pfSense is a free and open source firewall and router that is widely used in the enterprise. It has a wide range of features and can be configured to suit any network environment.
One of the most important aspects of configuring pfSense is creating firewall rules. Firewall rules define what traffic is allowed into and out of the network. They are the first line of defense against attacks and can help prevent sensitive data from being leaked.
In this article, we will discuss 10 best practices for creating firewall rules in pfSense. By following these best practices, you can ensure that your pfSense firewall is properly configured to protect your network.
1. Use the most specific rule possible
If you have a rule that allows all traffic from a specific IP address, and then another rule that blocks all traffic from that same IP address, the second rule will never be reached. This is because the first rule will always match and allow the traffic, so the second rule will never even be checked.
To avoid this issue, make sure to use the most specific rule possible. In the example above, the rule blocking traffic from the specific IP address should come before the rule allowing all traffic from that IP address. That way, the blocking rule will be checked first, and only traffic that isn’t explicitly allowed will be blocked.
2. Put more specific rules before less specific ones
When the pfSense firewall is processing traffic, it goes through each rule one at a time in the order that they are listed. So if you have a rule that allows all traffic from a specific IP address, and then a rule that blocks all traffic from another IP address, the first rule is going to take precedence.
This might not seem like a big deal, but it can cause some serious problems if you’re not careful. For example, let’s say you have a rule that allows all traffic from your office IP address range, and then a rule that blocks all traffic from a specific malicious IP address.
If you put the rule for your office IP address range first, then the rule for the malicious IP address will never be reached. This means that the malicious traffic will be allowed through, even though you were trying to block it.
To avoid this problem, always put more specific rules before less specific ones. In the example above, you would want to put the rule for the malicious IP address first, so that it takes precedence over the rule for your office IP address range.
3. Block traffic by default
If you don’t block traffic by default, any new traffic that arrives on your network will be allowed unless you have a rule specifically blocking it. This can be a major security risk since it’s easy to overlook new traffic types.
By contrast, if you block all traffic by default, you know that any traffic that is allowed is explicitly allowed by a rule. This makes it much easier to spot potential security risks since you can quickly see which traffic is allowed and which isn’t.
Of course, this doesn’t mean that you should never allow any traffic. You’ll still need to create rules to allow the traffic you want. But blocking traffic by default is a good starting point for creating a secure firewall configuration.
4. Allow only what is needed
By only allowing what is needed, you are essentially locking down your network so that only authorized traffic can flow through. This helps to prevent unauthorized access and also helps to improve performance by reducing the amount of traffic that needs to be processed.
To implement this best practice, you will need to create firewall rules that allow only the specific traffic that you want to allow. For example, if you only want to allow HTTP traffic, you would create a rule that allows only traffic from port 80. By doing this, you are ensuring that only the traffic that you want to allow is able to pass through your firewall.
5. Be consistent with your firewall policy
If you’re not consistent with your firewall policy, it will be difficult to troubleshoot issues that may arise. For example, if you allow traffic from one subnet but block it from another, it can be difficult to determine why the traffic is being blocked.
It’s also important to be consistent with your rule naming convention. This will make it easier to remember what each rule does, and it will also make it easier to search for specific rules.
Finally, it’s a good idea to document your firewall rules. This documentation can be in the form of comments within the rules themselves, or it can be in a separate document. Either way, it’s important to have a record of what your firewall rules are and why they’re in place.
6. Avoid using aliases in firewall rules
When you add an alias to a firewall rule, pfSense will automatically update the rule when the IP address or range of addresses in the alias changes. This can be handy in some situations, but it can also cause problems if the IP addresses in the alias change frequently or without your knowledge.
For example, let’s say you have a rule that allows traffic from a specific IP address to access your web server. You add the IP address to an alias so that you can easily update the rule if the IP address changes.
However, what happens if the IP address in the alias changes without you knowing? Your firewall rule will now allow traffic from a different IP address than you intended, which could potentially be harmful.
To avoid this problem, don’t use aliases in firewall rules. Instead, add the specific IP addresses or ranges of addresses that you want to allow or block to the rule itself. That way, you’ll always know exactly which IP addresses are being allowed or blocked by the rule.
7. Minimize the number of firewall rules
The more firewall rules you have, the more complex your rule set becomes. This can make it difficult to troubleshoot issues and can also lead to security vulnerabilities.
