This article introduces the following

What is curl

What does cURL do

What is a proxy server

What does a proxy server do

How to use the Curl command to set up a proxy server

I. What is curl?

cURL (Client URL) is an open source command line tool and a cross-platform library (libcurl) for transferring data between servers and distributed to almost all new operating systems. cURL programming is used almost anywhere data needs to be sent or received over the Internet Protocol.

II. What does cURL do?

cURL is designed to transfer data over the Internet Protocol. Everything else is outside its scope. It doesn't even process the data being transferred, it only performs the transfer process.

cURL can be used for debugging. For example, using "curl -v https://piaproxy.com" can display a detailed output of a connection request, including details such as user agent, handshake data, port, etc.

There are too many cURL command options to list and explain. Fortunately, there is an option "curl –help" that lists all curl command line usages with short explanatory comments. Although these command line usages do not include background information on how to use cURL, users can learn some command line usage through the list.

III.What is a proxy server

A proxy server is an intermediate server located between a client and a server, acting as an intermediary between the two. When a client (such as a browser, application, etc.) wants to access resources on a server (such as a website server), it does not directly connect to the target server, but first sends a request to the proxy server. After receiving the request, the proxy server will access the target server in its own name, obtain the required resources, and then return these resources to the client

VI.What is the role of a proxy server

• Protect privacy and security

• Accelerate access

• Bypass network restrictions

• Load balancing and bandwidth saving

V. How to set up a proxy server using the Curl command

Curl is a powerful command line tool for transmitting data, supporting multiple protocols, including HTTP, HTTPS, FTP, etc. When processing network requests, it is often necessary to make requests through a proxy server, especially when you need to bypass network restrictions or access specific resources. The following is a detailed guide on how to set up a proxy server using the Curl command.

1. Setting up an HTTP proxy

To set up an HTTP proxy, you can use the -x or --proxy option followed by the URL of the proxy server. The proxy URL is usually in the format of http://[user:password@]proxy.server.com:por

If authentication is required, you can add a username and password

2. Setting up an HTTPS proxy

For an HTTPS proxy, the protocol portion of the URL needs to be changed to https

3. Using a SOCKS proxy

Curl also supports SOCKS proxies, which can be set up with the -x option followed by the URL of the SOCKS proxy, but you need to add socks4:// or socks5:// to the beginning of the URL to specify the SOCKS version

4. Proxy lists

It is important to note that Curl does not directly support setting up multiple proxies in a single command. Each request needs to explicitly specify a proxy. However, you can write a script to cycle through different proxies.

5. Disable proxy

If you have previously set environment variables or global configuration to use a proxy by default, but want a certain Curl request not to use a proxy, you can do so by following the -x option with an empty string.

6. Environment variables for proxy settings

In some cases, you may want to set a proxy for all requests using Curl, rather than specifying it in the command each time. This can be achieved by setting the environment variables http_proxy (HTTP proxy) and https_proxy (HTTPS proxy). For SOCKS proxies, there is no direct environment variable support, but you can do so by configuring the .curlrc file or using the --proxy option

Summary,

By using the -x or --proxy option of the Curl command, you can flexibly set a proxy server to meet your network request needs. Whether it is accessing restricted resources, accelerating network access, or achieving anonymous access, a proxy server is a powerful tool.