Securing the system login
by Uday R. Sawant, William Leemans, Jonathan Hobson, Oliver Pelz
Linux: Powerful Server Administration
- Linux: Powerful Server Administration
- Table of Contents
- Linux: Powerful Server Administration
- Linux: Powerful Server Administration
- Credits
- Preface
- 1. Module 1
- 1. Managing Users and Groups
- 2. Networking
- Introduction
- Connecting to a network with a static IP
- Installing the DHCP server
- Installing the DNS server
- Hiding behind the proxy with squid
- Being on time with NTP
- Discussing load balancing with HAProxy
- Tuning the TCP stack
- Troubleshooting network connectivity
- Securing remote access with OpenVPN
- Securing a network with uncomplicated firewall
- Securing against brute force attacks
- Discussing Ubuntu security best practices
- 3. Working with Web Servers
- Introduction
- Installing and configuring the Apache web server
- Serving dynamic contents with PHP
- Hosting multiple websites with a virtual domain
- Securing web traffic with HTTPS
- Installing Nginx with PHP_FPM
- Setting Nginx as a reverse proxy
- Load balancing with Nginx
- Setting HTTPs on Nginx
- Benchmarking and performance tuning of Apache
- Securing the web server
- Troubleshooting the web server
- 4. Working with Mail Servers
- 5. Handling Databases
- Introduction
- Installing relational databases with MySQL
- Storing and retrieving data with MySQL
- Importing and exporting bulk data
- Adding users and assigning access rights
- Installing web access for MySQL
- Setting backups
- Optimizing MySQL performance – queries
- Optimizing MySQL performance – configuration
- Creating MySQL replicas for scaling and high availability
- Troubleshooting MySQL
- Installing MongoDB
- Storing and retrieving data with MongoDB
- 6. Network Storage
- 7. Cloud Computing
- 8. Working with Containers
- Introduction
- Installing LXD, the Linux container daemon
- Deploying your first container with LXD
- Managing LXD containers
- Managing LXD containers – advanced options
- Setting resource limits on LXD containers
- Networking with LXD
- Installing Docker
- Starting and managing Docker containers
- Creating images with a Dockerfile
- Understanding Docker volumes
- Deploying WordPress using a Docker network
- Monitoring Docker containers
- Securing Docker containers
- 9. Streaming with Ampache
- 10. Communication Server with XMPP
- 11. Git Hosting
- Introduction
- Installing Git
- Creating a local repository with Git CLI
- Storing file revisions with Git commit
- Synchronizing the repository with a remote server
- Receiving updates with Git pull
- Creating repository clones
- Installing GitLab, your own Git hosting
- Adding users to the GitLab server
- Creating a repository with GitLab
- Automating common tasks with Git hooks
- 12. Collaboration Tools
- 13. Performance Monitoring
- 14. Centralized Authentication Service
- 2. Module 2
- 1. Installing CentOS
- Introduction
- Downloading CentOS and confirming the checksum on Windows or OS X
- Creating USB installation media on Windows or OS X
- Performing an installation of CentOS using the graphical installer
- Running a netinstall over HTTP
- Installing CentOS 7 using a kickstart file
- Getting started and customising the boot loader
- Troubleshooting the system in rescue mode
- Updating the installation and enhancing the minimal install with additional administration and development tools
- 2. Configuring the System
- Introduction
- Navigating text files with less
- Introduction to Vim
- Speaking the right language
- Synchronizing the system clock with NTP and the chrony suite
- Setting your hostname and resolving the network
- Building a static network connection
- Becoming a superuser
- Customizing your system banners and messages
- Priming the kernel
- 3. Managing the System
- Introduction
- Knowing and managing your background services
- Troubleshooting background services
- Tracking system resources with journald
- Configuring journald to make it persistent
- Managing users and their groups
- Scheduling tasks with cron
- Synchronizing files and doing more with rsync
- Maintaining backups and taking snapshots
- Monitoring important server infrastructure
- Taking control with GIT and Subversion
- 4. Managing Packages with YUM
- 5. Administering the Filesystem
- 6. Providing Security
- 7. Building a Network
- 8. Working with FTP
- 9. Working with Domains
- 10. Working with Databases
- 11. Providing Mail Services
- 12. Providing Web Services
- 13. Operating System-Level Virtualization
- 14. Working with SELinux
- 15. Monitoring IT Infrastructure
- 1. Installing CentOS
- 3. Module 3
- 1. Working with KVM Guests
- 2. Deploying RHEL "En Masse"
- 3. Configuring Your Network
- 4. Configuring Your New System
- 5. Using SELinux
- 6. Orchestrating with Ansible
- 7. Puppet Configuration Management
- 8. Yum and Repositories
- 9. Securing RHEL 7
- 10. Monitoring and Performance Tuning
- Bibliography
- Index
The default settings applied to system login are based on what Red Hat deems basic security. If, for some reason, you want to change this, this recipe will show you a couple of examples. Authconfig has two tools that you can use to configure authentication: authconfig and authconfig-tui.
These two tools configure pam for you in such a way that the changes are consistent throughout rpm updates.
The authconfig-tui tool is not as feature-rich as the plan authconfig tool, which I personally recommend you to use as it allows you to do more.
You can manually edit the files located in /etc/pam.d if and when you know what you're doing, but this is not recommended.
Perform the following steps:
First, change the hash encryption of the passwords stored in /etc/shadow to sha512, as follows:
~]# authconfig --passalgo=sha512 --update
Enable NIS authentication through the following command:
~]# authconfig --enablenis –nisdomain=NISDOMAIN --nisserver=nisserver.example.com --update
Now, set the minimum length requirement for passwords to 16 via the following:
~]# authconfig --passminlen=16 --update
The user requires at least one lowercase letter in the password; you can set this requirement by running the following:
~]# authconfig --enablereqlower --update
Also, the user requires at least one uppercase letter in the password, for which you can run the following:
~]# authconfig --enablerequpper --update
Now, the user requires at least one number in the password. Execute the following command for this:
~]# authconfig --enablereqdigit --update
Finally, the user requires at least one nonalphanumeric character in the password, which you can set using the following command:
~]# authconfig --enablereqother --update
authconfig and authconfig-tui are wrapper scripts that modify a variety of files, including, but not limited to, /etc/nsswitch.conf, /etc/pam.d/*, /etc/sssd.conf, /etc/openldap/ldap.conf, and /etc/sysconfig/network.
The advantage of the tool is that it uses the correct syntax, which can sometimes be a little tricky, especially for the files in /etc/pam.d.
One of the interesting features of this tool is the backup and restore functions. In case you do not use any centralized identification and authentication infrastructure, such as IPA, you can use this to make a backup of a correctly configured machine and distribute this through whichever means you wish to use.
To back up your authconf configuration, execute the following:
~]# authconfig --savebackup=/tmp/auth.conf
This will create a /tmp/auth.conf directory, which contains all the files modified by authconfig.
Copy this directory over to another server and restore the configuration by executing the following:
~]# authconfig –-restorebackup=/tmp/auth.conf
All of the security changes you apply through authconfig can also be managed through IPA.
For information about and more configuration options, take a look at the authconfig (8) man pages.
You can also find more information on Red Hat's page on authentication at https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/System-Level_Authentication_Guide/Configuring_Authentication.html.
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