Proxy Server (Demo)
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Video Transcription
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>> Hey Cybrarians and welcome back to
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the Linux+ course here at Cybrary.
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I'm your instructor Rob Gail and in today's lesson,
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we're going to be discussing proxy servers.
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Upon completion of this lesson,
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you're going to be able to understand why
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proxy servers are used and we're going to
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install the squid proxy server role
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in both CentOS and Ubuntu.
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Proxy servers are anything that really stand between
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a client that is trying to reach a destination server.
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They can be used for a lot of different reasons.
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They can monitor network traffic,
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they can also filter traffic based on content.
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They can block certain websites.
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They can block website access to users.
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They can bypass filters.
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Their traffic appears to be coming from
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another system or network and then finally,
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they can also cache static data to improve performance.
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If you're constantly going out to a website,
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it doesn't make sense to constantly download
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the data when you can cache any kind of
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static data on their website
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and just get it from the proxy server.
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Now there are two different proxy servers in use
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today and they are Squid and the NGINX web server.
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We've looked at the NGINIX web server in
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the previous lessons but it can also
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be used as a filter or a caching web proxy server.
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That is another very common use for NGINIX.
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Today we're going to be working with Squid.
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A proxy server gently
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work on web traffic but they use ports like
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8080 and any non-registered port
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can be used as a proxy port.
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What you'll see in Squid is it actually uses Port 3128.
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With that, let's go ahead and
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install Squid with some demo time.
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Here we are in our demo environment.
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In order to install Squid, we're going to do a DNF
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install Squid on CentOS.
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It's going to give us the option.
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We're going to go ahead and accept all of
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the packages and dependencies that
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>> need to be installed.
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>> There we are. We've installed Squid.
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Now we can clear our screen or hit "Control
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L" just to get some more screen real state back.
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Then in order to get this running,
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we do a system CTL enable dash dash now on Squid,
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the Squid package, and that will start and
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enable Squid at the same time. There we go.
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Now we can check and verify
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that everything is up and running by
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just going back and getting a status on this.
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We see that everything is up and running.
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It's loaded, it's enabled, it's active
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>> and it's running.
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>> Good. Off the races. Not quite.
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What do we need to do now?
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We need to look at the configuration file.
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The configuration file for Squid is
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stored in Etsy Squid, squid.gov.
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If we go in this file, we're going to see
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a bunch of good information in here.
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For our purposes, we're going
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to comment out all these rules and
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just to find our own rule just so
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that we can play around with this and set it up.
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That's a little too far down. Let's go
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back up to the top of the page where we were.
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Apologies. There we go.
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I'm just going to go ahead and comment out all of
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these rules and I'm going to add in my own rule.
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What I'm actually doing here is I'm setting what's
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called an access control list or an ACL.
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I'm going to set up an ACL and I'm going to call this,
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let's call this guy proxy network.
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We're going to give it the network that we have which
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is a 1921681.0/24 network.
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We'll call it that. We can
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leave all these ports. These are fine.
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Down here, let's go ahead and change
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the HTTP access that's allowed or denied.
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What we're going to do here is instead
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of using these options,
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we're going to say that we want to do HTTP
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access allow but only allow it for proxy network.
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Let me grab that.
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I have this shared so we can do this real quickly,
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save ourselves some time and frustration.
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Let's go ahead and comment this out.
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What I'm going to do is comment this one out actually.
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What we're going to do here is paste this
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in and I'm going to comment this one out.
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We'll also comment out the name manager
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and then we should be good to go there.
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Now a couple of other things that we can deal with is,
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we can also configure the proxy to
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hide our internal IP address.
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I'm just going to go ahead and copy
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that in and show you guys here.
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We're going to do that by doing this option.
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We forwarded for off that
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>> hides the internal IP address.
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>> Then I'm also going to go ahead and
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uncomment the line for caching.
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If you want to turn on caching,
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we can do that here by uncommenting
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this line and this will set up
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a cache for the proxy server.
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Now that we've done all that, we can
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go ahead and exit this file.
