Linux Troubleshooting Course with Practical Examples | Imran Afzal | Skillshare

Linux Troubleshooting Course with Practical Examples

Imran Afzal, Systems Manager / Instructor

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77 Lessons (12h 52m)
    • 1. Course Promo Video

    • 2. Course Syllabus

    • 3. Welcome to Troubleshooting Best Practice

    • 4. Follow Policies and Standards

    • 5. Documentation Or Ticketing Process

    • 6. Patience To Work with the Users Group

    • 7. Get Online Help

    • 8. Understanding the Issue Before Making a Decision

    • 9. Involve Vendors if Needed

    • 10. Log Monitor

    • 11. Be Honest and Ask Questions

    • 12. Welcome to lab setup

    • 13. What is VirtualBox

    • 14. Download and Install VirtualBox

    • 15. Creating First Virtual Machine

    • 16. Linux CentOS Installation

    • 17. Welcome to Conceptual Troubleshooting

    • 18. Who is who

    • 19. Cannot Access Server

    • 20. Cannot Install OS

    • 21. VM Running Slow

    • 22. Welcome to System Access Troubleshooting

    • 23. Server is Not reachable

    • 24. Cannot Connect to a Website or an Application

    • 25. Cannot SSH as Root or Other User

    • 26. Firewall

    • 27. Terminal or Client is Not Working

    • 28. Troubleshooting Putty Connection

    • 29. Welcome to Filesystem Troubleshooting

    • 30. Cannot CD Into a Directory

    • 31. Cannot Open a File Or Run a Script

    • 32. Having Trouble Finding Files and Directories

    • 33. Cannot Create Links

    • 34. Cannot Write to a File

    • 35. Cannot Delete, Copy, Rename or Move a File

    • 36. Cannot Change File Permissions Ownership

    • 37. Disk Space Full

    • 38. Add Disk and Create Standard Partition

    • 39. Add Disk and Create LVM Partition

    • 40. Extend Disk with LVM

    • 41. How to Delete Old Files

    • 42. Script to Delete Old Files

    • 43. Filesystem Corruption

    • 44. fstab Corruption

    • 45. Welcome to System Administration Troubleshooting

    • 46. Running Out of Memory

    • 47. Add Swap Space

    • 48. System Rebooted Or Process Restarted

    • 49. Unable to get an IP Address

    • 50. IP Address Assigned but not Reachable

    • 51. Having Trouble Using vi Editor

    • 52. Cannot Run Certain Commands

    • 53. Cannot Change Password

    • 54. User Has No Home Directory

    • 55. How to Change Every Instance of a Word in a File

    • 56. How to Use sed Command

    • 57. How to Kill a Process, User or Terminal

    • 58. Recover Root Password

    • 59. Sosreport

    • 60. List of Users Logged in by Date

    • 61. System is Running Slow

    • 62. Rollback Updates and Patches

    • 63. Welcome to System Recovery

    • 64. Recover Virtual System

    • 65. Recover Physical System

    • 66. Disaster Recovery

    • 67. Welcome to Bonus Section

    • 68. Introduction to File System

    • 69. File Ownership Commands

    • 70. Files and Directory Permissions

    • 71. System Log Monitoring

    • 72. Hard and Soft Link

    • 73. Curl and ping

    • 74. Programs and Service Management

    • 75. Processes and Jobs

    • 76. New network command

    • 77. Difference Between Linux 5, 6 and 7


About This Class

Maintain a reliable and highly available Linux server infrastructure, and reduce costly downtime. In this Linux troubleshooting training course, you gain the expertise to effectively diagnose and fix common and complex Linux server configuration and administrations issues, and learn to apply those skills in production environment

Linux Troubleshooting Course

Section 1 – Introduction and Course Overview

• What is this course about

• Syllabus Overview

• Download Syllabus

Section 2 – Troubleshooting Best Practices

• Follow Policies and Standards

• Documentation or Ticketing Process

• Patience To Work With the Users / Group

• Get Online Help

• Understanding the Issue Before Making a Decision

• Involve Vendor If Needed

• Log Monitor

• Be Honest and Ask Questions

Section 3 - Lab Setup

• What is VirtualBox?

• Installing Oracle VirtualBox

• Creating First Virtual Machine

• Linux Installation

Section 4 - Conceptual Troubleshooting

• Who is Who?

• Cannot Access Server

• Cannot Install Linux

• Linux Virtual Machine Running Slow

Section 5 - System Access Troubleshooting

• Server is Not Reachable

• Cannot Connect to a Website or an Application

• Cannot SSH as root or a Specific User

• Firewall Issue

• Terminal Client is not working

• Cannot Connect using Putty to a VirutalBox VM

Section 6 - FileSystem Troubleshooting

• Cannot cd into a Directory

• Cannot Open a File or Run a Script

• Having Trouble Finding Files and Directories

• Cannot Create Links

• Cannot Write to a File

• Cannot Delete, Copy, Move or Rename a File

• Cannot Change File Permissions or View Other Users Files

• Disk Space Full or Add More Disk Space

• Add Disk and Create Standard Partition

• Add Disk and Create Standard Partition

• Add Disk and Create LVM Partition

• Extend Disk with LVM

• How to Delete Old Files

• FileSystem is Corruption

• Corruption in /etc/fstab

• Script to Delete Old Files

• Handouts

Section 7 - System Administration Troubleshooting

• Running Out of Memory

• Add Swap Space

• System Rebooted or Process Restarted

• Unable to get IP Address

• IP Assigned but not Reachable

• Having Trouble using vi Editor

• Cannot Run Certain Commands

• Cannot Change Password

• User Account has no Home Directory

• How to Change Every Instance of a Word in a File

• How to Use sed Command

• How to Kill a User Terminal or Process

• Recover Root Password

• SOS Report

• List of Users Logged in by Date

• System is Running Slow

Section 8 - System Recovery

• Recover Virtual System

• Recover Physical System

• Disaster Recovery

Section 9 - Bonus Section

• What is FileSystem

• File Ownership Commands (chown, chgrp)

• Files and Directory Permissions (chmod)

• System Logs Monitor (/var/log)

• Soft and Hard Links

• curl and ping commands

• Programs and Service Management

• Processes and Jobs (systemctl, ps, kill, top, crontab, at)