It’s important to remember that each rule has the potential to introduce a security vulnerability. Therefore, it’s crucial to only create firewall rules for the services and applications that you absolutely need.
Additionally, you should review your firewall rules on a regular basis to ensure that they are still relevant and that there haven’t been any changes to the services or applications that you are using.
8. Keep a log of all changes to the firewall configuration
If you ever need to troubleshoot an issue or roll back a change, having a log will make it much easier to find the cause of the problem and fix it. Additionally, if you have multiple people working on the firewall, a log can help prevent accidental changes from being made.
To enable logging in pfSense, go to Status > System Logs and click the Settings tab. Then, check the boxes next to the types of logs you want to keep track of.
9. Test your firewall rules
When you make a change to your firewall, there’s always the potential to break something. By testing your changes before you deploy them, you can be sure that they work as intended and that you’re not accidentally blocking traffic that you need.
There are a few different ways to test your firewall rules. One is to use a tool like pfSense Test Center, which will allow you to simulate traffic and see how your firewall handles it.
Another option is to use a tool like WireShark to capture live traffic and then analyze it to see what’s being blocked and what’s getting through.
Either way, testing your firewall rules is an essential best practice to ensure that your changes don’t break anything.
10. Monitor your firewall logs
Your firewall is constantly being bombarded with traffic, both good and bad. By default, pfSense will log all this activity, which can be useful for troubleshooting purposes. However, if you’re not regularly monitoring these logs, you could be missing important information about attacks on your network.
There are a few different ways to monitor your firewall logs. The easiest way is to use the built-in Log Viewer in the pfSense web interface. This will give you a real-time view of all the activity passing through your firewall.
If you want more comprehensive logging, you can enable syslogging and send your logs to a central syslog server. This is a bit more complex to set up, but it’s worth it for the added security.
Finally, you can also use a third-party logging tool like Splunk or Graylog. These tools will provide you with even more detailed information about the traffic passing through your firewall.
There are two basic philosophies in computer security related to access control: default allow and default deny. A default deny strategy for firewall rules is the best practice.What are the four 4 best practices for firewall rules configuration including allow access? ›
- Block by default. Block all traffic by default and explicitly enable only specific traffic to known services. ...
- Allow specific traffic. ...
- Specify source IP addresses. ...
- Specify the destination IP address. ...
- Specify the destination port. ...
- Examples of dangerous configurations.
Each firewall rule is composed of six parts, which together define conditions under which a given network request is permitted or denied. These components are action, direction, target, source/destination, protocol and ports, and priority.What are the four basic firewall rules? ›
- Source IP address(es)
- Destination IP address(es)
- Destination port(s)
- Protocol (TCP, ICMP, or UDP, etc.)
Explanation. The four techniques used by firewalls to control access and enforce a security policy are Service control, Direction control, User control and Behavior control.What are the 5 steps to configure a simple firewall? ›
- Secure the Firewall. ...
- Establish Firewall Zones and an IP Address Structure. ...
- Configure Access Control Lists (ACLs) ...
- Configure Other Firewall Services and Logging. ...
- Test the Firewall Configuration. ...
- Manage Firewall Continually.
Where most firewall rules only inspect headers at layer 3 (IP address), 4 (Transport), and 5 (Port), a layer 7 rule inspects the payload of packets to match against known traffic types.What is firewall checklist? ›
Identification of all Internet Service Providers (ISP) and Virtual Private Networks (VPN) All relevant firewall vendor information including OS version, latest patches and default configuration. Understanding all the key servers and information repositories in the network and the value of each.How to set firewall rules in pfSense? ›
Creating a Firewall Rule
Navigate to the Firewal `> Rules on pfSense web GUI. Select the interface that you want to define a rule, such as WAN, LAN, VLAN10 or GUESTNET, etc. This will list the existing firewall rules on the selected interface.
Firewall rules have a priority order that determines the order in which the rules are applied to network traffic. Firewall rules are shown as a list on the Rules page. The rules are applied from top to bottom, and the first rule that matches the traffic overrides all the other rules below.
- MS RPC TCP, UDP Port 135.
- NetBIOS/IP TCP, UDP Port 137-139.
- SMB/IP TCP Port 445.
- Trivial File Transfer Protocol (TFTP) UDP Port 69.
- System log UDP Port 514.
