Best Cyber Security

What is the Most Important Functionality of a Firewall?

Every large corporate network today, should have at least one firewall.

The purpose of the firewall is to enable the existing network to automatically avoid being connected to a particular network which may otherwise be malicious or have other problems.

It is used to keep threats away from the corporate network.

The most important functionality of a firewall is to detect connections that belong to another application and that it can use.

Based on this, the firewall is in charge of blocking, redirecting or accepting the traffic. In Linux, the firewall is often known as iptables, syslinux or autofs. iptables is the default firewall built in the upstream Linux kernel.

You can use syslinux, or you can build your own firewall in place.

One of the major factors that increase the amount of data traffic is also the impact of the internet, websites, blogging etc. which now allow people to publish their work on the net for a wide audience.

Many people also make use of the net for internet shopping, online gaming and shopping etc.

This implies a lot of traffic which becomes a real security risk

The need for a firewall is no longer a question of security for the average network but also when network usage is immense and very much out of the norm, to keep things in order.

The most essential function of a firewall is to block the traffic that has an identifying characteristic of malicious or criminal activity.

They also do this by detecting the source of the malicious network traffic. 

The unique characteristic may be known as MAC address or TCP port or even UDP port number.

The special character in a word is the port number. 

The combination of a man-in-the-middle attack, a worm or other malicious software that could intercept and control or even make permanent changes to your network traffic.

By using a firewall, it prevents the same port from being exploited to carry out these malicious activities. 

Stop Unnecessary Traffic

Many people often complain of their firewall and other network tools logging traffic.

The question then is why is it logging the traffic?

Why not stop the unnecessary traffic first?

This is because the analysis of the incoming traffic allows you to determine the type of application, the type of operating system and the operating system version.

Proper analysis will enable you to know how you should handle the system.

Thus, it is necessary to stop the potentially malicious traffic to avoid a breach of security.

The Make no Mistake! What is the primary function of a firewall is to secure the network.

The number of incoming connections should be monitored to determine the threat before you do any compromise with the network.

The moment a threat is identified, it must be immediately stopped and the traffic contained.

Do not wait until an attack or breach happens before you act.

This would allow an attacker to see how you manage your network.

Assess and Improve

However, the best way to determine how effective the firewall is is to look at its performance.

When you are moving to a new network, it is always advisable to install a new firewall on it.

If the firewall is functioning efficiently, then you can go ahead and change the location of the firewall.

If there are issues with it, you may need to change it.

The reason is simple – the strength of the firewall lies with its performance.

So, by examining its performance, you can determine the status of it.

If there are a lot of errors and by not blocking out legitimate traffic, then you will need to improve its performance.

Often times, you can get this done with the help of a firewall pro.

When you are looking at the available firewall tools, you should examine and test to see which ones you find satisfactory and which you can recommend to your network.  

Cyber Security Technology and Techniques

Firewalls are used to secure your networks.

Firewalls prevent malicious attacks by controlling access to the network.

Who has access to the network?

If your firewall prevents clients from connecting to a specific host, then it prevents clients from connecting to an organisation’s data or resources that are not supposed to be accessible to them.

How do I get a firewall?

You can buy a firewall by yourself or get a vendor to make a custom solution for you.

You can read more about the advantage of buying your firewall made by the vendor versus buying it yourself.

Why a firewall?

Firewalls separate networks by using rules.

Why does firewall need to be more granular?

When you consider how the Internet has evolved, there are more and more of these kinds of tools available.

If your firewall is just trying to block access to a web browser that also accesses a file or a printer, then you are not doing the job it’s supposed to do.

How can I monitor my firewall?

To monitor your firewall, you can login to the web interface from a trusted IP address to monitor it.

It is useful for people that don’t know how to use the firewall and for security professionals.

How can I configure my firewall?

When setting up a firewall, there are several different options.

One is to use a setup utility to perform the configuration; the other option is to edit configuration files directly.

When you configure a firewall, you should have your primary firewall, a secondary firewall for on-premise deployments and a path breaker (firewall for public cloud deployments).

When configuring a secondary firewall, it is often helpful to identify on which hosts the primary firewall can’t reach.

This prevents your primary firewall from leaking data about your cloud hosts or public cloud hosts.

In the same way, when configuring a primary firewall, if you have the ability to scan your network, you should configure a secondary firewall for on-premise deployments so that it can be configured for service discovery.

