H 151: Making a Custom Docker Container (10 pts)

What You Need for this Project

A Linux machine--I used a Google Cloud Debian 12 headless server

Purpose

To practice using Docker for simple tasks.

I am following this tutorial .

Installing Docker

Make sure your Linux machine has:

2 CPUs or more
4 GB of free memory
20 GB of free disk space

On your Linux server, execute these commands, replacing "debian" in the third command with your username.


sudo apt update
sudo apt install curl docker.io -y
sudo usermod -aG docker debian
newgrp docker

Making a Custom Dockerfile

On your Linux server, execute these commands:


mkdir nmap-server
cd nmap-server
nano Dockerfile

Paste in the code below.


FROM debian
MAINTAINER YOURNAME
RUN apt-get update && \
    apt-get install -y nmap iproute2 && \
    apt-get clean
ENTRYPOINT ["/usr/bin/nmap"]
CMD ["-sn", "-v", "172.17.0.1-10"] 
# Scan docker network 172.17.0.1-10 for running containers

Your code should look like the image below.

Save the file with Ctrl+x, y, Enter.

Building the Image

On your Linux server, execute this command, replacing "yourname" with a version of your name using only lowercase letters and no spaces:


docker build -t yourname/nmap-server:1.0 .

Your build should succeed, as shown below.

Troubleshooting
If you get error messages like:
Failed to fetch http://deb.debian.org/debian/dists/bookworm/InRelease Temporary failure resolving 'deb.debian.org'
Execute this command to restart Docker:
sudo service docker restart

Running a Container from your Image

On your Linux server, execute this command:


docker images
docker run yourname/nmap-server:1.0

The container runs an Nmap scan, as shown below.

Flag H 151.1: Viewing the Container (10 pts)
On your Linux server, execute this command:
docker ps -a
The flag is covered by a green rectangle in the image below.

Posted 3-8-25
Final image fixed 3-12-25
Video added 3-26-25