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Securing Your RHEL8 Server with Firewall

Introduction to RHEL8 Firewall

Introduction to RHEL8 Firewall

Red Hat Enterprise Linux (RHEL) is a robust and leading operating system used by organizations, businesses, and individuals worldwide. One of the essential components of any Linux system, including RHEL, is the firewall. A firewall plays a vital role in securing networks and systems from unauthorized access, giving system administrators peace of mind and assurance that their systems are well-protected. In this article, we will dive deep into the RHEL8 firewall and explore its various components, features, and functionalities.

The RHEL8 firewall is powered by the firewalld daemon, a dynamic firewall management tool that simplifies the configuration of network traffic rules and provides a flexible interface for managing network traffic. With firewalld, system administrators can easily define rules for incoming and outgoing network traffic, permit only specific types of traffic, and block unwanted traffic. Firewalld ships with a rich set of features, making it a preferred choice for many organizations looking to secure their infrastructure.

The RHEL8 firewall architecture is divided into three primary zones; Public, Internal, and DMZ (Demilitarized Zone). The firewall zones define the trust levels of network interfaces on the system, with Public being the least trusted and DMZ being the most trusted. The Public zone is typically used for external network interfaces, such as the internet, while the Internal zone is used for local network interfaces, such as LANs. The DMZ zone is often used for servers that require direct communication with both the internal and external networks.

In addition to the three primary zones, the RHEL8 firewall uses a set of rich predefined services to define network traffic rules. A service is a named set of network ports, protocols, and related information that describes a particular service. For instance, the “http” service defines the ports and protocol used by the web service, while the “ssh” service defines the ports and protocol used by the SSH service. The predefined services allow system administrators to define rules that are specific to their infrastructure and ensure that only authorized traffic is permitted.

The RHEL8 firewall also comes with advanced security features such as Network Address Translation (NAT) and Port Forwarding. NAT enables the firewall to dynamically modify the source and destination IP addresses of network traffic, making it look like the traffic originated from a different IP address. Port Forwarding, on the other hand, allows system administrators to forward traffic from a particular port on the firewall to another port on a particular server or device within the network. This feature is particularly useful for exposing network services to the public internet while maintaining network security.

Conclusion: The RHEL8 firewall is a robust and feature-rich firewall solution that provides organizations with a flexible and easy-to-use firewall management tool. With its powerful features such as predefined services, zones, NAT, and port forwarding, the RHEL8 firewall provides system administrators with the necessary tools to secure their infrastructure effectively. As such, it is a recommended firewall solution for any organization looking to secure their network and systems quickly and efficiently.

Configuring RHEL8 Firewall

Configuring RHEL8 Firewall

The Red Hat Enterprise Linux 8 (RHEL8) firewall is an essential tool in network security that every administrator needs to configure carefully. A firewall is a network security tool that is designed to prevent unauthorized access to or from a private network. It is a critical component that prevents malicious packets from accessing the system or network. To configure RHEL8 Firewall, it is necessary to have a basic understanding of how it works.

The firewall is divided into two zones, namely the public and private zones. The private zone refers to the internal network that needs to be protected, while the public zone refers to the external network that should be blocked to prevent unwanted traffic. Firewall rules are implemented on the zones, configuring how the traffic flows between the two zones. The rules can be used to allow or block traffic on specific ports or services.

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In RHEL8, the default firewall is called firewalld. Firewalld is a dynamic and flexible firewall tool that can be controlled via the command line interface or graphical user interface. The following steps show how to configure RHEL8 Firewall via the command line interface:

Step 1: Identify the Firewall Zones in RHEL8. RHEL8 Firewall is configured based on predefined zones. Zones determine the traffic that is allowed to pass through the firewall. The default zones are public, dmz, and home. Use the following command to list all the available zones:

# firewall-cmd --get-zones

Step 2: Change the default zone. By default, the RHEL 8 Firewall is set to the public zone. However, you can change this to any zone that suits your network environment. To change the default zone, enter the following command:

# firewall-cmd --set-default-zone=

Replace with the name of your chosen zone.

Step 3: Enable the Firewall service. You cannot configure RHEL8 Firewall without first enabling the service. Use the following command to start the Firewall service:

# systemctl start firewalld

Alternatively, use the following command to check the status of the Firewall service:

# firewall-cmd --state

If it returns running, it means the service is already active.

Step 4: Configure the Firewall rules. RHEL8 Firewall uses zones to configure firewall rules. To add a new rule, use the following command:

# firewall-cmd --permanent --zone= --add-service=

Replace with the name of the zone you want to apply the rule to, and with the name of the service you want to allow or block.