For a very simple example, you might have a rule that says, “Allow any traffic from IP address X to port Y.” When a packet arrives at the firewall, the firewall reads its source and destination. If the packet's source is X and its destination Y, it passes through.How do pfSense firewall rules work? ›
In pfSense® software, rules on interface tabs are applied on a per-interface basis, always in the inbound direction on that interface. This means traffic initiated from hosts connected to the LAN is filtered using the LAN interface rules.What are the 8 types of firewall? ›
- Software firewall. ...
- Hardware firewall. ...
- Packet filtering firewall. ...
- Circuit-level gateway. ...
- Proxy service application firewall. ...
- Cloud firewall. ...
- Stateful inspection firewall. ...
- Next-Generation firewall (NGFW)
Functions of Firewall
Therefore, a firewall's primary function is to secure our network and information by controlling network traffic, preventing unwanted incoming network traffic, and validating access by assessing network traffic for malicious things such as hackers and malware.
Firewall Rules can take the following actions: Allow: Explicitly allows traffic that matches the rule to pass, and then implicitly denies everything else. Bypass: Allows traffic to bypass both firewall and Intrusion Prevention analysis.What are the 2 methods of firewall? ›
There are two types of firewalls based on what they protect: network-based and host-based. Network-based firewalls, which are frequently hardware, protect entire networks. Host-based firewalls, which are frequently software, protect individual devices known as hosts.What are the two types of firewall policies? ›
You can use two types of Firewall policies in Network Security Platform — advanced and classic. Functionally, these two types are similar. However, as the names might suggest, advanced Firewall policies provide you more options to filter traffic when compared to classic.How many rules are there in firewall? ›
The maximum number of firewall rules that can be set in WFBS depends on the number of exceptions configured in one policy or rule. The maximum number of limitations that can be inserted in a policy or rule is 1024. Also, the number of exception rules configured in one policy may affect how many rules can get inserted.What are the five 5 practices to ensure security for enterprise networks? ›
- Catalog all enterprise data. ...
- Understand data usage. ...
- Categorize data. ...
- Use data masking. ...
- Use data encryption. ...
- Implement strong access controls.
- Keep Informed. ...
- Educate Your Team. ...
- Know Avenues of Attack and Preempt Them. ...
- Install Antivirus and Other Security Programs. ...
- Make Sure Your System is Physically Secure. ...
- Test Your Security. ...
- About the Author.
Layer 3 Firewall rules provide an administrator granular access control of outbound client traffic. With the MR series, outbound traffic refers to client traffic originating from the wireless network that is destined for the wired LAN or Internet.What are the Layer 7 attacks? ›
Application layer or Layer 7 DDoS attacks are among the most sophisticated and powerful types of attacks that can be launched against a website or application. These attacks work by overwhelming the target with requests that appear to come from genuine users, thereby preventing legitimate traffic from getting through.What is a Level 4 firewall? ›
L4 Firewalls or Layer 4 firewalls (i.e., session filtering firewalls): Ability to do this, plus adding the ability to actively track network connections and allow/deny traffic based on the state of these sessions (i.e., stateful packet inspection). sessions (i.e. stateful packet inspection).What are common firewall tasks? ›
Firewalls can also perform various functions, such as packet filtering, stateful inspection, proxy service, and deep packet inspection, to control and monitor the traffic between your network and the internet.What are the basic elements of firewall? ›
- Internet Protocol (IP) packet filtering.
- Network address translation (NAT) services.
- SOCKS server.
- Proxy servers for a variety of services such as HTTP, Telnet, FTP, and so forth.
- Mail relay services.
- Split Domain Name System (DNS)
- Real-time monitoring.
At its most basic, a firewall is essentially the barrier that sits between a private internal network and the public Internet. A firewall's main purpose is to allow non-threatening traffic in and to keep dangerous traffic out.What are floating rules in pfSense? ›
Floating Rules are a special type of advanced rule that can perform complicated actions not possible with rules on interface or group tabs. Floating rules can act on multiple interfaces in the inbound, outbound, or both directions.What firewall does pfSense use? ›
Stateful Filtering. pfSense software is a stateful firewall, which means it remembers information about connections flowing through the firewall so that it can automatically allow reply traffic.What is better than pfSense? ›
OPNsense is a free, open-source firewall and routing platform based on HardenedBSD. It was created as a fork of pfSense, aiming to provide a more modern and secure alternative.
