tftp

TFTP

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This container starts a TFTP server that allows uploads and downloads using the TFTP protocol. The corresponding storage location is mapped to the top level resource folder of the container and can be accessed from your local host system (e.g. ~/arsenal/tftp/).

Example Usage

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First of all, we start the container on our local machine:

[qtc@devbox ~]$ car run tftp
[+] Environment Variables:
[+]	car_local_uid                 1000
[+]	car_tftp_folder               /home/qtc/arsenal/tftp
[+]	car_tftp_port                 69
[+] 
[+] Running: sudo -E docker-compose up
Creating car.tftp ... done
Attaching to car.tftp
car.tftp    | [+] Adjusting volume permissions.
car.tftp    | [+] Starting tftpd.

This should open the UDP port 69 (default TFTP port):

[qtc@devbox ~]$ ss -ulnp
State                    Recv-Q                   Send-Q                                     Local Address:Port                                       Peer Address:Port
UNCONN                   0                        0                                                0.0.0.0:69                                              0.0.0.0:*

From a different host, we can now attempt to upload a file:

[user@other ~]$ echo Hello World :D > test.txt
[user@other ~]$ tftp 192.168.42.124
tftp> put test.txt
Sent 16 bytes in 0.0 seconds

Back on our local machine, we should be able to find the uploaded file within our tftp resource folder (e.g. ~/arsenal/tftp):

[qtc@devbox ~]$ cat arsenal/tftp/test.txt
Hello World :D

Networking Mode

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Using TFTP in combination with docker has some difficulties, as the TFTP protocol uses additional ports apart from 69 (UDP) for the actual data transfer. These issues can be solved by applying specific options to the tftp daemon (namely adjusting the port-range). However, as the main goal of container-arsenal is to achieve file and process level isolation, the tftp container is run in host networking mode instead. This means, that the network stack of the container is not isolated, but uses your ordinary host network. This solves all networking concerned problems and TFTP connections should work as the service would be running on your host system.

Configuration Options:

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The following configuration options can be adjusted within your car.toml configuration file:

• tftp_folder: Top level resource folder of the container (volume).
• tftp_port: TFTP port that will be opened on your local machine.

You can also specify these options by using environment variables. The command car env tftp explains their corresponding usage:

[qtc@devbox ~]$ car env tftp
[+] Available environment variables are:
[+] 
[+] Name                Current Value              Description
[+] car_tftp_port       69                         TFTP port opened on your local machine.
[+] car_tftp_folder     /home/qtc/arsenal/tftp     TFTP root folder used as volume in the container.
[+] car_local_uid       1000                       UID of the TFTP user.