System Administration

Transcription

1 System Administration MTAT ECTS Markko Merzin markko.merzin@ut.ee 1/55

2 Markko Merzin Lecturer worked as a System administrator: 15 years (and counting) Researcher: 2 years (and counting) Lab instructor: 3 years Lecturer: 2 minutes (and counting) 2/55

3 Outline Administrative topics Introduction to course Terminology Description of systems administrator's duties Basic concepts of IP networking and file tree 3/55

4 Course schedule Lectures Thursdays Labs Group 5: Tuesdays Group 2: Tuesdays Group 4: Wednesdays Group 7: Wednesdays Group 3: Thursdays Group 1: Thursdays Group 6: Thursdays Liivi Liivi /55

5 6 ECTS = 156 hours Course schedule Lectures: 32 hours Lab sessions: 32 hours Independent work: 92 hours 5/55

6 Course homepage Contains: Lecture recordings Lecture slides Additional reading Lab materials 6/55

7 Composition of the final grade Final grade: Tests: 50% from labs 30% from tests during the semester (3 tests) 20% from course project or exam every 3-4 weeks take place during lectures (15-20 minutes) 3-4 questions 1-4 sentences per answer or multiple choice 7/55

8 Composition of the final grade (2) Grade from labs will be recorded by the end of 11. lab Student still has to complete 100% of the lab tasks before project presentation or exam 8/55

9 Composition of the final grade (3) Project or exam? Most students will do course project and present it in last two or three lectures (about 5 min. each) 15% of top scoring and 15% low scoring students can take an exam instead (conditions apply (formalized later)) 9/55

10 Composition of the final grade (4) Course project Setup you own virtual system/environment At least on server and one client image Use some other operating system (FreeBSD, Solaris, Windows etc.) or Linux distribution then the one used in labs Individual work or small groups Possible topics and other details will be on course page 10/55

11 Basic knowledge of: Prerequisites Administering a single desktop system Networking (TCP/IP) UNIX command line Personal qualities: persistence stress tolerance 11/55

12 Acknowledgment This lecture is based on templates and material from Marti Taremaa and Ulrich Norbisrath! Thanks! 12/55

13 Before: Relation to other courses Network Technology I Operating Systems Same skill level: After: Computer Security Network Technology II Operating Systems Structures 13/55

14 Lecture topics: resources Storage and Backup Processing Power and Bandwidth Software Resource Virtualization 14/55

15 Lecture topics: processes Incident and Problem Management Service Desk System Administration Standards and Best Practices 15/55

16 Style of the lecture? Talking head (only lecturer talks)? Seminary form (everybody discusses)? Something in between? 16/55

17 Reading Materials The Practice of System and Network Administration Thomas A. Limoncelli Christina J. Hogan Strata R. Chalup 17/55

18 Labs there is one system per student you have to build a simple system offering some typical services the platform is Debian Linux every lab builds upon the previous labs the result will be graded 18/55

19 Lab topics Web Server Remote File Access Monitoring Incident Management 19/55

20 Hidden motives What we actually want to happen: Coherent building process Systematic monitoring Troubleshooting 20/55

21 Terminology Administration vs. Management administration ~ technical level management ~ organizational level 21/55

22 Terminology (2) system organized, purposeful set of objects, regarded as whole; the structure of the system does not allow the components to be randomly rearranged; system as a whole can have properties/capabilities which the individual components do not have 22/55

23 Terminology (3) any element which has no relationship with any other element of a system, cannot be a part of that system. 23/55

24 Computer system Terminology (4) a set of hardware and software which processes data in a meaningful way has interconnected components is organized, has structure is purposeful can consist of (semi-independent) subsystems the goals of the system are determined by its owner 24/55

25 Computer system 25/55

26 Subsystem 1 26/55

27 27/55

28 The BIG Why? Activity 1 Why computer systems need to be administered? Hints: why refrigerators need no administrating? why modern computers have two types of data storage devices, memory and hard disk? 28/55