Step 5: Reload the Firewall service. After adding or modifying firewall rules, reload the Firewall service using the following command:

# firewall-cmd --reload

The above steps show how to configure RHEL8 Firewall via the command line. However, there is a graphical user interface that provides an easy-to-use interface for configuring RHEL8 Firewall. The interface allows you to configure the Firewall rules, manage zones, view logs, and troubleshoot network issues.

In conclusion, RHEL8 Firewall is an essential tool for network administrators to ensure network security. Configuring RHEL8 Firewall is a straightforward process that requires a basic understanding of firewall rules. Firewalld is the default firewall tool in RHEL8 and can be controlled via the command line or graphical user interface. Firewall rules are configured based on zones, and it is necessary to enable the Firewall service before configuring the rules.

Advanced Features of RHEL8 Firewall

Advanced Features of RHEL8 Firewall

Red Hat Enterprise Linux 8 (RHEL8) Firewall comes with some advanced features that enhance security and provide more control over network traffic. In this subtopic, we will discuss some of the advanced features of RHEL8 Firewall.

1. Network Zones

RHEL Network Zones

Network Zones is a feature that allows different network interfaces to be assigned to different zones. Each zone has its own set of rules that control incoming and outgoing traffic. This feature provides flexibility and enables network administrators to define different security levels based on the type of traffic or device. For example, an interface can be assigned to a "DMZ" zone, where traffic from untrusted networks or the Internet is allowed, while another interface can be assigned to a "private" zone, where only trusted traffic is allowed.

The Firewall configuration tool (firewall-cmd) can be used to manage network zones. To list all available zones, run the following command:

firewall-cmd --get-zones

To assign an interface to a zone, run the following command:

firewall-cmd --zone=<zone-name> --add-interface=<interface-name>

2. Rich Rules

RHEL8 Rich Rules

Rich Rules is a feature that allows complex firewall rules to be defined using a syntax based on XML. This syntax provides more flexibility and control over network traffic than the basic syntax used for simple firewall rules. Rich Rules can be used to define rules based on the source or destination IP address, protocol, port, and other criteria.

An example of a Rich Rule that allows traffic from a specific IP address and port is:

firewall-cmd --permanent --zone=<zone-name> --add-rich-rule='rule family="ipv4" source address="" port protocol="tcp" port="22" accept'

This rule allows incoming traffic to port 22 (SSH) from the IP address in the specified zone.

3. nftables


nftables (Netfilter Tables) is a modern firewall framework that replaces the traditional iptables framework in RHEL8. nftables provides improved performance, scalability, and flexibility compared to iptables. It also supports a more concise and expressive syntax for defining rules.

The Firewall configuration tool (firewall-cmd) uses nftables to implement firewall rules in RHEL8. However, nftables can also be used directly to manage firewall rules. To list all nftables rules, run the following command:

nft list ruleset

To add a rule using nftables, run the following command:

nft add rule <chain> <rule>

Where <chain> is the name of the chain (e.g. "input", "output", "forward"), and <rule> is the rule to be added, specified using the nftables syntax. For example, to allow incoming HTTPS traffic, the following rule can be added:

nft add rule input tcp dport 443 accept

This rule adds a new rule to the input chain that allows incoming traffic to port 443 (HTTPS) using the TCP protocol.

Overall, the advanced features of RHEL8 Firewall provides improved security and more control over network traffic. Network administrators can use these features to define more complex rules and assign different security levels to different network zones. The use of nftables also provides improved performance and scalability compared to the traditional iptables framework.

Troubleshooting RHEL8 Firewall

Troubleshooting RHEL8 Firewall

Firewalls are a central part of any IT infrastructure. They ensure that all inbound and outbound traffic is monitored and filtered, reducing the risk of unauthorized access and malicious attacks. The RHEL8 firewall is one of the most popular firewalls in the market, providing a highly secure and reliable solution for many organizations. However, like any software, the RHEL8 firewall can encounter some problems. This article explores some common RHEL8 firewall issues and their solutions.

Problem 1: Firewall not starting

Firewall not starting

If the RHEL8 firewall does not start after installation, it could be due to a variety of factors. The first thing to verify is that the firewall has been installed correctly. You can do this by running the following command:

systemctl status firewalld

If the output shows that firewalld is not active, you can activate it by running:

systemctl start firewalld

If it still does not start, you may need to check the firewall configuration and ensure that it is set to start automatically. You can do this by running:

systemctl enable firewalld

Problem 2: Firewall is blocking desired traffic

Firewall blocking desired traffic

If the firewall is blocking desired traffic, you need to check the firewall rules. To do this, use the following command:

firewall-cmd --list-all

This command lists all the firewall rules that are currently in effect. If the desired traffic is not listed, you will need to add a new rule. For example, to allow incoming traffic on port 80 (HTTP), you can use the following command:

firewall-cmd --add-port=80/tcp --permanent

This allows incoming traffic on port 80, and the '--permanent' flag ensures that the rule is saved even after a reboot.

