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==Advanced Storage Configuration==
==Printer Administration==
*You can choose from many different advanced storage technologies.
:*'''Common UNIX Printing System''' (CUPS) is a printing system used by Linux computers.  
*The book focuses on SCSI and RAID
:*Information that will be sent to a printer is called a print job.
:*The '''lp''' command is used to specify and print the print job.
:*To check the status of a printer(s) the '''lpstat''' command is used.
:*The cups daemon (cupsd) will assign all print jobs a unique print job
::ID and put them in the print queue.
:*The print queue is a special temporary directory where the print jobs are
::stored before being sent to the printer.
:*The path of the queue is usually '''/var/spool/cups''' on most Linux systems.
:*If the printer is accepting print jobs,the cupsd will put the print job in to the queue.
:*This is called spooling or queuing.
:*Adding the –t option shows all the printers and there statuses on the system.


===SCSI Hard Disk Configuration(Small Computer System Interface)===
::kevin@kubuntu1:~$ lpstat -t
“designed as a way to connect multiple peripherals to the system in a scalable, high-speed manner.
::scheduler is running
Other types of SCSI disk configurations and technologies available,
::system default destination: Samsung-ML-2152W
Parallel SCSI, Serial Attached SCSI, and iSCSI.
::device for Samsung-ML-2152W: smb:///192.168.0.195
::Samsung-ML-2152W accepting requests since Tue 17 Jan 2012 11:25:40 PM CST
::printer Samsung-ML-2152W is idle. enabled since Tue 17 Jan 2012 11:25:40 PM
::CST
::kevin@kubuntu1:~$
:*To manipulate the status of a printer by using the cupsaccept, cupsreject,
::cupsenable, or cupsdisable commands.
::kevin@kubuntu1:~$ cupsaccept Samsung-ML-2152W
::kevin@kubuntu1:~$ cupsdisable Samsung-ML-2152W
::kevin@kubuntu1:~$ lpstat -t
::scheduler is running
::system default destination: Samsung-ML-2152W
::device for Samsung-ML-2152W: smb:///192.168.0.195
::Samsung-ML-2152W accepting requests since Fri 23 Mar 2012 11:35:18 AM CDT
::printer Samsung-ML-2152W disabled since Fri 23 Mar 2012 11:35:18 AM CDT -
::Paused
::kevin@kubuntu1:~$
:*The –r option is used to give a reason why the printer’s status is set as
::such.
::kevin@kubuntu1:~$ cupsdisable Samsung-ML-2152W -r "OMG the printer is on fire"
::Samsung-ML-2152W
::kevin@kubuntu1:~$ lpstat -t
::scheduler is running
::system default destination: Samsung-ML-2152W
::device for Samsung-ML-2152W: smb:///192.168.0.195
::Samsung-ML-2152W accepting requests since Fri 23 Mar 2012 11:35:18 AM CDT
::printer Samsung-ML-2152W disabled since Fri 23 Mar 2012 11:35:18 AM CDT -
::OMG the printer is on fire
::kevin@kubuntu1:/$
:*Use the lp command to print.
::kevin@kubuntu1:/$ lp -d Samsung-ML-2152W /home/kevin/Documents/reports
::request id is Samsung-ML-2152W-2 (1 file(s))
::kevin@kubuntu1:/$
:*Other options can be added to the lp command as shown.


===Parallel SCSI Configuration===
       
*The traditional SCSI technology
{| class="wikitable"
*A device called a terminator is used to stop signals from bouncing back
|-
*Adopted as an industry defined standard in 1986 referred to as SCSI-1
!Options
***used an 8-bit-wide data path
!Function
***held up to seven devices
|-
***transfer speed of 5MB per second
|−i
*By 1994: SCSI-2 had evolved
|Print job ID Specifies a certain print job ID to modify
***16-bit-wide data path
|-
***hold up to 15 devices
|−d
***20MB per second
|printername, Specifies the name of the printer to send the print job to
*SCSI-3
|-
***speeds of over 160MB per second
|−n
|Number Prints a certain number of copies, where number can be any number
|-
|−m
|Mails you confirmation of print job completion
|-
| −o
| option Specifies certain printing options. Common printing options include the following:
|-
|}


'''Note:  a.''' The SCSI ID of a SCSI hard disk can be configured using software on the SCSI controller or using jumper switches on the physical hard drive itself.
:*cpi=number—Specifies the number of characters per inch, where number is the number of characters.
:*landscape—Prints in landscape orientation
:*number-up=number—Prints the number of pages on a single
:*page, where number is 1, 2, or 4
:*sides=string—Sets double-sided printing, where string is
::either ”'''two-sided-short-edge'''or ”'''two-sided-long-edge'''”


