I found a really good article on securityskeptic.com that points out 5 best practices when implementing firewalls.
1. Document all firewall rule changes
2. Install all access rules with minimal access rights
3. Verify every firewall change against compliance policies and change requests
4. Remove any unused rules form the firewall rule bases when services are decommissioned.
5. Perform a complete firewall rule review every 6 months
Policy specific advice includes to have strong change control policies, maintain your policies compliant with periodic reviews of standards and regulations, Life cycle management of firewall policies include the management of unused rules, decommissioning service,
If there were loopholes in the firewall, there should be compensating controls to catch these vulnerabilities. For example, having an IDS, or even routine monitoring controls(checking the logs routinely), performing vulnerability scans are all compensating ways to mitigate the flawed firewall.
Loopholes in the firewalls can be dangerous and attackers are often looking for loopholes to exploit them. Excess in loopholes and not patching these loopholes defeats the purpose of the firewall. Strict controls against these loopholes are therefore critical for successful firewall program for advanced system security.
Hi Xinyi,
DMZ is to solve the problem that the external network cannot access the internal network server after the firewall is installed. On the other hand, through such a DMZ area, the internal network is protected more effectively, because this type of network deployment, compared with the general firewall solution, has one more barrier for the attacker.
Public servers are put in the DMZ because they have to be accessed by the public, such as web servers. The DMZ is generally separated from the private network by a firewall. Because public servers are attacked often, such as web servers, this helps protect the internal network. It can also help mitigate an attacker from pivoting to an internal server with more important data.
Hello, Mei. I think the organization can use a web application firewall, and also can protect website and any real traffic that it receives. Also, organization should monitoring website traffic, DDoS attacks will occur huge upticks in traffic, so monitor website traffic can track the attack timely. That will help organization to stop some DDoS attacks and build stronger DDoS defenses against.
I know that some firewalls address SYN floods by pre-validating the TCP handshake. This is done by creating false opens. Whenever a SYN segment arrives, the firewall itself sends back a SYN/ACK segment, without passing the SYN segment on to the target server. Only when the firewall gets back an ACK, which happens only in legitimate connections, does the firewall send the original SYN segment on to the server for which it was intended.
Your servers should be protected by network firewalls and more specialized web application firewalls, and you should probably use load balancers as well. Many hardware vendors now include software protection against DDoS protocol attacks such as SYN flood attacks, for example, by monitoring how many incomplete connections exist and flushing them when the number reaches a configurable threshold value.
A major benefit of major advantage is of a transparent firewall is that you can insert it into a network without making any IP address changes on other devices. However, your are limited in the number of interfaces you can use.. With a restriction of two interfaces per firewall and using a bridge group you can raise that number to 8 interfaces per firewall.
Routed mode doesn’t have this limitation. Routed is the usual default mode and is more flexible in that it is easier to set up.
what happened when firewall let a true attack package go through, and is there a kind of firewall that will also detect a true attack package when it is not a provable attack packet
Firewalls can’t detect every attack packet. Most firewalls out there are still port based firewalls. That said it is just looking at the SRC, DEST, and PORT headers of the packet. If they match, it goes through. This type of firewall does nothing to prevent any kind of application level attacks. Even if you are using a WAF or a firewall with application filtering, attackers can still send malformed through the firewall hoping to avoid detection. Hopefully there is some kind of IDS behind the firewall that well look into the packet and send an alert to the SIEM if a possible malicious packet does get through,
An application-proxy firewall is a server program that understands the type of information being transmitted for example, HTTP or FTP. It basically acts as a browser to the server and a server to the browser. It functions at a higher level in the protocol stack than do packet filtering firewalls and hence provides for better monitoring and control of accessibility. Application proxy firewall examines the application message whereas packet filtering and SPI firewalls do not.
NAT plays an important role in securing a network because it can be used to protect an organization from attackers using sniffers and performing some reconnaissance on the network. NAT will hide the internal IP addresses and port numbers by converting it into a different external IP address and port number before the packet is sent to the destination. In other words, it protects the identity of the internal network from the internet.
