Linux Lpic 102

Front 1

Objective:
105.x - Shells, Scripting & Data Management (17%)

Back 1

Section 105.1
Customizing the shell environment

Front 2

/etc/profile

Back 2

Global profile for the bash shell is stored here. This calls all files in /etc/profile.d and It also points to the bash profile which is located in /etc/bash.bashrc or /etc/bashrc (which contains global aliases). After /etc/profile.d is called it will call the users bash profile. It looks for this bash profile in this order: /home/user/.bash_profile or /home/user/.bash_login or /home/user/.profile . Whichever file exists will also point to /home/user/.bashrc which contains profile specific aliases.

Front 3

/home/user/.bash_logout

Back 3

k

Front 4

/etc/skel

Back 4

When a new user is added with useradd -m command, all files located in /etc/skel will be added to the new /home/user

Front 5

Aliases & Functions

Back 5

Aliases are simple substitutions for quicker cmds. ex. ll = `ls -l`
Functions are shell scripts that get loaded into memory for use in your shell.

Front 6

Variables

Back 6

Variables are only stored in the current shell and its processes.
Environment variables are stored for current and any child processes

VARNAME="variable contents", reference as $VARNAME

env : lists all environment variables
set : shows all variables and ftns the shell is aware of (does not actually set a variable)
export : exports variable to environment variable
unset : deletes var

Front 7

PATH

Back 7

Environment variable that determines te search order for executing files in bash; can be modified in one of those 3 possible profile locations:
/home/user/.bash_profile
/home/user/.bash_login
/home/user/.profile

Front 8

Objective:
105.x - Shells, Scripting & Data Management (17%)

Back 8

Section 105.2
Writing shell scripts

Front 9

shell script syntax

Back 9

#! /bin/bash
(shbang) (the interpreter needed to run this script)
#
(line is commented out)

Front 10

command substitution

Back 10

command results being used as arguments

ex.
VAR=$(ls -l)
or
VAR=`ls -l`

Front 11

CMD syntax

test -options expression

Back 11

-x : is the file executable
-e : does the file exist
-eq : are the values equal
-ne : are the values not equal
-z : is there a value to the expression

will result in an exit code which is stored in variable $? :
0 = True
Not 0 (any number other than 0)= False
It assigns the exit code in background; use echo $? for it's result

Front 12

Conditional statement syntax

Back 12

if [ condition ] ;
then
command1
command2
else
fi

Front 13

conditional mailing to superuser

Back 13

if [ condition ] ;
then
command1
echo "email content here" | mail -s "email subject title" root
else
fi

Front 14

Loops

Back 14

for _x_ in ___
do
command
done

while [ condition ]
do
command
done

Front 15

Objective:
105.x - Shells, Scripting & Data Management (17%)

Back 15

Section 105.3
SQL Data Management

Front 16

CMD
mysql -options database

Back 16

-u : the user to be logged in

Front 17

mysql syntax

Back 17

command convention for the commands is all caps while database names in lowercase.

ex.
SELECT * FROM fruit WHERE color = "yellow" AND size = "small";
<=>
CMD field CMD table CMD field = "" CMD field = ""

INSERT INTO table (field1, 2, 3) VALUES (attr1, 2, 3);

DELETE FROM ____ WHERE _____ = "";

UPDATE table SET field = 'attr' WHERE field = 'attr';

SELECT * FROM table1 JOIN table2 ON tbl1.field = tbl2.field;

Front 18

Objective:
106.x - User Interfaces and Desktops (8%)

Back 18

Section 106.1
Install and Configure X11

Front 19

sudo X -configure

Back 19

creates file
/home/user/xorg.conf.new
which gets put into directory
/etc/x11

Front 20

X font server

Back 20

renders fonts for x server process, configured in /home/user/xorg.conf.new

Front 21

~/xorg.conf.new

Back 21

Understand what things could be configured in this file:

Sections:
"ServerLayout"
"Files"
"Module"
"InputDevice"
Identifier "Keyboard0"
Indentifier "mouse0"
option
option
Endsection
"Monitor"
"Device"
Indentifier
Driver
"Screen"
Indentifier
Subsection
Subsection
EndSection

Front 22

xwininfo

Back 22

gives info all about that selected program's window

Front 23

xdpyinfo

Back 23

gives info about the X server itself

Front 24

startx -- :1

Back 24

k

Front 25

xhost +192.168.xxx.xxx

Back 25

user from that ip address would be able to open windows on your computer

Front 26

Objective:
106.x - User Interfaces and Desktops (8%)