As mentioned earlier, firewall rules are evaluated on a top-down basis. The first rule that matches a packet is executed, and the rest are skipped. It is important to consider the order of firewall rules. Often specific rules will proceed more general rules.What ports should never be open? ›
Ports 80, 443, 8080 and 8443 (HTTP and HTTPS)
HTTP and HTTPS are the hottest protocols on the internet, so they're often targeted by attackers. They're especially vulnerable to cross-site scripting, SQL injections, cross-site request forgeries and DDoS attacks.
Commonly hacked TCP port numbers include port 21 (FTP), port 22 (SSH), port 23 (Telnet), port 25 (Simple Mail Transfer Protocol or SMTP), port 110 (POP3), and port 443 (HTTP and Hypertext Transfer Protocol Secure or HTTPS).How do hackers find open ports? ›
Hackers do not have a preference for which ports they use. They will use port scans to identify ports to open. Commonly targeted ports include widely used programs by network teams for remote administration, web applications, file transfer services, conferencing software and common remote connectivity.What is the last rule in the firewall? ›
Implicit deny is usually the last rule by default in current firewalls, however an administrator may put an Explicit deny rule last so that they can log that traffic as well.What is the default rule of firewall is to allow? ›
By default, the firewall prevents all traffic from a lower security zone to a higher security zone (commonly known as Inbound) and allows all traffic from a higher security zone to a lower security zone (commonly known as Outbound).How do I check my firewall rules? ›
- Click Start, click Run, and then type wf. msc.
- Look for application-specific rules that may be blocking traffic. For more information, see Windows Firewall with Advanced Security - Diagnostics and Troubleshooting Tools.
- Remove application-specific rules.
- Harden the firewall and establish a firewall configuration plan.
- Map out your firewall deployment.
- Protect the firewall.
- Routinely audit the firewall.
- Block traffic and monitor user access.
- Implement a centralized management tool for multi-vendor firewalls.
- Update your firewall software.
- Block all access by default. When configuring a firewall, it's important to start by blocking access to the network from all traffic. ...
- Regularly audit firewall rules and policies. ...
- Keep the firewall up-to-date. ...
- Keep track of authorized users.
The Firewall Filtering policy has one default rule, which handles all the traffic that does not match any user-defined rule with a higher rule order. The default rule always maintains the lowest precedence and cannot be deleted. Only admins with the super admin role can modify the default rule.
A firewall policy is a filter that allows or denies traffic based on a matching tuple: source address, destination address, and service. By default, firewall policy rules are stateful: if client-to-server traffic is allowed, the session is maintained in a state table, and the response traffic is allowed.What is the best practices in the firewall domain environment? ›
3. What is the best practice in the firewall domain environment? Explanation: All live servers or workstations are kept in a separate zone than inside and outside to enhance protection. 4.What are 3 tasks carried out by a firewall? ›
They've since become the foundation of network security in the client-server model -- the central architecture of modern computing. Overall, firewalls play an important role in preventing cyber attacks, protecting sensitive data, and maintaining the privacy and security of computer systems and networks.What is the firewall rule management process? ›
Firewall rule management is the process of periodically reviewing and optimizing firewall rules. This process involves the following: Analyzing rule anomalies that affect the performance of the firewall. Reordering existing rules to improve rule performance.How do I make Pfsense secure? ›
- Restricted Admin access. Just like any other software, Pfsense comes with an Admin access. ...
- Avoid unencrypted traffic. ...
- Restrict internal network access. ...
- Proper updates. ...
- Periodic backup. ...
- Managing from console. ...
- Avoid abrupt shutdown.
Firewall rules are stored under the Software\Policies\Microsoft\WindowsFirewall\FirewallRules key. Each value under the key is a firewall rule.How do I manage firewall permissions? ›
Click the Start button, then type Windows Firewall in the Search box. Click Windows Firewall, and then click Allow a program or feature through Windows Firewall. Click the Change settings button. If a User Account Control window appears, click Yes, or enter your user name and password, then click OK.What is default deny in firewall rules? ›
Definition(s): To block all inbound and outbound traffic that has not been expressly permitted by firewall policy.What is the default timeout for firewall? ›
Idle timeout is the maximum length of time that a TCP connection can stay active when no traffic is sent through the connection. The default global idle timeout for all traffic is 3600 seconds (1 hour).