This ensures that the primary firewall doesn’t accidentally connect to the wrong host.

Once you have configured your firewall, you can use any of the information that it provides, such as port forwarding or device discovery.

When should I replace my firewall?

When your firewall stops working; that means that it’s time to replace the device.

How do I get an alternative for my firewall?

There are many options for protecting your network, some are free and some require you to pay.

Some of them are easier to install than others.

What should I use a proxy to protect my network?

Proxy applications are used to protect the network by transparently forwarding internet traffic through a virtual, secure and controlled proxy server, bypassing the ‘redirection’ or filtering done by your firewall.

Firewalls by themselves don’t need to know about the origin or the destination of the traffic, they are able to apply policies based on application, destination or protocol.

How can I make my existing firewall harder to bypass?

Some firewall software can choose a certain policy to apply based on which ports the firewall listens or can block.

To get around this, make sure that all ports are closed in your firewall and don’t enable any of the firewall settings.

What should I use as a firewall in my cloud?

In a cloud, you need to do the following:

Ensure that your private internet traffic, and public internet traffic, is treated equally.

Create a virtual bridge that route traffic based on the destination.

Ensure that your proxy works with this routing and the firewall.

How can I make my firewall more useful?

If you are considering replacing your firewall, you should consider the following factors:

This article was written by:

Traditionally, firewalls have been used for network security.

In the past decade, we’ve seen a huge evolution in how firewall protects networks.

However, nowadays, there are more important things to consider:


Any malware, like rootkits or viruses, is classified as a zero-day exploit by Microsoft.

Malware is the number one cause of intrusion on networks today.

Trends in the cyber-sphere

Let’s be honest, there’s a good chance that you or your company is being targeted by an advanced attacker today.

The good news is that, from the sounds of it, some of these advanced attacks are getting less advanced every year.

As an example, even ransomware (in which you make a ransom payment in order to regain access to your files) is becoming less and less popular every day.

However, this type of advanced attack is still very threatening, and businesses still need to be prepared.

So, what do we need to do to protect our networks from attackers?

Whenever you think about the bad guys, you think about complex networks and elaborate malware.

You may not have thought about your infrastructure.

As you can see, it’s probably a good idea to start by developing a healthy security habit and protection for your infrastructure.

What kind of attack is on your systems?

Is it your email, your virtual private network, your website, a cryptocurrency exchange, a chat platform, a social media platform?

Is there a high volume of users?

What if there was a vulnerability on your systems?

What if some of your systems could be hijacked?

Are there common vulnerabilities?

Let’s now have a look at some of the best practices you should adopt:

Lock down your data by checking and fixing the default user accounts and passwords on your laptops, desktops and servers.

Enable two-factor authentication on your devices and your corporate networks.

This is often known as multifactor authentication.

In order to be able to make a log out request, you will first need to enter a password, which will then be verified with a one-time password sent via SMS or generated by a physical security token, such as a USB Flash drive or a mobile phone.

Integrate your VPNs, mail servers and more in to one secure network, using a virtual private network or tunnel.

Enable proxy technologies like VFL, vFLip, VNC, L2TP and SSL to route the traffic in a way that is less susceptible to detection and audit.

Disable JavaScript on your website and only use JavaScript that’s needed for a web page.

Look at your reputation and see how people are referencing your brand.

Check for data redundancy, failure analysis, and reliability and test your network.

Is there any way to protect your systems and data?

The good news is that some of the above threats are evolving and becoming less complex.

However, you’ll still need to protect your systems. And sometimes, even the simplest solutions can go a long way.

Worry not, be happy

Why do we always need to be worrying? For example, is the frequency of cyberattacks increasing or decreasing?

According to Gartner, the frequency of cyberattacks may have decreased. However, the severity of these attacks is rising.

The final question to ask yourself is, is your network safe?

Steps to avoid data breaches

How can we know if our systems are as safe as we need them to be? How do we ensure our systems are as protected as we should be?

Here are some of the steps you can take:

You can hire a security consultant to give you a better understanding of the risks your organization is facing and the solutions to take.

They may also be able to help you identify a new security partner that is best for your business needs.

Make sure your employees are trained and well informed about the latest threats and how to protect your company.

This is a good training exercise for them.

Ensure your employees are protected by implementing anti-malware solutions. Malware is still the number one cause of intrusion on networks today.