Back 26

Section 106.2
Setup a Display Manager

Front 27

/etc/inittab

/etc/default/grub
update-grub

Back 27

where to change the default runlevel and x11 login in RedHat

change it here in Ubuntu

Front 28

/etc/sysconfig/desktop

/etc/x11/default-display-manager

Back 28

add this line to change display manager in RedHat
DISPLAYMANAGER="KDE" or "GNOME" or "XDM"

edit this file to change display managers in Ubuntu

Front 29

/etc/gdm/custom.conf

Back 29

Add these lines to these sections to customize gdm login.

[daemon]
Greeter=/usr/libexec/gdmlogin
RemoteGreeter=/usr/libexec/gdmlogin

[xdmcp]
Enable=true : (allows remote users to login)

[greeter]
DefaultWelcome=false
Welcome=Your welcome here

Front 30

use
locate kdmrc
(location can vary)

/usr/share/config/kdm/kdmrc

Back 30

edit these lines to customize kdm login

GreetString=Your greeting here

[Xdmcp}
Enable=true

Xaccess=/usr/share/config/kdm/Xaccess
Willing=/usr/share/config/kdm/Xwilling

UseTheme=false

/usr/share/config/kdm

there are two asterisks in this file that need to be uncommented to allow "any user" to connect.

:0 local /usr/bin/X -depth 24
(add this depth tag to change color depth)

Front 31

/etc/x11/xdm/xdm-config

/etc/x11/xdm/Xresources

Back 31

in /etc/x11/xdm/xdm-config

!DisplayManager.requestport: 0
(comment this line out to enable remote clients [xdm uses ! as comments instead of #])

/etc/x11/xdm
uncomment the two asterisk lines to allow remote logins

in /etc/x11/xdm/Xresources

xlogin*greeting: your greeting here

Front 32

Objective:
106.x - User Interfaces and Desktops (8%)

Back 32

Section 106.3
Accessibility

Front 33

Sticky/Repeat Keys

Slow/Bounce/Toggle Keys

Mouse Keys

GOK

emacspeak

Back 33

Adjust these settings in Assistive Technologies and Universal Access Preferences aka Access X:

Sticky - used for those that have trouble pressing two keys at once. ex capitalized letters, it allows to press shift then letter rather then simultaneous

slow - only accept longer keypresses
bounce - ignore fast duplicate keys
toggle - gives a beep when toggle key pressed ex caps lock num lock
mouse - use numpad to control mouse cursor

Orca- program that has screen reader and has magnifier

GOK - Gnome On-Screen Keyboard

emacspeak - on-screen reader for emacs

Front 34

Objective:
107.x - Administrative Tasks (20%)

Back 34

Section 107.1
Manage user and group accounts and related system files

Front 35

/etc/passwd

/etc/shadow

/etc/group

/etc/skel

Back 35

Follow this structure
/etc/passwd
username:passwd:uid:gid:info:homedir:shell

(passwd field has x meaning it's stored in shadow file)(uid usually starts at 500 or 1000)(change shell to /bin/false to disable login)

/etc/shadow
username:passwd:timesincepasschange:minpasslifetime:maxlifetime:warningdays:inactivedays:acctdisable

(shows encrypted passwd, if * then login to that account is disabled)(time is given since Jan1,1970)

/etc/group
groupname:passwd:gid:members

/etc/gshadow
groupname:passwd:gid:members
(! means no passwd)

Front 36

CMDS

useradd

Back 36

-d : home directory
-m : creates home dir
-s : specify the shell
-g : specify group num
-G : add additional groups by name
-u : specify uid
-c : comments (if spaces uses quotes)

Front 37

CMD

usermod

userdel

Back 37

same tags as useradd and:
-L : locks or disables acct
-U : unlocks or enables acct
-aG : add to group (if only using -G you will need to specify every group the user is member of, need the -aG to add a new group to the previous list of groups)

-r : also deletes home dir

Front 38

CMD

passwd

groupadd

groupdel

groupmod

Back 38

changes a user password

-g : specify gid

Front 39

CMD

chage

Back 39

-l username : check user's aging info

-E YYYY-MM-DD : sets expiration date of user acct (this adjusts field in /etc/shadow)

