System and Network Administration course

Spring 2012 CSE 265: System and Network Administration ©2004-2012 Brian D. Davison
CSE 265: System and
CSE 265: System and
Network Administration
Network Administration
MW 9:10-10:00am Packard 258
F 9:10-11:00am Packard 112
http://www.cse.lehigh.edu/~brian/course/sysadmin/
Find syllabus, lecture notes, readings, etc.
Instructor: Prof. Brian D. Davison
davison@cse.lehigh.edu
http://www.cse.lehigh.edu/~brian/

Who is this course for?
Who is this course for?
● Students interested in learning
– The roles and responsibilities of a computer systems
and network administrator
– How to configure & manage their own linux systems
– How to diagnose and debug problems
– How some of the major system services operate
– Why they need to be nice to the sysadmin
● UNIX/Linux familiarity and programming
experience required (CSE17)

What will the course cover?
What will the course cover?
● Understand the role & responsibilities of a system administrator
● Configure the Linux operating system
● Describe the system boot process
● Setup and manage user accounts and groups
● Manage the resources and security of a computer running Linux
● Make effective use of Unix utilities and scripting languages
(bash, Perl)
● Configure and manage simple network services on a Linux
system
● Develop an appreciation of the documentation available as part
of an installed Unix/Linux system

What will it not cover?
What will it not cover?
● Networking in depth
– Take CSE342 or CSE404 instead
● Network security in depth
– Take CSE343 instead
● Windows administration
● Many hardware issues
● All the details needed for certification
– Lots of certification courses available

What does a sysadmin do?

● User account management
● Hardware management
● Perform filesystem backups, restores
● Install and configure new software and services
● Keep systems and services operating
– Monitor system and network
– Troubleshoot problems
● Maintain documentation
● Audit security
● Help users, performance tuning, and more!

User Account Management
User Account Management
● User Ids
● Mail
● Home directories (quotas,
drive capacities)
● Default startup files (paths)
● Permissions, group memberships,
accounting and restrictions
● Communicating policies and procedures
● Disabling / removing user accounts

Hardware Management
Hardware Management
– Capacity planning
– Inventory
– Hardware evaluation and purchase
– Adding and removing hardware
● Configuration
● Cabling, wiring, DIP switches, etc.
– Device driver installation
– System configuration and settings
– User notification and documentation

Data Backups
Data Backups
– Perhaps most important aspect!
– Disk and backup media capacity planning
– Performance, network and system impact
– Disaster recovery
● Onsite/Offsite
● Periodic testing
● Multiple copies
– User communication
● Schedules, restore guarantees
and procedures, loss tolerance

Software Installation/Maintenance
Software Installation/Maintenance
● Evaluation of software
● Downloading and building (compiling and
tweaking)
● Installation
● Maintenance of
multiple versions
● Security
● Patches and updates
● User notification, documentation

System Monitoring
System Monitoring
– Hardware and services functioning and operational
– Capacity
● Disk, RAM, CPU, network
– Security
● Passwords
● Break-ins
– System logs
● Examination
● Periodic rotation and truncation

Troubleshooting
Troubleshooting
● Problem discovery, diagnosis, and resolution
– Root cause analysis
– Often quite difficult!
● Often requires
– Broad and thorough
system knowledge
– Outside experts
– Luck
● Expediency

Local Documentation
Local Documentation
● Administrative policies and procedures
– Backup media locations
– Hardware
● Location
● Description, configuration, connections
– Software
● Install media (or download location)
● Installation, build, and configuration details
● Patches installed
● Acceptable use policies

Security Concerns
Security Concerns
● System logging and audit facilities
– Evaluation and implementation
– Monitoring and analysis
– Traps, auditing and monitoring programs
● Unexpected or unauthorized use detection
● Monitoring of security advisories
– Security holes and weaknesses
– Live exploits

User Assistance
User Assistance
– Time intensive!
– Techniques
● Help desks
● Trouble-ticket systems
– Software availability and usage
– Software configuration settings
– Hardware usage, maintenance, and troubleshooting
– Writing FAQs

Administration Challenges
Administration Challenges
– Need
● Broad knowledge of hardware and software
● To balance conflicting requirements
– Short-term vs. long-term needs
– End-user vs. organizational requirements
– Service provider vs. police model
● To work well and efficiently under pressure
● 24x7 availability
● Flexibility, tolerance, and patience
● Good communication skills
– People think of sysadmins only when things don't work!

