How to Use cURL to Ignore an SSL Certificate

There is no doubt that SSL certificates (sometimes called TLS) are a critical component of keeping people safe online, but they also get in the way of a variety of tasks that can, in some situations, be necessary to ignore. Most often, SLL certificates are tasked with providing a layer of protection so that as you move through the internet throughout the day, you do not have to worry about your private information being compromised.

Bypassing SSL certificates is not recommended most of the time. If you decide to do that, you should know the risks and what it may mean to your internet security. Keeping that in mind, let us break down what you should know about SSL certificates and cURL.

What Is cURL?

A good starting point is understanding with cURL is. It refers to client URL. It is a command line tool used to transfer data to and from a server. In the simplest of language possible, cURL allows you to talk to the server by providing a location and the data you want to send to that destination. You specify the location in the form of a URL.

For the most part, cURL supports numerous protocols. This includes HTTPS, FTP, and HTTP. It also runs on all platforms, making it an important and commonly used tool overall.

One of the most important ways to use cURL is by using it for testing communications from a device to a local server or edge device. To do this, the device must have a command line as well as a connection to the network.

You are likely to know that the most basic cURL command is:

Curl http://example.com.

In this situation, the cURl command has a URL after it. In this command, you are telling the system you would like to retrieve some type of data from that source. In this situation, the command would provide you with the html source for example.com

Why would you use cURL?

There are various reasons to use cURL. This includes these benefits:

• It is a highly portable tool since it works with virtually every operating system and any connected device.
• It allows for testing endpoints to determine functionality.
• It can be rate limited.
• It can also be a good option for error logging.

There are obvious benefits to using this command line. Now, consider how this impacts SSL certificates and how you may be able to use it for that need.

What Is an SSL Certificate?

An SSL certificate or TLS certificate is a digital object that allows systems to verify who is connecting. Once it identifies the system, it can then establish an enrupted network connection to another location that has a SSL certificate.

SSL, which stands for Secure Sockets Layer, protocol helps to create some level of security online. These certificates can be used in a wide range of ways within a cryptographic system called the public key infrastructure (PKI). This is a way for one location to establish the identity of another location. Both parties trust the third-party, which is the certificate authority issuing that certificate.

Consider SSL certificates as a type of permission. The identification of one site is verified and considered trusted, reducing the risk of moving forward.

There are various reasons why SSL certificates are not just important but critical to the security of the internet:

• They protect users and their private data from being exposed.
• They help to build strong customer confidence.
• They can help support regulatory compliance.

Considering these factors, it is clear that SSL are important. So, now that you know what they are, how can you use cURL to ignore SSL?

As noted, cURL is a command line tool and a library that enables the transferring of data using URLs. It works with most protocols. If you look at the official website for cURL, it will tell you that it’s been downloaded and used millions of times. In fact, it is used daily by virtually every person using the internet around the world – though most people have no clue they are doing so.

It’s used readily so in medical devices, smartphones, programming, and even most smart TVs use it. It is also used in API documentation.

Did you know?

What about the actual terminology?

When you write cURL: the references are for the entire cURL project. That means it includes the command-line tool as well as the library (curl) and (libcurl).

If you use Curl, with just the first letter capitalized, you are referring to the programming language. That is a very different component than the project itself.

From this point out, we will be discussing just the programming component or command-line tool. That’s why we will keep with just curl.

The Curl and SSL Connection

As noted, SSL provides a layer of protection for securing communications over a network. Curl, then, is a tool used to transfer that data. SSL secures the transfer of that data.

As a result of this, curl is a component of SSL certification verification, then. That is a given. But your goal here is to use curl to ignore SSL. To be clear, you can do this for various reasons. You can ignore SSL curl connections for any reason, but when you do, you need to be aware of the risks involved in the process.

First, Learn Why You Would Want to Use Curl to Ignore SSL

It does not seem logical to let your guard down and allow this type of lack of verification to happen when you are transferring and accessing data. SSL is a very important form of security, and most of the time, you want it to help minimize the risk of safety risks online.

That said, there are several reasons why you may wish to use curl to skip SSL verification.

#1: You are testing things out

One of the most common reasons to ignore SSL with curl is because you are working on developing and want to test various factors. When developing, it is very common for users to select self-signed certificates. That would meany you would not need an SSL certificate.

Onter times, you may be working in an environment there were are no need for these certificates just yet – or they may not have yet been set up. You still need to test your tools, and using curl to ignore SSL certicate requirements makes sense.

#2: You are working on the bugs holding you back

Another reason may be because you want curl to ignore SSL errors, which is not uncommon in the development process. By learning how to use curl to ignore SSL cert, you are then able to find out what the problem is, especially as it relates to the SSL certificate itself.

#3: The system is much older

There are some situations where you may be working in a much older system. These are often referred to as a legacy system. In these situations, you may not have an up-to-date SSL certificate.

Or, if you are using an API that is older and its SSL certificate is no longer in line, that could prove to be a valuable reason to use Curl to ignore SSL errors that are likely to show up.

There are a variety of reasons why you may wish to do this. The key here is that you can use curl to skip SSL, and once you learn how it is a matter of just taking a few seconds to do so.

What Is the Big Deal: Why You Have to Understand the Security Risks

We have already mentioned the security that SSL certificate offers. It is worth mentioning this again since it is such an important part of the safety that all people using the internet face.

