User:Holt/XS Community Edition/Documentation/Hacking

Summary

This is the Documentation for initial version of the School Server - Community Edition, Version 0.1.

The target audience will be the 7 people working from Holt's home. Experienced Linux users and admin with a strong interest in hacking. Enough interest that they made the trip to Toronto February 6-10th, 2013. Stage 2, hopefully for version 0.2 will include the larger school server development community. Stage 3, hopefully for version 0.3 will begin the emphasis on end user documentation.

Based on practical experience and this document a hacker should be able to download the XS code, modify the code, build an rpm, and install an RPM. Secondary goals will be to download a RPM and install a fully functioning School Server.

Purpose

The purpose of this iteration of documentation will be to provide a stable enough starting point from which hackers can load and modify it for their individual purposes.

Design and architecture

Conceptually, the school server is a collection of common network services which can be easily installed and configured as necessary. Modularity is important in order to provide a core base of services on top of which extended service modules can be installed. Their is an ongoing discussion about what are Core Services versus Extended Services, previewed below. Over time this should settle down.

Code layout

Currently the code lives in the xs-config/ dir. Consider these 3 subdirectories of xs-config:

1. scripts/
   Configuration consists of a series of scripts which live in the scripts/ dir. The process is kicked off by running xs-setup. xs-setup calls a series of scripts with the naming convention the xs-[ServiceName] each of which set up an individual service.
2. cfg/etc/
   When necessary, the xs-[ServiceName] scripts installs files from under cfg/etc as necessary.
3. cfg/html/top/
   The web based GUI is located under cfg/html/top/

Core Services

• Dynamic Host Configuration Protocol (dhcpd) DHCP (Dynamic Host Configuration Protocol) allows the school server to assign IP addresses to connected XOs. DHCP is a network protocol used to configure network devices so that they can connect and communicate over an IP network.
• Internet Domain Name Server (named) The Domain Name System (DNS) converts the name of a Web site (www.google.com) to an IP address (65.115.71.34). Named is a daemon within BIND that responds to DNS queries from remote machines.
• Network Address Translation/NAT, Gateway, IP Masquerading, Firewall (iptables) NAT. The School Server used Network Address Translation to provide security, privacy, and scalability. NAT enables all of the XOs within a school to appear to the world as a single machine. As a security measure all packets pass through the server. This can be further augmented by additional filtering. Privacy in enhance because students machines are not directly accessible from the public internet. Finally NAT enhances scalability as an entire school only needs a single IP address.
• XMPP server (ejabberd) Extensible Messaging and Presence Protocol (XMPP)is a communications protocol for near real-time, instant messaging (IM), presence information, and contact list maintenance. The protocol was originally named Jabber.
• ?(idmgr)?