Which OS to learn to admin?
Which OS to learn to admin?

Why (Red Hat/CentOS) Linux?
Why (Red Hat/CentOS) Linux?
– Need to use some OS to make ideas concrete
– Really only two choices:
● Windows (I'm not qualified)
● UNIX (and UNIX-like OSes such as Linux)
– Both are useful and common in the real world
– Linux is popular, free, and usable on personal
machines, but also handles large-scale services
– Red Hat/CentOS is relatively polished, popular
● I've been using it since ~1996
● There are, of course, many alternatives

What is Linux?
What is Linux?
much is courtesy of www.kernel.org
much is courtesy of www.kernel.org
● Linux is a clone of the operating system Unix, written by a loosely-knit
team of hackers across the Net. It aims towards POSIX and
Single UNIX Specification compliance.
● Like any modern fully-fledged Unix, Linux includes true multitasking,
virtual memory, shared libraries, demand loading, shared copy-on-
write executables, proper memory management, and TCP/IP
networking.
● Linux really refers to the kernel – most of the commands that you are
familiar with are really separate programs, not specific to Linux, and
often are part of the Free Software Foundation's GNU project.
● Linux was first developed for 32-bit x86-based PCs (386 or higher).
These days it also runs on dozens of other processors.

Brief history of UNIX
Brief history of UNIX
● Originated as a research project in 1969 at AT&T Bell Labs
– Made available to universities (free) in 1976
● Berkeley UNIX started in 1977 when UCB licensed code from
AT&T.
● Berkeley Software Distribution started in 1977 with 1BSD, and
ended in 1993 with 4.4BSD
● Licensing costs from AT&T increased, so Berkeley attempted to
remove AT&T code, but ran out of funds before completion.
● Final release of AT&T-free code called 4.4BSD-Lite.
– Most current BSD distributions (FreeBSD, NetBSD, OpenBSD) are
derived from 4.4BSD-Lite.
● Most commercial versions of UNIX (Solaris, HP-UX) are derived
from the AT&T code

Brief history of Linux
Brief history of Linux
● Created as a personal project (and still
controlled) by Linus Torvalds, a Finnish
graduate student, in 1991
● Conceived as an offshoot of Minix (a model OS)
– Not derived from AT&T or BSD UNIX
● Red Hat (one of many Linux vendors) founded
in 1993
● Kernel v1.0 released 1994
● Most recent (Jan 2012) kernel release is 3.2.1

Where to get answers
● Linux/UNIX documentation can be found in
many places
– Manual pages (man pages, using man command)
– Texinfo documents (read with info command)
– HOWTOs – focused descriptions of a topic
– Distribution-specific documentation
– Your favorite Web search engine
● Will typically find online versions of the above

man pages
man pages
– Usually my first resource
– Provide OS installation-specific
information
– Man pages document (almost)
every command, driver, file
format, and library routine
– “man -k topic” will list all man
pages that use topic
– Parameters are not the same
for every UNIX, e.g.:
● Linux: man 4 tty
● Solaris: man -s4 tty

man page organization
man page organization
● Man pages are divided into sections (somewhat Linux specific)
– 1: User-level commands and applications
– 2: System calls and kernel error codes
– 3: Library calls
– 4: Device drivers
– 5: Standard file formats
– 6: Games and demonstrations
– 7: Miscellaneous files and documents
– 8: System administration commands
– 9: Obscure kernel specs and interfaces
● Some sections are subdivided
– 3M contains pages for math library
– Section “n” often contains subcommands (such as bash built-in cmds)
● Sections 6 and 9 are typically empty

Where do we go from here?
Where do we go from here?
– In this course, I'll assign homework projects that
require root access on a RHEL/CentOS 5 system.
– In our first lab, you will be provided with a hard drive
that can be used in the Sandbox lab (PL112) with the
OS, and root privileges so that you will administer it.
– In addition, you can (and should) use
● the department Suns for most things
● A CentOS 5 system (on the CSE network) called
edgar.cse.lehigh.edu to explore a minimal working system
– See course web page for syllabus and schedule for
topics and readings.

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