Install intrusion detection and prevention systems on your devices and network to keep an eye on suspicious behavior and prevent potential intrusions.

Monitor your network, endpoint security solutions and network monitoring systems to watch for intrusions.

Cloud-based services

It’s all about the cloud. Whether your business is based in the cloud, or you operate in a hybrid, many of your staff should use cloud-based services.

We use different cloud storage services: AWS, Microsoft Azure and Google Cloud.

By choosing the cloud, you no longer need to buy, maintain and deploy hardware on premises.

Everything is stored in the cloud.

The benefits are many. Using the cloud, you don’t need to worry about hardware maintenance, updates, or replacements.

As your data is in the cloud, you no longer need to worry about hardware maintenance, updates, or replacements.

You can download apps to your devices, laptops or PCs to access your data and process it at a lower cost.

For example, when working remotely, employees can access their documents and work seamlessly.

You can also integrate your apps to your cloud services.

This is a great way for employees to access information anywhere on any device.

Cloud computing also reduces your IT complexity

You don’t need to buy all the computers, servers and storage you need to operate the business.

You can work with a few cloud services instead of buying them all.

Cloud storage is the third place where people can store their personal information.

According to IBM, the third place where people store their personal information is cloud storage.

This has important implications because when a breach occurs, the first thing people will do is look for their information.

While most cloud storage services have security in place, you still need to ensure your system is fully protected from viruses and malware.

Use redundancy

To increase your data protection, you can work with different cloud storage services. This gives you the flexibility to move files back and forth.

You can keep the data on your premises or you can move it to the cloud. There is also a slight performance increase, which is a good thing.

The benefits of the cloud can be highly beneficial for your business.

Monitor security

You can easily set up your security measures to monitor whether your employees are doing anything that is detrimental to the system.

There are many tools available to help you monitor your network and security.

These tools alert you to possible threats, help you block them and make sure your network is safe.

The resources available are really useful.

You need to pay attention to what these tools provide to you because they can help you protect your company from cyber threats.

Reduce IT complexity

Enterprise security can be overwhelming. The network systems need to be properly configured.

It is also important that you have a team to maintain the network and IT security.

Having a trained team and also having the proper tools to do the job is important.

Don’t use old hardware

According to Cisco, 60% of security incidents have occurred using outdated tools or technologies.

So, while your network is out of date, your IT system is also too.

A secure, reliable and secure network that is built on modern technology is what your business needs.

This can help you make use of the cloud to help improve your business productivity.

Use security

The best way to protect your data is to deploy security measures from the start.

You can ensure your company’s security by using firewalls, and encryption to store your data.

It is very important that you have this kind of system installed to stop potential security threats.

With the cloud you don’t need to worry about things like data leaks. You can store everything in the cloud.

The same is true for backup. You can easily protect your backup data from malicious attacks. One of the best cloud backup providers is Rubrik.

They have great customer support that can help you save time and money.

Cloud has potential

The cloud is very attractive. The advantages of using the cloud for your business can be highly beneficial for your company.

Using the cloud, you don’t need to worry about hardware maintenance and repairs, nor about updating the software.

You can easily recover your data from the cloud when there is an incident.

The cloud is an ideal option when you need your data to be accessible from anywhere.

You can also use the cloud for your backups. If your computer goes down, the data is safe.

This is important for protecting your data from malicious attacks.

The cloud also helps you cut costs. You don’t need to purchase a big data center for your data storage.

With cloud, you can store your data on shared or private cloud services.

Your business can benefit from improved efficiency, faster access to the data and more security.

If your business depends on IT, you can use the cloud to reduce the complexity and increase productivity. 

Firewall key strength

No doubts, the most important functionality of a firewall is to protect the system from attacks coming from the network.

So, by getting access to these attack vectors, the adversary can try to achieve various goals by gaining remote access or by modifying the internal information.

“Security Through Obscurity” is a cornerstone of digital security.

That is a famous saying of Dan Brown, the author of the best selling novel, The Da Vinci Code.

The author of the book states that information security and strong authentication will hinder the success of an adversary by providing key sources for information on the target system that is to be used as part of a deception.

Many times, security by obscurity can lead to a problem in which the attacker not only can access the system but also modify its internal information.

To get access to the compromised system, an attacker needs to understand the limitations of an existing solution and how it can be attacked.

As a result, an attacker will need to figure out the weakness of the previous system.

