Docker Security: A Comprehensive Guide
Docker containers have become increasingly popular in recent years, but with this popularity comes increased security concerns. Containers are more complex than traditional virtual machines, and securing them can be challenging.
In this article, we will discuss the importance of Docker security, the reasons for the complexity of Docker containers, and default environments and practices for better security. We will also provide a comprehensive guide to container security.
The importance of Docker security
Docker containers are a powerful tool that can be used to streamline development and production workflows. However, they also present a number of security challenges.
Containers are often shared between developers and operations teams, which can lead to confusion and misconfiguration. Additionally, containers can be used to deploy malicious code or to attack other containers on the same host.
It is important to implement security measures to protect your Docker containers. This includes measures such as using trusted images, scanning images for vulnerabilities, and using network isolation to prevent containers from communicating with each other.
The complexity of Docker containers
Docker containers are more complex than traditional virtual machines for a number of reasons. First, containers share the kernel of the host system. This means that a vulnerability in the kernel can be exploited to gain access to all of the containers on the host.
Second, containers often run multiple services. This can make it difficult to identify and isolate security vulnerabilities.
Finally, containers are often ephemeral, meaning that they are created and destroyed frequently. This can make it difficult to track and monitor the security of containers.
Default environments for better security
Docker provides a number of default settings that can help to improve the security of your containers. These settings include:
- Docker Hub: Docker Hub is the default registry for Docker images. Docker Hub provides a number of security features, such as image scanning and image signing.
- Docker Swarm: Docker Swarm is a container orchestration platform that can be used to deploy and manage Docker containers at scale. Docker Swarm provides a number of security features, such as network isolation and Docker Content Trust.
Practices to monitor containers for security
In addition to using default settings, there are a number of practices that you can follow to monitor your containers for security. These practices include:
- Image scanning: Image scanning can be used to identify vulnerabilities in Docker images. There are a number of image scanning tools available, both commercial and open source.
- Runtime monitoring: Runtime monitoring can be used to detect suspicious activity in running containers. There are a number of runtime monitoring tools available, both commercial and open source.
- Logging and auditing: Logging and auditing can be used to track and monitor the security of your containers. There are a number of logging and auditing tools available, both commercial and open source.
Comprehensive guide to container security
In addition to the information provided above, there are a number of resources available that can provide more detailed information on Docker security. These resources include:
- Docker documentation: The Docker documentation provides a number of articles and tutorials on Docker security.
- Docker Security Best Practices: This guide provides a comprehensive overview of Docker security best practices.
- Docker Security Workshop: This workshop provides hands-on training on Docker security.
Following is the complete guide for container security:
Challenges faced by dockers container security:
Many organizations used virtual machines or bare-metal servers before Docker to host applications. These technologies are quite simple when seen from a security perspective. When hardening your development and monitoring for security relevant events you need to focus on just two layers. As APIs, overlay networks or complex software defined storage configuration are not a major part of virtual machine or bare metal developments so you do not have to worry about these.
A typical Docker environment has many moving parts hence its security is much more complicated. Those moving parts include:
- Probably you have multiple Docker container images and individual micro services will be hosted by each one of your containers. Also probably multiple instances of each imagine will be running at a time. Proper security and monitoring will be required for these instances and images.
- To keep the containers and its host safe, the Docker daemon need to be secured.
- Bare metal or virtual machine might be the host server.
- Another layer to secure is service like ECS if you use it to host your containers.
- Communication between containers is facilitated by APIs and Overlay networks.
- Other storage system that exists externally from your containers is Data volume.
And if you are thinking that learning to secure Docker is tough because dockers security is undoubtedly much more complex than any other security system.
Best practices of Docker container security:
Luckily we can overcome the challenges. this article is not a tiring guide to security of docker but you can use this official Docker documentation),as a reference. Below are some best practices:
#1 setting of reference quotes
One easy thing in docker is configuring of resource quotas. Resource quotas helps us to limit the memory amount and resources of CPU which is consumed by the container.
This is helpful for many reasons. It helps to keep the environment of docker efficient and saves one container from mixing with other system resources. It also increases the security by saving the container from using large space or resources so that it gets prevented from any harmful activity.
Resources quotas are easily set by use of commands. View this Docker documentation.
#2 Root should not be run
We all know the feeling when we are tired and don’t want to get entangled in problems related to permission setting to get an application work properly so running in root is the only option left so you don’t worry about issues related to permission restrictions.
if you are a beginner it is sometimes okay to use Docker testing environment but there is no reason good enough to let a Docker container run with roof permissions in production.
Because Docker doesn’t run containers as root by default so this is an easy docker security to be followed. So you don’t have to make amendments to prevent running as a root by default in a default configuration. letting a container as a root is a temptation that needs to be resisted as it is more convenient in some situations.
If you use kubernetes to orchestrate your containers for added Docker security, you can explicitly prevent containers from starting as root. We can use Must Run As Non Root directive in a pod security policy.
#3 Secure container registries
Docker is powerful because of the container registries. It makes it easy to set central repositories which helps us in downloading the container images.
Using the container registries is a security risk if one does not know the evaluation of the security constraints. We can use Docker Trusted Registry which can be installed in the firewalls to eradicate the risk of viruses.
The registry can be accessed from the back of firewalls and we can limit the unknown access of uploading and downloading images from our registry. Using role based access can control explicitly of unknown users or access. It is nice to leave our registry open to others but it is useful only if it stops the access of viruses and harmful things.
#4 Use of trusted and secure images
We should be sure that the the images or container images we use are from a trusted source. This is obvious but there are many platforms from where we can download images and they might not be trusted or verified.
One should consider not using public container registries or try to use official trusted repositories, like the ones on Docker Hub.
One can use image scanning tools which help to identify harmful sources Most upper level container have embedded scanning tools. The ones like Clair.
#5 Identify the source of your code
Docker images contain some original code and packages from upstream sources. sometimes the image downloaded can come from a trusted registry, the image can have packages from untrusted sources. these unknown packages can be made up of code taken from multiple outside sources.
That is why analysis tools are important. Downloading the sources of the Docker images and scanning the code origin we can know if any of the code is from unknown sources.
#6 network security and API
As we have seen above Docker containers depend on APIs and networks for communication. It is important to make sure that your APIs and network architectures are secure and monitoring the APIs and network activity for any unusual activity must also be checked.
As APIs and networks are not a part of Docker and are resources of Dockers so steps for securing APIs and networks are not included in this article. But it is important to check the security of the sources.
Docker security is an important topic that should be considered by all organizations using Docker containers. By following the recommendations in this article, you can help to improve the security of your Docker containers. But one has to think carefully about steps to secure your Docker containers, and strengthen your container environment at many levels. This is the only way to ensure that you can have all the benefits of Docker containers without having major security issues.