running the image

docker run -dp 3389:3389 --restart=always swined/rdp

adding users manually

run the image, find it's id with docker ps, then run docker exec -it <containerId> adduser <username> --ingroup sudo and follow the prompts. the user will have admin access, check out man adduser for more details on configuring user's permissions.

building custom images with predefined users

run echo -n <password> | openssl passwd -crypt -stdin and copy the hashed password, that is returned. create a folder, and put there a 'Dockerfile' with the following content:

FROM swined/rdp
RUN useradd -mp <hashedPassword> -s /bin/bash -G sudo <username>

run docker build -t <imageName> . and then run the image as usual, replacing 'swined/rdp' with your custom image name

building custom images with preinstalled software

create a Dockerfile as described earlier, and put a line with RUN apt-get update && apt-get install -y --force-yes <listOfUbuntuPackageNames> && apt-get clean instead of 'RUN useradd ...', or combine both 'useradd' and 'apt-get' if you need both custom users and custom software