'''b.''' Some SCSI devices act as a gateway to other devices; if this is the case, each device is associated with a unique Logical Unit Number (LUN).
:*To print a list of all users logged in, pipe the who command to the '''lp''' command.
:kevin@kubuntu1:/$ who | lp -d Samsung-ML-2152W
:request id is Samsung-ML-2152W-4 (0 file(s))
:kevin@kubuntu1:/$
:*To remove all print jobs from a specific user, add the '''–u'' <username> before
::the cancel command. To remove all print jobs use the –a as shown.
::kevin@kubuntu1:/$ '''cancel -a'''
::kevin@kubuntu1:/$ lpstat
::kevin@kubuntu1:/$
:*The Line Printer Daemon (LPD) is an alternative to CUPS, that is used by older
::Linux systems.
:*The '''LPD''' commands can be used in CUPS.
:*LPR command = print documents
:*LPC command = view printer status
:*LPQ command = see jobs in the queue
:*LPRM command =remove job form queue
:*You can find the cupsd configuration file in the /etc/cups/cupsd.conf directory.
:*The /etc/cups/printers.conf contains settings about the specific printer.
:*The command system-config-printer will launch a GUI-based program; the Printer Configuration tool.
:*This program lets you add printers with Plug and Play
::(PnP) or specify the Uniform Resource Identifier (URI). Hewlett-Packard
::JetDirect, Internet Printing Protocol (IPP), Line Printer Daemon (LPD or
::Windows (SAMBA) allows you to print to a printer across the network. From the
::Printer Configuration tool you are also able to give users and groups
:*permission to print to specific printers.
:*You can use CUPS to administer and remotely administer printes through a web browser.
:*To open the CUPS web-based control panel, navigate to http://servername:631.


Parallel SCSI controllers support up to 15 devices and identify these devices with the numbers 0– 15  The highest priority device is given the number 7, followed by 6, 5, 4, 3, 2, 1, 0, 15, 14, 13, 12, 11, 10, 9, and 8
==Log File Administration==


[[File:[[File:Scis.jpg]]
*For identifying and troubleshooting problems on a Linux System
*Called  log files most Daemons record information and error messages to files stored on the file system.
*Typically stored in the /var/log directory
::*'''Example:''' /var/log/samba contains log files created by the samba file-sharing daemons


'''Above: Two SCSI Configuration examples'''
'''Common Linux log files found in /var/log'''
{| class="wikitable"
|-
! logs
! description
|-
| boot.log
| Contains basic information regarding daemon startup obtained during system initialization
|-
|cron
|Contains information and error messages generated by the cron and at daemons
|-
| dmesg
| Contains detected hardware information obtained during system startup.
|-
| maillog
| Contains information and error messages generated by the sendmail daemon.
|-
| secure
| Contains information and error messages regarding network access generated by daemons such as sshd and xinetd.
|-
| wtmp
| Contains a history of all login sessions.
|-
| rpmpkgs yum.log
| Contains a list of packages installed by the Red Hat Package Manager and related error messages.
|-
| xferlog
| Contains information and error messages generated by the FTP daemon.
|-
| Xorg.0.log XFree86
| Contains information and error messages generated by X Windows.
|-
| lastlog
| Contains a list of users and their last login time; must be viewed using the lastlog command.
|-
| messages
| Contains detailed information regarding daemon startup obtained at system initialization as well as important system messages produced after system initialization
|}


[[FILE:[[FILE:SCSI2.jpG]]


===System Log Daemon===
*logging of most events is handled centrally in Linux in the System Log Deamon
*When the daemon is started on the system
::*Creates a socket /dev/log
::*This is for other system processes to write to
::*It then reads any information written to this socket and saves it to the appropriate log file according to :::/etc/rsyslog.conf
::*To view use cat /etc/rsyslog.conf


*Sample output showing the '''Facility,''' '''Priority''' and '''Location''' of the '''/etc/rsyslog.conf''' file
:::news.=crit /var/log/news/news.crit
:::Facility: "news."
:::The area of the system to listen to and log
::::Priority: "=crit"
:::::The importance of the information being logged
::::Location: /var/log/news/news.crit
:::::The location and path of the log file


'''Above: Listing of Parallel SCSI Types as well as speed, connector type
and number of devices supported per controller card.'''


===Serial Attached SCSI (SAS) Configuration===
'''Examples of kernel log facilities with differing priorities'''
*recent SCSI technology
{| class="wikitable"
*transfer data at up to 768MB/s
|-
Up to 65,535 Serial Attached SCSI hard disks can be connected to a single controller card
! kernel logs
*Uses serial connectors (between 7 and 36 pins)
! function
|-
| kern.warning  /var/log/logfile
| logs warning messages and those with more serious priorities to the '''/var/log/logfile'''
|-
| kern.=warning  /var/log/logfile
| logs just the warning messages to the '''/var/log/logfile'''
|-
| kern.* /var/log/logfile
| logs all error messages to the '''/var/log/logfile'''
|-
| \*.=warn;kern.none  /var/log/logfile
| logs all warnings from all facilities except the kernel to the /var/log/logfile
|}


===iSCSI Configuration Internet SCSI (iSCSI)===
*Recent SCSI technology
*Uses network cables to transfer data to and from remote hard disks
*The computer connected to a remote hard disk via iSCSI is referred to as an '''iSCSI initiator'''
*the remote hard disk is called the iSCSI target.
***To connect the Linux computer to the remote iSCSI device (Prior to Install)
***you must specify the configuration settings while installing Linux.
***must understand the configuration settings used by your iSCSI device
***ensure that your computer has an iSCSI-compliant
***network card prior to install
*During installation
***you need to select Specialized Storage Devices (instead of Basic Storage Devices)


