Best Docker Kubernetes Online Course - Docker and Kubernetes Training
                     Docker Content Trust (DCT) and Kubernetes 
Network Policies
Ensuring Security in Containerized Environments
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Introduction
• Objective: Understand how Docker Content Trust and 
Kubernetes Network Policies help enhance container security.
• Agenda:
– What is Docker Content Trust?
– Benefits of DCT
– What are Kubernetes Network Policies?
– Use cases and examples
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What is Docker Content Trust (DCT)?
 Definition: Docker Content Trust enables digital 
signature verification for Docker images.
 How it works:
oUses Notary for signing and verification
o Ensures the integrity and publisher authenticity of 
images
• Key Concept: Only signed and verified images can 
be pulled and deployed
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Benefits of Docker Content Trust
 Prevents the use of tampered or unauthorized images
 Enhances CI/CD pipeline security
 Enables trust in image publishers
• Compliance support for secure deployments
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Enabling Docker Content Trust
 Command: export 
DOCKER_CONTENT_TRUST=1
 Behavior:
o Enforces verification on pull, push, and build
o Blocks unsigned images by default
• Note: It requires signed images to function 
properly
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What are Kubernetes Network Policies?
 Definition: Kubernetes Network Policies are rules that control 
traffic flow at the IP address or port level between pods.
 Purpose: Improve cluster security by controlling communication 
between workloads
 Scope:
o Ingress (incoming traffic)
o Egress (outgoing traffic)
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How Kubernetes Network Policies Work
 Applied to pods using labels
 Define allowed sources/destinations using 
selectors
 Implemented via network plugins (e.g., Calico, 
Cilium)
• Example YAML snippet (brief and non-code 
explanation)
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Use Cases & Best Practices
 DCT Use Cases:
o Secure software supply chain
o Prevent rogue image deployment
 Network Policy Use Cases:
o Isolate sensitive pods
o Implement zero-trust architecture
 Best Practices:
oAlways sign images
o Start with default deny rules for Kubernetes policies
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Conclusion & Takeaways
 Docker Content Trust secures image authenticity
 Kubernetes Network Policies protect internal 
communication
 Combine both for a stronger container security 
posture
• Final Tip: Regularly audit and test your policies 
and image signing setup
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For More Information About 
Docker and Kubernetes
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