Web Administration Introduction to Linux. Linux – The Basics Core component Kernel Kernel along...
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Transcript of Web Administration Introduction to Linux. Linux – The Basics Core component Kernel Kernel along...
Web Administration
Introduction to Linux
Linux – The Basics
Core component Kernel Kernel along with supporting
function libraries written in C Different software apps modify
appearance but all kernels are common to all distributions
Kernel is directly responsible for controlling the hardware (via device drivers)
Kernel Cont’d
Upgrade kernel Take advantage of new technologies Fix problems
www.kernel.org www.opensource.orgKernel is small – performs faster due to
less code for the processor to analyze.Developed first by Linus Torvalds.
More Sites
www.linuxdoc.org LUG Linux Users Groups (local to
area) www.gnu.org
Linux Basics Cont’d
Package Manager Red Hat RPM’s
Tarball compressed archive of files like zipped files
Linux iso’s downloaded from: www.linuxiso.org
Common Uses
Internet servers File & Print servers Application servers Super computers Scientific / Engineering
workstations Office workstations
Internet Server
Hundreds of network services that provide the framework for an internet server. Mail services Routing FTP services Firewalls & Proxy services Web services News services DNS services
Mail Services
E-mail is distributed via a network of e-mail servers, mail transfer agents (MTA’s). Sendmail, postfix, smail, and qmail.
An MDA (Mail Delivery Agent) downloads from the MTA for the user Procmail, fetchmail
MUA (Mail User Agent) user views e-mail Mutt, pine, printmail, elm, mail, Netscape,
Eudora
Routing
A core service that is necessary for the Internet to function.
Internet a large network of interconnected smaller networks.
Router provides interconnect – it contains information regarding the structure of the Internet sends this info from one network to another.
Linux is a good choice for routers: Linux router Project www.linuxrouter.org
FTP Services
Most common and efficient method for transferring files over Internet.
File Transfer Protocol Keep updated – security issues www.wu-ftpd.org
Firewalls & Proxy Services
Firewalls are placed between network and connection to the internet.
Linux has firewall support built directly into the kernel; utilities ipchains and netfilter/iptables used to configure rules.
netfilter.samba.org
Proxy Services
Requests Internet resources such as URL’s and FTP sites on behalf of the internal computers.
Keep track of the information passed to the client by maintaining a Network Address Translation (NAT) table.
Common linux proxy server is Squid. www.squid-cache.org
Web Services
Internet browser Basic level – web server is just a
server using HTTP provide information.
However – they can process programs CGI/ Perl scripts, PHP scripts
SSL (Secure Socket Layer) is a method for communicating with encrypted material.
www.apache.org
DNS Services
Uniquely identified computers – IP address is assigned. 204.26.82.3
DNS translates URL’s or FQDN such as www.linux.org into an IP address.
BIND (Berkely Internet Name Daemon)
www.isc.org
Typical Install Partitions
/boot -> contains Linux kernel and boot files -> 50MB
/home -> User home dir’s ->200 MB / user/usr -> System commands and utilities -> ~ 2GB/usr/local -> Location of add programs -> ~4GB/opt -> Alternate location of add programs ->
~4GB/var -> Logs and spools -> 2GB/tmp -> Temp files created by programs -> 500MBSwap -> typically twice installed RAM
Filesystem
Linux supports over 50 different filesystems.
ext2 is traditional filesystem used on most Linux systems.
Ext3 and REISER are much more robust as they perform a function called journaling.
A journaling filesystem is one that keeps track of the information written to the hard drive in a journal.
Boot Loader
Is a program started by the BIOS ROM after POST, which loads the Linux kernel into memory.
Can also be used to load other OS’s.
Two types: LILO (LInux LOader) GRUB (GRand Unified Bootloader
Basic Linux Usage
Recall that an OS is merely a collection of software that allows you to use the system hardware in a meaningful fashion.
Kernel in Linux is simply a file called “vmlinux”
There must exist a channel that allows a certain user to communicate with the kernel.
In Linux, called a terminal – allows login access.
Putty – ssh into our box from outside this lab
Shell
Once logged in the basic user interface is a shell – accepts input from user and passes into the kernel for processing.
Default shell – BASH shell (Bourne Again Shell)
It interprets all info the user enters onto the command line.
Commands indicate the name of the program to execute and are case sensitive.
Basic Shell Commands
Options are specific letters that start with a dash “_” appear after the command name and alter the way the command works.
Arguments do not start with a dash. Specify parameters that the command works upon.
Common Commands
clear clears terminal screenreset resets to default terminal settingsFinger displays info on system userswho displays current logged on userswhoami displays your login nameid displays the number associated with
your user acct namedate current date and timecal dispalys calendar for the current
monthexit exits the shell
Help
Linux contains manual pages that help you gather information about any command.
Can be accessed with man “command”
Command for shutdown: shutdown –h now halt reboot