Even if you are using curl for SSL certificate ignore during the development process, you cannot overlook the risks of this process. There are a number of types of attacks that seem to be just waiting for this opportunity. That includes man-in-the-middle attacks, one of the most common types of threats. You are also facing data breach risks, even if there is very minimal time when you have this connection occurring.

If you use curl to ignore SSL certificates for very long, you are also losing user trust, and that is very difficult to recover in today’s demanding environment.

Now that we have talked about these risks (and made sure you understand them) it is time to consider how to use curl to ignore SSl.

Steps To Using Curl to Ignore SSL

The easiest way to ignore SSL certificate errors, the most common reasons why you may wish to use curl like this, is with the following.

Pass -k curl command:

1  |  curl -k https://www.expireddomains.net

Now, this is what would happen.

Let’s say you are going to a website that is called https://www.brokenlinkcheck.com.

You would get an invalid error message like the following:

curl https://www.expireddomains.net/

curl: (60) SSL certificate problem: certificate has expired

More details here: https://curl.se/docs/sslcerts.html

curl failed to verify the legitimacy of the server and therefore could not

establish a secure connection to it. To learn more about this situation and

how to fix it, please visit the web page mentioned above.

That is a good thing. This means that SSL does not let anyone move into the bad site.

In this situation, then, you could enter the -k curl command as noted before:

curl https://www.expireddomains.net/

Doing this would allow you to skip past the SSL verification process.

A secondary way to do this is to use – -insecure :

curl –insecure https://www.expireddomains.net/

In these situations, you are getting into an insecure connection.

How to Use Curl to Ignore SSL in the Script

In some situations, you may want a more thorough process, perhaps a system-wide ignoring of the SSL certificate (or the lack thereof). In this situation, you will need to incorporate a way to ignore SSL in the script itself.

You could use a curl configuration file such as ~/.curlrc and then add insure to the script. This would help you to avoid the problem (if you are using curl with Python, for example, and you do not want to work through each instance on its own).

Remember that if you did this, it would disable the SSL verification process from that point out. That means that until you fix it, this will remain less protected.

Why Does Curl Face SSL Certification Errors?

Now that you have the basics down let’s explore some of the factors that may provide you with more insight about this process. First, consider why curl faces SSL cert errors in the first place. It is all about the processes in place.

Curl needs a secure connection. As a result, it will default to the behavior of validating the SSL certificate before moving forward. In some situations, an error will occur. When that error occurs, there is a discrepancy, and the process stops.

That is because, curl is set up to establish an SSL connection to a domain, It relies on the certificate bundle to verify the server’s digital certificate. If there is no certificate available, for any reason, that typically means the certificate is not recognized by the Certificate Authority (SSL). That stops the process from moving forward.

Some of the most common reasons for this to occur include:

• Self-signed certificates
• Untrusted certificates for any reason
• Expired certificates (the most common reason)

At some point, there is a missing certificate that is necessary to move the connection process forward.

You Can Make Curl Ignore Those Errors

A bit more of an in-depth explanation to the previous one, consider how you can get curl to ignore SSL verify requirements.

When you use the following to execute a command, you would expect a website to display:

# curl myexplaedwebsite.com

But it does not because the curl fails to connect due to an invalid SSL certificate or other error message. You get an error message. In some cases, that message may look like:

curl: (60) SSL: no alternative certificate subject name matches target host name ‘myexplaedwebsite.com’

In this example, you can use one of the two commands we provided previously to help you. To do this, you will need to use the following command syntax:

# curl –insecure [URL]

Plug in the URL of the website you want curl to ignore.

Or, you can use:

# curl -k [URL]

This is not a complex command and it really only takes a few seconds to set up, but once you have it in place, remember that you have allowed an unsecured access point to occur.

Final Thoughts

We cannot tell you in good faith that it is okay to use curl SSL certificate ignore for any reason beyond a development and testing process. There is risk in doing so even if you do so for a short amount of time.

Yet, there are real reasons why you may need to use curl to ignore SSL, and the overall complexity of the command line function is simplistic.

When you learn how to bypass SSL certificate errors like this, you are able to dive into the problem and find out what could be causing that error in the first place. It is not uncommon to have to do this and know how to do this when you are facing certificate verification obstacles as well, including any type of server interaction.

You can use this method to track down what is occurring, even if it is due to an unrecognized Certificate Authority, an incomplete certificate chain, or for other reasons. Make sure that if you take these steps, no matter which of the two formats we have provided here, you are absolutely protected from the risks that could occur and that you do not allow for this to continue long-term.

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FAQs

Can you use curl with proxies?

Yes, it is possible to use curl with proxies. To do so, we encourage you to check out how Rayobyte can help you with that process.

What is the latest curl?

The most recent stable version of curl is 8.8.0. It was released on May 22, 2024.

How do I ignore SSL certificate problems in curl?

To ignore SSL certificate issues with curl, use the -k or the insecure syntax proxy-insecure.

How do I disable certificate verification system-wide?

If you need to disable the certificate verification process across your system, an easy way to do so to temporarily disable the SSL verification is to add insecure and then, if desired, proxy-insecure to your ~/.curlrc file.

What is an example of ignoring SSL certificate errors in curl?

Try this command to see an example of a SSL certificate error:

$ curl -k https://example.com

This would allow yout to ignore SSL certificate errors and set up a connection to the example.com website anyway.

What is the curl command to work with “insecure” SSL certificates without https certificates?

Use the syntax the follows:

curl -k url

curl –insecure url

curl –insecure [options] url

curl –insecure -I url

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