• New Network Commands

• Script to Delete Old Files

• Difference Between CentOS/Redhat 5, 6 and 7


1. Course Promo Video: Hello, everyone. And welcome to my course Lennox troubleshooting course. This course is designed for people who are already in i t. Or people who actually trying to get into I. D. Who have the basic to somewhat at vast knowledge off legs already. Now they want to refine their skills in terms off how they could troubleshoot regular everyday issues to the advanced level. Trouble shoots. I have included pretty much a lot of things that actually a system administrator and engineer experiences in their life in their career life. So that's about my course. Now let me tell you about myself. My name is Enron absolute, and I have almost 17 years off experience in I t field, primarily in system administration, system engineering and systems management. I have bashes degree in computer information systems from Peru, College City, University of New York, and I have a Masters degree MBA from New York Institute of Technology. So that's what pretty much about me and thank you again for clicking into my course and enrolling in my course. So good luck to you 2. Course Syllabus: Hello, everyone, ever welcome to the course syllabus. This is where you have to spend a few minutes and then decide whether this is the right course for you. I'm going to cover exactly what I am or what I have included in this entire training. The first section is about the introduction and course overview. This is introduction, which I'm already going through. This is about what the horse course and tales of what are the things included the syllabus overview, which I'm going to right now with you. And after that, if you decide in roles, you could download the syllabus. Section two is about troubleshooting best practices, meaning how What are the fault of the policies that you should follow? What other standards that you should follow through the documentation and go through the ticketing process patient to work with users and groups. When people actually work in a group at you, you probably experience that other groups or other departments toe or finger pointing at you eat at each of them, then how you should act to avoid situations like that. Get online. Help understanding the issue before making a decision involved the vendor. If there is a need. Or if you cannot resolve at what point you have to pick up a phone and call your window the log monitoring and be honest and ask questions. The third section is about setting up a lab ill will cover up of about what is a workable box installing Oracle virtual box, creating for social machine and doing the Leninist installation. Now, of course, if you already have a Lennix machine like a lab Blinis machine where you could practise this training that you do not have to go through this entire section you could just simply skip through it and practice all those, um, all those lectures and all those troubleshooting commands that I will show you in your lab set up. But if you don't, that's fine. Just follow this section, and I'll show you exactly how you could run a little machine. Then we'll talk about the conceptual troubleshooting who is who meaning which server. When someone reports a problem, how do you know what show where they're talking about? Who is the source? Who was the target? Who is the client who's the server and what Pearl called they're using cannot access server cannot install a Lennox machine Lennox washing machine a running slow, then Section five system access troubleshooting Many time people have a problem when there cannot access a system or can a log into the system. So what are the topics we will cover is about Server is not reachable, cannot connect to a website, and application cannot ssh as root or a Pacific User Firewall issue. Terminal Clyde is not working. Cannot connect. Is using Putty be a war Shal box? By the way, all these topics that I'm covering is all based on real life examples, which I have experience in my life, which my students actually have experienced in and in their life or during taking my course . Section six is about file system troubleshooting can not see the into the fall. Cannot open a file or Rana script. Having trouble finding files and directories cannot create links. Cannot write to a file cannot delete copy, move, Rename of all cannot change file permission or a few other user files as you notice. I have included cannot word on every lecture because this course is all about troubleshooting, and then you cannot do certain things. That's where you have to come in and do the troubleshooting this base full or ADM or disc disc and create standard tradition. Continuing Section six ad disk and create standard petition when you run auto disc. How you could add a disk in Crete. L V m Petition Extend disc using LV and partition. How did the lead old files file system is corrupted than how you could fix it? Corruption at CFS Tab Scripts to delete all files and then, of course, in Section 60 have handouts where you could review some off the documentation that I have attached. Section seven is the biggest section, which is we're talking about system administration troubleshooting that could involve anything that you have to deal with your system, which is like running out of memory ads off space system rebooted ah, process restarted. How do you know? Unable to get an I p address networking issues I p assigned, but I cannot reach it again. Networking issues having trouble using V I editor cannot Ron. Certain commands cannot change Password moving on on the same section of system administration user account has no home directory. How do you troubleshoot how to change every instance, Off award in a file. How do you said command cassette Come as very powerful. So I have included in this as a part of the troubleshooting. How to kill a user terminal or process Recover Rule password If you for gotten about it S. O s report list off users logged in by date System is running slow. I have included so many commands in system running slow. When you're going to review this lecture, you will see I have included, like TCP Dump Top D of command Free Command, I o stat. So many commands that I cannot even list every one of them moving on to section eight. It's about system recovery Will talk about recover for troll system, recover for the physical system and disaster recovery Section nine, which is a last section. This is the bonus section. I have included many, many different lectures, but few of them that I have listed here that are about the followership logs softly Heartland coral pink commands program service never commands scripts to delete all files. The difference between Cento as 56 and seven and many more. I cannot include all of them in bonus section but I will be including many more again. This is my, um course syllabus. Please remember one thing. This course syllabus is not limited to what I have shown you just now. This will and I as I speak, I will be including many, many different lectures as I'm getting it. A feedback from my students. So hopefully you learn a lot from this from this course and Gluck to you. 3. Welcome to Troubleshooting Best Practice: Welcome to my section Number two. This is where we will talk about troubleshooting best practices like what is there the exact rules that we need to follow in order to have the best troubleshooting? There are a few list of things that I will go with you in this section, and those are not like a real troubleshooting that we will do. But there are basic concept that you should a basic format that everyone should follow to perform an effective troubleshooting. And those are one of them is full of policies in place, meaningful or any policies that you have for your company. Any standards that you have for your company. Follow that when you are going through the troubleshooting steps, whether it is opening up a ticket, notifying a certain person or whatever the policy they have, you have to follow that before you have to start trouble shooting anything and then wire hman. Then we'll talk about the documentation or tracking. Sorry, ticketing process. Documentation, meaning, if there is an issue heavy actually looked at any prior documentation, or are we going to document this existing issue? Or is there any ticketing process and nine out of 10. Every company has a ticketing system in their environment. Then we'll talk about the patients, the patient, that you really need to work with, users and groups. And how can we get that? Patients? That's the most important things when you're troubleshooting issues. If you get angry, waited during the troubleshooting process, trust me, you're not gonna get anything done. Then we'll talk about how you could get some online help. All line help is one of the biggest tool that I use it personally. And many, many other system administrators are engineers they use on a regular basis so they could go online and look for solutions. Will talk about understanding the issue before you make a decision. We'll talk about involving Wenders whenever you need help and the log monitor. There's so many laws that you have to monitor before you make. It's a decision or before you make a change in your environment and the last one be honest and ask question. You don't have to make up anything, and if you don't be afraid to ask any type of questions that you have, so these are the few things that all go were in this section. It is very important that you go over all of these, um, flies with me and these topics because that will really set your base to get starting on the troubleshooting lessons. 