Proxy / proxy server
A proxy is a service that serves as a cache within a network to service accesses to always the same data and files from memory.
The term proxy refers to a server or service running on a server. The proxy service is a program that works in the background on a server.
Proxy means proxy. In the simplest case it is a kind of cache for websites. He accepts requests from clients and evaluates them. As a representative, he forwards the request to the Internet.
The returned data is stored by the proxy before forwarding. In the case of another request for the same destination, the data is not downloaded from the Internet, but sent directly from the proxy memory to the recipient. In this way, traffic to the Internet is saved. This reduces costs and increases bandwidth for other applications.
The clients do not send their access directly to the internet, but to the proxy. This server acts as a mediator to connect to the web server. Frequent Internet pages or downloads then no longer need to be re-transmitted over the Internet, but can be sent directly from the proxy server to the clients. This reduces data traffic to the Internet and returns the data to the clients faster.
The reverse proxy works the other way around and is similar to load balancing. For example, the clients access the Internet without a proxy. A group of web servers is hidden behind a proxy. The web servers are not directly accessible.
The proxy does not forward frequent identical accesses from the Internet to the web server, but works it off itself if it has cached the data.
So a simple load distribution is possible, without expensive or complicated load balancing. Reverse proxies can also prevent unauthorized access.
In another application, the access authorization for multiple servers is handled centrally by a proxy.
- Faster access to always the same data
- Cost savings on Internet traffic
- Integration of virus and spam filters possible
A proxy provides more protection for systems that communicate through a proxy rather than directly to the Internet.
Unnecessary packets from external computers no longer reach the local network because the proxy can only forward accesses from the Internet if an outgoing connection has previously existed.
In addition, a virus filter can be installed on the proxy. To be able to work effectively, every internet access must be done via the proxy. This is achieved by the fact that the default gateway is not the router to the Internet, but an upstream proxy.
- Cache coherency due to outdated content in the cache
- Not every application supports proxies
- There are not proxies for every Internet protocol
The disadvantage of proxies is that a proxy must be installed for each Internet protocol if all the traffic is to be handled via the proxy server.
This means the proxy program must be able to handle all the possible protocols that the Internet has to offer. It’s not enough just to support HTTP to access web servers. Also POP and SMTP for the E-Mail communication must be mastered.
Typically, the programs on the clients must support traffic through a proxy. This is not a problem with simple Internet services, such as WWW and e-mail. But online games and P2P file sharing will be difficult or not work at all.
Proxies have been a means for Internet service providers to save traffic in the early days of the commercial Internet.
At that time, the Internet connections were even slower and more expensive. In addition, many Internet users were still on the road with a modem or ISDN card. To deliver the data faster, proxies have been set up to serve customers faster and save traffic.
Meanwhile, the network expansion of the Internet is designed very generously, so that a proxy offers no benefits.
Exceptions are transitions from local networks to the Internet, where a proxysite is used for security reasons. On the one hand, to limit the possibilities of the users.
And second, to check traffic for malicious content, such as viruses and worms. It’s usually about protecting the local network.