Front 40

Objective:
107.x - Administrative Tasks (20%)

Back 40

Section 107.2
Automate system administration tasks by scheduling jobs

Front 41

CMD

cron

Back 41

cron scheduling format

min hour dayofmonth month dayofweek (user) command
(Sunday can be a 0 or a 7) (user to runas [only used in the system-wide crons])

02 14 * * * -> everyday at 2:02pm
00 15 3 3 3 -> 3:00pm every March3rd which is a Wed
01,15,45 * * * * -> 1,15, and 45min past every hour
*/15 * * * * -> every 15 minutes
01 01 * * 1-5 -> 1:01am on weekdays

Front 42

/etc/crontab

/etc/cron.d/

/etc/cron.daily or hourly or monthly or weekly

Back 42

/etc/crontab : system-wide crontab, only root has access, where the scheduled tasks are listed.

/etc/cron.d/ : location where installed programs can add cron jobs

/etc/cron.daily/ : scripts are placed here, not cron files, the files inside these directories are executed by the system, configured in that /etc/crontab file.

Front 43

CMD

crontab
(program for creating user crons)

Back 43

-e : edit

these are stored in
/var/spool/cron/crontabs

Front 44

CMD

anacron

at

Back 44

if a system gets shutdown and a cron doesn't get run, anacron looks for these and runs them at next system launch.

looks for these timestamps in /var/spool/anacron

at scheduler is used for one time events
at [time]
ctrl-d to exit scheduler
atq : shows scheduled actions
atrm -jobnumber : deletes scheduled actions

Front 45

/etc/cron.allow or deny
/etc/at.allow or deny

Back 45

deny is usually used but if cron.allow does exist it takes precedence...so if allow exists and no users specified then nobody has access.

Front 46

Objective:
107.x - Administrative Tasks (20%)

Back 46

Section 107.3
Localisation and Internationalisation

Front 47

Locale variables

Back 47

locale cmd used to show the localisation variables

$LANG :default language setting
LANG=en_US.utf8
LANG=en_GB.utf8

LC_ALL :variable takes precedence over all other LC.* variables so if LC_ALL=en_US.utf8 then everything will use en_US.utf8 setting

LANG=C : uses default encoding, avoiding translation issues

Front 48

character encoding

Back 48

convert character on screen to a number for the computer

ASCII : only 128 characters
ISO-8859 : many subset/variations used with diff character sets
UTF-8 : unicode translation format, includes most all languages rather than needing subsets

convert between these encoding schemes with
iconv
-f : from
-t : to, then specify the path of the file wanting converted, ex. /etc/fstab
--list : shows all formats supported

Front 49

cmd

tzconfig : has been replaced with
tzselect

Back 49

/etc/timezone : file referring to /usr/share/zoneinfo folder which specifies the timezone
/etc/localtime : copy of the binary file referenced by /etc/timezone

date MMDDhhmmYYYY
(cmd used to set system time)

Front 50

Objective:
108.x - Essential System Services (17%)

Back 50

Section 108.1
Maintain system time

Front 51

hwclock

Back 51

date cmd controls system clock

hardware clock runs on battery when computer is off. sets system clock when computer boots.

hwclock cmd shows hwclock time

/etc/adjtime
shows whether hwclock is set to your LOCAL time or UTC time

hwclock --set --date="dd/MM/YYYY hh:mm" : manual set hwclock
hwclock -w :writes system time to the hardwareclock
hwclock -u : sets to UTC format
hwclock --local : sets to local format

Front 52

pool.ntp.org

Back 52

geographically close ntp servers

ntpdate 0.us.pool.ntp.org
cmd to accurately update ntp

/etc/ntp.conf : file to configure list of ntp servers

Front 53

Objective:
108.x - Essential System Services (17%)

Back 53

Section 108.2
System Logging

Front 54

syslog

Back 54

RedHat uses syslog
Ubuntu uses rsyslog

syslog setup:
facility.priority action

facilities are pre-set and include but not limited: auth, cron, daemon, ftp, kern, mail, user
priorities include: emerg/ panic, alert, crit, err, warn, notice, info, debug
actions include: file, user, pipe, remote host