4. Follow Policies and Standards: follow policies and standards. Let's look at a were what other things that we should follow when you are working in a corporate environment, The first thing is communication. Communication is the most important things that you should do or notify the users or your boss or management that what is being done to the system or why you're troubleshooting or what happened, Why there is a failure. So troubleshooting Asari Communication is the key, so find out how you communicate. Is there a Pacific tool that you have to use to notify user? Or do you just simply have to have to send an email? These other things you have to follow then involved the right people involving the right people? Meaning, Do you have to notify your boss? Or do you have to notify your boss's boss You? Do you have to notify if you're working in a customer room environment? Do you have to notify the implementation managers or the engagement managers? Anybody who actually deal directly with the customers to do? How do you have to let them know that the customer system is down? Then open up a ticket if they have a ticketing platform and I said before nine out of 10 Every company has a ticketing platform where they open up a ticket if there's any issue, or you could open up a ticket at their if you are doing a maintenance. If you open, you open up a ticket if you are upgrading certain system, so you need to use a ticket for everything. So same thing for troubleshooting. If you're troubleshooting anything you need to find out if you need to open up a ticket. Sometimes if it is critical issue and impacting more than one customer or more than one stakeholder than you require to open up a ticket resolution techniques are mattered. What are the techniques that you need to follow the resolution method? Do you have to go through a certain procedure toe access system? Um, council system? Milo. Do you have to notify someone? Is there Pacific password So these other resolution techniques or math? Third, Um, do we have to go from A to Z the format? Or you could just jump in to the to the machine and find out what happened to trust our troubleshooting. You have to know the matter, maintain a schedule like. Is your company following the maintenance schedule like they only do. Maintenance is on the beacon. Or are they doing? Maintenance is only on the week. Sometimes people don't like to do ah, maintenance on Friday or on the weekend. So these are the things you need to find out when you're doing maintenance or even troubleshooting. Let's say the reason I'm bringing this up is because if you are troubleshooting an issue and during the troubleshooting you are, you're being told by the window or you just to find out from an article that you need to upgrade in order to fix this issue. The upgrade, of course, requires a maintenance window, that maintenance window. If you are troubleshooting an issue on the weekend and the only maintenance takes places during the week, then you need to know these things approval process. Who approves the process If you need to, um, apply a pash, or if you need to troubleshoot something that is related to an upgrade, you need to know what the poor processes. Sorry, I'm Vendela ahead. So these are the few things that you need to follow in terms off following policies and standards 5. Documentation Or Ticketing Process: next one we have in line is the documentation or ticketing process. That is one of my favorite part because I strongly believe anything that is document did correctly. It will always help you down the road. Meaning if I have an issue today and I document that issue, that issue can re occur maybe a year from now or 10 years from now. You can always go back to that ticket or always go back to the document and see exactly what happened. It is just the same way if you are Ah, lawyer. And you are actually, um, fighting a case. You lawyers do that many times that they go back to certain ah, incident or certain word X that took place in the past. And they bring it up as an example. You know, in 1988 this gentleman what took place because of that, That that How do they know that? Because there is a documentation off every trial that took place. Same thing, same format we wanted to follow here. We have to have a documentation off every troubleshooting or every issue the Viet, Whether you do a documentation or like a raw document on a ward format or you're doing a ticketing process. So look at for look, for any existing documentation your company has. And I'm telling you, every company has documentation if they do not have any kind of proper documentation than this is your time to shine star creating documents, stock rating, fancy documents. Put a process together. How on issue takes place. So if an issue comes in, then how do you troubleshoot? Who do we notify? All that comes in a documentation. If they have a ticketing system, put it. Put that together in a taking system. They probably have a Vicky, a lot of companies to have Wikipedia's and internal ones look for the documentation. And if they don't go ahead and posted your article in there ticketing system, as he discussed, um, nine out of 10 people do have ticketing system postmortem or incident report. Um, many big companies. Every time there's an issue, they would require you to put a post mourn or an incident report together. An incident report is something like, which will give you a brief summary off what exactly happened and what steps that were taken to resolve the issue. If they don't. If your company does not have any of these documents again, start creating one incident report. You can find it online as a templates that you could put together so you could follow that root cause analysis. This is also some of the things that people follow their root cause analysis. Maybe not. Not at the time when issue happened after the fact when issue took place. So they everybody come together on a call and they try to find out what exactly happened and what can be done to prevent issues like that. So please go through this route cause analysis with your boss. If they do not have a process in place like that, tell them this is something that you want to come out with. That every time there's an issue especially critical issue, you wanted to create a call. And that call includes all the team members ever involved during the troubleshooting and yourself, your manager and someone else who could document all that put together records and what happened and what can be done to actually mitigate that issue. So you need to find that out if they have that in place. If not again. There are many tools online that you could look into. And to find out if there are any tools that could provide you the format of root cause analysis, Document vendor could recommendation. So if there are any ah, recommendation from the document meeting you troubleshooting issue. And the vendor says, Hey, you're you're actually working on version two Dato and you need toe upgraded to $2 5 in order to fix this issue, then you need to document that. And then, of course, present that to your manager or whoever they're pulling, whatever the approval procedure is, then training. Of course, the training comes the last. The reason because you went through the whole, um, incident, you went through the whole troubleshooting. You fix the issue, you documented the issue. Now the training comes in for those people who were not involved in this rubbishing or who are your juniors or subordinates or even your peers, you need to sit together with them and have a discussion that what exactly happened and what you did and what should be avoided that you did that actually going to make the whole prop process more efficient. So this is why I focus more on documentation and take this system because it actually provides ah, huge ton off value to your troubleshooting and, of course, to your documentation skills as well. 6. Patience To Work with the Users Group: patients to work with users and groups. The first thing is that, of course, when there is an issue, please do not panic. I have seen many incident in my life in my career, off all the system administration that work that I did. The people get panic, and when they get panic, nothing can be done the right way. Things can go haywire, so don't do that. Don't get panicked. You need to stay calm. The things do get break, they do the do break. That's fine as perfectly All right. And that is why you are here. The company have you to fix those issues. So stay calm, bring everybody together, then involve others. As I was saying that just in my last sentence involved others in your group to seek help if you know, noticed that your system is working fine and you being told the system is down or system is not working fine and or your, um, or the user cannot connect to the database or cannot connect to the Web server. Bring the people who are actually directly responsible for that. If that's a database, bring the database guys online. Bring everybody together. If you have If you if you need help from your superiors or for people been there for a while or you manager, do not hesitate. As for their help, ask that What can be done is this is something that I've seen. Do you think that is something that you have experience in the past? Work patiently with other groups? I know when you start putting together a big group of people, there is always finger pointing. Hey, this is not a systems issue. This is data basis. You know, this is a networking issue. Oh, no, this is application related issue. Everybody will solve pointing fingers. It's OK. It's It's fine. Most of the time, fingers are being pointed always on the system side. And the reason they point fingers at system sizes because we the system seem actually per wide. The platform for database Toronto for applications to run for operating system to run. So we are the main providers for the entire platform. So that's why they always come back and say it because of the resource or compute Resource is not working fine. So it's OK. You could just take that, um, professionally and come back with a good, reasonable arguments that why do you think that it is not our issue? And the only reason you could say that is if you have a solid proof, explain the situation when others get panic or annoyed. Yes, because you're you're not panic. Okay, Perfect. By What about if the other person is annoyed and on on the call or in the bridge? Then you have to stake Panic 10 sorry. You have to stay calm. Of course. Then tell the person it is perfectly fine to tell the other person. Please become Let's get this thing resolved together. If you stay calm, do not think off. If I say that, maybe he will get offended. No, People don't get offended if you just tell them nicely. Just don't say Hey, relax. You keep your talking too much. Don't say that. So just say please stay calm. Let's