'''Note:''' A single iSCSI target can be used by multiple computers, or iSCSI
initiators. The computers that use the same iSCSI target are said to
::*logs all but the warning priority messages to /var/log/logfile
be part of the same Storage Area Network (SAN). iSCSI is often
::*\*.=warn;kern.none  /var/log/logfile
referred to as a SAN technology as a result
::*logs all warnings from all facilities except the kernel to the /var/log/logfile




'''Facilities used by the System Daemon Log'''


{| class="wikitable"
|-
! Daemon Log
! description
|-
| auth or security
| Specifies messages from the login system, such as the login program, the getty program, and the su command.
|-
|authpriv
| Specifies messages from the login system when authenticating users across the network or to system databases.
|-
| cron
| Specifies messages from the cron and at daemons
|-
| daemon
| Specifies messages from system daemons, such as the FTP daemon
|-
| kern
| Specifies messages from the Linux kernel.
|-
| lpr
| Specifies messages from the printing system (lpd)
|-
| mail
| Specifies messages from the e-mail system (sendmail).
|-
| mark
| Specifies time stamps used by syslogd; used internally only.
|-
| news
| Specifies messages from the Inter Network News daemon and other USENET daemons.
|-
| syslog
| Specifies messages from the syslog daemon.
|-
| user
| Specifies messages from user processes.
|-
| uucp
| Specifies messages from the uucp (UNIX to UNIX copy) daemon.
|-
| local0-7
|Specifies local messages; these are not used by default but can be defined for custom use
|-
|}


===RAID Configuration===
'''Priorities used by the System Daemon Log (listed in ascending order)'''
*There are 7 basic RAID configurations (RAID 0 - 6)
[[File:[[File:RAIDSNIP.JPG]]


{| class="wikitable"
|-
! Daemon Log
! Description
|-
| debug
| Indicates all information from a certain facility.
|-
| info
| Indicates normal information messages as a result of system operations
|-
| notice
| Indicates information that should be noted for future reference, yet does not indicate a problem
|-
| warning or warn
| Indicates messages that might be the result of an error but are not critical to system operations.
|-
| error or err
| Indicates all other error messages not described by other priorities.
|-
| crit
| Indicates system critical errors such as hard disk failure.
|-
| alert
| Indicates an error that should be rectified immediately, such as a corrupt system database.
|-
| emerg or panic
| Indicates very serious system conditions that would normally be broadcast to all users
|-
|}


===The etc/rsyslog.conf file can also send logging information to another computer===
*Facility.priority @hostname:portnumber
::*The remote computer
:::*Must have modules that listen to TCP or UDP protocol uncommented in the /etc/rsyslog.conf


Below is an illustration of '''RAID Level 5''' parity bits, parity bits are the sum of the information on the other 2 disks. If one disk fails the remaining bits
*'''Commented'''
[[File:[[File:Striperaidwp.jpg]]
::# Provides UDP syslog reception
 
::#$ModLoad imudp.so
 
::#$UDPServerRun 514
 
::# Provides TCP syslog reception
'''Side notes:''' RAID levels are often combined; RAID level 15 refers to a Stripe Set
::#$ModLoad imtcp.so
with Parity (RAID level 5) that is mirrored (RAID level 1) to another
::#$InputTCPServerRun 514
Stripe Set with Parity.
 
 
 
 
 
 
===Installation Methods===
There are 4 methods to installing Linux
DVD Installation / CD Installation
Fedora 13 ISO will fit on 6 CDs and can be downloaded from the internet. To install from CD or DVD simply put the disk in the CD/DVD drive, set the bios to boot first from that drive.
 
USB Flash Drive Installation
Most modern computers have a BIOS that allows the computer to boot from a flash memory.
Steps: To install from USB
*'''Un-Commented'''
1. download the DVD Fedora 13 ISO image from http://fedoraproject.org
:::Provides UDP syslog reception
2. use disk imaging software  to write the ISO image to the USB drive
:::$ModLoad imudp.so
If you already have an installed Linux system, you can instead use the dd command  to write the ISO image to your USB drive
:::$UDPServerRun 514
3. insert your USB flash memory drive into a free USB slot
:::Provides TCP syslog reception
4. boot your computer from the flash memory drive
:::$ModLoad imtcp.so
 
:::$InputTCPServerRun 514
Hard Disk Installation
:*This allows the system to accept incoming requests from another System Log Daemon on TCP and UDP port 514 (the ::default System Log Daemon port)
ISO must reside on a disk formatted as  FAT, FAT32, ext2, ext3, or ext4 filesystem provided that you have free space outside the partition that contains the ISO image.
Must boot from a CD / DVD or USB prior to install to locate the ISO on the hard disk.


Network-Based Installations
===Managing Log Files===
(less common than DVD, CD, USB flash memory drive, or hard disk installations)
Log files can contain a lot of important system information so it's a good idea to clear the contents of the log files from time to time.
With the network install the ISO image must reside on the server and use one of the following protocols can be installed to the target computer.
Network File System (NFS)
File Transfer Protocol (FTP)
Hypertext Transfer Protocol (HTTP)


Above: Specifying the location of the Fedora ISO image on an NFS server,
'''DO NOT''' remove the log files, the permissions and ownership will be removed as well!!!


Above: Specifying the location of the Fedora ISO image on an HTTP server
We're just going to clear out the contents of the log file.


To do so the ''> redirect'' symbol can be used.


