In CentOS 7 environments, keeping software packages updated and secure is critically important. One way to achieve this is by utilizing tools like Clair and Trivy for automatic vulnerability monitoring and updates. This article provides detailed instructions on how to set up and effectively use these tools on CentOS 7.

Prerequisites

Before proceeding with installation and configuration, ensure that the system has Docker installed, as both Clair and Trivy are distributed as Docker images, which facilitate their deployment and usage.

Installing Docker on CentOS 7

1. Adding the Docker repository: Run the command sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo to add the official Docker repository.
2. Installing Docker Engine: Proceed with Docker installation using sudo yum install docker-ce docker-ce-cli containerd.io.
3. Starting Docker service: After installation, start the Docker daemon with sudo systemctl start docker and ensure it starts automatically on system boot with sudo systemctl enable docker.

Setting Up Clair on CentOS 7

Clair is an open-source project designed for static vulnerability analysis of Docker and rkt containers.

1. Downloading Clair configuration file: First, download the sample configuration file for Clair from the official GitHub repository. You can use the command wget https://raw.githubusercontent.com/quay/clair/v2.0.9/config.yaml.sample -O config.yaml for this purpose.
2. Running Clair: With the configuration file prepared, run Clair using Docker: docker run -d -e POSTGRES_PASSWORD="" -p 5432:5432 postgres:9.6 followed by docker run -d -p 6060:6060 -p 6061:6061 --link postgres:postgres -v /path/to/config.yaml:/config/config.yaml quay.io/quay/clair:v2.0.9 -config=/config/config.yaml.

Setting Up Trivy on CentOS 7

Trivy is a simple yet comprehensive vulnerability scanner for containers and other artifacts.

1. Downloading and installing Trivy: Trivy can be easily installed by running the command wget https://github.com/aquasecurity/trivy/releases/download/v0.18.3/trivy_0.18.3_Linux-64bit.tar.gz -O trivy.tar.gz && tar zxvf trivy.tar.gz && sudo mv trivy /usr/local/bin/.
2. Updating Trivy database: Before the first scan, run trivy image --download-db-only to update the vulnerability database.

Automating Scans

With Clair or Trivy now set up on your CentOS 7 system, you can configure cron jobs for regular scanning of your Docker images.

1. Editing crontab: Run crontab -e to edit the cron table.
2. Adding cron job: To automatically trigger scans, add a line similar to the following: 0 2 * * * trivy image [image_name] > /path/to/log/file 2>&1, which will initiate a scan every day at 2 AM.

By leveraging Clair or Trivy on CentOS 7, you can effectively monitor and address vulnerabilities in your software packages. It's important to regularly update the vulnerability databases and scan your systems to maintain maximum security levels.