work this thing together and let's find out where the issue is. And when they see you working on the issues so calmly, they will automatically get calm. Step. Sorry. Set up a conference call to bring everyone together. Of course, when you need to have the people together, there has to be a platform to bring them together. Some people use a Skype or some kind off video. Um, application. Some people just do. Ah ah, phone bridge calls. Some people actually get physically together on a conference room. That's fine. Whatever your medium is, you could utilize that to bring everybody together. Hand over to someone with more experience, meaning. If you think there's a situation and there's a troubleshooting that you're doing that is above your expertise, then do not take it personal. And please give it to someone who has more experience. When I say that, it means, let's say, if you are a system administrator, like I could tell tell you about myself if I'm a system administrator and there's something comes up that involves scripting a script that cause an issue, and I'm looking at a script and that script is probably written in PERL now, I do not have much experience in Pearl. I could read it, but I really don't understand what exactly it is doing at certain certain things. So what I would do, I will give it to this someone who has more experience with pearl or E one, my junior, if the person has been hard to the company, um, two months ago and I've been with the company's six years again, don't get personal. The person who came into six months ago, he probably had more experience from Pearl. Just tell him. Hey, take this called. You have more experience on Pearl. Tried troubleshooting it. Then do not let others derail you from the issue. Yes, this happens many times what I mean about what that is. People with a lot of people get involved in a call and they start talking and they start stepping on each of the toes. They actually start talking something that is not relevant to the entire conversation if the system is drowned or crashed or something. Yes. Start talking something else. Oh, you know what that happened? Something like that when I was, um, working on a database issue, and that database had an issue that I had never seen it because Hey, Paul, do you know why that had the databases you had? Because it has some, um, table extension problems. See these other things? I'm already taking you off of the subject, and I don't want to take you the office, the subject and to keep them everybody on the same subject. Tell them Hey, guys, please. Can we please concentrate on this issue? It is perfectly fine to say that and again going back to my main topic. Stay patient. 7. Get Online Help: getting online help. Well, for me, this is one off the more sufficient tool to get your issue resolved because nine out of 10 the issue that you're having someone else had the same issue. So go online and search for it. So before we do that and if you have never done it, you select a preferred search engine. Meaning are you going to use Give Google, yahoo or whatever that is. Just stick with one look for Pacific error in messages. When you sticking up a message on search, do not type like my server is down. So where you gonna get you? Probably gonna get tons of article and that's going to go nowhere. Basically picked exact error message that you're getting and put it in there and then you will see that you're gonna get so many related articles out there that is only Pacific to your search. Or maybe it's gonna go mawr and mawr and more narrow down if you try to search for Pacific error. If you do not have an Arab, then put your search specific to your environment. Kneeling meaning, say server is down in Lenox Environment Severin down in Lenox Red hat server is down in Lenox. Red hats aversion. Seven servers down in Lenox, right? Had 7.5. See how much? Narrowing it down. That's how you're going to get the exact same problem. And if someone has the same issue, sign up for Lynas committed forums. There are so many community forums out there, I will recommend you to go sign up. Um, not on Lee, because you wanted to get helped and troubleshoot your issues, but also help others as well. And you know, as as they say, what goes around comes around. If you help as much many people out there, you will be get help. And it's just a car month thing that I believe are asked Question if you cannot find your answer, meaning if you are searching for something, you can't find exact answer and there are forums there that you could put in and you could put your question on, um, if you have a support with the vendor than a perfect that you go there. If not some people just wait. If it's not critical, that just post a question online and they just wait for the answer and I tell you, you'll be amazed how many answers you're gonna get. People actually jump on the question and answer that, Um, then moving on. Be aware of security issues, though, so that's Ah, that's a other side of reality. Um, getting all the help is very good, but there's a dark side off it as well, and that is a security risk risk. Do not let anyone log into your system if someone is willing to help you. And they said, Hey, why not let me log in and see what's going on? You don't know the person. Of course, I'm sure you know that this is a basic ABC. You probably not gonna let them anybody come in. Other thing is hide your I p address or host name. If you are copping a string from your log, most likely it will have ah, host name to what? Or i p address to it. Just dark it out, Or just simply take it out and then search for it, or then send a message to someone to look for it. Do not search online from the server, which is having issue meaning. If you're sober, is having issue and you're getting online from that server. Don't do that. Go from a server. Your own laptop, Not the ones that are actually this over to a production environment server. Do not send any documents that has company information, which I mean, like, sometimes you, um you have Ah, no pad or word pad that you want to share with People. Do not send that. I'm gonna recommend that sometimes those documents. If you go to detail of that document, you'll see the company name and when it was created, your name and a whole bunch of information Do not download a file or script and run in your environment. You probably going to see helpful articles. Hey, this issue could be resolved. If you don't load this file and run it a lot of time, you'll find these type of things in windows. Not as much a new next. But of course. Um, keep an eye on it, be aware off it, do not download anything or any script, or even if you think that script will help you resolve the issue. Don't do that. If you're working in the corporate environment and the last thing I have, make sure to add a thank you note to a helpful article. If you found that and one of the article help you resolve the issue. That is perfect. Please do thank the person who actually put that article together or actually help someone else resolve the issue. Send one more. Thank you, too, to him or her saying that you did result my issue as well. To said it is just to put a smile on his or her face, all right. 8. Understanding the Issue Before Making a Decision: understanding the issue before making a decision. Ah, many times we do make that mistake without knowing the exact our message of without knowing . Ah, the exact problem will just come to a decision or we just implemented change. And next thing you know, that was not the issue. So just make sure ask yourself these questions. Who is the source meaning from where the issue is happening? Who is the target? What is the I P address or host? Name of the target? Same thing. What is the I P R R ah Host? Name off the source. What is a port number Whenever there is a problem? I know there's always a source and target and port numbers and wall, because if it's a communication issue from one server to another than most likely, that's the issue. But if it's a issue just with its own server, then you still need to know whether you are on the right server, whether what communication is being used, what kind off application issue it's having, who will be impacted. This is another thing that you need to ask yourself is if you are making this change, all right, if it's some Hassi decision and you're making this change. Who is going to be impacted? Is it a test environment that you get a word back or nothing gonna be? Nobody's gonna be noticed. Okay, Go right ahead. Make a chain find out what will happen. If not, do will change back. Nobody's gonna be noticing. But if it's a production environment, just be careful. Who do you need to notify? You covered that already. Make sure your boss knows about it. What you're doing, because he's the one at the end who actually is gonna cover your back. He's gonna stand behind you is gonna say, OK, that's fine. It this happened because I was aware off it. If you have not notified your boss, he cannot help you. And things could go go wrong. Trace the issue again to trace the issue. There's so many ways you could trace the issue from one system to another from logs and whole bunch of stuff. So again, try to understand the issue before making your decision. I know sometime people say is Ah, look, I'm very smart, and I know I found out this issue right away, and they say that during the call. Hey, I fixed it or they just implemented. And then next thing you know, they feel bad. Oh, I shouldn't have said that because that's not the issue. Then what should I do now? Well, that's why guys again, I'm saying, Please make sure you understand the issue thoroughly. 