Hi Priyanka,
A stateful firewall is a computer or router that can dynamically monitor and filter the traffic passing through it. This structure is called Stateful Packet Inspection (SPI) or dynamic packet filtering. It allows data packets to be inspected more thoroughly, while a stateless firewall can only monitor traffic based on static values. For example, when security is prioritized over speed, use a stateful firewall.
I don’t believe one great firewall will ever be a viable solution. The internet is an ever-changing landscape and new rules have to be added to keep up with new potential breaches and exploits.
The internet, computer security standards, enterprise IT architecture, and regulations are ever changing and evolving. There is no one great firewall solution that can take care of all vulnerabilities and threats. With the evolution of technology and internet, there is never be one true great firewall. Amendments, changes and upgrades will always be needed for the firewall to adapt to newer threats.
Agreed… but leep in mind there are Web Application Firewalls (WAF) that work on the application layer. These firewalls monitor and protect web applications/services from malicious HTTP traffic.
Found this great white paper on just this topic! Firewalls are only as good as what is provided by the Network Admin. This article focuses on “intelligent” firewalls that learn from the evolving world of network security using smart detection engine into a firewall. The engine will aim to detect classical IDSs, unusual structures in data packets. If you are interested in reading the article go to the site below and request the full text for free. https://dl.acm.org/doi/10.1145/2007052.2007094
Hi, Zhen! I think there are several ways to reduce the firewall vulnerability. First, the organization should maintaining a firewall’s firmware, which will help to scans and find out the vulnerability in the system. Second, they can back up the firewall’s configuration regularly, it will help to reset the correct configuration when erroer happens, and it can identifying the problem. Besides, the organization should keep the firewall security rules up to date. And every method is important to reduce the firewall vulnerability.
Hi Zhen,
I think they best way to avoid firewall attacks is companies should focus on blocking all inbound and outbound traffic by default, and encourage end users to explain why certain traffic should pass through the firewall. In addition, strictly control who has out-of-band management access to the firewall, and where each administrator is allowed to access management functions
In the digital business world, enterprises are not safe in the face of network threats. In fact, small and medium-sized enterprises are common targets of cybercrime, and the cost of an attack is usually between $84000 and $148000. If you want to protect customers’ data and avoid revenue and reputation damage, you need to pay attention to the security of it, website space, independent server, or virtual host and website program. A strong firewall is a necessary means.
First, the firewall runs in the network layer and identifies all incoming requests according to the Internet Protocol (IP) address. IP addresses are unique and assigned by Internet service providers (ISPs). When setting access control with a firewall for the first time, we must decide whether to start with open access or closed access. In the case of open access, all external IP addresses are allowed to send traffic to the network except the IP address that is explicitly blocked. Closed access, on the contrary, blocks all traffic except the IP address marked as allowed. For small businesses, it is obvious that they want to allow open access to public-facing websites so that external visitors can browse them. However, there should be more stringent control over the back-end servers that manage websites and related applications. In most cases, the firewall policy should be set to block access first.
Secondly, in the early days of the Internet, companies generally stored websites and applications on independent servers. Over time, this trend has transformed into putting resources in shared data centers and into today’s cloud computing movement. For small businesses, hosting data, applications, and services in the cloud often represents a wise financial decision. It needs a lot of energy and maintenance costs to maintain the independent server in an office environment or a small data center. Through cloud computing, you only need to pay for the services you use every month. However, cloud IT resources also have certain risks. This loses physical access to the data and becomes part of the shared network environment. Therefore, cloud customers need to maintain a strict firewall policy. Otherwise, the data may be exposed to hacker attacks. The security of cloud servers is also concerned. Of course, interested friends can learn more about how to improve the security of cloud servers.