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We can just save, I'm going to hit "Escape,
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colon WQ" to get out of that because we are in Vim.
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Now what we can do is we can make sure that
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this is ready to go by adding it to the firewall.
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Remember, we always want to
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check and see if a firewall is running.
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Firewall D is used here in CentOS.
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You do a system CTL status,
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firewall D, and you can see that it is running.
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In order to update this,
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we can do a firewall-cmd,
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and then we're going to do a dash, dash add,
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dash service,
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equals Squid because it's
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one of the services it knows about.
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Then we'll do a dash,
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dash permanent because we do want this to
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stick and not get reverted once we reboot.
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We'll do a double ampersand.
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We can do a firewall reload as well.
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With the firewall-cmd dash,
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dash reload and that
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will add the rule and also reload the firewall.
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We can see that it's done so.
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The first success is that the rule's been added,
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the second success message says that that has
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been successfully reloaded in the firewall,
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it has been reloaded with the new rule.
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Now let's take a look at this on our Ubuntu system.
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Here we are on our Ubuntu environment.
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If we're going to be installing this in
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our Ubuntu environment, really know the differences.
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We have to use apt or apt-get.
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We're going to do an app install Squid.
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[NOISE] It'll go ahead and accept that.
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Then we're going to see a bunch of lovely progress
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across the bottom there with
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their nice hash words and a GUI interface.
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Eventually, we're going to get
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back our prompt, and there we are.
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We're going to type clear to clear our screen.
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Now, what we can do is we can do a system CTL.
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Let's just do a system CTL status
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on Squid and look at that.
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It's already running, it's already enabled.
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Because remember when you're using app,
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it takes care a lot of that stuff for you.
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It assumes if you're installing something that can be
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installed and enabled to run and started,
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it'll just take care of that and do it for you.
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But we're not quite ready to go.
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Same thing we have to do as we did before,
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we just have to go in here and do vim Etsy Squid,
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squid.conf, it configure this as well.
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That is a lot more information in here, isn't there?
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Yes, it's a ton of information.
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This is the motif
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you'll actually find whenever
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>> you're working with Ubuntu.
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>> They put a lot of information into
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these [LAUGHTER] configuration files.
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Sometimes a lot more than you need.
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I'm going to use the same trick that
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we used previously when we
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were looking at another one
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>> of these configuration files.
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>> I'm going to copy this configuration file
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into a.bak file.
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Then what I'm going to do is use this bash
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one-liner to make it simpler and easier
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>> to read version.
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>> What I'm actually doing here is I'm using bash and I'm
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telling bash to run the command grep to
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grep and remove anything that starts with
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a pound sign or anything that
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has a semicolon at the beginning of it.
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Then use that, grab that information out of
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that file and then put it back
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into the original.com file.
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Now we go back and we actually do
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a vim Etsy Squid squid.conf.
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That file looks a lot more readable, doesn't it?
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Yes. We would have to do the
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>> same thing that we did here
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>> or in the previous configuration file in CentOS here.
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I'm not going to do that because we've already gone and
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done that on CentOS.
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Just to show you the process,
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if we have that file, we'll reconfigure that file.
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What we would deem to do now is
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actually add it to the firewall here in Ubuntu.
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Remember, Ubuntu uses
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the UFW firewall, the uncomplicated firewall.
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What we do is we tell Ubuntu to use Port 3128,
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that is the port for Squid and that's going to be TCP,
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and then we just a double ampersand.
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You have w enabled.
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Really what it's going to do is it's going to run
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this UFW allow command and then
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provided that that works
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properly which is what double ampersand says,
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it's going to also run and enable the firewall.
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Let's hit "Enter" and we can see the rules are
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updated and the firewall has been reloaded as well.
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But with that, that's really all that we need to
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know about installing Squid.
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With that, we've reached the end of the lesson.
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In this lesson, we covered
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some common use cases for proxy servers and
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we talked about installing
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the squid proxy server on CentOS and Ubuntu.
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Thanks so much for being here and I look
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forward to seeing you in our next lesson
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>>
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