Steps to installing over a network
This function can be scheduled as well using the logrotate command to backup and clear logfiles stored in ''/etc/logrotate.conf'' file and files stored in ''/etc/logrotate.d'' directory
1. Assuming the ISO Image is already on the server
2. boot the computer on which you plan to install Linux using a CD / DVD or USB drive
3. When you reach the welcome screen, press Tab on the keyboard and add askmethod to the end of the boot options line
4. choose an installation language (such as English), a keyboard layout (such as US), and
5. select a network installation method
a. Options should be
i. Local CD/DVD
ii. Hard Drive
iii. NFS Directory
iv. URL
6. configure the IP settings on your computer’ s network adapter
7. enter the address to the location of the ISO image and proceed with the rest of the install process


**The log rotate command renames (rotates) log files on a cyclic basis


**test.log becomes test.log.YYYYMMDD


**A new test.log file is created to accept system log info.


*Can be set to keep a certain number of log files
::*If configured to keep 2 log files, logrotate will only keep 2 copies. Then when it cycles logrotate will automatically remove the oldest copy.


*Most rotation information within /etc/logrotate.conf is overridden from files stored in the ''/etc/logrotate.d directory.''


On most Linux systems, the logrotate utility is automatically scheduled to run daily via the file ''/etc/cron.daily/logrotate,'' however it can be run manually by typing ''logrotate /etc/logrotate.conf''  at a command prompt


Over time the logrotate  command generates several copies of each logfile /var/log to view this we type ''Ls /var/log''


==Administering Users and Groups==


:*Bash shell prompts for user accounts information this is called authentication.


:*User accounts and passwords are located in the '''/etc/password''' and '''/etc/shadow''' and are encrypted


:*'''/etc/password''' and a line that contains the encrypted password and


:*'''/etc/shadow''' is where the expiration information is stored in.


:*You can use the dfdffpwunconv command to revert to using an /etc/passwd file only, This is not best
::practice for security


Automated Installation 267-282
:*You can use the pwconv command to configure the system again using an /etc/shadow file for
::password storage.


-Instillation script is often called a Kickstart File
:* This is the format used in /etc/password file “name:password:UID:GID:GECOS:home directory:shell”


-A Kickstart file is automatically made after normal instillation in “/root/anaconda-ks.cfg”
:*examples: root:x:0:0:root:/root:/bin/bash


-To view use “Cat ks.cfg” in “/root/anaconda-ks.cfg”.
:*8bin:x:1:1:bin:/bin:/sbin/nologin


- Code in a Kick-start file that starts with “#” sing is disregarded and can be used as a comment .
:*daemon:x:2:2:daemon:/sbin:/sbin/nologin


-It is best practice to copy the template  Kickstart file and rename it ks.cfg and make changes to ks.cfg if need before mass instillation .
==UID & /etc/passwd==


-It is best practice when creating the code for partition configuration to use the # sing till configurations is complete and one is sure of the specifications of the partitions that will be created.
:*The User Identifier (UID) specifies the unique User ID that is assigned to each user.


-It Is also advised that one  has “zerombr yes” command and “clearpart --all”  to make sure that the MBR is created and  all other partitions are destroyed before creating new ones.  
:*The root user always has a UID of zero.
-The kickstart file can also be created with a too called the “Kickstart Configurator”


- The Configurator can be installed using the “YUM install system-config-kickstart” command in terminal.
:*UIDs that are less than 500 refer to user accounts that are used by daemons when logging in to
::the system.


-The configurator can started by “system-config-kickstart” command If in a graphical desktop environment.
:*The root user is usually listed at the top of the /etc/passwd file


-To use the ks.cfg. whale booting form the cd or instillation image make confirm that install on new system or upgrade existing system  is selected then press. A command line may show up  and you can designate  the Kick start files path by using  “ks=device:absolute path KS file”
:*In the /etc/passwd file passwords are replaced with the letter “X” password are actually stored
::in the shadow file and are encrypted.


-You will still need to use first boot wizard.
:::password times are expressed in days.


:*You can change the password expiration time in the shadow file. In the shadow file '''min''' = time
::before user can change password again. '''max''' = time that user can use current password.


:*'''warn'''= the number of days before a user is prompted to change their password


:*by default min =0 max=99,999 days and warn= 7days


==Groups==


:*The Group Identifier (GID) is the primary Group ID for the
::user.


:*primary group ID’s designate file/directory ownership


Troubleshooting installation  272-274
:*Each user can be a member of several groups, but only one
problems of high Probability
::of those groups can be the primary group.
Problems starting instillation
-Boot order in BIOS


-Bad CMOS battery
:*primary groups are listed in the password file.