Front 55

syslog.conf
syslogd

Back 55

/etc/syslog.conf : file to edit syslog
in this file it has a list of the facilities that are set to which priority alerts and where they send them.
(if there is an * in the action field then that means all users get notified, usually with emerg priorities)
ex.
#Save user facility to separate server
user.* @192.168.1.240
(send user logs to this server)
(issue cmd : service syslog restart : when adding an entry to this file)

to setup your server to accept logs from remote locations (like this example) you need to add -r to syslogd startup
(location differs across distributions)

Front 56

logger

Back 56

logger used to add log entries manually
-p
ex.
logger -p user.crit Danger we are in trouble
(sends it to the location specified in the /etc/syslog.conf)

Front 57

klogd

Back 57

kernel logger, uses same location as syslog for its configuration but its a separate process

Front 58

Objective:
108.x - Essential System Services (17%)

Back 58

Section 108.3
Mail Transfer Agent (MTA) Basics

Front 59

Common MTAs

Back 59

sendmail : most popular and most difficult to configure

qmail : made to replace sendmail, made with security in mind, it is public domain and not GPL

exim : lots of features, supports authentication and ACLs

postfix : default for many distros, supports encryption, virtual domains, and clear configuration files

Front 60

Sendmail Emulation Layer

Back 60

config files are diff for every MTA but common commands remain compatible with sendmail for ease of use.
ex.
mailq : cmd shows current mail in queue, regardless of MTA

Front 61

Email Aliases

Email Forwarding

Back 61

/etc/aliases
(system-wide)
file structure
user: user
ex.
mailer-daemon: postmaster
postmaster: root
(anything sent to mailer-daemon, send to postmaster, anything sent to postmaster, send to root)
any time you add to that file then run the newaliases cmd

users can forward email to other accts by creating /home/user/.forward

Front 62

cmd line mail program

Back 62

used to send mail interactively, easy to use and manage but simple

Front 63

Objective:
108.x - Essential System Services (17%)

Back 63

Section 108.4
Manage printers and printing

Front 64

CUPS

Back 64

Common Unix Printing System

webinterface configuration http://localhost:631/
which edits: but can also be configured manually

/etc/cups/cupsd.conf
print server and ACL configuration file
will need to adjust the listen line:
Listen localhost: 631 (from)
Listen 631 (to)
(so it will listen for connections outside of the local pc)
Browsing Off (from)
Browsing On (to)
(so people can browse this server for printer)

/etc/cups/printers.conf
(configuration file for actual printer hardware)

DeviceURI socket://192.168.x.x

Front 65

lpd : legacy printing program/interface

Back 65

/var/spool/cups
active print jobs stored here, FIFO
lpd cmds
lpq : shows info about queued jobs, -a flag lists queue for all printers

lprm -jobnum : delete specific print job (found with lpq), no jobnum specified and just a - deletes all jobs

lpr filename: sends file to printer,

-Pprintername (to send to non-default printer, no space between P and printername)
exs.
lpq -PUSB_Laser
lpq -PHP_Laser
lpr -PUSB_Laser document.txt
lprm -PUSB_Laser -

Front 66

cmds

Back 66

lpc status all
shows state of all printers installed on your system

cupsaccept printername :
cupsreject printername : all jobs are rejected, nobody can send a job to the printer queue

cupsenable printername :
cupsdisable printername: jobs still get accepted into the queue but the printer won't print them until it is enabled

lpmove jobnum printername : move specific job from one printer queue to another printer queue
lpmove printer1 printer2 : move all jobs from printer1 to printer2

Front 67

Objective:
109.x - Network Fundamentals (23%)

*if somebody else is using these, I didn't take very many notes on networking because I knew most of it, but be aware there is much more on the test than what my cards represent.

Back 67

Section 109.1
Fundamentals of Internet protocols

Front 68

cmd

route

Back 68

shows routing table

route add default gw 192.168.x.x
to add default route to the routing table
route del default
to delete default route

Private Address Range
10
172.16-31
192.168

Front 69

TCP and UDP Ports

Back 69

20 TCP ftp-data
21 TCP ftp-control/login
22 TCP/UDP SSH
23 TCP telnet
25 TCP SMTP
53 TCP/UDP DNS
80 TCP/UDP HTTP
110 TCP/UDP POP3
119 TCP NNTP (usenet news)
139 TCP/UDP NetBIOS
143 TCP/UDP IMAP
161 TCP/UDP SNMP
443 TCP/UDP HTTPS (using SSL or TLS)
465 TCP SMTPS (SSL)
993 TCP/UDP IMAP (SSL)
995 TCP/UDP POP3 (SSL)

