub command.

Limitations for input/output

Output files are only fetched to the current directory and to it's sub directories. This is a safety feature to block dockerized tools for overwriting arbitrary filesystem files. E.g. the following does not produce any output files to /tmp.

% cincan run cincan/tshark -r myfile.pcap -w /tmp/result.pcap

However, depending on the WORKDIR value of the container, you may get unexpected files to current directory, such as tmp/result.pcap in the sample above.

As default, the 'cincan' tool treat all existing files listed in command line arguments as input files, so it may also upload output files if those already exists when command is invoked. E.g. when you run the following command several times you notice that the file result.pcap gets uploaded to the container only to be overwritten.

% cincan run cincan/tshark -r myfile.pcap -w result.pcap
cincan/tshark: <= myfile.pcap in
cincan/tshark: <= result.pcap in
cincan/tshark: => result.pcap

This may become problem e.g. when you must give the command and output directory which contains a lot of data already and all that data gets (unnecessarily) copied to the container.

Avoid uploading content from output directories

On many cases a tool writes files into an output directory and you may run the tool several times to produce many files to the output directory. However, as 'cincan' does not know which files are output and which are input, it repeatedly copies also the output files from the previous runs to container. This may process may slow down your work and requires extra disk space.

This is avoided by using run argument --mkdir (or -d) to explicitly create output directory into container without copying over any possible content.

For example, consider the tool 'volatility' which expects you to give an output dump directory when extracting process data, e.g. the following extracts the memory dump of process 123 to directory dump/

% cincan run cincan/volatility -f image.raw --dump-dir dump/ memdump -p 123
cincan/volatility: <= image.raw
cincan/volatility: <= dump
cincan/volatility: => dump/123.dmp

However, if you extract again you notice that the already extracted file gets copied into the container as potential input file:

% cincan run cincan/volatility -f image.raw --dump-dir dump/ memdump -p 456
cincan/volatility: <= image.raw
cincan/volatility: <= dump
cincan/volatility: <= dump/123.dmp
cincan/volatility: => dump/456.dmp

This can easily slow down your analysis a lot when many process files are copied around unnecessarily. You can address this by explicitly creating dump/ directory to the container this way:

% cincan run -d dump cincan/volatility -f image.raw --dump-dir dump/ memdump -p 789
cincan/volatility: <= image.raw
cincan/volatility: <= dump
cincan/volatility: => dump/789.dmp

You can provide the argument many times to create multiple directories.

Input and output file filtering

You can explicitly filter input files, which are copied to the container, and output files, which are copied from the container. The filtering is done by giving a glob-style pattern by run command arguments --in-filter (or -I) for input file filtering and --out-filter (or -O) for output file filtering. Negative filters for filtering-out files are prefixed with ^.

Argument	Description
--in-filter pattern	Match files to upload by the pattern
--in-filter ^pattern	Filter out files to upload which match the pattern
--out-filter pattern	Match files to download by the pattern
--out-filter ^pattern	Filter out files to download which match the pattern

For example, consider the previous case with tool 'volatility'. An alternative approach would be to filter out copying of files under dump/ like this:

% cincan run -I "^dump/*" cincan/volatility -f image.raw --dump-dir dump memdump -p 789
cincan/volatility: <= image.raw
cincan/volatility: <= dump
cincan/volatility: => dump/789.dmp

Filtering by .cincanignore - file stored inside container

Downloadable files can be filtered by .cincanignore file as well, which should be stored inside tool container in build phase. All files listed in that file are not downloaded from the container. Paths are relative of the working directory of container.

Ignore file supports # char as comment character.

See example file in here.

This works with user supplied filters as well.

Argument --no-defaults can be passed for run command to not use this file.

Providing tool input as tar file

Instead of letting the tool to figure out the input files from command-line, you can provide the input files directly as tar-file. When this is done, the tool does not try to apply any logic to upload files, so you have the full control. You cannot use input file filtering with this approach.

The input tar file is specified with option --in and you can provide a file or use - to read from standard input. For example:

% tar c myfile.pcap | cincan run --in - cincan/tshark -r myfile.pcap

Getting tool output as tar file

You can also request the tool output files in a tar container. This is done with argument --out. You can provide for the argument either a file name or -for standard output. You can also apply output file filtering to limit the number of files copied into the output tar archive.

For example, the following should write file output.tar

% cincan run --out output.tar cincan/tshark -r myfile.pcap -w output.pcap

Running tool with interactive support

We are using radare2 as example here. Tool with interactive mode requires --interactive (or -i) and --tty (or -t) switches. Start radare2 disassembler for local file /bin/ls by running command:

% cincan run -it cincan/radare2 r2 /bin/ls
 cincan/radare2: <= /usr/bin/ls
 -- We are surrounded by the enemy. - Excellent, we can attack in any direction!
[0x00005b10]> aaa
[x] Analyze all flags starting with sym. and entry0 (aa)
[x] Analyze function calls (aac)
[x] Analyze len bytes of instructions for references (aar)
[x] Check for objc references
[x] Check for vtables
[x] Type matching analysis for all functions (aaft)
[x] Propagate noreturn information
[x] Use -AA or aaaa to perform additional experimental analysis.
[0x00005b10]> 

radare2 should open /bin/ls file, and this can be analysed by typing aaa and pressing enter.

All run options

The following table lists all command-line options available for the run -sub command:

Specific to cincan		Description
--in tar-file		Upload input to container in a tar
--out tar-file		Download output files from container to a tar
--in-filter pattern	-I	Filter input files, prefix ^ to negate the filter
--out-filter pattern	-O	Filter output files, prefix ^ to negate the filter
--mkdir directory	-d	Mark output directory, not uploaded as input
--no-defaults		Ignore all container specific output filters. (Defined inside container in .cincanignore file)

Similar to docker run		Description
--tty	-t	Allocate a pseudo-TTY
--interactive	-i	Keep STDIN open even if not attached
--network value		Network to connect
--user name		User to run with
--cap-add CAP		Add kernel capability
--cap-drop CAP		Drop kernel capability
--runtime		Container runtime

Consult Docker run documentation for more details.

Invoking tool without 'cincan' wrapper

Sometimes you cannot use the services provided by the 'cincan' frontend. For example, as files are copied around you may ran out of disk space or experience long delays when working with large files. An another reason might be use of some 'docker' options which are not available in the 'cincan' tool.

Good luck with that! (seriously, no pun intended) Please consult Docker documentation for details.