How to Use cURL With Proxies to Send HTTP Headers: A Guide

Sep 20, 2024 Reading time : 5 min

If you do not know what cURL is, it’s a tool that helps in transferring data across servers. You must have heard of some protocols like HTTP, HTTPS, FTP, SMTP, and more. All these protocols are supported by the cURL.

It is pretty common that your cURL gets blocked while accessing some specific websites. The solution for this issue is pretty simple. Just get yourself connected to a proxy server, and it’s done.

But how does it work? Read this article till the end as we tell you how to use proxies with cURL and also give you insights on what happens during the process.

Keep reading.

cURL: What Is It?

cURL is extremely helpful for web developers and system administrators to interact and communicate with the web’s complex infrastructure with simple commands.

However, the cURLs are sometimes unable to do so, since their requests usually get blocked if the traffic is identified as non-human. So, proxies provide access to such websites with ease.

Speaking of its responsibilities, it allows users to:

Make HTTPS Requests: You can send any type of request to HTTPS with the help of cURL (GET, POST, PUT, DELETE, etc).
Transfer Data: You can download or upload files.
Authentication Handling: It can authenticate, API tokens, and sessions.
Manage Cookies and Headers: You can easily customize HTTP headers, cookies, and other request details.

Why Use cURL With Proxies?

Along with VPNs, proxies are the best way to access blocked or restricted content. Here are some benefits that they provide:

Privacy: cURLs shield your IP address so that your location and other information stay private.
Access Control: Proxies give you access to global content, even if it’s banned in your home country.
Security: Not all the traffic that flows in or out is safe for you. Hence, proxies help to filter undesirable information that might harm your system.

Using cURL to Send HTTP Headers

HTTP headers consist of various custom information about user agents, content types, etc. cURL multiple headers allow communication between the client and the server with the “-H” option when you want to add some specific information.

The basic syntax for sending these headers is:

curl -H “Header-Name: Header-Value” https://example.comHere, “-H,” tells the cURL that it is a custom header.

“Header-Name: Header-Value” accommodates the value or information you are about to send.

Transmitting Headers via a Proxy

When you use a proxy, delivering HTTP headers becomes much more significant. Here’s how cURL operates when you are routing requests through proxies:

Using cURL to Establish a Proxy

At this stage, the cURL is requested to send the request through proxy via -x or –proxy options.

Here’s how the command looks like:

curl -x http://proxy.example.com:8080 https://targetwebsite.com

Combining the Use of a Proxy With Headers

To access an API that does not allow your interaction, you may need some specific headers. These headers include an “Authorization” token or a custom “User-Agent” to identify yourself.

For instance:

curl -x http://proxy.example.com:8080 -H “Authorization: Bearer YOUR_ACCESS_TOKEN” -H “User-Agent: MyCustomUserAgent” https://api.example.com/data

Managing Various Types of Proxies

There are not only one but multiple types of proxies that can be taken into use. Depending on their use cases, they all work differently. Let us tell you about their functioning:

DID YOU KNOW?
26% of internet users globally utilize VPNs or proxies for secure browsing and accessing restricted content, the importance of proxies for privacy and bypassing geo-restrictions.

HTTP Proxy

HTTP proxy is the simplest to use. The key USP of this proxy is that it works straightforwardly. It uses the -x option to forward the message to the server.

The command through the HTTP proxy looks like this:

curl -x http://proxy.example.com:8080 -H “User-Agent: MyCustomAgent” https://example.com

SOCKS Proxy

SOCKS proxy works at a lower network level if compared to the HTTP proxy. In simple words, it not only handles web-related activities but also deals with a wider range of network protocols and traffic types. Further, it uses the –socks5 option to send the information.

Here’s what its command looks like:

curl –socks5 http://socksproxy.example.com:1080 https://example.com

Troubleshooting Typical Problems

Users typically face problems when they use cURL with a proxy. cURL very often fails to connect to the internet if passed through a proxy. Hence, troubleshooting becomes a necessary skill to learn in situations like that.

To fix this issue, you can try:

Checking the credentials: Ensure you are entering the correct login details (username and password) when start using the proxy.
IP address blocking: If you are accessing banned content with your current IP address, consider masking it through the proxy.

End Note

Finally, cURL paired with a proxy lets you access the content that is blocked in your location. However, there might be some issues that you may face during the process. Hence, you must learn how to troubleshoot in such situations.