Hi Prince,
The security strategy of the firewall is one of the most important features of the firewall. Firewall policies usually consist of thousands of security rules. Each rule generally consists of message traffic source IP, destination IP, source port, destination port, application type, user or user group, VPN instance, valid time period, rule operation, V4 or V6 distinction, log configuration, and other attributes information. Match user traffic according to the rules in the security policy. If the match is successful, the corresponding rule action is executed; if the match fails, the default action is executed.
Hi, Prince.
In my opinion, firewall policies can help companies how to review the firewall. Once the person identifies the vulnerability, he or she can use the policy as a guideline to solve the issue and document it whenever a similar issue occurs again, the person knows how to solve it. In addition, the management can use the policies to evaluate the firewall regularly. After a result of the evaluation is issued, the management can update any new technology in the policies so that the policies will not be out of date.
Hello, Junhan. Generally, firewalls only can filter traffic at wire speed and which is the maximum speed of the lines. When firewall faces the a major attack, the massively increased traffic will make it drop all the packets it cannot process.
NAT is an important part of securing a network as it improves security and decreases the number of IP addresses an organization needs. The router appears as a single machine with a single IP address which masks many computers on the LAN side of the router that may be simultaneously sharing the single IP. NAT routers also functions as very effective hardware firewalls which prevents unexpected or dangerous traffic from the public internet from passing through the router and entering the user’s private LAN network.
What are the efficient ways to avoid firewall policy conflict?
I found a really good article on securityskeptic.com that points out 5 best practices when implementing firewalls.
1. Document all firewall rule changes
2. Install all access rules with minimal access rights
3. Verify every firewall change against compliance policies and change requests
4. Remove any unused rules form the firewall rule bases when services are decommissioned.
5. Perform a complete firewall rule review every 6 months
Policy specific advice includes to have strong change control policies, maintain your policies compliant with periodic reviews of standards and regulations, Life cycle management of firewall policies include the management of unused rules, decommissioning service,
If there are loopholes in the firewall, what is the most effective control?
If there were loopholes in the firewall, there should be compensating controls to catch these vulnerabilities. For example, having an IDS, or even routine monitoring controls(checking the logs routinely), performing vulnerability scans are all compensating ways to mitigate the flawed firewall.
Loopholes in the firewalls can be dangerous and attackers are often looking for loopholes to exploit them. Excess in loopholes and not patching these loopholes defeats the purpose of the firewall. Strict controls against these loopholes are therefore critical for successful firewall program for advanced system security.
Why do companies put public servers in the DMZ which don’t have firewall protection?
Hi Xinyi,
DMZ is to solve the problem that the external network cannot access the internal network server after the firewall is installed. On the other hand, through such a DMZ area, the internal network is protected more effectively, because this type of network deployment, compared with the general firewall solution, has one more barrier for the attacker.
Public servers are put in the DMZ because they have to be accessed by the public, such as web servers. The DMZ is generally separated from the private network by a firewall. Because public servers are attacked often, such as web servers, this helps protect the internal network. It can also help mitigate an attacker from pivoting to an internal server with more important data.
What are some things organizations can do to make firewalls less susceptible to DDoS attacks?
Hello, Mei. I think the organization can use a web application firewall, and also can protect website and any real traffic that it receives. Also, organization should monitoring website traffic, DDoS attacks will occur huge upticks in traffic, so monitor website traffic can track the attack timely. That will help organization to stop some DDoS attacks and build stronger DDoS defenses against.
I know that some firewalls address SYN floods by pre-validating the TCP handshake. This is done by creating false opens. Whenever a SYN segment arrives, the firewall itself sends back a SYN/ACK segment, without passing the SYN segment on to the target server. Only when the firewall gets back an ACK, which happens only in legitimate connections, does the firewall send the original SYN segment on to the server for which it was intended.
Your servers should be protected by network firewalls and more specialized web application firewalls, and you should probably use load balancers as well. Many hardware vendors now include software protection against DDoS protocol attacks such as SYN flood attacks, for example, by monitoring how many incomplete connections exist and flushing them when the number reaches a configurable threshold value.