29 The BIG Why? Activity 1 Why computer systems need to be administered? Possible answers Computer systems are universal tools and need to be adjusted and fine tuned to specific task Computer systems have lot of technical shortcomings that need working around 29/55

30 Terminology (5) user interacts with the system makes some use of this interaction can change some internal state of the system usually cannot change the structure of the system 30/55

31 Terminology (6) System administration periodical activities restructuring aims to keep the system aligned with the goals performed by the system administrator 31/55

32 service, customer Terminology (7) from the business point of view we provide a service regulated with contracts internal and external services customer is the receiving side of the service user and customer may be the same person, but not necessarily 32/55

33 System administrator's duties (1) planning, implementing new technologies hardware installation, configuration, maintenance software installation, configuration, maintenance auditing the systems 33/55

34 System administrator's duties (2) monitoring the system responding to incidents, providing workarounds identifying problems, providing long-term solutions preventing the problems 34/55

35 System administrator's duties (3) consulting the users performing user account maintenance documenting light programming security administration data protection 35/55

36 What of those duties have You performed before? Activity 2 36/55

37 Basic Principles in System Administration (1) Take care of the basics first Plan ahead Keep solutions clear and simple Automate 37/55

38 Basic Principles in System Administration (2) Know your systems and tools Know your users and enterprise - communicate Document 38/55

39 Drop two of those principles Activity 3 Take care of the basics first Plan ahead Keep solutions clear and simple Automate Know your systems and tools Know your users and enterprise - communicate Document 39/55

40 Bad Choice Bad Choice 40/55

41 Basic networking (1) Packet Portion of data which is transmitted as whole Consists header and payload Header consists source and destination ipaddresses, destination port and some other technical information Payload consists user and/or protocol data 41/55

42 IP-address Basic networking (2) numerical label assigned to each device participating in a computer network that uses the Internet Protocol for communication. Identifies networked computer globally or locally (private address) 4 numbers separated by dots Numbers are between 0 and /55

43 Basic networking (3) Port Numeric value that identifies different services in networked computer Port 80 http Port 22 ssh Port https 43/55

44 Router, gateway Basic networking (4) Specialized computer which is responsible for packet delivery between networks 44/55

45 Basic networking (5) Network mask, netmask Describes surroundings of the networked computer If destination ip-address is under the mask then packet is sent to that computer directly If destination is outside of the mask then packet is delivered through router 4 numbers separated by dots /55

46 Basic networking (6) Network mask, netmask Actually a bitmask over ip-address For a start is sufficient to know that ip with netmask means that computers with ip-address ANY are reachable directly and all other are possibly reachable trough router Notation / means ipaddress with netmask /24 is the same in different notation 46/55

47 Basic networking (7) Default router, default gateway Router that is used when there are no specific routes Typical network has only one router 47/55

48 File tree (1) File A computer file is a block of arbitrary information which is available to a computer program 48/55

49 File tree (2) Folder, directory, catalog Each folder can contain an arbitrary number of files, and it can also contain other folders. These other folders are referred to as subfolders. Subfolders can contain still more files and folders and so on, thus building a tree-like structure in which one "root folder" can contain any number of levels of other folders and files. 49/55

50 File tree (3) 50/55

51 File tree (4) Working directory, current directory Every program considers one folder as its working directory Some programs allow user to change working directory, for example bash, common command interpretator or shell 51/55

52 File tree (5) Every file in system can addressed by absolute path or by relative path Path consists of: folder name(s), file name, path separator(s) ( / in linux systems) Absolute path always starts with / /etc/debian_version /etc/network/interfaces 52/55

53 File tree (6) Relative path can start directly with folder or file name etc/debian_version Or with single dot, which means current working directory./etc/debian_version Or with double dots, which means one folder up from current working directory../etc/debian_version 53/55

54 File tree (7) Example: command ls displays folder contents ls. ls /etc ls.. Displays content of the current directory Displays content of the etc folder in root folder Displays content of the folder upwards from current folder 54/55

55 Questions? 55/55