Proxy server

What is a proxy server

Proxy server (proxy) is a dedicated server or software module that acts as an intermediary (gateway) between a user's device and the Internet. Instead of connecting directly to a site, a user's request first goes to the proxy, which then forwards it, changing network identifiers (IP address) and, if necessary, filtering or caching the content.

In simple terms, a proxy server is like a postman who takes your letter, puts it in a new envelope with a different return address and sends it to the recipient. The reply comes to the postman's address, and he then passes it to you. The recipient does not know your real address, only the postman's.

In the corporate environment, proxy servers are an important element of the network infrastructure, along with firewalls. They are used not only for anonymization, but also for traffic filtering (blocking unwanted sites), data caching (speeding up the loading of frequently visited pages) and organizing access control to external resources within security policies.

According to analytical companies, more than 60% of large organizations use proxy servers to control Internet access and ensure the security of employees. In Russia, the use of proxy servers is also regulated by the requirements of 187-FZ for CII facilities and 152-FZ for the protection of personal data.

How a proxy server works

The operating principle of a proxy server consists of several sequential stages that ensure the redirection of traffic:

1. The user sends a request to open a web page (for example, through a browser), specifying the site URL.
2. The request is redirected to the proxy server (instead of a direct request to the DNS server and site). This is configured in the browser or at the operating system level.
3. The proxy server substitutes its own outgoing IP address (often located in another country) and redirects the request to the target server.
4. The target server processes the request and sends the response back to the proxy server.
5. The proxy server receives the response and passes it back to the user, while saving its IP address as the sender.

It is important to understand the difference between a proxy and VPN (virtual private network): VPN encrypts all traffic at the operating system level and creates a secure tunnel, whereas a proxy works only with specific applications (for example, a browser) and does not provide full data encryption. A proxy is more often used to bypass blocks or for filtering, VPN — for full anonymity and security.

Main types of proxy servers

The classification of proxy servers depends on the protocol, the level of anonymity and the scope of application:

• HTTP/HTTPS proxy: The most common, work only with web traffic (HTTP and HTTPS). They support page caching, URL and content filtering. Used to bypass blocks and control access.
• SOCKS proxy (SOCKS4/SOCKS5): More versatile, can transmit any type of traffic (email, messengers, torrents, games), but do not cache data. SOCKS5 supports authentication and UDP traffic.
• Anonymous (Elite / High Anonymity): Hide the fact of using a proxy, not transmitting client headers (for example, X-Forwarded-For). Provide maximum anonymity.
• Transparent: Do not hide your IP address and do not change headers. Used for caching and access control in corporate networks, as well as by providers for caching popular content.
• Reverse proxies: Installed in front of servers for load distribution, traffic balancing and security (they hide the real IP addresses of servers). Often used in combination with WAF to protect web applications.

In the conditions of import substitution and restrictions on foreign software, organizations often choose domestic solutions for organizing proxy access, which makes it possible to comply with the requirements of 187-FZ on CII security.

Why use a proxy server

Proxy servers solve a wide range of tasks in the field of IT security, administration and network optimization:

1. Bypassing geographic blocks: Access to resources restricted by country (for example, foreign sites, streaming services).
2. Increasing anonymity: Hiding the real IP address for protection from surveillance, data collection and targeted advertising.
3. Accelerating access: Caching frequently requested pages and files on server disks, which reduces the load on the channel and speeds up loading for users.
4. Content filtering: Blocking access to prohibited sites (in office networks, in educational institutions) in accordance with security policies.
5. Load balancing: Distributing requests between several servers (Reverse Proxy) to increase fault tolerance and performance.
6. Audit and control: Logging all user requests for activity analysis and incident investigation.

The choice of proxy type and its configuration require professional knowledge.

For specialists ensuring network security, skills in managing proxy servers are important. Advanced training can be obtained on training courses, which consider the fine tuning of proxies and integration with other protection tools.