What factors determine when to install a routed firewall versus a transparent firewall?
It really depends on what your needs are.
A major benefit of major advantage is of a transparent firewall is that you can insert it into a network without making any IP address changes on other devices. However, your are limited in the number of interfaces you can use.. With a restriction of two interfaces per firewall and using a bridge group you can raise that number to 8 interfaces per firewall.
Routed mode doesn’t have this limitation. Routed is the usual default mode and is more flexible in that it is easier to set up.
what happened when firewall let a true attack package go through, and is there a kind of firewall that will also detect a true attack package when it is not a provable attack packet
Firewalls can’t detect every attack packet. Most firewalls out there are still port based firewalls. That said it is just looking at the SRC, DEST, and PORT headers of the packet. If they match, it goes through. This type of firewall does nothing to prevent any kind of application level attacks. Even if you are using a WAF or a firewall with application filtering, attackers can still send malformed through the firewall hoping to avoid detection. Hopefully there is some kind of IDS behind the firewall that well look into the packet and send an alert to the SIEM if a possible malicious packet does get through,
What distinguishes an application proxy firewall from static packet filtering firewalls and SPI firewalls?
An application-proxy firewall is a server program that understands the type of information being transmitted for example, HTTP or FTP. It basically acts as a browser to the server and a server to the browser. It functions at a higher level in the protocol stack than do packet filtering firewalls and hence provides for better monitoring and control of accessibility. Application proxy firewall examines the application message whereas packet filtering and SPI firewalls do not.
Why is Network Address Translation (NAT) an important part of securing a network?
Hi Jonathan,
NAT plays an important role in securing a network because it can be used to protect an organization from attackers using sniffers and performing some reconnaissance on the network. NAT will hide the internal IP addresses and port numbers by converting it into a different external IP address and port number before the packet is sent to the destination. In other words, it protects the identity of the internal network from the internet.
What is the different between stateful and stateless firewalls?
Hi Priyanka,
A stateful firewall is a computer or router that can dynamically monitor and filter the traffic passing through it. This structure is called Stateful Packet Inspection (SPI) or dynamic packet filtering. It allows data packets to be inspected more thoroughly, while a stateless firewall can only monitor traffic based on static values. For example, when security is prioritized over speed, use a stateful firewall.
What are some conflict resolution strategies in relation to security policies?
Is this possible to build a new great firewall in the US? Why? How?
I don’t believe one great firewall will ever be a viable solution. The internet is an ever-changing landscape and new rules have to be added to keep up with new potential breaches and exploits.
The internet, computer security standards, enterprise IT architecture, and regulations are ever changing and evolving. There is no one great firewall solution that can take care of all vulnerabilities and threats. With the evolution of technology and internet, there is never be one true great firewall. Amendments, changes and upgrades will always be needed for the firewall to adapt to newer threats.
Which OSI layer’s do firewalls work?
Hi Anthony,
In my opinion, the firewall mainly works on the third layer, filtering IP and protocol types, and does not involve the application layer.
Hi Zibai,
Agreed… but leep in mind there are Web Application Firewalls (WAF) that work on the application layer. These firewalls monitor and protect web applications/services from malicious HTTP traffic.
How could newer AI / ML tools be used to better manage firewall policies?
Found this great white paper on just this topic! Firewalls are only as good as what is provided by the Network Admin. This article focuses on “intelligent” firewalls that learn from the evolving world of network security using smart detection engine into a firewall. The engine will aim to detect classical IDSs, unusual structures in data packets. If you are interested in reading the article go to the site below and request the full text for free.
https://dl.acm.org/doi/10.1145/2007052.2007094
What are the effective control to reduce the Firewall vulnerability? Which one is the best one?
