Secure the network with firewalld
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
firewalld is a set of scripts and a daemon that manage netfilter on your RHEL system. It aims at creating a simple command-line interface to manage the firewall on your systems.
By default, firewalld is included in the "core" rpm group, but it may not be installed for some reason (that you left it out of your kickstart would be one!). Perform the following steps:
- Install
firewalldvia the following command line:~]# yum install -y firewalld - Now, enable
firewalldthrough the following:~]# systemctl enable firewalld - Finally, ensure that
firewalldis started by executing the following command line:~]# systemctl restart firewalld
List all the allowed services using the following command:
~]# firewall-cmd –list-services
You can see the output as follows, where all the allowed services are listed:
Now, show the tcp/udp ports that are allowed by your firewall using the following command:
~]# firewall-cmd --list-ports
Here's what the output should look like:
Perform the following steps to allow NFSv4 traffic on your system:
- First, allow
nfstraffic via this command:~]# firewall-cmd --add-service nfs –-permanent success ~]#
- Then, reload the configuration as follows:
~]# firewall-cmd --reload success ~]#
- Now, check the newly applied rule by executing the following command line:
~]# firewall-cmd –-list-services nfs ~]#
Perform the following steps to allow incoming traffic on port 1234 over both tcp and udp:
- First, allow traffic on port
1234overtcpandudpby running the following:~]# firewall-cmd --add-port 1234/tcp --permanent success ~]# firewall-cmd --add-port 1234/udp --permanent success ~]#
- Reload the configuration by executing the following command:
~]# firewall-cmd –-reload success ~]#
- Check the newly applied rule via the following:
~]# firewall-cmd –-list-ports 1234/tcp 1234/udp ~]#
firewalld comes with a set of predefined port configurations, such as HTTP and HTTPS. You can find all such definitions in /lib/firewalld/services. When creating your own port definitions or modifying the existing ones, you should create new port definition files in /etc/firewalld/services.
When creating new "rules" by adding ports, services, and so on, you need to add the --permanent option, or your changes would be lost upon the rebooting of the system or the reloading of the firewalld policy.
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