Problems during instillation
:*All groups and their members are listed in the '''/etc/group'''
- Video card incompatibility. use “install with basic video driver”


-Instillation environment doesn't recognize mouse.  Press escape before graphic instillation appears.
==Creating User Accounts==


- If instillation locks up disable P&P in BIOS.
:*useradd command is used to create commands


-If fatal signal 11 is displayed  Then there may be something wrong with the ram. You may need to run memtest86 to test it. If the ram has no errors turn off CPU cache memory or set set more of it to wait state in the Bios.
:::Example: '''useradd bobg'''
:*There is two files that are used to create default account information.
:*(UID,shell and home directories)


-Other problems ram motherboard speed miss-mach,  improper voltage configuration  for CPU and ram.
::*The first is '''/etc/login.defs''' and sets default locations for email password
Problems after instillation
:::expiration minimum password length and the rage of UID and GIDs for
- After instillation if some somethings like a program is not working correctly or a Peace of hardware is not showing up. you should  look at the instillation log  found in  root/install.log.
:::the users.
::*The second is '''/etc/default/useradd''' file. It controls default primary
:::groups, locations of home directories, number of days to disable
:::accounts with expired passwords, date to disable user accounts, and the
:::skeleton directory.
:*A skeleton directory contains files that are copied to new users home
::directories when a new user is created.


-Use /proc to look at hardware settings  “ls -f /proc”
==Creating User Accounts==


-To look up info use “cat /proc/cpuinfo” the same can be done with “/meminfo”  and modules
===Typical contents of the default/useradd file===
:useradd defaults file
:GROUP=100
:HOME=/home
:INACTIVE=-1
:EXPIRE=
:SHELL=/bin/bash
:SKEL=/etc/skel
:CREATE_MAIL_SPOOL=yes
:[root@server1 ~]# _


-Modules are used to insert drivers into the Linux kernel.  
:*You can alter some of the user creation parameter using the options below.


- To view hardware outputs during boot up use the “Dmesg | tail”
{| class="wikitable"
|-
! Options
! Function
|-
| -e
| Specifies a date to disable the account from logging in.
|-
| -d
| Sets absolute pathname to the users directory.
|-
| -c
| Adds conscription entry to the GECOS of the /etc/passwd file.
|-
| -f
| Sets number of days until a users password is disabled.
|-
| -k
| Specifies the skeleton directory.
|-
| -G
| Specifies all other group memberships for the user account.
|-
| -m
| specifies that a home directory should be created for the user.
|-
| -g
| Specifies the primary group for the user account.<br /> by default a group is created with the same name as the user and made the primary group for that user
|-
| -s
| sets path to the shell used for accounts.
|-
| -u
| sets the UID of a account.
|}


- Review table  6-2  (other log or config files found in /proc directory )
*To modify user accounts after creation you
:may edit the ''''/etc/passwd'''' or '''shadow file''', but
:it is not best practice because it may cause
:topographical errors.
*The recommended method of editing user
:accounts is to use the '''usermod''' command.
:example: '''usermod -l barbg bobg''' will change
:the the user name from bobg to barbg.


=== usermod ===
{| class="wikitable"
|-
! Options
! Function
|-
| -f
| sets the number of days until an expired password is disabled.
|-
| -c
| specifies a new description for the user in the GECOS field of  /etc/passwd.
|-
| -d
| Specifies absolute pathname to a new home directory.
|-
| -g
|Specifies a new primary group for the user account.
|-
| -G
|specifies all other group memberships for the user accounts.
|-
| -l
| sets new login name.
|-
| -e
| Specifies exasperation date.
|-
| -s
| sets new absolute pathname to a new shell used for  a user account.
|-
| -u
| sets new UID for user account.
|}


:* '''User-mod''' command can not be used to change password expirations in the
::shadow file.
:*To unlock an account you can '''usermod -U''' or '''passwd -u''' commands.


-You can view other logs about services and processes in “/var/log/messages”
==Deleting user accounts==


:*You can remove user accounts by using the
::'''userdel''' command. This removes entries from the
::'''/etc/passwd''' and the '''/etc/shadow file.'''
:*If you use '''-r''' option it will remove the that user's
::home directory and its contents.


:*if a user is deleted the files are owned by the next
::users with the same UID. The new recipient will
::have a folder that has the name of the former owner.
==Managing Groups==


System Rescue 281-285
:*To you can add Groups by editing /etc group file with a text editor,
-Instillation files have a bootable kernel of Linux.
::or use the groupadd
:*If you use -r option it will remove the that user's
::home directory and its contents.
:*To use the groupadd command you need to use -g option with the GID number and the
::group name. Example : '''groupadd –g 492 group1''' command.


-To used insert or mounted instillation image/ files and select rescue system in the instillation welcome-screen
:*You can also add users to a group by using the '''usermod''' command with the -G option
::followed by the username. example: '''usermod –G group1 maryj'''
:*The '''groupmod''' command that can be used to modify the group name and GID, there is also
:*you can see a list of groups you or a user belongs to by using the groups command. To see
::what GID the Groups have use the '''id''' command.


- A menu will prompt you to Mount your Linux instillation under  under “mnt/sysimage”
:*you can use the newgrp command. to change primary groups and change file ownership.
:*groups can be managed using a GUI environment in the by navigating to System menu,
::select Administration, Users and Groups.


-You will have a menu that will allow you to enter bash shell 
:*you can see a list of groups you or a user belongs to by using the groups command. To see
::what GID the Groups have use the '''id''' command.


- You will also be able to run the fakd diagnostic
:*you can use the '''newgrp''' command. to change primary groups and change file ownership.


-You can check witch root directory is the system that you are trying to rescue with the  “System Rescue command.
:*groups can be managed using a GUI environment in the by navigating to System menu,
::select Administration, Users and Groups.

