10. Securing the System with SELinux | Learning RHEL Networking

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Learning RHEL Networking

By : Andrew Mallett

4.3 (4)

Learning RHEL Networking

4.3 (4)

By: Andrew Mallett

Overview of this book

This book is ideal for administrators who need to learn the networking abilities of Red Hat Enterprise Linux 7. You may not be a Linux administrator already, but you will need to be able to test files in Linux and navigate the filesystem.

Preface

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Free Chapter

1. Introducing Enterprise Linux 7

1. Introducing Enterprise Linux 7

Red Hat Enterprise Linux

CentOS

Fedora

Determining your distribution and version

Summary

2. Configuring Network Settings

2. Configuring Network Settings

Elevating privileges

Using ip and hostnamectl

Introduction to the Red Hat NetworkManager

Interacting with the NetworkManager using the Control Center

Adding a new profile with the Control Center

Interacting with the NetworkManager using nmtui

Extreme interaction with NetworkManager using nmcli

Summary

3. Configuring Key Network Services

3. Configuring Key Network Services

Domain Name System

Configuring a DHCP server

Configuring time services on RHEL 7

Implementing e-mail delivery on RHEL 7

Summary

4. Implementing iSCSI SANs

4. Implementing iSCSI SANs

The iSCSI target (server)

Managing logical volumes with LVM

Installing the targetd service and targetcli tools

Managing iSCSI targets with targetcli

Creating iSCSI targets

Working with the iSCSI Initiator

Summary

5. Implementing btrfs

5. Implementing btrfs

Overview of btrfs

Overview of the lab environment

Installing btrfs

Creating the btrfs filesystem

The Copy-On-Write technology

Resizing btrfs filesystems

Adding devices to the btrfs filesystem

Balancing the btrfs filesystem

Mounting multidisk btrfs volumes from /etc/fstab

Using btrfs snapshots

Optimizing btrfs for solid state drives

Managing snapshots with snapper

Summary

6. File Sharing with NFS

6. File Sharing with NFS

An overview of NFS

Overview of the lab environment

The NFS server configuration

Using exportfs to create temporary exports

Hosting NFSv4 behind a firewall

Hosting NFSv3 behind a firewall

Auto-mounting NFS with autofs

Summary

7. Implementing Windows Shares with Samba 4

7. Implementing Windows Shares with Samba 4

An overview of Samba and Samba services

An overview of the lab environment

Configuring time and DNS

Managing Samba services

The Samba client on RHEL 7

Configuring file shares in Samba

Troubleshooting Samba

Summary

8. Integrating RHEL 7 into Microsoft Active Directory Domains

8. Integrating RHEL 7 into Microsoft Active Directory Domains

Overview of identity management

An overview of the lab environment

Preparing to join an Active Directory domain

Using realm to manage domain enrolment

Logging on to RHEL 7 using Active Directory credentials

User and group management with adcli

Delegating Active Directory accounts with sudo

Leaving a domain

Understanding Active Directory as an identity provider for sssd

Summary

9. Deploying the Apache HTTPD Server

9. Deploying the Apache HTTPD Server

Configuring the httpd service

Controlling the Apache web service

Loading modules

Virtual servers

Automating virtual hosts

Summary

10. Securing the System with SELinux

10. Securing the System with SELinux

What is SELinux

Understanding SELinux

Working with the targeted policy type

SELinux tools

Troubleshooting SELinux

Summary

11. Network Security with firewalld

11. Network Security with firewalld

The firewall status

Routing

Zone management

Source management

Firewall rules using services

Firewall rules using ports

Masquerading and Network Address Translation

Using rich rules

Implementing direct rules

Summary

Index

Index

Troubleshooting SELinux

Let's take a look at different ways of troubleshooting SELinux.

The log file

If we were left uncertain as to the problem that was causing errors that we encountered before with the web server, then our troubleshooting should always start with log files. For SELinux, this is the /var/log/audit/audit.log file. Logging in from SELinux will be marked as AVC (Access Vector Cache). We can search the log file with grep using something similar to the following command:

# grep AVC /var/log/audit/audit.log

However, more appropriately, there is also the ausearch command that we can use. If an error has just occurred, we can use the recent time start code to help reduce returned results. This is a shortcut for displaying errors within the last 10 minutes:

# ausearch -m avc -ts recent

Other than this, we can supply an actual time, date, or both. In the following example, we will use 16:00 as the starting time to search. In the absence of the date, today's date is implied as follows...

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