Since the system is hard to discover and almost impossible to hack, the attack can be conducted for long periods without being noticed.

This is exactly how a network firewall works. In a network firewall, the system is used to protect network traffic and the internal information against attacks coming from the external environment.

The process of configuring a network firewall is very simple. And the configuration process varies from system to system.

However, there is one main principle that is the same for all the configuration tools.

Security By Obscurity

In a nutshell, this principle means to restrict access to critical system functions by the network attackers.

The attacker will not be able to perform his desired actions in a secure network.

For example, the attacker who wants to do something harmful to the network will not be able to do so, if he can’t find out the specific port to connect to.

In fact, the firewall shouldn’t allow connection to certain external ports.

This way, the system will be more secure by providing protection against external attacks and man-in-the-middle attacks.

Complexity should not be the enemy of security

When developing a network firewall, it is very important to make it as secure as possible.

However, complexity should not be the enemy of security. In fact, the more complex the firewall, the more secure it is.

The more features a firewall has, the more options it can support, making it more useful for the customers.

Also, the more features a firewall has, the harder it is to maintain.

On the other hand, if a firewall has too few features, it will be difficult to configure and control.

It will be harder for the administrators to understand all the configurable options.

This may lead to a scenario where no options are supported and all users may not have access to the settings.

So, if a system has too few features or too many features, it can be a huge investment in time and money.

However, if the system is complex enough, but not complicated enough, it is easier to integrate with other security systems, as it will integrate easily with other systems used for security.

Also, it will be easier to detect problems when they occur. If you have a multi-layered architecture that integrates with various security systems, it is much easier to detect problems.

Let’s take a look at the software firewall I defined in the previous article as an example.

This example comes with almost all the features.

For example, it has a variety of features such as User-Agent, Client-Application, port-based, HTTP-based, TCP/UDP-based, and even NNTP based.

And if we are to build a multi-layered architecture, we can have many such security systems. The firewall itself acts as the middle layer.

On one side, the firewall needs to integrate with the management system.

On the other side, we have another layer that must interface with other security systems, such as the System, our RAID array, NFS, etc.

“Our firewall should be so good that it integrates with all the security systems.”

The more the interface between layers, the easier it will be to secure the network.

A complex architecture makes it easy to manage and integrate.

Why multilayer architecture?

Multilayer architecture is good because each layer should be as secure as possible, and each layer should also be as simple as possible.

Multilayer architecture is also good, because the more layers you have, the more easy it will be to integrate a multi-layered firewall, as long as each layer is as secure as possible.

This way, if you implement a security solution for your environment, you should not worry about how to protect your firewall, because you don’t have to.

If you integrate a security solution, you should worry about how to maintain it.

If you are developing a security solution, how to integrate with other security systems?

When designing your firewall, the goal is to combine as many features as possible with fewest number of settings.

When designing your firewall, the goal is to combine as many features as possible with fewest number of settings.

For example, this particular layer of our firewall can also integrate with NFS.

We could define a multi-layer architecture that integrates with everything, even when an enterprise is configured with a single NAS.

If we combined all the features we have into one layer, such as the self-service portal, we will have a more integrated environment.

For example, let’s say the SMTP server is managed with one host, and users have to configure SMTP on their own.

We could use a self-service portal that can control the SMTP server on our firewall, while also managing it.

The user could configure and manage all his devices on the firewall without a problem.

The beauty of using this multi-layered architecture is that it integrates with all other security systems, and will not take up as much space and resources as if we made the same setup with separate firewalls.

This is why we use the term “multi-layered architecture”. We are talking about multi-layer architecture.

“Each layer should be as secure as possible, and each layer should also be as simple as possible.”

Other advantages:

Easy to manage/deploy security solutions (Multi-layer architecture means that security solutions are not too large and difficult to manage.

If you use a self-service portal, you can easily manage your security solutions.)

Separates from the management system.

The management system can focus on its core responsibilities, such as managing servers and services, while the firewall focuses on security.

This allows us to keep the management system simple and lightweight, while giving security systems enough room to breathe. 

If you look at the architecture of the firewall running at a major city ISP, you may have noticed that you have a different configuration than a tier 1 ISP.

The tier 1 is running the NTP infrastructure, and the tier 2 is running the DNS servers.

They are both connecting to the same public IP address, which is the public IP address for the physical layer, the first IP layer in the network.