Problem 3: Firewall is causing connectivity issues

Firewall causing connectivity issues

If the RHEL8 firewall is causing connectivity issues, you can try disabling it temporarily to check if it is the root cause of the problem. You can disable the firewall using the following command:

systemctl stop firewalld

You can then check if the connectivity issues have been resolved. If they have, you can re-enable the firewall and add exceptions for the required traffic. Alternatively, you can check the firewall logs for any errors or issues that may be causing the connectivity problems. You can do this by running:

journalctl -u firewalld

This command displays all the logs related to firewalld, allowing you to troubleshoot any issues.

Problem 4: Firewall is conflicting with other software

Firewall conflicting with other software

If the RHEL8 firewall is conflicting with other software, such as antivirus software or other security tools, you may need to adjust the firewall settings to allow these applications to function correctly. You can do this by adding a new zone dedicated to those specific applications.

firewall-cmd --permanent --new-zone=apps
firewall-cmd --zone=apps --add-source=
firewall-cmd --zone=apps --add-service=http

The first command creates a new zone called 'apps', which is used to define the specific settings for the new zone. The second command specifies the IP addresses of the devices that will be using this zone, and the third command allows incoming traffic on port 80 (HTTP) for those devices.

With these adjustments, the conflicts between the firewall and other software should be resolved. If the conflicts persist, it may be necessary to contact the vendor of the other software for assistance.

The RHEL8 firewall is a powerful tool that provides robust security for your IT infrastructure. However, like any software, it can experience issues. By following the above troubleshooting steps, you can resolve most RHEL8 firewall problems and ensure that your network is secure and protected against unauthorized access and malicious attacks.

Securing Network with RHEL8 Firewall

Red Hat Enterprise Linux 8 firewall

The firewall is one of the most essential tools to secure a network on any operating system. A firewall is a software program designed to prevent unauthorized access to or from your network. It is used primarily to protect a system or network from unauthorized access while permitting legitimate communications to pass. Red Hat Enterprise Linux 8 provides a firewall called "Firewalld," which replaces the previously used "iptables." The following are some of the guidelines that can be used to secure a network with RHEL8 Firewall.

1. Enabling the Firewall

Cliking on Firewall

By default, Firewalld is enabled on RHEL8. However, in case it is disabled, follow the below steps to enable it:

Navigate to the command terminal and execute the following commands:

sudo systemctl enable firewalld

sudo systemctl start firewalld

After running the above commands, you can verify whether the firewall is running by typing:

sudo systemctl status firewalld

2. Creating Firewall Rules

Red Hat Enterprise Linux 8 firewall rules

Firewalld works by creating permanent and temporary firewall rules. The permanent rules will automatically start the next time you start the firewall on your system, while the temporary rules are only available for the current session and will not be saved for the next time the firewall is restarted. You can use either permanent or temporary rules to configure Firewalld. However, using permanent rules is more convenient. You can use the following command to create permanent rules:

firewall-cmd --add-service=ssh --permanent

3. Configuring Ports

Red Hat Enterprise Linux 8 firewall ports

If you want to open a specific port permanently, use the following command:

firewall-cmd --add-port=80/tcp --permanent

However, to open a port temporarily, use the following command:

firewall-cmd --add-port=80/tcp

4. Blocking IP Address

Red Hat Enterprise Linux 8 firewall IP address

If you want to block a particular IP address, use the following command:

firewall-cmd --add-rich-rule='rule family=ipv4 source address= reject'

5. Configuring logging Rules of Firewalld

Red Hat Enterprise Linux 8 firewall logging

Firewalld allows administrators to configure logging rules to track traffic and actions of the firewall. By default, logs are stored in the /var/log/messages directory. Moreover, firewall-cmd enables you to customize the log location and the detail levels of the logs for specific events. To configure logging rules:

firewall-cmd --set-log-denied=echo

After running the command, the blocked packets will be visible in the output.

firewall-cmd --set-log-denied=all

This command will log all the traffic that the firewall blocks, including ICMP packets. But if you need to log only specific protocols or services, you can use this rule:

firewall-cmd --add-forward-port=80/tcp --to-port=8080 –logprefix="http-traffic"

The command above will log every packet passed to port 80 to a custom file in the firewall log directory.

RHEL8 Firewall offers a range of features to secure the network and prevent unauthorized access to your systems. With this article, we have explored how to enable a firewall, create firewall rules, open specific ports, block IP addresses and configure logging rules for Firewalld. By following these guidelines, the security level of a network can be significantly improved.