Hi, Zhen! I think there are several ways to reduce the firewall vulnerability. First, the organization should maintaining a firewall’s firmware, which will help to scans and find out the vulnerability in the system. Second, they can back up the firewall’s configuration regularly, it will help to reset the correct configuration when erroer happens, and it can identifying the problem. Besides, the organization should keep the firewall security rules up to date. And every method is important to reduce the firewall vulnerability.
Hi Zhen,
I think they best way to avoid firewall attacks is companies should focus on blocking all inbound and outbound traffic by default, and encourage end users to explain why certain traffic should pass through the firewall. In addition, strictly control who has out-of-band management access to the firewall, and where each administrator is allowed to access management functions
What types of internal firewalls would you implement and where would you put them?
Why are firewall policies important?
In the digital business world, enterprises are not safe in the face of network threats. In fact, small and medium-sized enterprises are common targets of cybercrime, and the cost of an attack is usually between $84000 and $148000. If you want to protect customers’ data and avoid revenue and reputation damage, you need to pay attention to the security of it, website space, independent server, or virtual host and website program. A strong firewall is a necessary means.
First, the firewall runs in the network layer and identifies all incoming requests according to the Internet Protocol (IP) address. IP addresses are unique and assigned by Internet service providers (ISPs). When setting access control with a firewall for the first time, we must decide whether to start with open access or closed access. In the case of open access, all external IP addresses are allowed to send traffic to the network except the IP address that is explicitly blocked. Closed access, on the contrary, blocks all traffic except the IP address marked as allowed. For small businesses, it is obvious that they want to allow open access to public-facing websites so that external visitors can browse them. However, there should be more stringent control over the back-end servers that manage websites and related applications. In most cases, the firewall policy should be set to block access first.
Secondly, in the early days of the Internet, companies generally stored websites and applications on independent servers. Over time, this trend has transformed into putting resources in shared data centers and into today’s cloud computing movement. For small businesses, hosting data, applications, and services in the cloud often represents a wise financial decision. It needs a lot of energy and maintenance costs to maintain the independent server in an office environment or a small data center. Through cloud computing, you only need to pay for the services you use every month. However, cloud IT resources also have certain risks. This loses physical access to the data and becomes part of the shared network environment. Therefore, cloud customers need to maintain a strict firewall policy. Otherwise, the data may be exposed to hacker attacks. The security of cloud servers is also concerned. Of course, interested friends can learn more about how to improve the security of cloud servers.
Hi Prince,
The security strategy of the firewall is one of the most important features of the firewall. Firewall policies usually consist of thousands of security rules. Each rule generally consists of message traffic source IP, destination IP, source port, destination port, application type, user or user group, VPN instance, valid time period, rule operation, V4 or V6 distinction, log configuration, and other attributes information. Match user traffic according to the rules in the security policy. If the match is successful, the corresponding rule action is executed; if the match fails, the default action is executed.
Hi, Prince.
In my opinion, firewall policies can help companies how to review the firewall. Once the person identifies the vulnerability, he or she can use the policy as a guideline to solve the issue and document it whenever a similar issue occurs again, the person knows how to solve it. In addition, the management can use the policies to evaluate the firewall regularly. After a result of the evaluation is issued, the management can update any new technology in the policies so that the policies will not be out of date.
Why is it that a firewall can keep up with traffic in general but fail to do so during a major attack?
Hello, Junhan. Generally, firewalls only can filter traffic at wire speed and which is the maximum speed of the lines. When firewall faces the a major attack, the massively increased traffic will make it drop all the packets it cannot process.
Do you think the new method of subdivision and firewall like DevOps/Cloud will replace our current process?
What is NATs purpose in a firewall?
NAT is an important part of securing a network as it improves security and decreases the number of IP addresses an organization needs. The router appears as a single machine with a single IP address which masks many computers on the LAN side of the router that may be simultaneously sharing the single IP. NAT routers also functions as very effective hardware firewalls which prevents unexpected or dangerous traffic from the public internet from passing through the router and entering the user’s private LAN network.
What is the difference between a Stateful Firewall and a Stateless Firewall?