Av. Tibidabo, 39-43, 08035 Barcelona2009-09-01 1
The interconnection between machines and high-speed communications has meant that the resources that are used can be at a different geographical location to that of the user. UNIX (and of course GNU/Linux) is probably the best example of this philosophy, because from its beginning, the focus has always been on the sharing of resources and the independence of the 'devices'. This philosophy has been realized in the creation of something that has now become very common: the services. A service is a resource (which may or not be universal) that makes it possible to obtain information, share data or simply process information remotely, under certain conditions. Our objective is to analyse the services that make it possible for our network. Generally, within a network, there will be a machine (or various machines, depending on the configuration) that will make it possible to exchange information with all the other elements. These machines are called servers and they contain a set of programs that centralise the information and make it easily accessible. These services help to reduce costs and increase the availability of information, but it should be remembered that a centralised service also involves some disadvantages, as it can come offline and leave the users without the service.
The servers should be designed so that all the servers are mirrored to solve these situations.
The services can be classified into two categories: those linking computers to computers or those linking users to computers. In the first case, the services are those needed by other computers, whereas in the second, the services are those required by the users (although there are services that may fall into both categories). In the first category, there are the naming services, such as the domain name system (DNS), the user information service (NISYP), the LDAP information directory or the services for storing in proxies. In the second category, we have interactive connection and remote execution services (SSH, telnet), file transfer (FTP), user-level information exchange such as email (MTA, IMAP, POP), news, World Wide Web, Wiki and files (NFS). To demonstrate all the possibilities of GNU/Linux Debian-FC6, we will describe each of these services with a minimal and operative configuration, but without leaving out the aspects related to security and stability.