> For the complete documentation index, see [llms.txt](https://riteshs4hu.gitbook.io/infosec-notes/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://riteshs4hu.gitbook.io/infosec-notes/linux-server-administrator/package-management/red-hat-enterprise-linux-rhel.md). # Red Hat Enterprise Linux (RHEL) ## **Package Management** CentOS, as a distribution based on Red Hat Enterprise Linux (RHEL), primarily uses the **Red Hat Package Manager (RPM)** for package management. CentOS also provides **YUM (Yellowdog Updater, Modified)** and **DNF (Dandified YUM)** as high-level package managers that handle dependencies automatically, whereas RPM works at a lower level. *** ## **Red Hat Package Manager (RPM)** RPM is a low-level package management tool designed for managing `.rpm` packages in RHEL-based distributions like CentOS and Fedora. It does not handle dependencies automatically, so users may need to resolve them manually. ### **Types of RPM Packages** 1. **Binary RPM (RPM)** – Contains precompiled binaries of an application. 2. **Source RPM (SRPM)** – Includes the source code, configuration files, and build instructions, allowing users to compile the package manually. *** ### **RPM Package Architecture** RPM packages are designed for different system architectures: * **i386** – Built for 32-bit systems. * **x86\_64** – Built for 64-bit systems (most modern systems). * **noarch** – Platform-independent package that does not rely on a specific architecture. *** ### **Contents of an RPM Package** An RPM package consists of multiple components, including: * **Application binaries or libraries** – The main software files. * **Documentation files** – Manuals, license agreements, and release notes. * **Configuration files** – Predefined settings for the application. * **SPEC File (`.spec`)** – Defines how the package is built, installed, and maintained. * **RPM Database Location** – Stores information about installed RPM packages in `/var/lib/rpm`. *** ### **RPM Package Management Commands** #### **Querying Installed RPM Packages** To check the details of installed packages, use the following commands: * Query if a package is installed ```sh rpm -q ``` * List all installed packages ``` rpm -qa ``` * Show all files installed by a package ``` rpm -ql ``` * Display the state of package files ``` rpm -qs ``` * List documentation files of a package ``` rpm -qd ``` * Display configuration files of a package ``` rpm -qc ``` * Show license files of a package ``` rpm -qL ``` * List dependencies required by a package ``` rpm -qR ``` * Show detailed package information ``` rpm -qi ``` *** #### **Verifying RPM Packages** * Verify integrity of a specific package ```sh rpm -V ``` * Verify all installed packages ``` rpm -Va ``` * Verify which package a file belongs to ``` rpm -Vf ``` * Verify package without checking digital signature ``` rpm -V --nodigest ``` *** #### **Installing, Upgrading, and Removing Packages** * Install a package ```sh rpm -i package.rpm ``` * Install with verbose and progress indicators ``` rpm -ivh package.rpm ``` * Reinstall an already installed package ``` rpm -ih --replacepkgs package.rpm ``` * Upgrade or install a package ```sh rpm -U package.rpm ``` * Upgrade only if the package is already installed ``` rpm -F package.rpm ``` * Remove a package ```sh rpm -e ``` ⚠️ **Removing an RPM package does not automatically remove its dependencies.** *** #### **Viewing an RPM Package Without Installing** You can inspect the contents of an RPM package before installation: * Query package details without installing ```sh rpm -qp package.rpm ``` * List files contained in the package ``` rpm -qpl package.rpm ``` * Show detailed package information ``` rpm -qpi package.rpm ``` *** ## **YUM (Yellowdog Updater, Modified)** YUM (Yellowdog Updater, Modified) is a high-level package manager developed by **Duke University** to simplify the installation, updating, and removal of **RPM** packages. Unlike **RPM**, which does not handle dependencies automatically, YUM resolves dependencies and ensures smooth package management. ### **Understanding Repositories** A **repository** is a storage location that contains software packages and metadata used by YUM to install and manage applications. #### **Types of Repositories** 1. **Offline Repository** – Used in **isolated networks** (e.g., **banks, data centers**) where internet access is restricted. 2. **Online Repository** – Used for internet-based package management. #### **Why Use a Repository?