This public IP address is normally associated with an DHCP server. You may also notice that when you have more than four network zones configured, they would all be specified on this same public IP address.

The public IP address is normally set to, and it is commonly referred to as 172.16.0.x.

What happens when I open up the box to connect my network into the box? The first thing I have to do is to activate the firewall for the first zone.

This has to be done by simply editing the configuration file, or if I use Windows, I can just right-click on the Network tab of my file manager and I can just select Network > Enable firewall. Once this first zone has been activated, it has a default IP address of

At a tier 1 ISP, the first IP address for your first network zone is typically 10.0.1.x, and this is because at the major Tier 1 ISPs, if you go and look at the internet configuration, you can usually see that you are routing traffic to a "Tier 1" DNS server on the public IP address of 10.0.1.x, and this is where all the traffic is going to go. At a tier 2 ISP, the first network zone's IP address is 10.0.2.x, and it is usually assigned to a DHCP server.

At a tier 2 ISP, you would normally have this router and its associated DHCP server at

If you were routing traffic to a local DNS server on a public IP address, you would route it to the Tier 1's IP address of 172.16.0.x.

So for me to just connect into my tier 2 ISP network without configuring any sort of firewall, I would have to have an active or modified firewall for every single network zone that I wanted to connect into.

In order to be able to talk with multiple other devices on your network, the first network zone would have to be able to accept packets that originated on another network zone that is on the same network as this first zone.

In order to accomplish this, you would have to configure a router in the first network zone that would accept all of the traffic from any other network zones on your network.

If you go back to the architecture of a tier 1 ISP, the router would usually be configured to accept packets that originate on the network of tier 1, and it would forward these packets onto the network of tier 2.

You may also notice that the same router is responsible for being the DHCP server of the network, and when you have multiple DHCP servers, the traffic to each one of them is forwarded onto the network of tier 1.

Can a Firewall Stop All Attacks?

If your answer is that it stops all network attacks, you're not alone. But a firewall that simply blocks the "WannaCry worm" (aka WannaCrypt) isn't likely to be all that effective.

Most firewalls block just about anything it encounters when connecting to the Internet.

One common method of detection is a binary scan, where the firewall checks for any connections that are not allowed by a specified ruleset.

Of course, there is more to a good firewall than just looking for malicious traffic.

A good firewall is also important for defending against accidental access, keeping unapproved devices from malicious actors, and doing proper infrastructure monitoring.

In this article we're going to look at what a good firewall does, and how to tell when one isn't behaving properly.

Understanding the Cybersecurity Defenses of Your Organization To better protect your organization from cyber attacks, you will need to protect against multiple forms of vulnerability.

Modern networks are heterogeneous, composed of physical devices, applications, and services that may be connected to the internet through Ethernet, IPv4, IPv6, IPSec, SMTP, and HTTP.

An effective cybersecurity strategy requires protection against vulnerabilities of all types, for all connections to the internet. Read More

Why Do Firewalls Work?

Almost all network attacks try to hide their malicious behavior behind other protocols.

The WannaCrypt malware uses the C2 protocol, and DNS is the protocol that it uses to connect to the command and control servers. DNS tries to match the domain name requested by the client against a list of possible DNS records.

But the DNS record is stored only in the memory of the computer at the time the request is made, and the requests are sent out simultaneously over the internet.

Your firewall will either try to force those connections through, or it won't allow them through.

Unlike DNS, C2 packets are supposed to be received by the remote server, but for whatever reason, the server wasn't able to complete the request. In the case of WannaCry, the malware would not connect to the malicious C2 server and would then try to connect back to the C2 server again.

This behavior is known as DNS cache poisoning, and some firewalls will prevent users from making such requests because it gives an attacker an easy way to bypass all of the data filters that are typically built into firewalls.

In the case of the WannaCry attack, DNS cache poisoning did not work because there was a short amount of time between when the packets were sent and when they were received by the C2 server.

Once the server acknowledged receipt of the packet, it didn't need to accept another packet for a similar attack to succeed. When this happens, the firewall will allow the traffic to pass through.

Firewalls also check to see if the DNS server is responding, because it might be part of a botnet that is trying to capture victim's credentials and sell them to other malicious parties.

As part of a botnet, a DNS server could be used to perform brute force attacks against other servers, making the DNS request from the victim just another piece of data to be sent over the network.

