|
|
This section is about the administration of Linux servers. According to traditional definitions:
In the following section, the main topics that an administrator will encounter are presented. Since it's from the administrator's point of view, the network server software (rather than client software) is discussed more. The TCP/IP protocol suite is the most widely used today, by network applications and forms the backbone of the Internet. Network software usually invloves clients commnuicating with servers over a network. The client software such as a web browser communicates with the server software such as a web server. The complexity of the software can vary from a simple program to very large multi-tasking complex programming achievements. Each of the following topics has hypertext links into the relevant manual, FAQ, HOWTO, and online book entries. As well as online example configuration files and links to distribution RPM and TGZ files. Click here for a list of places to go for Linux Software.
Diagnostic ToolsThere are many tools to help you diagnose problems when using the network. For example the output from the ifconfig command can be useful after using the ping command. The number of packets transmitted out of a network interface may indicate that no packets were sent and hence you should check the routing table. More powerful tools such as tcpdump and ethereal let you look at the contents of the packets to determine what is happening on your network. Port scaners such as nmap and nessus allow you to check how vulnerable your systems are and also informs you on how to fix problems with services, while network intrusion detection systems such as snort allow you detect possible attacks, while acid is used to display the log files.
Super-ServerThe secure super server xinetd is used to protect services such as telnet, ftp and imap. Many newer services such as vsftpd and cyrus-imap prefer to run as standalone daemons and hence are not started via a super server. The tcp_wrappers software is still used by other services such as remote procedure calls and can be used with any service which has been built with tcp_wrappers libraries.
RoutingThe quagga/zebra software allows you to quickly setup routing using protocols such as RIP, OSPF and BGP. The quagga/zebra interface is similar to that used by CISCO systems. The gated software and documentation is included here for historical reasons.
Name Services (DNS)Domain Name System maps the names of devices on the Internet to IP addresses. The DNS used by most unix systems is called BIND, this software has recently added some security features such as authentication between master and slave name servers. The alternative DNS name server software djbdns developed by D.J. Bernstein is worth considering.
Centralised Authenication SystemsSingle sign-on systems typicalliy use a directory tree, Windows has Active Directory, Novell has E-directory and Open Source users have openLDAP and Radius servers. The database contains information about users such as name, phone, location, passwords, access privileges, etc. To validate access Linux users can use Pluggable Authentication Modules. PAM allows a common authentication scheme to be used for programs such as login, su and X windows server
The Lightweight Directory Access Protocol LDAP is based on X.500, it provides a directory database, which can be used to store information about users such as login names, phone numbers, passwords and access privileges.
Radius servers become popular again with the introduction of wireless networks.
Electronic mail is delivered via the mail transport agent (MTA) such as sendmail. The e-mail interface software or mail user agent (MUA) is usually run on the end-user's workstation. The end-user downloads their e-mail from the mail server using imap or pop protocol. The e-mail is sent using SMTP protocol to the email server, which is effectively a gateway for the end-user's workstation.
Web SoftwareThe Apache web server is currently very popular on Unix systems. Extensions such web dav allow end-users to drag and drop files to the web server file systems.
Proxy Web ServerThe squid proxy web server provides a gateway by which internal network users can surf the Internet. The proxy web sever has a large cache so that the cost of surfing the Internet can be reduced. A squid server can also be used for external users to reduce the load a web server.
Search EnginesYou can use google to search the Internet but if you setup a web server you may wish to consider setting a search engine. The swish-e software is used on the ADIOS Linux CD.
File SystemsDistributed file systems are used to share files between workstations and servers. The Network File System (NFS) was developed for use between Unix systems. The Samba software was developed to share files between Unix and Windows systems. The Novell NetWare solution was developed to share files over the IPX protocol. To support diskless workstations the DHCP protocol was developed so that the workstation could automatically connect to the server sharing the filesystem.
Remote Access
X WindowsThe desktop environment for Unix systems has evolved on top of the X windows manager. For Linux the two most popular desktops are Gnome and KDE.
|
|
Linux Administration
Linux® is a registered trademark of Linus Torvalds.