ufw Configuration
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Course
Difficulty
Intermediate
Video Transcription
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>> Hello Cybrarians, welcome back to
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the Linux plus course here at Cybrary.
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I'm your instructor Rob Goelz,
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and in today's lesson, we're going to
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do some ufw configuration.
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Upon completion of today's lesson,
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you're going to be able to understand how
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ufw implements firewall configuration.
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We're going to use the ufw command to modify
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firewall rules in our demo at the end of the lesson.
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Ufw is the uncomplicated firewall.
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It's also sometimes called
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the Ubuntu firewall because it's
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the default implementation for firewall in Ubuntu.
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Like firewall, the ufw is
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just an interface a net filter,
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remember net filter is what does all the heavy lifting
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when it comes to dealing with
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the firewall stuff in the kernel.
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Now for ufw default policies are
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found in etc/default/ufw.
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But we can also set custom rules.
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Custom rules are set up in the etc/ufw directory.
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Now one of the nice thing about ufw rules is that they
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don't have to be reloaded
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and they are persistent by default.
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By comparison to IP tables and firewall D,
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we don't have to save anything soon as we set
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a rule in ufw is good to go is persistent.
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We don't have to worry about it getting lost on reboot.
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Now the ufw command is
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what we actually use to work with ufw.
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By default you ufw is disabled.
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We actually have to start and enable
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it using ufw enable command.
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Keep in mind here we're not working with system CTL.
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Ufw has its own thing.
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It has its own control commands.
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Ufw to start,
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enable, we can do ufw to disable,
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ufw that's going to stop it and disable it
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just like enable starts and enables.
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We have reset which completely clears the boards.
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It disables the ufw,
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it stops it, and it clears out any and all rules.
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That's an optional last resort.
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You're going to be reloading rules if
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you run that or we could
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do ufw reload to reload the firewall.
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We can also do ufw status
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to display the current firewall state,
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and it will also display any
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>> kinds of rules that are put in place.
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>> Talking about doing rules,
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in ufw there's actually called policies.
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We create or modify ufw policies.
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We can allow one by doing ufw allow and then
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providing identifier like a name
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of an application or a port.
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We can do ufw deny to deny or drop packets,
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and then we could do ufw reject to reject
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packets and provide a message
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back as to why they were rejected.
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Let's have a look at all this with some demo time.
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Here we are in our demo environment
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and the first thing that we're going to have to
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do is a sudo ufw enable.
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When I type in my password this is going to
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go ahead and start and enable the system.
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Let's try that again. There we go.
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Firewall is active and enabled on system startup.
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Now, this is running and when we
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reboot we won't have to worry
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>> about this getting cut off.
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>> It's going to keep running.
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Like I said, we can see
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>> that we have enabled by default,
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>> by doing sudo, ufw status.
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We can see the status is active and we
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also see some rules that are in place.
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On this particular system,
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we have 80 TCP and engine X setup.
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Basically, it's just a web server. Well,
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let's go ahead and allow ssh.
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We're going to need ssh if we want
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to land on this thing remotely.
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There's sudo ufw allow ssh, and that's added.
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Now we can do a status and we'll see that this
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is active and is provided here.
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Now if I were to reboot from
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here, it would just come back up.
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It's persistent, we don't have to
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save anything. We're good to go.
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Now, let's see the new status
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and also get verbose output so we can do
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a sudo ufw, status verbose.
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Now we can see a little bit more information.
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We can see information on the default settings.
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We can also see the actions.
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Give a little bit more detail,
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and we can also see that there
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are some more information on the port.
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Instead of just seeing engine X fall, for example,
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we see that that means that it's enabling
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ports 80 as well as 443 across TCP.
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We can also see that any rules that have been
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added by using another command,
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let's clear our screen first.
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I'm just going to type clear. You can also
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do Control L to clear your screen.
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I'm going to do sudo ufw show added.
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These are the added rules that have just been added.
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We can do ufw status to see all
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of the running firewall stuff,
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but these are just the specific rules that are there.
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We can also see these numbers.
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We could do sudo ufw status numbered.
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Now we can see the numbers of the rules.
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Now, this is helpful because if you want to
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delete a rule by number, you can do that.
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Use sudo ufw, delete.
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and we're going to say six.
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We're going to say yes. Now if we run another status,
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we can see that we only have what we started with here.
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We've deleted our TCP version 6 IPV6.
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If he wanted to, we could also delete three.
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Now we'll see we're back to where we started.
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We only have the web server stuff
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and nothing else. That's it.
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With that, we reached the end of the lesson.
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In this lesson, we covered how
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ufw implements firewall configuration.
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Remember etc/default/ufw
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>> is the default policy location.
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>> We can also set custom rules in etc/ufw,
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and then we can also use the ufw command to
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create and modify firewall rules.
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Thanks so much for being here and I look
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forward to seeing you in the next lesson.
Up Next
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Dynamic Rule Set: DenyHosts
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