Latest revision as of 13:48, 26 March 2012

Printer Administration

  • Common UNIX Printing System (CUPS) is a printing system used by Linux computers.
  • Information that will be sent to a printer is called a print job.
  • The lp command is used to specify and print the print job.
  • To check the status of a printer(s) the lpstat command is used.
  • The cups daemon (cupsd) will assign all print jobs a unique print job
ID and put them in the print queue.
  • The print queue is a special temporary directory where the print jobs are
stored before being sent to the printer.
  • The path of the queue is usually /var/spool/cups on most Linux systems.
  • If the printer is accepting print jobs,the cupsd will put the print job in to the queue.
  • This is called spooling or queuing.
  • Adding the –t option shows all the printers and there statuses on the system.
kevin@kubuntu1:~$ lpstat -t
scheduler is running
system default destination: Samsung-ML-2152W
device for Samsung-ML-2152W: smb:///192.168.0.195
Samsung-ML-2152W accepting requests since Tue 17 Jan 2012 11:25:40 PM CST
printer Samsung-ML-2152W is idle. enabled since Tue 17 Jan 2012 11:25:40 PM
CST
kevin@kubuntu1:~$
  • To manipulate the status of a printer by using the cupsaccept, cupsreject,
cupsenable, or cupsdisable commands.
kevin@kubuntu1:~$ cupsaccept Samsung-ML-2152W
kevin@kubuntu1:~$ cupsdisable Samsung-ML-2152W
kevin@kubuntu1:~$ lpstat -t
scheduler is running
system default destination: Samsung-ML-2152W
device for Samsung-ML-2152W: smb:///192.168.0.195
Samsung-ML-2152W accepting requests since Fri 23 Mar 2012 11:35:18 AM CDT
printer Samsung-ML-2152W disabled since Fri 23 Mar 2012 11:35:18 AM CDT -
Paused
kevin@kubuntu1:~$
  • The –r option is used to give a reason why the printer’s status is set as
such.
kevin@kubuntu1:~$ cupsdisable Samsung-ML-2152W -r "OMG the printer is on fire"
Samsung-ML-2152W
kevin@kubuntu1:~$ lpstat -t
scheduler is running
system default destination: Samsung-ML-2152W
device for Samsung-ML-2152W: smb:///192.168.0.195
Samsung-ML-2152W accepting requests since Fri 23 Mar 2012 11:35:18 AM CDT
printer Samsung-ML-2152W disabled since Fri 23 Mar 2012 11:35:18 AM CDT -
OMG the printer is on fire
kevin@kubuntu1:/$
  • Use the lp command to print.
kevin@kubuntu1:/$ lp -d Samsung-ML-2152W /home/kevin/Documents/reports
request id is Samsung-ML-2152W-2 (1 file(s))
kevin@kubuntu1:/$
  • Other options can be added to the lp command as shown.


Options Function
−i Print job ID Specifies a certain print job ID to modify
−d printername, Specifies the name of the printer to send the print job to
−n Number Prints a certain number of copies, where number can be any number
−m Mails you confirmation of print job completion
−o option Specifies certain printing options. Common printing options include the following:
  • cpi=number—Specifies the number of characters per inch, where number is the number of characters.
  • landscape—Prints in landscape orientation
  • number-up=number—Prints the number of pages on a single
  • page, where number is 1, 2, or 4
  • sides=string—Sets double-sided printing, where string is
either ”two-sided-short-edge” or ”two-sided-long-edge
  • To print a list of all users logged in, pipe the who command to the lp command.
kevin@kubuntu1:/$ who | lp -d Samsung-ML-2152W
request id is Samsung-ML-2152W-4 (0 file(s))
kevin@kubuntu1:/$
  • To remove all print jobs from a specific user, add the '–u <username> before
the cancel command. To remove all print jobs use the –a as shown.
kevin@kubuntu1:/$ cancel -a
kevin@kubuntu1:/$ lpstat
kevin@kubuntu1:/$
  • The Line Printer Daemon (LPD) is an alternative to CUPS, that is used by older
Linux systems.
  • The LPD commands can be used in CUPS.
  • LPR command = print documents
  • LPC command = view printer status
  • LPQ command = see jobs in the queue
  • LPRM command =remove job form queue
  • You can find the cupsd configuration file in the /etc/cups/cupsd.conf directory.
  • The /etc/cups/printers.conf contains settings about the specific printer.
  • The command system-config-printer will launch a GUI-based program; the Printer Configuration tool.
  • This program lets you add printers with Plug and Play
(PnP) or specify the Uniform Resource Identifier (URI). Hewlett-Packard
JetDirect, Internet Printing Protocol (IPP), Line Printer Daemon (LPD or
Windows (SAMBA) allows you to print to a printer across the network. From the
Printer Configuration tool you are also able to give users and groups
  • permission to print to specific printers.
  • You can use CUPS to administer and remotely administer printes through a web browser.
  • To open the CUPS web-based control panel, navigate to http://servername:631.

