A proxy server is an intermediary computer between a local computer network and the Internet that can help increase a network's security or reduce its workload. An open proxy server is a public proxy server that any Internet user with the proxy's address and port number can access. Although open proxies are public, this is usually because of a lack of proper configuration. Therefore, online security risks can occur with an open proxy server because of the lack of authentication required to use the server.
A proxy server usually requires the user to connect from a specified network address to use its services. Open proxy servers do not have this requirement and let anyone on the Internet connect to the proxy server's computer. When a user configures a web browser to use an open proxy server, the user's request is sent to the proxy server before reaching the Internet. As a result, this provides a sense of anonymity, because the intended server will see the information of the proxy rather than the user's personal network information. Data sent from the Internet also reaches the proxy server before it is forwarded to the user's computer.
There are several reasons why a user may want to use an open proxy server. For example, an Internet user may want to protect his or her identity when visiting websites, posting on message boards, using chat rooms or downloading files. Another use is to access websites that are blocked on a local network, because the proxy server has the capability to access websites the user's computer cannot access directly. Finally, proxy servers support caching and can improve performance when surfing the web. This is particularly useful when the proxy server stores data the user needs to access.
Although an open proxy server has many uses, there are also problems that must be considered. First, connecting to the open proxy requires the user to directly connect with an unknown computer that hackers could use to house computer viruses and spyware. Second, the proxy server keeps track of everything that reaches and leaves the proxy server, so the degree of anonymity may not be as anonymous as one might think. Some potential security problems include intercepted passwords and email that the open proxy's owner can access. Last, some users use open proxy servers for illegal reasons, such as piracy and fraud, but this can also be traced if necessary.