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Hackers often need to move process, and an operating system like color is ideal for this.

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The hackers maybe have a port scanner running while running a vulnerability scanner and an exploit similar

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to the here.

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So this requires that the hacker managed his processes efficiently to based your system resources and

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complete the tasks.

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In his lecture, you will show how to manage multiple processes.

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So changing processes priority with nice.

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You don't often hear the word nice used in the context of hackers, but there you will.

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So the nice command is used to influence the privacy of persons to the kernel, as you saw when we ran

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the P.S. command.

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You're.

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Yes, comment here.

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Uh, numerous numerous businesses run on the system at once and um.

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And all of them are contending for available the resources, the colonel will have a final say over

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the priority of princesses.

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But you can use the nice and nice to suggest that the princess should be evaluated in priority.

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So the idea behind the use of the term nice is that when you use it, you are reminding how nice you

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will be.

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Others and users if you is using the most of the system resources, you know, and it's being very nice

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device from nice range from minus twelve or twenty to plus nineteen.

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So which are being the default value here?

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Yeah, so.

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So if.

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Bold.

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Zero, you.

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So.

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A high nice value translates to a low priority and a low nice value translates to high priority.

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We are not being so nice to the users and other users and processes, so when a person is startled,

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it inherits the nice value of its parent process.

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So the owner of the process can lower the priority of the person but cannot incur its priority.

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Of course, the super user route users can arbitrarily set a nice value, whether they please.

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So when you start in process, you can set the priority level with a nice command and then after the

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priority after the process has started running with the really nice comment.

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Really nice.

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Very nice.

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Yeah.

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So once absolute value for niceness.

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So let's look at an example, demonstrate this.

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So for demonstration purposes, let's assume we have a person's name, slow process that's located in

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this scene at being slow process here.

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So if you want it to speed up its completion, we called start the process with the nice command here

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in nice minus and minus 10 being a slow process here.

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We shall use of pseudo rights here.

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And enter your password here.

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So that personal such files.

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Yes, because this is just an example here.

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So the command will increment on nice value by minus 10, increasing its priority and allocating it

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more resources.

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On the other hand, we want if we want to be nice to our fellow users and profile cases and give slow

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process and lower priority.

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We called increment.

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It's a nice value positively by 10.

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Ten.

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So give you this trial process you have currently training under John P is to see how it changed and

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if Donald.

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So Changi Airport, the training, the priority of running processes with three nice.

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So.

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The very nice command man takes absolute values between minus 20 and 19 and sets the priority to that

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particular level, rather than increasing or decreasing from the level at which it started.

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In addition, Regeni's requires the process I.D. of the persons you are targeting rather than the name.

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So if the sort of person is using an inordinate amount of resources on your system and you want to give

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it a lower priority, there's allowing the other processes in higher priority and more resources in

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poultry.

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Nice slow process, not by name, which is, for example, but the processing of, for example, six

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nine nine nuts, for example, ranges 12 to six nine nine nine six, for example.

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This is the process name, for example, but it's a six, nine and six.

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So as with nice only the root user kind of arena as a process, as you can see, followed until you

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get priority.

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No such process here, but we can use.

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So the simplicity of the search process here.

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So actually, it's nice.

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The only root user can realize a process to a negative value to give it a higher priority.

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But any user can be nice and reduce it to a priority.

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It's really nice.

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So you can also use a top utility, uh, talking to a team, uh, to Chengdu.

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Nice value with a top utility running simple press that are key here.

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Uh, it's.

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Let's run it again.

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And simpler, simpler press that are key here.

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And then, um.

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Separately, the process idea.

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Uh, and the nice value, for example, um, if I want to change society of Metasploit era supremacy,

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there is a running.

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Um, near.

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Or just a, for example, sincere and nice with 12, when I settle into an integer because the nice

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thing is maximum, very simple six, eight years.

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So now I will show you the killing processes at times a process will consume way too many system resources,

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except in usual behavior or at worse, freeze up.

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A process that executes this type of behavior is often referred to as the zombie process.

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So for you, you're probably the most problematic symptom that'll be waste, the resources used by the

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zombie that caused but better allocated to use for persons.

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When you identify a problematic process, you may want to stop it with the kill command.

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Here there are many different ways to create a program, and each has its own fuel number.

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So the kill command has six to four different signals.

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So and each does something slightly different.

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So, for example.

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I want this here in Mouse Pad Notepad here, so cignal name, for example, I'm the most important signal

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names.

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So if you don't provide a signal for luck, it defaults if you don't provide proof of space or if you

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don't provide a signal flight, it defaults to C term.

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So we have a signal name, and I want created here so, so sick hump, for example.

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So you can now name.

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Name, uh, number or auction and description.

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You're so sick up here, no of auction is one, so, uh.

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And hand signal signal, so it stops the disc.

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The signal, if the processes and the press starts to do with this same process idea restart.

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Same process I did.

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So it starts with the same society.

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So we have segued into 30 years in an into interrupting, not the director and a number of options to

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him.

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So this is the interrupt single intel wrapped signal.

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So it is a weak signal that it's current year to work, but it works in most cases.

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We signal.

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But what's actually?

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The math works here, so we have a SIG.

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Appear as number of option is three.

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So this is known as the kurdum core number.

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Here it is.

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The processes and saves the process information in memory and then it saves this information in the

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current working directory to a file named court.

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Decisions for doing this are beyond the scope of this course, so but you will learn in later lectures.

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And so we have a 10 here.

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No of is 15, but this is determination and tender and termination signal.

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Um, it will it.

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Which is the cue in the phone signal signal.

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Here.

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It's.

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Yes.

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And last night, I want to show you, is he killed?

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So he kill.

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He's using no for option nine.

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So this is the absolute kill signal.

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So it forces the process to stop by sending the process resources to a special device, the not absolute

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kill signal.

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And, uh, so very serious here and now.

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Using the top command, you can identify which processes are using too many resources.

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Often this process is willing to give it and they get to it.

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But there are.

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I mean, there may be malicious processes taking these sources that you will want to kill here.

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And let me look at our lecture time here.

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So, uh, if you if you just want to restart the process with a whoop signal, enter the minus one option

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with Q here, for example, peel minus one kill minus one.

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Actually, let's use this kill Metasploit here.

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Let's find this Pierce, Alex, here is the matters played here.

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Metasploit, Metasploit, Metasploit.

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And that's fine, that's great.

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Here he is out here and grab a massive console here.

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So the our society is one thousand nine hundred seven.

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So we can kill it with that.

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Actually, it's probably one thousand six hundred seventy one, so keel minus one, one thousand six

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hundred seventy one.

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So you can see here our Metasploit is killed.

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Clearly, in the case of the zombie or malicious process, you likely want to send this clear signal

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nine So this is this is the absolute kill signal, and it's very serious.

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So with this kill minus nine and.

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Process, name, process, idea.

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Like that, but good morning, this one here.

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So if you don't know the president's idea, you can use the kill all command killall command to kill

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the processes.

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This command takes the name of the process instead of the process idea as an argument.

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For example, kill all minus nine.

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Uh, zombie process.

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That's not a racist font.

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Uh, so finally, you can also terminate the process in the top comment here, simply press that key

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card key and into the process.

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I'd like that.

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So I will, uh, cause this year so.

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And we can run Linux.

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Run in background of Linux as well here.

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Uh, so.

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Actually, how many minutes we have, so I have it and you will learn this in the next lecture.

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So I'm waiting here in this lecture.