The SOCKS Protocol was developed long ago, but it is still topical and more modern as compared with the HTTP proxy. The SOCKS Protocol is compliant with almost all protocols, for example, a Socks 4 version – with TCP, and Socks 5 - with TCP and UDP, etc. Data is transferred from a SOCKS protocol client to a server. Besides, it’s not necessary to look into the essence and contents of the data itself, so it’s possible to work via HTTP, FTP, SMTP, POP3, NNTP protocols, etc.
In terms of a web-server, a SOCKS Protocol is considered to be a client (as SOCKS transfers data directly from a client to a server without examining the transfer content). This is a cogent argument in favor of the data transfer anonymity of such types of proxy servers.
As of today, there exist two variants of the SOCKS protocol, namely, SOCKS 4 and SOCKS 5.
SOCKS 4 is spread wider, but SOCKS 5 is not less popular as it is compliant with most up-to-date applications and software. A SOCKS proxy server enables to work with such software as ICQ, Napster, AudioGalaxy or eDonkey2000 (for a direct download of audio files). Some old ICQ versions could use only SOCKS servers for their work. A SOCKS proxy can be applied for e-mail clients and mailing programs as it can support any TCP UDP protocol, though it’s not in common practice. That’s why a necessary software, a socksificator, have been developed.
Socksificators intercept connection requests from specific applications and sends the requests directly to a SOCKS proxy server. A SOCKS proxy server can use the mentioned principle for browser operations.
As a SOCKS proxy server transfers data from one computer to another without changing it or analyzing it, necessary chains of SOCKS proxy servers of any required length can be easily created. For this purpose, it’s necessary to apply special software as common software can use only one SOCKS proxy server. But chaining is a topic for the other article.
A SOCKS proxy server can be chained directly with other proxy server protocols, such as HTTP and GI. These protocols should be obligatory located in the beginning of a chain, otherwise you fail.
The following sequence can be built:
You cannot built a chain like this: CGI proxy SOCKS proxy.
A SOCKS proxy can be used if only the original corporate proxy server does not support a SOCKS protocol. To this effect, a special port 1080 is conventionally allocated for a SOCKS proxy.
Thus, you can check your mail in e-mail clients (e.g., on the Outlook) via a SOCKS proxy server.