Lab 8 Overview

Apache Web Server

SCRIPTSLinux Tricks

Scripts

Small programs to help the maintaining and configuring of an operating system

Executed by the shellSyntax dependent on shell

Typical use:Create a bunch of new usersConfigure a service

De facto extension: .sh

Change terminal color

#!/bin/bash# script to turn the screen bluesetterm -background blueecho It is a blue day

Line 1: specifies which shell should be used to interpret the commands in the script.Line 2: is a comment (has no effect when the script is executed).Line 3: sets the background colour.Line 4: displays a message.

Assuming the file is executable:

To execute if the PWD has this file:

Assume a file named changecolor:

./changecolor

If in another directory use the fully qualified name:

/home/mydir/utils/changecolor

Simple Menu Script

#!/bin/bash OPTIONS="Hello Quit" select opt in $OPTIONS; do if [ "$opt" = "Quit" ]; then

echo done exit

elif [ "$opt" = "Hello" ]; then echo Hello World else

clear echo bad option

fi done

These can be as complex as needed with conditional and loop controls (among many other things)

Running Scripts Basics

Make sure the first line is a directive of which shell to use (if needed) Starts with a shebang: #! For Debian it is the bash shell

/bin/bash

Make sure it is executable rwxr-xr–-

User can run, edit and view Group can run and view World can view

chmod 754 script.sh

If the shell is in a directory defined in the PATH echo $PATH

Will show the directories

type: filename

If it is not in PATH but it is in the PWD type: ./filename

If not in PATH and not in the PWD type full filename starting with the root: /home/ajkombol/Desktop/script.sh

Script one: netconfig.sh

#!/bin/bashNETCONFIGFILE=/etc/network/interfacesRESOLVECONF=/etc/resolv.confifdown $1vi $NETCONFIGFILE#vi $RESOLVECONFifup $1echo 'nameserver 172.16.1.254' >> $RESOLVECONFecho 'nameserver 172.16.1.250' >> $RESOLVECONF

myprompt#./netconfig.sh eth0

Desired action: • stop the NIC• open the interfaces file to edit• restart the NIC• add two nameservers to the resolve.conf fileThe script:

To execute the script:

Quick script introParameters passed to a script are

denoted by $1, $2, $3, … $1 is the first parameter, $2 is the second, etc.$# is the number of parameters passed

Variables are case sensitiveEnvironment variables

Used by the system in generalAre UPPER case by convention

Quick script intro (cont.) Conditionals are done by an if…elif…else…fi structure

if and elif are followed by a command that evaluates to true or false elif and else are optional

elif can be repeatedOnly one else may be used, if needed

if is closed with the fi statement To stop in the middle of a script use exit n

n = 0 is a normal exit• If n is not specified it is assumed 0

n = 1 is an error exit• Actually any non 0 value is an error

If a value needs to be checked the test command is usedNumbers use conditionals

• e.g. –gt, -lt, and –eq greater than, less than, equal

• EX: test 1 –gt 2

Strings use operators• e.g. = or !=

equal and not equal• EX: test $1 = "opt1"

There are other comparisons that can be done, check the internet

Script two: go

#!/bin/bashIFILE=/etc/network/interfacesifdown eth0if test $1 = "static" ; then cp $IFILE.static $IFILE echo "Static interfaces loaded!"elif test $1 = "dhcp" ; then cp $IFILE.dhcp $IFILE echo "DHCP interfaces loaded!"else echo "Parameter must be static or dhcp"fiifup eth0

Desired action: • stop the NIC, • check which option • copy the proper template to interfaces,• restart the NIC

To execute the script:myprompt#./go static…myprompt#./go dhcp

Today's labs scripts summaryChanging network configuration

Script one – editing the interfaces filestop NICedit interfacesadd some additional routing informationstart NIC

Script two – alternating interfaces templatesMake two interfaces templatesstop NICCopy the desired templatestart NIC

You may wish to keep these scripts Use netconfig.sh to edit the interfaces file

After making appropriate changes

Use go or go2 to switch between DHCP addressesStatic addresses

Reminder

ALWAYS make a backup copy of a configuration file BEFORE editing itWill allow the file to be restored

If you mess it upIf something else messes it up

Examples:cp interfaces interfaces.backup cp apache2.conf apache2.conf.orig

Make a copy of a line to be changed in a file and comment it out before changing the originalExample:

# This is the original lineThis is the changed line

APACHEMain Lab

Apache Web Server

Main GoalsInstall ApacheConfigure basic systemConfigure restrictions

Side goalsInstalling packages on a Debian SystemReinforce VM environmentReinforce use of vi editor

Apache Web Server Overview

Install Apache on your Debian VM apt-get

Backup: Synaptic Package ManagerNo credit for Synaptic install

Check if installation workedCreate new directories

“Install” the web applicationConfigure Apache to “find” the new “application”Copy Web page files into proper directories

Hint: assume the Web application is being moved from a different Web server to this machine

Configure Apache for restrictions Allow directory access Deny directory access

Browse the application from another machine

Misc. Notes

Debian required for the Apache Server CentOS recommended for the browsing client

Can be any OS with a browser

Use ifconfig to identify your IP address Web files (.htm and pics) available on hades.lab

Use browser to locate /apachelab

• e.g. lab302-web.hades.lab/classes/apachelab (172.16.1.250)

In /public directory Also available

ON websiteon thumbdrive

You will need to figure out on your own where the images go to be properly displayed All web pages except home have an image A subdirectory is involved!

IMPORTANT!!!!

This Debian VM must be working and saved!

Will be used as the basis for the DNS Lab!

Apache Overview

“Open source” web serverDefault browser “root” directory

NOT the same as the host’s root directory!

To access the web server:Use the IP address or host namePort 80

Bonus:At end of lab add port to browse on port 8080

Document results

Last minute notes:

Check the links to test1.htmltest2.htmlThey should go to the ITIS2110 directory

Watch the IP addresses of your VMDHCP OK this lab

Need to look up address for browsing

If address was assignedBe sure does not conflict with another machine

• Can use machine ID as subnet or host id• Can use your subnet (see listing on post)

Apache Lab

Lab 20 pts