Log File Administration

  • For identifying and troubleshooting problems on a Linux System
  • Called log files most Daemons record information and error messages to files stored on the file system.
  • Typically stored in the /var/log directory
  • Example: /var/log/samba contains log files created by the samba file-sharing daemons

Common Linux log files found in /var/log

logs description
boot.log Contains basic information regarding daemon startup obtained during system initialization
cron Contains information and error messages generated by the cron and at daemons
dmesg Contains detected hardware information obtained during system startup.
maillog Contains information and error messages generated by the sendmail daemon.
secure Contains information and error messages regarding network access generated by daemons such as sshd and xinetd.
wtmp Contains a history of all login sessions.
rpmpkgs yum.log Contains a list of packages installed by the Red Hat Package Manager and related error messages.
xferlog Contains information and error messages generated by the FTP daemon.
Xorg.0.log XFree86 Contains information and error messages generated by X Windows.
lastlog Contains a list of users and their last login time; must be viewed using the lastlog command.
messages Contains detailed information regarding daemon startup obtained at system initialization as well as important system messages produced after system initialization


System Log Daemon

  • logging of most events is handled centrally in Linux in the System Log Deamon
  • When the daemon is started on the system
  • Creates a socket /dev/log
  • This is for other system processes to write to
  • It then reads any information written to this socket and saves it to the appropriate log file according to :::/etc/rsyslog.conf
  • To view use cat /etc/rsyslog.conf
  • Sample output showing the Facility, Priority and Location of the /etc/rsyslog.conf file
news.=crit /var/log/news/news.crit
Facility: "news."
The area of the system to listen to and log
Priority: "=crit"
The importance of the information being logged
Location: /var/log/news/news.crit
The location and path of the log file


Examples of kernel log facilities with differing priorities

kernel logs function
kern.warning /var/log/logfile logs warning messages and those with more serious priorities to the /var/log/logfile
kern.=warning /var/log/logfile logs just the warning messages to the /var/log/logfile
kern.* /var/log/logfile logs all error messages to the /var/log/logfile
\*.=warn;kern.none /var/log/logfile logs all warnings from all facilities except the kernel to the /var/log/logfile


  • logs all but the warning priority messages to /var/log/logfile
  • \*.=warn;kern.none /var/log/logfile
  • logs all warnings from all facilities except the kernel to the /var/log/logfile


Facilities used by the System Daemon Log

Daemon Log description
auth or security Specifies messages from the login system, such as the login program, the getty program, and the su command.
authpriv Specifies messages from the login system when authenticating users across the network or to system databases.
cron Specifies messages from the cron and at daemons
daemon Specifies messages from system daemons, such as the FTP daemon
kern Specifies messages from the Linux kernel.
lpr Specifies messages from the printing system (lpd)
mail Specifies messages from the e-mail system (sendmail).
mark Specifies time stamps used by syslogd; used internally only.
news Specifies messages from the Inter Network News daemon and other USENET daemons.
syslog Specifies messages from the syslog daemon.
user Specifies messages from user processes.
uucp Specifies messages from the uucp (UNIX to UNIX copy) daemon.
local0-7 Specifies local messages; these are not used by default but can be defined for custom use

Priorities used by the System Daemon Log (listed in ascending order)

Daemon Log Description
debug Indicates all information from a certain facility.
info Indicates normal information messages as a result of system operations
notice Indicates information that should be noted for future reference, yet does not indicate a problem
warning or warn Indicates messages that might be the result of an error but are not critical to system operations.
error or err Indicates all other error messages not described by other priorities.
crit Indicates system critical errors such as hard disk failure.
alert Indicates an error that should be rectified immediately, such as a corrupt system database.
emerg or panic Indicates very serious system conditions that would normally be broadcast to all users

The etc/rsyslog.conf file can also send logging information to another computer

  • Facility.priority @hostname:portnumber
  • The remote computer
  • Must have modules that listen to TCP or UDP protocol uncommented in the /etc/rsyslog.conf
  • Commented
  1. Provides UDP syslog reception
  2. $ModLoad imudp.so
  3. $UDPServerRun 514
  4. Provides TCP syslog reception
  5. $ModLoad imtcp.so
  6. $InputTCPServerRun 514
  • Un-Commented
Provides UDP syslog reception
$ModLoad imudp.so
$UDPServerRun 514
Provides TCP syslog reception
$ModLoad imtcp.so
$InputTCPServerRun 514
  • This allows the system to accept incoming requests from another System Log Daemon on TCP and UDP port 514 (the ::default System Log Daemon port)

Managing Log Files

Log files can contain a lot of important system information so it's a good idea to clear the contents of the log files from time to time.

DO NOT remove the log files, the permissions and ownership will be removed as well!!!

We're just going to clear out the contents of the log file.

To do so the > redirect symbol can be used.

This function can be scheduled as well using the logrotate command to backup and clear logfiles stored in /etc/logrotate.conf file and files stored in /etc/logrotate.d directory

    • The log rotate command renames (rotates) log files on a cyclic basis
    • test.log becomes test.log.YYYYMMDD
    • A new test.log file is created to accept system log info.
  • Can be set to keep a certain number of log files
  • If configured to keep 2 log files, logrotate will only keep 2 copies. Then when it cycles logrotate will automatically remove the oldest copy.
  • Most rotation information within /etc/logrotate.conf is overridden from files stored in the /etc/logrotate.d directory.

