What is the anonymity level of proxy IP

In the process of using web crawlers to crawl data today, the security of protecting real IP addresses has become the focus of users. Proxy IP has become a common solution, through proxy IP, users can hide their real IP address, so as to achieve anonymous access and secure crawling of public data. However, proxy IP is not universal, and different proxy IP have different degrees of anonymity. In the following sections, we will explore the principle of assigning anonymity to proxy IP.

1. Type of agent

Proxy IP can be divided into three types according to the degree of anonymity: transparent proxy, ordinary anonymous proxy and high anonymous proxy. From a security point of view, these three proxy types can be ranked as High Anonymous > Normal Anonymous > Transparent.

2. Agency principle

The degree of anonymity of proxy IP addresses depends on the configuration of the proxy server. Different configurations result in different proxy types. Three variables play a decisive role in the configuration: REMOTE_ADDR, X-Forwarded-For (XFF), and HTTP_VIA.

REMOTE_ADDR

REMOTE_ADDR indicates the real IP address of the client, but this value is not provided by the client, but is specified by the server based on the client's IP address. If the user accesses a website directly through a browser, the Web server for that website (such as Nginx, Apache, etc.) sets REMOTE_ADDR to the IP address of the client. However, if the user has a proxy set up, the request to visit the target website will first pass through the proxy server, which will then forward the request to the target website. At this point, the site's Web server sets REMOTE_ADDR to the IP address of the proxy server.

①What is an API proxy

X-Forwarded-For (XFF)

X-Forwarded-For is an HTTP extension header that represents the real IP address of the HTTP requestor. When a client uses a proxy, the Web server cannot know the real IP address of the client. To avoid this, proxy servers usually add an X-Forwarded-For header message, adding the client's IP to the header information.

HTTP_VIA

Via is a header in the HTTP protocol that records the proxy and gateway through which an HTTP request passes. After a proxy server is passed, information about a proxy server is added. After two agents, information for both agents is added, and so on.

3. Agent type difference

Transparent Proxy

Although transparent proxy can directly "secure access" to the IP address of the client, it can still find the real IP address of the client through the source.

Common Anonymous Proxy

The common anonymous proxy can protect the IP address of the client. However, when a user uses the common anonymous proxy, the server can still know the behavior of the client.

②This section describes three methods for changing proxy IP addresses

Elite Proxy (or High Anonymity Proxy)

The high-hiding proxy not only provides secure access to client IP addresses, but also ensures that the server cannot obtain the real IP address of the client. This makes it impossible for the server to confirm that the client is using a proxy, thus achieving the highest degree of anonymity.

By understanding the anonymity grading principle of proxy IP addresses, users can select appropriate proxy IP types according to different requirements to ensure the security and effectiveness of data crawling and access.