Leonardo da Vinci Programme – Project RO/03/B/P/PP175006 LESSON E19_EN. INTERNET TROUBLESHOOTING, DISTURBANCES, MAINTENANCE. Parent Entity: IPA SA, Bucharest, Romania, 167 bis, Calea Floreasca; Fax: + 40 21 316 16 20 Authors: Gheorghe Mincu Sandulescu, University Professor Dr., IPA SA, Bucharest, Romania, 167 bis, Calea Floreasca, Mariana Bistran, Principal Researcher, IPA SA, Bucharest, Romania, 167 bis, Calea Floreasca, e-mail: [email protected]. Consultations: Every working day between 9.00 a.m. and 12.00 p.m. After studying this lesson, you will acquire the following knowledge: Understanding the troubleshooting methodology and procedures. Ethical, economic and managerial aspects of the troubleshooting activities. Essential diagnosis tools for troubleshooting and their mode of use. The control of connectivity through the use of powerful and simple to apply troubleshooting tools. The use of the Microsoft ©®WINDOWS environment for troubleshooting. The use of elements from the Unix / Linux environment for troubleshooting. CONTENT OF THE LESSON 1. TROUBLESHOOTING PROCEDURES. 2. UNIX UTILITIES AND SYSTEM FILES RELATED TO NETWORKING AND TROUBLESHOOTING. 3. DIAGNOSIS TOOLS AND UTILITIES IN MICROSOFT ®WINDOWS. 4. PATHPING MICROSOFT ®WINDOWS DIAGNOSIS TOOL FOR TROUBLESHOOTING CONNECTIVITY. 5. THE Netstat DIAGNOSIS TOOL. MICROSOFT ®WINDOWS 6. OTHER DIAGNOSIS TOOLS. MICROSOFT ®WINDOWS LEARNING OBJECTIVES: After learning this lesson you will accomplish the ability to: apply the troubleshooting methodology and procedures. respect the ethical constraints and take into consideration the economic and managerial aspects of the troubleshooting activities. accomplish the necessary information for troubleshooting actions inside your specific activities, to apply the troubleshooting tools.. The control of connectivity through the using of the powerful and simple to apply troubleshooting tools. The using of diagnosis tools for troubleshooting of the Microsoft ©®WINDOWS environment. The using of elements and tools of Unix / Linux environment for troubleshooting. 1. TROUBLESHOOTING PROCEDURES. Troubleshooting is the basis of the Network Administration profession. This profession includes two categories of actions: configuring and troubleshooting. Troubleshooting has to be solved systematically, methodically, based on thorough TCP/IP knowledge, on splitting the problem into manageable parts, and on understanding phenomena. In troubleshooting activities, security barriers must be taken into consideration: firewalls and other security devices may block Ping, Tracert (Traceroute in Unix), ICMP error messages. Normally, these simple tools may diagnose the troubles. Small things such as plugs, connectors etc., may cause big problems. The troubleshooting consists of 3 parts: collecting information, also through the application of the adequate collecting / diagnosis tools, the evaluation of the situation and the application of the troubleshooting actions, and testing the efficiency of the applied actions. The troubles are of two types: normal failures and system failures (as a result of the interaction of different parts of the system). 1.) The management of troubleshooting. The troubles are easier to be solved if the system is understood and the failures indication tools and diagnosis tools are used. Troubleshooting has to be proactive: it is better to prevent than to repair. The network troubleshooting is in the strong connection with the mode of management of the network. 317 Leonardo da Vinci Programme – Project RO/03/B/P/PP175006 Between the elements which help the troubleshooting actions are: Troubleshooting management includes: The resources for the troubleshooting accomplishment: o Documentation. The management of documentation includes the dating of all elements which enter the system (software, printed materials etc) and the recording of all the changes of the system. Maintaining up-to-date, correct, omission- and error-free documentation, at the time of the network’s evolution is one of the principal responsibilities of the net worker / network administrator. o Software sources. Hardware and hybrid sources. o Diagnosis tools. Knowledge, training, professionalism. 2.) Legal and ethical aspects. With troubleshooting actions, attention must be paid to respecting privacy, confidentiality, and other ethical and legal aspects. If you collect information by using the Data packets capture software, you may be aware that collecting the Data may be illegal and you have to convene, in advance, the related aspects with your customers. 