On most Linux systems, the logrotate utility is automatically scheduled to run daily via the file /etc/cron.daily/logrotate, however it can be run manually by typing logrotate /etc/logrotate.conf at a command prompt

Over time the logrotate command generates several copies of each logfile /var/log to view this we type Ls /var/log

Administering Users and Groups

  • Bash shell prompts for user accounts information this is called authentication.
  • User accounts and passwords are located in the /etc/password and /etc/shadow and are encrypted
  • /etc/password and a line that contains the encrypted password and
  • /etc/shadow is where the expiration information is stored in.
  • You can use the dfdffpwunconv command to revert to using an /etc/passwd file only, This is not best
practice for security
  • You can use the pwconv command to configure the system again using an /etc/shadow file for
password storage.
  • This is the format used in /etc/password file “name:password:UID:GID:GECOS:home directory:shell”
  • examples: root:x:0:0:root:/root:/bin/bash
  • 8bin:x:1:1:bin:/bin:/sbin/nologin
  • daemon:x:2:2:daemon:/sbin:/sbin/nologin

UID & /etc/passwd

  • The User Identifier (UID) specifies the unique User ID that is assigned to each user.
  • The root user always has a UID of zero.
  • UIDs that are less than 500 refer to user accounts that are used by daemons when logging in to
the system.
  • The root user is usually listed at the top of the /etc/passwd file
  • In the /etc/passwd file passwords are replaced with the letter “X” password are actually stored
in the shadow file and are encrypted.
password times are expressed in days.
  • You can change the password expiration time in the shadow file. In the shadow file min = time
before user can change password again. max = time that user can use current password.
  • warn= the number of days before a user is prompted to change their password
  • by default min =0 max=99,999 days and warn= 7days

Groups

  • The Group Identifier (GID) is the primary Group ID for the
user.
  • primary group ID’s designate file/directory ownership
  • Each user can be a member of several groups, but only one
of those groups can be the primary group.
  • primary groups are listed in the password file.
  • All groups and their members are listed in the /etc/group

Creating User Accounts

  • useradd command is used to create commands
Example: useradd bobg
  • There is two files that are used to create default account information.
  • (UID,shell and home directories)
  • The first is /etc/login.defs and sets default locations for email password
expiration minimum password length and the rage of UID and GIDs for
the users.
  • The second is /etc/default/useradd file. It controls default primary
groups, locations of home directories, number of days to disable
accounts with expired passwords, date to disable user accounts, and the
skeleton directory.
  • A skeleton directory contains files that are copied to new users home
directories when a new user is created.

Creating User Accounts

Typical contents of the default/useradd file

useradd defaults file
GROUP=100
HOME=/home
INACTIVE=-1
EXPIRE=
SHELL=/bin/bash
SKEL=/etc/skel
CREATE_MAIL_SPOOL=yes
[root@server1 ~]# _
  • You can alter some of the user creation parameter using the options below.
Options Function
-e Specifies a date to disable the account from logging in.
-d Sets absolute pathname to the users directory.
-c Adds conscription entry to the GECOS of the /etc/passwd file.
-f Sets number of days until a users password is disabled.
-k Specifies the skeleton directory.
-G Specifies all other group memberships for the user account.
-m specifies that a home directory should be created for the user.
-g Specifies the primary group for the user account.
by default a group is created with the same name as the user and made the primary group for that user
-s sets path to the shell used for accounts.
-u sets the UID of a account.
  • To modify user accounts after creation you
may edit the '/etc/passwd' or shadow file, but
it is not best practice because it may cause
topographical errors.
  • The recommended method of editing user
accounts is to use the usermod command.
example: usermod -l barbg bobg will change
the the user name from bobg to barbg.

usermod

Options Function
-f sets the number of days until an expired password is disabled.
-c specifies a new description for the user in the GECOS field of /etc/passwd.
-d Specifies absolute pathname to a new home directory.
-g Specifies a new primary group for the user account.
-G specifies all other group memberships for the user accounts.
-l sets new login name.
-e Specifies exasperation date.
-s sets new absolute pathname to a new shell used for a user account.
-u sets new UID for user account.
  • User-mod command can not be used to change password expirations in the
shadow file.
  • To unlock an account you can usermod -U or passwd -u commands.

Deleting user accounts

  • You can remove user accounts by using the
userdel command. This removes entries from the
/etc/passwd and the /etc/shadow file.
  • If you use -r option it will remove the that user's
home directory and its contents.
  • if a user is deleted the files are owned by the next
users with the same UID. The new recipient will
have a folder that has the name of the former owner.

Managing Groups

  • To you can add Groups by editing /etc group file with a text editor,
or use the groupadd
  • If you use -r option it will remove the that user's
home directory and its contents.
  • To use the groupadd command you need to use -g option with the GID number and the
group name. Example : groupadd –g 492 group1 command.
  • You can also add users to a group by using the usermod command with the -G option
followed by the username. example: usermod –G group1 maryj
  • The groupmod command that can be used to modify the group name and GID, there is also
  • you can see a list of groups you or a user belongs to by using the groups command. To see
what GID the Groups have use the id command.
  • you can use the newgrp command. to change primary groups and change file ownership.
  • groups can be managed using a GUI environment in the by navigating to System menu,
select Administration, Users and Groups.
  • you can see a list of groups you or a user belongs to by using the groups command. To see
what GID the Groups have use the id command.
  • you can use the newgrp command. to change primary groups and change file ownership.
  • groups can be managed using a GUI environment in the by navigating to System menu,
select Administration, Users and Groups.