/etc/services
shows the services and their reserved ports

Front 70

CMDs

host
dig
traceroute
tracepath
ftp
telnet
ping

Back 70

traceroute and tracepath use ICMP

Front 71

Objective:
109.x - Network Fundamentals (23%)

Back 71

Section 109.2
Basic Network Configuration

Front 72

DNS files

Back 72

/etc/hostname
contains hostname of machine

/etc/hosts
dns info for the host

/etc/resolve.conf
where the computer looks for dns info

/etc/nsswitch.conf
determine order it uses for name resolution

Front 73

Network files

Back 73

RedHat
/etc/sysconfig/network-scripts/ifcfg-eth0
/etc/sysconfig/network

Debian
/etc/network/interfaces

Front 74

CMDs
ifconfig

ifup

ifdown

Back 74

display and configure network interfaces

config and activate network interfaces based upon config files

Front 75

Objective:
109.x - Network Fundamentals (23%)

Back 75

Section 109.3
Basic Network troubleshooting

Front 76

Network Interfaces

Back 76

Auto and manual restart interface

/etc/init.d/network restart
(automated script)
ifdown eth0
ifup eth0
or
ifconfig eth0 down
ifconfig eht0 up

To add a card
ifconfig eth1 ip 192.168.1.2 subnet 255.255.255.0

to remove a card (other than physically removing it)
lsmod
to find the kernel module of the eth card
rmmod modname

Front 77

Routing Table

Back 77

netstat
listens to all network activity on your computer

-n : translate numbers
-t : tcp
-u : udp
-a : all interfaces
-r : shows routing table (same as route cmd)

Front 78

Objective:
109.x - Network Fundamentals (23%)

Back 78

Section 109.4
Configure client side DNS

Front 79

k

Back 79

/etc/nsswitch.conf
edit the hosts line in this file to change the order of dns lookup
hosts: files dns
hosts: dns files
(files refers to /etc/hosts file)

/etc/hosts
127.0.0.1 localhost
::1 localhost6

Front 80

Objective:
110.x - Security (15%)

Back 80

Section 110.1
Perform security administration taks

Front 81

using find cmd

Back 81

find / -perm -u+s
(find every file that has permission with the set user id on)
find / -perm -g+s
(find every file that has permission with the set group id on)
find / -perm -u+s,g+s
only show files that have both set
find / -perm /u+s,g+s
show files that have either set

Front 82

chage

Back 82

no tag with a username allows you to set the aging info

-l user
lists the users aging info

Front 83

ulimit
for user limits

Back 83

-a
shows all limit settings

-f
filesize limit

the limits only apply to processes in this shell, need to save in startup file to change for new logins

Front 84

setting system wide limits

Back 84

/etc/security/limits.conf


* hard maxlogins 1
(all users can only login one at a time, they can't login multiple times simultaneously)
* hard maxsyslogins 10
(only 10 users can login to the server at a time)
@faculty soft nproc 20
@faculty hard nproc 50
(members of faculty group have a soft limit of 20 concurrent processes and a hard limit of 50)

Front 85

lsof - i

nmap

Back 85

looks at /etc/services to match open ports and services

nmap 127.0.0.1
scans internal open ports
nmap 192.168.1.x
shows what open ports others can see on this system

Front 86

visudo

Back 86

use visudo to edit the
/etc/sudoers

user MACHINE=COMMANDS

Front 87

Objective:
110.x - Security (15%)

Back 87

Section 110.2
Setup host security

Front 88

passwords

Back 88

/etc/passwd
(can be read by all users)

/etc/shadow
(only readable by root)

sudo touch /etc/nologin
(nobody except root can now login to the server)

Front 89

unused services

Back 89

RedHat
/etc/init.d/httpd stop
stops http service temporarily

chkconfig --level 5 httpd off
(now everytime puter is booted with runlevel 5 http service will not start)

Ubuntu
/etc/init.d/apache2 stop

update-rc.d -f apache2 remove

Front 90

Super Servers
inetd (old)
xinetd (new)

Back 90

one process that manages many super server processes

/etc/inetd.conf


/etc/xinetd.conf
includes services files from dir at
/etc/xinetd.d/

Front 91

Objective:
110.x - Security (15%)

Back 91

Section 110.3
Securing data with encryption