9. Involve Vendors if Needed: Inbal vendors if needed. This is when that situation gets more critical. You're trying to resolve an issue and you cannot get a result. Then you have to actually escalated to the higher experts who could actually who actually deal with these things almost every day. Call for critical issues. Have someone from your team reach out toe winders. What it means is, if you are troubleshooting the issue while you are in the middle of a call with people troubleshooting and see what's going on, you probably do not have enough time to hang up and pick up another phone and call the window and find out what happened. Because when you call the Wender, they will ask you bunch of stuff last for the logs, so it will take some time. So if you are on another call already troubleshooting, ask someone and from your team to help you out To open up a ticket with the vendor, upload logs and allow lenders to look through the logs, they will probably not gonna tell you right away. Hate. The system is down. I know what the issue is because again, as I said previously in my last light and with the windows as well. They actually looked through the logs. They actually understand issue before they make a decision or before they tell you what is wrong with it. They're not going to tell you right off the bat. I I know this issue, and this is what happened with, um Thompson Company or X Y Z company as well. And this is what we did know. They would never say that because they know every company is different. Every system is different. It's the same where you have to, um, react the same way as well. Allow access to log in the system. Yes, of course. They will ask you to walk them through, shared the screen. Or even, like sometimes people do have remote log in access. Uh, vendors who have a devil again. They will work with you along side and see what the issue is Set up a call between the vendors to a wide finger pointing. What it means is, if you have ah one, render that say you have red hat and then there is ah, database involved and you have SQL Microsoft team involved. Then the best thing, if if they both are on a different calls and they're saying, Hey, this is not our issue or does not our issue. Then what do you do? The best thing you do is you merge the cost together or set up one new conference call and tell them to join the call. And they always do that. Offenders are not afraid to do that. They are open to it and they will join the call right away. Or, if you have a call already going on internal, you could open it up to your Wender as well and have them come in and take a look. Don't be afraid. The vendors coming in and you have a security risk. No, Wenders are already. They already got your con contract. They already got your confidence. So don't worry about sharing information with them. Record all render ticket notes and numbers because you need that when you have. When you are putting together the incident report or a post mortem report or any type of documentation you're putting together after the fact that your resolve issues 10. Log Monitor: log monitor. This is also one of the most effective tool or a way to troubleshoot issue long monitor. Think if it away. As if you have. Um if you go to a hospital, you have a problem or you or you just go to the hospital. Is it someone and you see, at the end of the end side off the bed there is a clipboard and a clipboard has some papers attached to it. Every time a doctor comes in, they actually look at the law clip and their write something on it. And, uh, and anesthesiology, I or ah, Medicaid, Education guy or someone comes or a nurse comes to your room and give you medicine. They actually write that down everything in the log. Have you noticed why they do that? Because the reason to do that if something goes wrong or if you start feeling pain, they would know exactly what was given to you by whom, At one time, at what time? Or if there's a non opposite reaction to it. So these are the things that all captured in the log. Well, nowadays, that probably clipboard thing is gone. Now they have all computerized system. Everything is recording the in the computer, but there is still and always going to be the log. Same way. Similar fashion and systems environment. Infrastructure vibrant. We have logs we need to monitor those logs. We need to check those logs for any errors or fate. ALS or ah, information or warnings that comes in those little logs are systems logs, application logs, hardware logs, networking logs, these air the type of logs that are out there depending on the issues you are having. You need to look at those logs and trace those logs. What happened again? Going back to my scenario. If you're having if your system is having issue communicating to database your stew, need to check your systems log and the database log and see where the disconnect er's. That's call tracing the logs. For example. Web server um, going to the application server applications that we're going to the database server. This is an example I picked for the environment that is dealing with the retail observers. So are anything that has ah, Web server interface. When you goto dubbed upto dot google dot com, they have observer in front in the middle layer. They have application server, which has the engine running and in the back. And they have a database server. Every server that you see has a log. So you will trace those logs, copy the long error and search it online. Um, those loggers, if you see a Pacific our message, see if you can find anything online regarding that Save the logs before system reboot because there are many logs that actually disappear when this system is rebooted. So but so the fact that you come back after the troubleshooting system is resolved, everybody's happy. Now. You need to do a root cause analysis and how you're going to do it. And you have the logs, right? But if the logs are gone, then you have no way of finding it. So make sure you save the logs by a different name, so the system reboot doesn't delete 11. Be Honest and Ask Questions: Okay. The last one of the newest we have is about being honest and ask question. What it means is, if you made a mistake, just admitted Yes. Tell everybody. Yes. You did something to the system or you do. You were doing something or you're performing maintenance. And then you accidentally rebooted the system or you accidentally, um, did something on the configuration file that cause the issue. So please admit it. People actually appreciate the honesty. They will tell you That's fine. You understand me? Six happened. Then what's the course of faction? They'll ask you and they will appreciate you down down the road. Then don't make up for if you have not find the problem. If you think that you are troubleshooting in the issue and you have not come to a conclusion and all we're already past or to our past just don't say anything just to make the other person feel better in terms off, like you have to lie. Hey, you know what? I found the issue. This is the issue about ah, one of those http Configuration file has this type of problem and you have no clue. You're saying that just be honest about it. Tell them. Hey, listen, it's been two hours. I understand. I'm trying my best. I'm gonna involve I'm gonna escalate it if there's a need to it. So just simply don't make up the stuff. Don't be afraid to ask questions. Recovered that already. If you need to ask question, ask your boss. Ask your subordinates. Ask your peers what it is stands for. If you know if there's an acronym in there, you need to know what that acronym stands for. Asked them That is fine. Sometimes you know a new person that is new to the system. There's so much application systems related things in there that you probably don't understand. That is okay. You asked them. I don't think, Hey, if I asked acronym for um even, let's say, um Http, right, it's It's some time. It it has, ah, Apache to it, and you say, Hey, I'm looking for a party dot log, but there's no party. The law. There's a CDPD law, so there are things when it might confuse you. But it's OK. You can ask question what they're stands for, how the issue was reported. You could tell them Hey, I was just sitting and I saw this alert coming in or someone else reported to me. Don't say that. Hey, I was the one who found that issue. Why do you think this? It's related to Lennox server or links related issue. Um, how the issue how the issue is resolved. So that's one of the things that you have to tell. Um, I have seen people in the past when the issue is result on its own and they just say, Oh, yes, it's resolved because we did something resolved. No, there are issues. There are situations when somehow magically issues gets results and you would never find out. So So just just be honest about that. Ah, tell tell people Tell the users eight issue got resolved itself. You have no clue what Holly got resolved, but you will definitely look into it to find out what was the issue and how a guy results. It's just that simple. And then you move on with your life. All right, OK, 12. Welcome to lab setup: Hello, everyone. And welcome to our lab set up section. This is a section where we are going to actually set up our lab. A lab is where we are going to perform our certain troubleshooting tasks because this training is all about troubleshooting, right? And we need some type off operating systems, specifically Lennox, where he could perform trouble. Shootings. So how we are going to set up a lab? So this is what I'm going to cover in this section. The first thing we will do is we will cover the voter environment. What exactly a virtual environment is how a warship machine runs on a physical machine. How multiple virtual machines can run on one physical machine. Then I will cover the Oracle virtual box, meaning there are so many other virtualization technology. For example, VM Ware, Microsoft's hyper V said tricks Virtualization, right? Have socialization there. So many of them. I am picking Oracle worship box because it's very simple, straightforward. If you per for any other virtualization technology, please be my guest to use that. Then the next topic will cover is about installing Oracle Warship box. I will take you to the website off or commercial box well together. Download the software. Once the download is completed, it will go through the installation and the configuration off Oracle Warship box. That Oracle Worship box will allow us to give us a platform where we could run virtual machines. So the first next step would be is to create our first washing machine. Once we have the Oracle warship box set up, that worship machine will be set up for our Lennox environment. So the next step would be is to install Lennox on that washing machine and the Lennox that are have picked the flavor off. The Lennox is sent O s. Now Santo s is similar to red hat and red hat. It has the biggest market share in corporate environment. That is why I am picking Red Hat or Santo s offering system for this entire training session. So one thing I do want to mention if you already have a lap set up or if you already have a machine off a virtual machine or physical machine that is running Lennox, whether it is a bun to Santo s Soucy or any other, and that you want to prefer to use it for this entire train session. Then just simply skip this section because you don't need to set up the lab. You don't see need to set up the Oracle warship box. You already have a Lennox machine. If you do not, then simply go through all these steps and let's get started. 