3.) Economic aspects. Among the important aspects one should be aware of, here are a few: Troubleshooting may be in strong connection with economic consequences. The aspects are connected to the mode of achievement of the contracts with the clients. The contract may be under SLA – Service-Level Agreement form. The SLA may specify [7.]: o Responsibilities and expectations, o Network metrics: speed, MTTR – Mean Time to Repair, MRBF-Mean Time Between Failures, Availability, where o Availability = 1000 [Uptime / (Uptime + Downtime)], and possible Five Nine (possible availability of 99,999%). o Other. The delays in solving failures may be related to financial losses. Another important aspect consists of the costs of repairing. New investment must also include the costs of maintenance, training of people, spare parts etc. 4.) The general procedures for troubleshooting. 4.1.) The system resetting. In the complex software / hardware systems, the resetting of the system is considered as one important means for troubleshooting, for some classes of troubles. The resetting of the system is necessary to be achieved while taking into consideration the implications and dangers. Resetting may be achieved through: warm reboot, without power cycling, and cold reboot, with power cycling. 4.2.) The use of diagnosis tools and of monitoring systems. See the next chapters. 2. UNIX UTILITIES AND SYSTEM FILES RELATED TO TROUBLESHOOTING. 1.) The evaluation of the environment of one server of ISP through UNIX/LINUX UTILITIES [4.]. The UTILITIES are UNIX commands, which work on your UNIX server, inform about the status of the configuration and of the networking environment. At the address www.die.net/doc/linux/man/ you can find a consistent alphabetical directory and explanations about thousands of Linux commands. The address: www.sauronz.com/imprimir/OReilly%20-20Network%20Troubleshooting%20Tools.pdf presents the important Handbook: Joseph D. Sloan Network Troubleshooting Tools, O-Reilly, ISBN: 0-596-00186-X [4.]. 318 Leonardo da Vinci Programme – Project RO/03/B/P/PP175006 One important excerpt of these utilities is presented below. 1.1.) ps. Displaying all processes owned by a specific user. Details on the web address indicated at [4.] depend on the software system used. ps commands offer, on screen, the listing of the processes which are running on the system and are owned by a specific user. Syntax and complete description at: [www.die.net/doc/linux/man/man1/ps.1.html]; [www.kingston.ac.uk/support/unix/man/ps.txt]: Example when running the FreeBSD command: $ ps -aux where: $ represents the prompt (initially set by the user), -a print all processes involving terminals, and (-x) without controlling terminals, and in detail (-u). -u print user information Example: $ ps PID TTY TIME CMD 331 1 0:06 vi test where PID is the process identifier; TTY is the number of the terminal from which the process is launched; TIME represents the time interval allocated cyclically for the respective process. You can also use the syntax "ps U username"[http://www.softpanorama.org/Utilities/index.shtml; Febr.2006] The ps command with the 'o' parameter can tell the ps command what you want to see: e.g. $ ps -o "%u : %U : %p : %a" where the %u represents the Runame; %U represents USER; p% represents PID (Process Identifier); %a represents COMMAND. The system responds, for instance, with: RUSER :USER :PID :COMMAND mary : mary :4 : :bash 1.2.) top [www.die.net/doc/linux/man/man1/top.1.html; Feb.2006]. Details on the web address indicated at [4.]. top command updates the listing of processes in the order of the CPU usage. Example of command: $ top Indications will be given of: the number of running and sleeping processes, CPU (Central Processing Unit) states; memory status, PID, USER, PRI - Priority of the task, NI (or NICE) – Nice values for the process, SIZE, RES- Resident size (kb)/ The non-swapped physical memory a task has used, STATE, CPU Time – Total CPU time the task has used since it started, CPU COMMAND – Command line or Program name, and others. top also works with arguments. 1.3.) netstat [www.die.net/doc/linux/man/man8/netstat.8.html; Feb. 2006. Details on the web address indicated at [4.]. netstat command indicates a variety of information including the essential data structure of the net system. netstat command indicates net connections, routing tables, interface statistics, masquerade connections, and multicast memberships. netstat works with arguments. Example of command: $ netstat –a where -a : Displays all active TCP connections and the TCP and UDP ports on which the computer is listening http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/netstat.mspx?mfr=true. The netstat is intensive used (with the argument –i) when it is suspected that the connection to the LAN is not reliable. The command is: $ netstat –i and the following will be indicated: Ierrs- Input Errors, Oerrs- Output errors, Queue- Packets which