The nauci_base_entry image is derived from the official debian docker image. When run it will it will update debian and install ca-certificates, sudo and ssh. Finally, it will expose port 22 and call the nauci_base_init.sh shell script entry point. The default argument for the entry point is -s option which will switch to an interactive shell.
For more information about the nauci_base_init.sh see https://github.com/BloggerBust/nauci_base_init.