About proxy servers
A proxy server, also known as a “proxy” or “application-level gateway”, is a computer that acts as a gateway between a local network (for example, all the computers at one company or in one building) and a larger-scale network such as the internet. Proxy servers provide increased performance and security. In some cases, they monitor employees’ use of outside resources.
A proxy server works by intercepting connections between sender and receiver. All incoming data enters through one port and is forwarded to the rest of the network via another port. By blocking direct access between two networks, proxy servers make it much more difficult for hackers to get internal addresses and details of a private network.
Some proxy servers are a group of applications or servers that block common internet services. For example, an HTTP proxy intercepts web access, and an SMTP proxy intercepts email. A proxy server uses a network addressing scheme to present one organization-wide IP address to the internet. The server funnels all user requests to the internet and returns responses to the appropriate users. In addition to restricting access from outside, this mechanism can prevent inside users from reaching specific internet resources (for example, certain websites). A proxy server can also be one of the components of a firewall.
Proxies may also cache web pages. Each time an internal user requests a URL from outside, a temporary copy is stored locally. The next time an internal user requests the same URL, the proxy can serve the local copy instead of retrieving the original across the network, improving performance.
Proxy and VPN Defined
Proxy servers work as an intermediary between the two ends of a client/server network connection. Proxy servers interface with network applications, most commonly web browsers and servers. Inside corporate networks, proxy servers are installed on specially-designated internal (intranet) devices. Some Internet Service Providers (ISPs) also utilize proxy servers as part of providing online services to their customers. Finally, a category of third-party hosted web sites called web proxy servers is available to end users on the Internet for their web browsing sessions.
Key Features of Proxy Servers
Proxy servers traditionally provide three main functions:
- Firewall and network data filtering support
- Network connection sharing
- Data caching