13. What is VirtualBox: what is Oracle Worship Box? And, of course, why do we need to know about worship box? Well, for this course, you do need to install sent OS Linux operating system on your computer, and there are two ways you could insult. One. You could remove the existing operating system that you have on your computer. Or you could install virtual box on top off your existing Windows operating system or Mac, and then you could install sent Oso you This way you won't lose anything. So basically, a virtual box is a free and open source hyper wiser for X 86 computers currently being developed by Oracle Corporation. It insults on your existing Intel array, MD based computers, whether they are running Windows Macklin excess LHarris. It extends the capabilities off your existing computer so that it can run multiple operating systems on one hardware at the same time. Let's see how it works. So you have when the hardware layer and then on top off it, you install the operating system. Of course, it could be anyone. You have that as Windows or Mac, and then you install Oracle Virtual Box. It's just a A program, a software that you installed on your machine like any other software that you would install. Once you have installed Oracle warship box, then you could install the Lennox on it as a separate small version off operating system. You could have windows on it, or you could have Mac on it, said this one. This virtual box allows you to have multiple operating system on the same hardware. 14. Download and Install VirtualBox: in this lesson, we will cover the Oracle Horschel Box download, and it's It's insulation. First of all, you would have to go to Google and type Oracle Virtual Box download and then the first link you will see here go to download. If your operating system is Windows, you'll click on Windows Host. Once you click on, it will ask you to save the file. I can't save the file, but since it takes some time, I have already saved the file previously to save some time. This is the file execute herbal file that's been saved. Run, click. Next, Leave everything default setting. Create a start menu entry You. Could you believe that? Create a shortcut on your desktop? That's fine. Create a shortcut in a quick lounge bore. I don't like that and Register File Association. You believe that networking installing the Oracle Worship box and network feature will reset your network adapter connection temporarily. That's fine. Proceed 10 and stole. Do you want to allow the following program to run since installed software years? Would you like to install this device software from Oracle? Yes, if you notice quickly. This created a quick desktop shortcut on your desktop. It is trying to install another device software That's fine. Click Install. Just going to say, Always trust anything that's coming from Oracle Corporation and just click on install. So this week it's not gonna bother me again. And there you go, Oracle be impartial. Box installation is complete. Click start Oracle of Urschel box after the insulation. Yes, you could leave the check box cook finish and is Cancel this man Dairy go! That's the first welcome page off the wardrobe box. And that's where we have actually completed the installation off the warship box from a hair on you could build, create a new wardrobe machine. And once we create a new washing machine, we will install Lennox Santo s operating system on that washing machine. 15. Creating First Virtual Machine: creating virtual machine. In this lesson, we will create our first social machine. And on victory will be installing are sent OS clinics operating system. But worker machine is basically nothing but a shell. Ah, container, which holds the information off a machine CPU memory disc and all the resource is this fortune machine is gonna be sharing. The resource is wherever it is installed. So let's say if it is installed on my laptop, it will be sharing. The resource is from a laptop, the Oracle work show box. I'm gonna open it up. Okay, so this is the window for the Oracle Horschel box. I'm gonna click on new. The name I will pick is my first Lennox, the M. And if you notice, um, the virtual box is smart enough to OPEC, the operatives, his assistant type and version for you. You probably noticed that you are going to see the 64 bit. You are probably seeing 32 big. Now, if you are seeing a 32 bit, then either your computer is 32 bit architecture or the virtualization technology is not enabled. First, let's find out if my computer is 64 or not. So let's go to start menu computer. I'm gonna click right click and go to properties. Once the property comes up, you will see here it will tell you if it's Win seven PC and right here you're gonna see or is this system type? It's a 64 bit operating system. So that's one way. That's one of the reason that when I'm building my worship machine, it is coming up 64 bed operating system. The second reason you might not gonna see it 64 is if you don't have virtual technology enabled in your bias sitting. If that's the case, I have actually pasted an article and in my in this lesson and there is a link to it, I would recommend that you could go that link and try the settings that are recommended and see if it changes the 64 setting. I'm sure it will work. If not, you will always email me back. So I'm gonna leave thes setting sugar click next Now here is gonna ask me the size off the memory I want to assign to this virtual machine. Now, by default is picking up one gig off memory now, you should also keep in mind How much memory do you have actually in your laptop? So in my laptop, I have Let's look at my computer again, Right? Click properties, and you will see here. My computer has installed memory is four gig. So it is. It is wise that I keep the memory below that digit. That number. So I have four gig, so I'm gonna give one gig up that memory to dis virtual machine. I'm click next, create a new Horschel desk. Yes. It will create a brand new Horschel disk. Next, leave the default dynamically allocated. Lee the default post. Um then this is the size of the disc. By default, it picks a gig. I wanted to pick 10 gig just to be safe. So I'm gonna just click inside this box, remove and type 10 and click create. And there you go. This is my first worship machine that is created again. Think off it as a piece of hardware that's been created for me. I'm on the assembly line. I'm putting the CPU and putting the memory and putting the hardest. I'm putting everything in that machine and I built a machine. So once the machine is built, what is the next step? Next step is to install the operating system, and in our course, we will be working with Santo s up a ring system. So I'm gonna power this on, and I'm gonna install the operating system. But of course, before I go ahead and install the offering system, I do need the software ISO image. So in the next lecture, we will cover how we're going to download the IRS. So, software, and then how you could attach that software to this Lennox of'em, and then we will boot off off that software. 16. Linux CentOS Installation: Hello and welcome to sent OS installation. This is the fun part. Yes, this is where we going to get our hands dirty. We gonna go ahead and download the center Will s I s O image file from the from the Internet. Once we have it downloaded, then we will go through the installation. A complete installation off sent OS Lennox operating system. So you ready? So now I want you to go ahead and open up your browser. Any browser that you prefer, whether it's ie, Firefox or chrome. So let's go in. I have my browser open already. Um, I will go into Google now. The second step is you could use Google or any search engine that you like and I want you to type sent os download and hit Enter. Once you hit enter, you will get the first length I want you go and click on it. Or you could simply go and click on download. But first, let's go to this first link. So in the first slink or the first page, you will see download Santo s Now, Sometimes you will see three options in this page. One is a DVD. I s o second one is everything DVD I eso and 3rd 1 is minimal. I s o If you are seeing three or if you're seeing too right now, it doesn't matter because what we need is DVD. I s so this is the one that we need to click on. So go ahead and click on DVD. I So this will bring you to the links where the eyes are. Images are saved. So all those links are actually the links to the servers or they're often time referred to as mirrors. These mirrors, when you click on it, will take you to the file where the file location is. So go ahead and a pick Anyone off your choice over recommend that you pick the 1st 1 So go ahead and click on the 1st 1 Once you click on the 1st 1 it will ask you or prompt you to save the file. You have to save the file. Ah, to you to the locations so going. Click. Okay, if you do not know where the file is being saved, you see this little arrow here? If you are using the, uh, fire walks, he will see this little arrow here. Click on it and it will tell you that it is being downloaded. Right now. I do not want to download because I have already downloaded that file previously because I don't want to waste time, your time and my time to go through the company download. So let's minimize this page. Let's go to a desktop because all my, um, downloads go into my desktop now. You already have this center west. Okay, Now, I want you to go ahead and click on a double click on your Oracle War Troll box. The icon you have on your