Lack of Response from A DNS Server

In a recent DNS flaw, malware writers were able to bypass firewalls by using a web server to perform a man-in-the-middle attack on a DNS server.

The DNS server, in turn, would pretend to respond to the request from the browser, allowing the malware to extract information about the victim.

The lack of any response from the DNS server allowed the malware to continue the attack.

There is no way for a firewall to know whether the DNS server it's blocking is part of a botnet or just a normal, legitimate DNS server.

So it doesn't matter how much time and energy a firewall devotes to filtering DNS traffic, if there's no response from the DNS server, it won't help.

Unlike the firewall mentioned earlier, the DNS server listed in the "Whois" lookup table can see all of the requests that are coming through.

The Whois lookup table includes the names of the person or company who owns the domain. If the owner's name is listed, the DNS server can see that the request is legitimate.

If the owner's name is not listed, the DNS server can see that the request is invalid, but it does not appear in the Whois lookup table, so it is not seen by the firewall.

So how do you protect yourself from DNS cache poisoning attacks?

It's not as easy as blocking every DNS request from an attacker's IP address, and that will protect you only if the attacker is malicious, in which case the firewall should block everything.

In the case of WannaCry, it's not clear that the attackers were malicious, so you probably don't need to filter DNS requests, but you should make sure that the DNS server you're using is not part of a botnet or compromised system.

What If I Have Multiple Firewalls?

You probably have a lot of firewalls. Fortunately, as long as they're all updated with the latest patches, there's not much of a problem.

As long as the C2 server is blocked on each firewall, there's not much you can do. However, you should remember that the same threat could be delivered to each firewall in your network.

So you shouldn't necessarily just connect to the Internet using only the firewall that is recognized as the main gateway. The other firewalls on your network should be checked to make sure they are all up to date.

Of course, if you have multiple firewalls, then you probably have multiple threat detection systems.

You might also have an antivirus system, a spam filter, and so on. So you might have a number of different systems for spotting attacks.

This is an important part of a layered approach to security, because you never know where an attack will come from, and you never know when an attack will actually succeed.

If all of these systems are working, you can reduce your attack surface.

How Do I Know When One of My Firewalls Could Be Interrupting My Network?

This is the part where a lot of people get worried, because they're not sure whether it's better to let one firewall go into an all-out attack mode and let the other systems catch up to that one, or whether it's better to stop one firewall in case it isn't up to date and is shutting down the whole network.

The answer is that you can't really tell without trial and error. One way to tell is to restart your firewall. If the firewalls all react within seconds, then you don't have a problem.

If the firewall that is holding up your network has been going on for more than a few seconds, then it's time to stop it. If your firewall is taking too long to respond, then you probably need to stop it.

However, you'll have to wait a bit before you can fully restart a firewall that isn't responding. A firewall that has been using all its CPU power to answer all of the requests and have no other idle time can take a while to respond.

If your firewall is compromised and going to cripple your network, then restarting it is likely to cause other problems that you don't want to deal with.

In that case, you need to stop it. However, as long as the firewall isn't doing anything illegal, or causing any problems to your network or other devices, you can wait a bit before you restart it.

You could also wait until the firewalls you want to use are rebooted, if they need it.

How Do I Know That I'm Safe?

You can tell if you're safe from DNS cache poisoning by checking the DNS server logs to see when the attack took place.

You should watch the logs for a few minutes to see how long it took for each DNS server to return an answer. In the case of WannaCry, it took a while for the DNS server to return an answer, so it was a little over three minutes before the systems all returned to normal.

The important thing is that the DNS servers were offline, which means that they weren't in the Whois lookup table, and so were not yet affected by the attacks.

If you're not sure that DNS cache poisoning has taken place, then you can still run a test. Just open your favorite browser and go to DNS lookup. Go to a large DNS name server.

You'll probably get an answer that includes the WHOIS domain name. Check to make sure that your DNS cache isn't corrupted, and then try to access the DNS information again.

If you have access to the DNS servers that you're not using, then you can run the same test using the other servers in the list.

If you're not sure that you're completely safe, then it's a good idea to disable your HTTP cache.

This can be done in your web browser. If your browser doesn't support it, then there are other means.

You can block access to any HTTP server that you don't trust, or you can try to block all HTTPS servers.

If you're not sure which of these methods you want to use, then you should probably check your firewall logs to see if there is anything there that suggests that HTTP or HTTPS connections are becoming corrupted.