** * Ensures a structured method to manage software packages. * Automatic dependency resolution. * Provides access to the latest software updates and security patches. *** ### **Creating an Offline YUM Repository** Offline repositories are useful for networks that **lack internet access**, such as **corporate environments** and **secure facilities**. #### **Requirements** * `createrepo` must be installed. * Access to the required RPM packages. #### **Commands to Create an Offline Repository** ```bash createrepo -d /path/to/package-folder/ ``` #### **Repository Configuration File Location** * `/etc/yum.repos.d/` (Stores repository configuration files) #### **Steps to Create an Offline Repository** 1. **Mount the ISO file (if applicable):** ```bash mount -t iso9660 iso_filename /mnt/ ``` 2. **Move the contents to a new folder:** ```bash mv /mnt/* /new_folder_name/ ``` 3. **Unmount the ISO:** ```bash umount /mnt ``` 4. **Create the repository metadata:** ```bash createrepo -v --database /package-folder-name/ -o /output-folder-name ``` 5. **Configure the repository by creating a `.repo` file:** ```bash cd /etc/yum.repos.d/ vim newrepo.repo ``` **Example `newrepo.repo` File** ``` [centos7] name=CentOS 7 Repository baseurl=file:///CentOS7-repo/Packages/ gpgcheck=0 enabled=1 ``` #### **Updating the Repository List** ```bash yum repolist all ``` #### **Removing an Offline Repository** ```bash rm -rf /package-folder-name yum clean all rm -rf /etc/yum.repos.d/centos7 ``` *** ### **Online YUM Repositories** Online repositories allow YUM to retrieve packages from the internet. Below are some commonly used repositories for CentOS. #### **Installing and Removing Online Repositories** **EPEL (Extra Packages for Enterprise Linux) Repository** EPEL provides additional packages for CentOS and RHEL. * **Install:** ```bash yum install epel-release.noarch yum repolist all ``` * **Remove:** ```bash yum remove epel-release.noarch yum clean all ``` **Remi Repository** Used for installing newer versions of **PHP** and other applications. * **Install:** ```bash yum install https://rpms.remirepo.net/enterprise/remi-release-7.rpm ``` **RPMFusion Repository** Provides additional **free and non-free software** for CentOS. * **Install:** ```bash yum install https://mirrors.rpmfusion.org/free/el/rpmfusion-free-release-7.noarch.rpm ``` **ELRepo Repository** Primarily used for **kernel and driver updates**. * **Install:** ```bash yum install https://www.elrepo.org/elrepo-release-7.el7.elrepo.noarch.rpm yum repolist all ``` **NUX Desktop Repository** Provides **multimedia applications** such as VLC. * **Install:** ```bash yum install http://li.nux.ro/download/nux/dextop/el7/x86_64/nux-dextop-release-0-5.el7.nux.noarch.rpm yum repolist all ``` **IUS Repository** Provides **up-to-date versions** of software such as Python and Git. * **Install:** ```bash yum install https://repo.ius.io/ius-release-el$(rpm -E '%{rhel}').rpm yum repolist all ``` *** ### **Essential YUM Commands** YUM provides various commands for efficiently managing **packages** and **repositories** in CentOS. #### **Repository Management** Retrieve the installed YUM version: ```bash yum version ``` List all enabled repositories: ```bash yum repolist ``` List all repositories (enabled and disabled): ```bash yum repolist all ``` Clear all cached repository data: ```bash yum clean all ``` Generate repository cache for faster lookups: ```bash yum makecache ``` #### **Package Querying** List all available packages in the repositories: ```bash yum list available ``` List all installed packages on the system: ```bash yum list installed ``` Check for package updates: ```bash yum check-update ``` #### **Package Installation and Removal** Install a package: ```bash yum install ``` Remove an installed package: ```bash yum remove ``` Reinstall an existing package: ```bash yum reinstall ``` Downgrade a package to an older version: ```bash yum downgrade ``` Update all installed packages to the latest version: ```bash yum update ``` Update a specific package: ```bash yum update ``` #### **Viewing Package Information** Display detailed information about a package: ```bash yum info ``` Find which package provides a specific command or file: ```bash yum provides ``` #### **Working with YUM History** View the transaction history of YUM: ```bash yum history ``` List all past YUM transactions: ```bash yum history list ``` Undo a specific transaction using its ID: ```bash yum history undo ``` #### **Group Package Management** List all available package groups: ```bash yum groups list ``` Install a predefined group of packages (e.g., Development Tools): ```bash yum groups install "Development Tools" ``` Remove a previously installed package group: ```bash yum groups remove "Development Tools" ``` Installing Wine to Run Windows Applications ```bash yum install wine ```