desktop. If you do not have that icon, your desktop, then you go to start menu and find that up and you will go ahead and start from here. When it opens up, you will see the my first Lennox for Lennox PM. The one recreated earlier. These two You're probably not going to see it because I was playing around with some windows. Were for machine anyway, it's just you could just ignore them. Um, click on the first, my first Linux VM and click on start. Now, this is powering up yours from machine. This is exactly the same way as if you powering on your physical machine, but pressing the button on it. So now it is asking, since this washing machine has no operating system, so by default is asking you to attach award actual disk to it. So it is asking where is the location off that were actual disc, which you want to install that operating system. So go ahead and click on this little icon which will browse us to our desktop where we have our eyes. So image safe. Click on this one, and you will see right here on our desktop folder. When you click on our desktop, you come down and you will see right here say, Santo s seven, which we have downloaded Ah, few minutes ago. So go ahead and click on open and click on start. Ah, by the way, this top thing right here is telling you have option to capture key ward option. Turn on. This will cause the upper virtual machine arm of the capture. You could just go ahead and cancel it. Now it's telling you at this green is selling you. This is a cent or seven installed center or seven. Test this media and installed center a seven, or do the troubleshooting right now by default. Test this media and install center. A seven is selected. You do not want to test this media. Usually this option is picked when you have a DVD install and the reason we do the test because sometimes the DVD have scratches on it. That's why we wanted to go through the test. So since this is I saw image. We don't do that. So go ahead and hit up arrow key on your keyboard and it will select or highlight the top one. It's State installed Cento a seven and now go ahead and hit. Enter It is actually bringing the eyes. So image copying the files that are needed to actually install the operating system so it will go through certain start up processes. It will start up the gui that will allow us to go through the installation off the lyrics Center s are bring system. We will give it a minute for the going to come up. See right here says starting installer one moment and installer. The Gui itself is called Anaconda. This is a name they have given Why? I don't know, But this is the name If you want to keep in mind Um you just remember that anaconda is the Gui tool or degree Viz erred. That will help you to install the Lennox offering system. Now you are under welcome to Cento a seven. Ah, welcome page. What language would you like to use during the installation? Ah, by default English and I'm in the United States. I'll pick English United States if you are in any other country. Ah, we recommend is you pick that country or if you want to pick a different language, you could pick that. However, I am not going to tell you how you could go through the installation with different language anyway, So I support for that. You stay on English and then you definitely you could pick a different country. Now go ahead and click on. Continue at the bottom. Right. Okay, so now it says, please complete items mark with this action. This icon before continue to the next step. Now the date and time is the 1st 1 we have already pre selected America's New York Time zone. If you wanted to change the time zone, depending on which times of your and go ahead and click on it and change the time zone keyboard by default. It selects English and U S um language support a gain. English United States installation Source. Local media, Which means that we are installing the operating system through the local Aiso image, so it's already been selected. Perfect. Next stop software selection. This is where it has by default the software selection as minimal install. If you leave that as is minimal installed, then it will install the lyrics operating system, but it will not have any gooey on it. Well, remember one thing most of the time. Incorporate Marmon. There are no gooey on Lennox, but since we are going through some practice, we will go through some GUI practices as well, because I do want you to know how Gui works in Lenox as well. So we'll go ahead and click on software selection, and that's where we will pick um, a couple of different additional software that are required in the middle installed. Ah, we have other options as well. If you want to use system administration tools are any other tools you could pick them. We could leave as default. Compute nodes, anything. Any debugging tools, directory clients, hardware monitoring tools, development tools. Most of these tools are used by developers. Since we are not going through the development training, we we will leave that. As is infrastructure server. Ah. What type off server are we going to run on this machine? I will tell you you could pick, um, anyone that you think you might need it later on. Um, you could pick the d n a server for now because we are going to core DNS, which is bind in this training so you could pick DNS if you do not pick Deanna Sarah this time, there is no issue. We could always insult the in a server or package later on, but anyway, just to show you how it works, I just selected one DNS name server. Anything else that you want to select here? You could. If you don't want to just follow my lead, then let's go to the next one says file and print server. You could leave everything as is a said basic Web server. You don't need it. Work authorization hosts and no several with Cool. Yes. This is where we have to come in. And if you notice as you are going down, all the other options that were available on the base environments are actually added here as well. So don't worry about it. They're repetitive. It's not that this option will have a different d n a server and with this based environment. So right now we are in the server with Gui Environment. I want you to go down and pick um que d e which is Katie easa. Plasma workspace are highly conferred with graphical user interface. I also want you to pick Java platform because if you are running certain application that requires Yaba, we could bring that up. Um, that see what we have? You have all the virtualization tool. Um, okay, I think we are good hair, but the Katie eat now The next one is genome desktop now Genome desktop are the ah, the desktop that also per wide some type of applications. Um, for the user, let's say if you want to use Firefox or if you want to use, um calculators or something on the gooey side, then you could select this. That stop as well. So go ahead and click on genome applications. Um, any other tools we need Internet application, email, chat, video conferencing software. We don't want that because most likely incorporate environment. You will not be using any of thes Katie plasma workstation workspaces development and creative workstation, and that's pretty much it. You don't really need any other applications or add ons for the selective environment. Now go ahead and click. Done. Now you will see this option right here. It will tell you checking software dependency. It means it is going toe our ISA image and asking that isa image. Hey, this user has selected thes these many packages. Do you have these packages for me to install on this harboring system is going to say, Hey, okay, no problem. Let me go ahead and check that. So it's checking the source, and it's checking the software dependency as well. So what is needed for those add ons that we need to install installation destination while it's running will go to the next one. It's his installation destination now. How do we want to protection our disk and solution destination right now? Says automatic partitioning selected If you want to change that? Meaning Right now, we have 10 gig. This is the discus size that we selected when we were creating the worship machine. This this size has shown up here is telling us we have 10 gig of disk space. How do you want to partition it? We're telling it automatically configure the partitioning if you know, or if your organization has a requirement to partition a disk into different slices or different partitioning than you will go ahead and click on. I will configure, Petitioning. Now, go ahead and click on. Done. Next one is K dump. Que dump is enabled If something goes wrong, K means Colonel, if there is something wrong with your system Ah, Colonel is going to write some messages, um, logs that is often referred in Lenox language as a dump that is enabled. So it's always a good practice to leave that enabled. So this way, if you are troubleshooting with your vendor, let's say if you have cento us red hat involved, they could go at and take a look at your logs. Next one we have is networking and host name. Okay, you We are on a network and host name configuration. At the bottom, you'll see Host name. Go ahead and highlight what we have right now and hit, delete and type in the host name off. The Lennox operating system will type the same one as we picked for R V M my first Lennox VM and click on Apply as soon as you click on apply. You'll see the current host name was changed to the host name that you have picked. Now the second thing is to configure the even it. Now, remember, by default if your machine or the washing machine, this is your washing machine. If it is running on a PC that has one gig, often network port, it will show up here as beat one gig, and right now it is showing its wired for me because I have selected or I are my machine where I'm running this worship machine is wired, so go ahead and click on configure and by default it will show up The tab as Ethan at E E and P zero s three is the name off our network adapter. So we'll click on General and we click automatically connect to this network when it is available that arrest of this setting is blacked out by default. You could leave as default I PV before setting is the setting for automatic DCP. If you want to assign an I P, then you would have to change it to manual. But