What is proxy ?

Proxy server — computer, connected to Internet, which saves traffic on hard disk. So, proxy server becomes faster access to data, however more frequently images , pages etc. are being loaded directly from it, but not from the original site, speed of the connection with which may be not much more.

Some proxy servers can can hide you original IP-address(address of your computer in the internet).

Proxy servers, with their ability to save the traffic, security, increasing the speed of web- serfing, becomes more and more popular. Currently there are few type of proxy servers, which have two main disadvantage: they are commercial and do not support ICP ( ICP is being used for information interchange about the presence of a URL in a neighboring cache ).

You can see the list of proxy servers we provide by clicking here.

Types of proxy servers

A proxy server may reside on the user’s local computer, or at various points between the user’s computer and destination servers on the Internet.

A proxy server that passes requests and responses unmodified is usually called a gateway or sometimes a tunneling proxy.
A forward proxy is an Internet-facing proxy used to retrieve from a wide range of sources (in most cases anywhere on the Internet).
A reverse proxy is usually an internal-facing proxy used as a front-end to control and protect access to a server on a private network. A reverse proxy commonly also performs tasks such as load-balancing, authentication, decryption or caching.

Open proxies

An open proxy is a forwarding proxy server that is accessible by any Internet user. Gordon Lyon estimates there are “hundreds of thousands” of open proxies on the Internet. An anonymous open proxy allows users to conceal their IP address while browsing the Web or using other Internet services. There are varying degrees of anonymity however, as well as a number of methods of ‘tricking’ the client into revealing itself regardless of the proxy being used.

Reverse proxies

A reverse proxy (or surrogate) is a proxy server that appears to clients to be an ordinary server. Requests are forwarded to one or more proxy servers which handle the request. The response from the proxy server is returned as if it came directly from the original server, leaving the client no knowledge of the origin servers. Reverse proxies are installed in the neighborhood of one or more web servers. All traffic coming from the Internet and with a destination of one of the neighborhood’s web servers goes through the proxy server. The use of “reverse” originates in its counterpart “forward proxy” since the reverse proxy sits closer to the web server and serves only a restricted set of websites. There are several reasons for installing reverse proxy servers:

1. Encryption / SSL acceleration: when secure web sites are created, the SSL encryption is often not done by the web server itself, but by a reverse proxy that is equipped with SSL acceleration hardware. See Secure Sockets Layer. Furthermore, a host can provide a single “SSL proxy” to provide SSL encryption for an arbitrary number of hosts; removing the need for a separate SSL Server Certificate for each host, with the downside that all hosts behind the SSL proxy have to share a common DNS name or IP address for SSL connections. This problem can partly be overcome by using the SubjectAltName feature of X.509 certificates.
2. Load balancing: the reverse proxy can distribute the load to several web servers, each web server serving its own application area. In such a case, the reverse proxy may need to rewrite the URLs in each web page (translation from externally known URLs to the internal locations).
3. Serve/cache static content: A reverse proxy can offload the web servers by caching static content like pictures and other static graphical content.
4. Compression: the proxy server can optimize and compress the content to speed up the load time.
5. Spoon feeding: reduces resource usage caused by slow clients on the web servers by caching the content the web server sent and slowly “spoon feeding” it to the client. This especially benefits dynamically generated pages.
6. Security: the proxy server is an additional layer of defense and can protect against some OS and Web Server specific attacks. However, it does not provide any protection from attacks against the web application or service itself, which is generally considered the larger threat.
7. Extranet Publishing: a reverse proxy server facing the Internet can be used to communicate to a firewall server internal to an organization, providing extranet access to some functions while keeping the servers behind the firewalls. If used in this way, security measures should be considered to protect the rest of your infrastructure in case this server is compromised, as its web application is exposed to attack from the Internet.

Accessing services anonymously

An anonymous proxy server (sometimes called a web proxy) generally attempts to anonymize web surfing. There are different varieties of anonymizers. The destination server (the server that ultimately satisfies the web request) receives requests from the anonymizing proxy server, and thus does not receive information about the end user’s address. The requests are not anonymous to the anonymizing proxy server, however, and so a degree of trust is present between the proxy server and the user. Many proxy servers are funded through a continued advertising link to the user.

Access control: Some proxy servers implement a logon requirement. In large organizations, authorized users must log on to gain access to the web. The organization can thereby track usage to individuals. Some anonymizing proxy servers may forward data packets with header lines such as HTTP_VIA, HTTP_X_FORWARDED_FOR, or HTTP_FORWARDED, which may reveal the IP address of the client. Other anonymizing proxy servers, known as elite or high-anonymity proxies, only include the REMOTE_ADDR header with the IP address of the proxy server, making it appear that the proxy server is the client. A website could still suspect a proxy is being used if the client sends packets which include a cookie from a previous visit that did not use the high-anonymity proxy server. Clearing cookies, and possibly the cache, would solve this problem.

QA geotargeted advertising

Advertisers use proxy servers for validating, checking and quality assurance of geotargeted ads. A geotargeting ad server checks the request source IP address and uses a geo-IP database to determine the geographic source of requests. Using a proxy server that is physically located inside a specific country or a city gives advertisers the ability to test geotargeted ads.

Security

A proxy can keep the internal network structure of a company secret by using network address translation, which can help the security of the internal network. This makes requests from machines and users on the local network anonymous. Proxies can also be combined with firewalls.

An incorrectly configured proxy can provide access to a network otherwise isolated from the Internet.

Web proxy servers

Web proxies forward HTTP requests. Some web proxies allow the HTTP CONNECT to set up forwarding of arbitrary data through the connection; normally this is only allowed to port 443 to allow forwarding of HTTPS traffic.

Examples of web proxy servers include Apache (with mod_proxy or Traffic Server), HAProxy, IIS configured as proxy (e.g., with Application Request Routing), Nginx, Privoxy, Squid, Varnish (reverse proxy only),WinGate, Ziproxy, Tinyproxy, RabbIT4 and Polipo.

SOCKS proxy

SOCKS also forwards arbitrary data after a connection phase, and is similar to HTTP CONNECT in web proxies.

Transparent proxy

Also known as an intercepting proxy, inline proxy, or forced proxy, a transparent proxy intercepts normal communication at the network layer without requiring any special client configuration. Clients need not be aware of the existence of the proxy. A transparent proxy is normally located between the client and the Internet, with the proxy performing some of the functions of a gateway or router.

RFC 2616 (Hypertext Transfer Protocol—HTTP/1.1) offers standard definitions:

“A ‘transparent proxy’ is a proxy that does not modify the request or response beyond what is required for proxy authentication and identification”.

“A ‘non-transparent proxy’ is a proxy that modifies the request or response in order to provide some added service to the user agent, such as group annotation services, media type transformation, protocol reduction, or anonymity filtering”.

TCP Intercept is a traffic filtering security feature that protects TCP servers from TCP SYN flood attacks, which are a type of denial-of-service attack. TCP Intercept is available for IP traffic only.

In 2009 a security flaw in the way that transparent proxies operate was published by Robert Auger, and the Computer Emergency Response Team issued an advisory listing dozens of affected transparent and intercepting proxy servers.