The name server provides the software required to translate domain names into IP address and IP addresses into domain names. With this software you can rembember addresses like instead of addresses like . There are other feautres (e.g., mail exchanger resolution, zone delegation, etc.) provided by this software that aren't used in the point-to-point configuration we describe in this chapter. To install this software, run the following command: yum install bind There is a bind-chroot packages, however, we aren't using it because SELinux is already enforced on the &TCD; filesystem and it provides far more security than the idea of bind-chroot package itself does. The mail server provides the software required to let you send/receive e-mail messages to/from others. The mail server is splitted in three basic components: The Mail Transfer Agent (postfix), The Mail Delivery Agent (Cyrus-Imapd) and an intermediary daemon named saslauthd to handle users' authentication. The mail transfer agent is the program your e-mail client sends e-mail messages to. The mail delivery agent, on the other hand, is the program your e-mail client reads e-mail message from (i.e., this is the place where your mailbox is stored in). The authentication daemon is used by the mail delivery agent to authenticate user's credentials (e.g., the information that let you access an specific mailbox). To install this software, run the following command: yum install postfix cyrus-imapd cyrus-sasl By default, the sendmail program is used as mail transfer agent, not postfix. For the sake of that point-to-point configuration we are implementing, I decided to use postfix instead as default mail transfer agent, not sendmail. To effectively achieve this decition, it is required to use the alternatives command, as it shown below: alternatives --config mta This command will present you a menu to chose between available mail transfer agents, so it is there where you choose to use posfix as default option. Now that you've changed postfix the default mail transfer agent, you can saftly remove the sendmail package to avoid unused software to remain inside the computer. To do this, you can run the following command: yum remove sendmail In addition to mail server specific packages, we also provide mailing list support. Mailing lists provide e-mail addresses that users registered inside the ISP can write to. When you sed an e-mail to a mailing list, your message is distributed to all members of that list. In order for this to happen, people registered inside ISP need to subscribe themselves into that mailing list they want to receive messages from. The subscription of mailinglist will be available through a secured web application in the following url: To install the mailing list software, run the following command: yum install mailman The web server provides the software required to support web interfaces like those one previously mention to register new users inside the ISP and subscribe mailing lists. The web server provided in this configuration will accept requests both unencrypted and encrypted. yum install httpd mod_ssl crypto-utils In addition to mailing lists support, the web server will provide access to Subversion. Subvesion provides a way to manage files through version control. The main purpose of providing Subversion support here is sharing the version of &TCAR; I've been working on. To install Subversion software, run the following command: yum install subversion mod_dav_svn The directory server provides the software required to unify user information. This server is access by other server whenever user information is required. You, as end user, can also use this server from your workstation to retrive a list of all users registered in the ISP. This list can be retrived by the web interface the ISP provides, or any application your workstation provide (e.g., most e-mail clients provide a way to configure LDAP servers to build address book from it.). To install the directory server sofware, run the following command: yum openldap-servers python-ldap