we want the I P to be assigned automatically. So if you leave it as is I'm the last one is i pp six settings. We don't use that right now, so go ahead and click on safe. So once you click on save, you will see its tells you automatically connected. It is given an I. P Already. And now you could go ahead and click on Done. Okay. And so our network and host name has been configured. Now, the last part is security profile. No profile is selected. You believe that as as unless your organization has a specific procedure to put in place for security policies, then you could define it here. But for now, you could just leave as is, and go ahead and click on begin installation. Once you click on begin installation, you will see at the bottom. It will start creating your your partitions. That were selected that you ask the system to select it for you. Now it's going to starting package installation process. While this is going through the package installation, we have to, um, uses settings to define. First is root password. So go ahead and click on root. Password is not set. And here you would have to put in the root password. Pick anything that you you will remember if you notice I picked a week Password. You should pick a strong password if you are, Um, if you're working for a company or for you or an organization, But if you are just following my lab or you're doing this everything as a tutorial, that is fine. You could pick a week password. However, if you notice at the bottom it says the password you have provided it is weak. The password fails. The directory check. It is based on a direction dictionary word which you will have to press done twice to confirm. So okay, I understand it is a weak password. In order for me to keep that password, I have to press it done twice. One to now it has taken that weak passwords, user creation Let's go ahead and create our first user. Full name. Let's put in our first name by default. Lennox takes the first name as the first letter. First initial last name is complete. Last name. So for me, the user name will be I of soul. Keep your user name shorter than 32 characters and you do not use spaces. That is fine. We are not using any spaces were wholly using six letters. Make this user administrator. You could lead that out. Requires a password to use this account. Yes, the pickup password. Again. It is weak. I understand. And I would have to do the same thing Done twice. Okay, it is done. Now if you come down and you notice right here it The operating system is installing or this Viz erred is installing packages for this offering system. Total number of packages that are required to be installed are 1397. You might have a little more or a little less, but that's okay. It depends and it changes over time. What other packages are installed? Water. The dependencies aren't still so again, If your packages do not match with my packages do not panic. You are. Okay, so now you'll see it is going through the packages installation. At this point, it is. It has installed almost 400 packages and they're still about ah 6 to 800 packages that needs to be installed. And this process will take. I would say somewhere between 10 minutes to 30 minutes, I am going to fast forward this entire process to save time. Now the packages installation has been completed. Now it is going to some post insulation set up. All right. Finally, our installation has been completed successfully. Now Santo s is now successfully installed and ready for you to use. Go head and reboot to starve using it. Click on Reboot West. Since the system comes back online, it will give you the initial set up page. The first page is about licensing. You have to accept the license. Click Accept license every hman click on done network and host name if you notice. We have already selected this network and host name configuration during our installation so that you don't need to do it again. Click done. And right here says finished configuration. Go ahead and click on finish configuration. All right. Finally, our entire Lennox installation has completed. Now we have to log in the first time, Click on your name or you could also log in as root. If if you remember, you have picked the root password, you would have to click on, not listed and type and using him crude and password. But for now, we'll go in as ourselves and we will put in a password, click on Sign in or had enter. All right, this is the desktop. This is how it looks like in Cento as it is very similar to Red Hat Cento s. You have these icons right here. You can resize them if you want to. You could delete any I conjugal create icon. Um and you could explore other things on the application and spaces. So also, one more thing when it starts up, it also gave you this welcome page. So you just leave as English. Go ahead and click on next typing. If you want to change anything you believe a default location services, I usually keep it off. If you want to leave it on, it's really up to you. Click next connect to online accounts. You don't have to do that clicked, skip, and then start using sent Os Lennox. So once again, congratulations. So now you know how to do the complete Lynn accent OAS installation? If you think that you missed something that I would recommend you to go ahead and delete this entire Lennox, we m and go ahead and create a new washing machine. And do the Lennox insulation again from scratch. The more you do, the more practice you'll do, the more you will learn. All right. Good luck. 17. Welcome to Conceptual Troubleshooting: 18. Who is who: who is who. This is a very basic thing that everybody should know about whenever they start troubleshooting any issues. So, of course, is the one of the basic fundamentals off a conceptual troubleshooting to know who is who. Meaning where the problem is, where the problem is coming from. So first, look at our client any machine that is trying to connect it to another machine. That machine is called a client. When it goes to the other machine to request something, that machine is called the host. You're gonna scare these names interchangeably back and four Klein host server or ah ah, a different type of server that is hosting those services. Ah, you need to make sure what is the difference between each one of them? Klein to talk to the host through many different protocols, which he will talk about later. If the Klein wants to talk to the host. Ah, and wants to access the website, they go through the portal call, which is http and so on many other protocols that is involved. So taken example off like a person who like a regular people who want to go to a restaurant , they go to the restaurant. So for them, the person who's going to a restaurant is a client, right client for the for the restaurant. When they go to the restaurant, they have, ah, host or who actually, there's a seeding host. There's a host who actually comes on the table for the water. There's a hose that comes into and take you in, um, your food information where you like to order one? Not so you see that that restaurant is actually serving. Use of the restaurant in this case is ah, host and the person who's requesting is the client now coming back to our I. T World will look at client as someone who's a requester, where the with a call goes from A to B. It's a request initiator who actually initiate the connection to the whole server and, of course, in a regular way or regular simple language. A pair, someone who is actually, for example, if you have a computer you want to go to Facebook, what do you do? You actually open up a browser so the browser is kind of a client, Ah, platform that allows you to connect to the host and the host has what? It's a server. It's a running of that server. It could run NFS DNS. Send mail or any kind of application. That is the reason you connect from client to host, right? Otherwise, if you do not get any of that information, or if you are not, um, trying to access some of the information online, then why do you actually need to connect to the host to begin with? Right? So that is why every time a request is initiated from plying to host, remember that there's a client that actually has some type off tool installing in it. For example, if you are trying to connect to the Windows server, you would need Rdp Klein. If you're trying to connect to a lyrics machine, you would need an ssh or pretty client. So you do need some type off tool to connect from Clyde to host, and the reason I include a pair here is because if you are, let's say, connecting to a DNS or NFS. There are companies, of course, who charges you for storing your data. For example, one drive. They have to give you some Dr Space to keep your files and they charge you for that. So in that case, you become a pair and they are the server. So this is what you need to remember in who's who. This thing will serve you a lot. A lot, A lot better down the road. If you have this concept clear, then you're become a proficient in troubleshooting any type of issues. Sounds good. 19. Cannot Access Server: cannot access server now this is the most common issue that every system administrator or engineer half face Orville face sometime in your life. And I would say not just some time. But these are the type of issues you will feel. It's almost like every day or every week. So what happens when you pick up a phone or get une email from someone saying, Hey, I cannot access over a orcs that ruby? So how do you resolve with so the first things before you start? Before we start getting into any technical type of issues, we have to ask ourselves some of the common sense or conceptual questions. And there are three things that you need to keep those things in mind. One. You need to know the source. Always ask whoever is, um asking you or whoever is complaining that the server or they cannot access the server. You need to know from where they are trying to accident from two. That would be a source. Second thing you need to know is the target or the destination server. So from where to wear they're trying to go to, and the third thing is the pro coal Like which protocol are they using to connect from source to target. And those poor a call. A few of them. An example that I have listed here are ssh SCP FTP website, NFS s