CIS 238DL Linux System Administration

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CIS 238DLLinux System Administration

• Ray Esparza
• GCC CIS Faculty

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Introductions

• Name
• Work or school major/minor
• Unix experience
• Expectations of the course

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Course Materials

• A Practical Guide to Red Hat Linux textbook
• Chapters 11-20, 23, 26
• Lab Exercises on syllabus, download at
• www.gc.maricopa.edu/business/cis238dl
• Compact Discs with Fedora Core 2
• Syllabus Overview
• Other
• Virtual PC account OR
• 5 GB or larger HDD in Inclose Drive Bay Model
  P96i-T

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Midas Setup

• Log onto Midas using Palette ID and password
• Select Account Info
• Input your Primary Email address in
• Internet Contact Information
• Input paletteid_at_student.gc.maricopa.edu as your
  Secondary email address, use YOUR paletteid
  above.
• Go to Message Cnt Personal Preferences
• Check box for Forward all messages to email
• Click Submit button
• Return to course screen, select Take an Exam
• Take Course Pretest exam.

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http//www.maricopa.edu/midas
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Enter Your Palette User ID and Password
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Select Account Info
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Enter your Cox.net, AOL, Hotmail, etc. email
address here. Enter your GCC email address here.
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Select Message Cnt then Select Personal
Preferences
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Check this Box
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Classroom Configuration HTC1-141
DNS and WINS to Internet
InstructorsComputer
\\Instructor01 192.168.0.1
\\ht1-141-xx
...
\\ht1-141-xx
\\ht1-141-xx
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Facilities
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Chapter 11

• System Administration and Superuser
• Rescue Mode
• SELinux
• System Operation
• Useful Utilities
• Setting up a server
• nsswitch.conf
• PAM

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System Administration

• System Administration Tools
• su/sudo
• consolehelper
• kill

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Rescue Mode

• boot linux rescue
• Takes you into rescue mode to change files and
  perform other maintenance
• boot /boot/vmlinuz

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SELinux

• DAC based on users and groups
• SELinux based on MAC, based on roles
• Use system-config-users to assign roles
• SELinux states
• Enforcing/Active
• Permissive/Warn
• Disabled

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System Operation

• Booting the system runlevel set in inittab
• Start and Stop services (init scripts)
• /etc/rd.d/rc.sysinit initial logging, time,
  etc.
• /etc/rc.d/rc runlevel setup
• Configure services II
• system-config-services
• redhat-config-services
• chkconfg Configures Services III

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Modes

• Single user 1
• Multi user 2
• Multi user with network 3
• Reserved 4
• Multi user with network and GUI 5
• Reboot 6

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Logging In

• PAM (pluggable authentication module)
• covered later
• /etc/shadow password file
• Uses MD5 hash
• /etc/profile and /etc/bashrc

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Bringing the system down

• shutdown
• -h halt system now
• -r reboots 5 (in 5 minutes)
• -k just kidding
• init 0
• Ctrl-alt-del

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Useful Utilities

• Red Hat utilities
• redhat-config-
• system-config- (Fedora)
• bind
• boot
• display
• netboot
• network
• samba
• List on pages 394 to 396

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Linux Utilities

• chsh clear
• dmesg e2label
• kudzu mkfs
• ping reset
• setserial umask
• uname

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Setting up a server

• Standard config file rules
• Ignore blank lines
• Comments begin with a in column 1
• Use \ or quotes to hide embedded spaces
• Break long lines into shorter lines with \

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Portmap

• rpcinfo to display information using portmap
• -p probe
• -n (port) number
• -u UDP
• -t TCP
• -b broadcast
• -d delete
• Example rpcinfo p hostname

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The xinetd Super Server

• Uses /etc/xinetd.conf file
• Used to start network services based on network
  requests

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Securing a Server

• TCP Wrappers
• hosts.allow and hosts.deny
• Stops at first hit so use wisely
• chroot jail
• Same as fake root
• Useful in hiding true directory structure

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DHCP

• Uses dhcpd.conf file on server
• default-lease-time 600 seconds or 10 minutes
• max-lease-time 86400 seconds or 1 day
• options (subnet-mask, routers, domain-name-servers
  )
• Or dhclient.conf on client machine
• Interface eth0
• send dhcp-client-identifier 1xxxxxxxxxxxx
  
• send dhcp-lease-time 86400

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nsswitch.conf

• name service switch configuration file
• Specifies which methods to use and the order to
  use them when looking for a certain type of
  information.
• passwd files nis
• hosts files dns
• passwd compat (requires - entries)

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PAM

• Linux Pluggable Authentication Modules
• Used to determine how various applications use
  authentication to verify the identity of a user.
• PAM-1.0
• auth required pam_securetty.so
• auth required pam_nologin.so
• session required pam_console.so
• session required pam_selinux.so multiple

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Any Questions?