This chapter describes how to configure &TCD; to provide some Internet services through the telephone line. In this chapter, the computer holding the Internet services is named the server and the computer that want to make use of such services is named the client. We assume that both server and client computers have been installed with &TCD; (release 5.5). In this configuration, both client and server computers use modems to transmit data in form of sound through the telephone lines system. The dial-up connection described in this chapter could be a choise when the only communication medium you have access to is the telephone lines system. This configuration emerged from the need of sharing information with my friends in a country where Internet access is limitted to statal organizations and controlled there with an increasing crazy obsession. However, in this environment, the telephone lines system provides an alternative platform to interchange information in a point-to-point fashion. It can be used to create small social groups and organize ideas safetly (e.g., by using TLS to encrypt connections). To be more specific, the goal would be to provide public access to an Internet Service Provider (ISP) where people can express themselves freely (e.g., through a mailing list with open subscriptions). Even this configuration tries to reduce the lack of communication, there are limitations around it that we cannot take away, yet. The following list shows what these limitations are: Only one connection (of 15 minutes) is possible at a time. More than 3 consecutive connections from the same phone number in a time range of 60 minutes means that that number is attacking the ISP to provoke a Denying of Service (DoS) attach. In such cases the phone number originating the call will be permantly banished from realizing further calls to the ISP. Fourtunly, such controls can be automated so I hope they achieve an acceptable degree of efficiency. The ISP is isolated from Internet, so it is not possible to provide Internet access through the ISP. The information generated inside the ISP is jailed to it. This way, it will be available to people registered inside the ISP only (e.g., through the web internface). The implementation of services that required persistent connections (e.g., chats) will not be considered as a practical offer. Instead, only asynchronous services (e.g., e-mail) will be supported. This restriction is required to reduce the connection effective times. For example, consider an environment where you connect the ISP to send/receive e-mails only and then disconnect. In fact, to force this behaivour the ISP will be configured to close connections after 15 minutes passed the connection establishment. Your user profile will be removed from ISP when no effective point-to-point connection is established by you in a period of 7 days since the last effective point-to-point connection you established to the ISP. When your user profile is removed, you will need to register yourself again inside the ISP, to access its services. I'm very sorry about these limitations, but this is the best I can offer with one PC, one modem, and one single telephone line. If you think this configuration can be improved somehow, please send me an e-mail to al@example.com. Notice that, for any mail to reach me, you should be registered inside the ISP first; I don't answer phone calls personally, the phone is very busy answering point-to-point connections ;). In order for you to share information with others, it is required that both you and the person you want to share information with, have an e-mail address registered inside ISP. This registration process is realized through a secured web interface accessable through an encrypted connection as the following url illustrates: The web interface should permit everyone to update or delete their personal profiles without compromising personal information. Notice that all actions realized through this web interface must be simple enough to be achieved in less than 15 minutes (the time the point-to-point connection reamins active from its first establishment on). User information is stored inside an LDAP server. The web application manipulates LDAP records and all related files inside the operating system that make possible a user to establish a poit-to-point connection to the ISP, as well as register, update or delate its profile inside the ISP. Care should be taken to prevent one user to modify/delete profiles from other users. The user's profile administration is individual to each user based on its identity. Notice that, all related subsystems (e.g., Postix, Cyrus-Imapd and Saslauthd) must use the user information from LDAP server. Likewise, the mailbox administration must be automated based on the users in the LDAP server. The web application must be able to be aware of all files related inside the infrastructure in a way that administration tasks can be automated and presented friendly to end users (this will required the web application to run some program that needs root privileges =:-|). The whole proces would be, establish a point-to-point connection to the ISP, register a new user through the web application and start using the e-mail client with your new address. The LDAP server will be available for everyone to consult from their mail clients. Inside the web application, verifications must be included to avoid duplicated values, invalid characters and similar stuff. In case some kind of force intend to confiscate me the computer where the ISP is installed in, I am plaing to encrypt the whole filesystem in a way that it would be very difficult to get any valid data from it. The encryption feature is applied before the operating system starts. In this configuration a password is required to decrypt the operating system filesystem in order to be able of booting up the operating system as expected. If the password is not provided, the only thing you get is a prompt to enter a password :). Another important matter to be aware of is about the ISP's policy. In order to keep freedom, it is required to define the boundaries of that freedom so you can determine and judge it. Absolute freedom (anarchism) will not be permitted (it would end up in total destruction) and communism will be avoided (it would suppress the natural freedom of human beings). So a middle point will be used. For example, if you think you have the freedom to abuse the ISP I provide (e.g., by spamming it, or by provoking denying of service attaks) you probably have it, but consider that I am free to banish you immediatly for trying to destroy my work. On the other hand, if you show yourself to be an educated person with solid ideas and reasons to share, you'll be totaly welcome to stay. The general idea behind this work is improving Cuban communication to make ourselves better persons, understand our nature and environment either social, economical or polital.