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Hey everyone and welcome back. Now in the previous nugget we had talked about a forward

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proxy. Now what I want to do is to talk to you about a reverse proxy. So really when

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we're talking about a reverse proxy versus a forward proxy we're ultimately talking

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about which end of the transaction is using the proxy. Now that might sound a little bit

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strange but just think about what we talked about. We had our server here in the original

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example. You know we had our client here and we had our forward proxy. Now ultimately as

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it transpires in this transaction both the client and the server are talking to the proxy

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because the client makes a request to the proxy and the proxy makes a request on the

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client's behalf and then the server talks back to the proxy with the response and the

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proxy passes that back. Now in the case of a reverse proxy the same type of thing is

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happening i.e. the client and the server are both still talking to the proxy but it really

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is all about who is configured to use the proxy directly. So what do I mean here? Well

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in this transaction here of the forward proxy it is the client that actually has the proxy

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setting so it is the one who is really forced into using the proxy. The server's participation

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in this transaction is kind of incidental it's because the client was configured to

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use the proxy and the proxy has given the server a request. Now with respect to a reverse

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proxy things are a little bit different. Again we have our proxy in the middle here but this

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time it's actually the server's configuration that is directly pointing to the proxy. So what

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this means is that when a client wants to make a request to a particular server it's got to

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make this request via the proxy itself. So this is why this can be a little bit confusing it

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almost looks like the same thing a client and a server are ultimately talking to each other

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and they're talking to each other via this middleman the proxy but like I say here in the

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case of a reverse proxy it's actually the server who has all the configuration files which are

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pointing to the proxy and with respect to a forward proxy the opposite is true it is the

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client which has all the configuration files which are pointing to the proxy to initiate the

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transaction. Now with respect to a reverse proxy this is very useful for things such as load

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balancing which ultimately promotes efficiency and performance. So really a reverse proxy is

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really very useful when you happen to have a popular and very frequently accessed service

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because if you just happen to have one server here and you had a whole bunch of people out on

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the internet whatever it may be all making lots and lots of requests to your server let's maybe

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say this server belonged to Amazon so lots of requests going into this server this one server

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could quite easily understandably get bogged down and ultimately you'd have a denial of service.

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So instead what you can do is you can present a proxy server to all of these end users so they

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make a simple request and they just talk to the proxy server and behind the proxy server you

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could have a cluster of these servers who are all configured to use this reverse proxy. So that

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means once the request comes in the proxy just relays that to another server within the cluster

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and that means we're now actually spreading out these transactions over different servers all

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hidden behind the same proxy server so no one is getting overloaded the load is instead being

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balanced across different servers and of course the actual backend servers here are not directly

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exposed to the outside internet say for example instead we're only exposing the proxy to the

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public or to another network and another big thing with respect to reverse proxy servers is

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caching if one user here happens to make a request from a particular server let's say this one here

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let's maybe say it's some type of graphical image that graphical image could be stored locally as

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cash on the proxy server so that when another user makes the same request the information is

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cached and quickly accessible and can be returned back to this user without having to bog down any

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of these backend servers making the same request again so this is really going to lessen the

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burden on these backend servers as well as improved performance from the perspective of the client

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who's going to receive that information really really quickly now with respect to reverse proxies one

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solution we want to be looking at is something called engine x now engine x is really really

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similar to Apache remember this was our web server we looked at recently but engine x is kind of seen

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as a more modern implementation of Apache it's a little bit more focused it's a little bit more

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lightweight now the details of comparing engine x and Apache is not actually within the objectives

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of the lpik 2 examination but understand that engine x happens to be a very popular solution

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to be configured as a web server and as a reverse proxy so let me quickly walk you through how we

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can actually install engine x and point out some of the basic configurations so what we'll do here

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is i'll just first uninstall my Apache 2 service for now so cd back and i'll just say sudo apt

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remove apache 2 and i'll type in my password okay so now i no longer have any web servers on my

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ubuntu machine i'm now going to install engine x i'll say engine x hit enter and i'll say yes now

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with engine x installed we're going to see that we have a main configuration file so now what i want

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to do is to open up my engine x configuration file this is any particular location that you do want

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to be remembering it's in the etsy directory within our newly created engine x directory and the file

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itself is called engine x dot conv if i open this up we're going to see here this is the main

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configuration file now one thing you will notice with respect to engine x is that we have a lot of

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crossover with what we saw with apache so let me just briefly show you what that is say for example

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if i go into etsy engine x and i do an ls you'll notice things such as sites available and sites

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enabled similarly to what we saw with apache if we go into sites enabled we're going to see a bunch

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of sim links which ultimately point to the sites available directory same as true with respect to

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the modules enabled directory which points to configurations within modules available we have

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a lot of crossover here with respect to these two solutions so what you learned in apache a lot of

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it is going to be irrelevant and applicable here now one thing to note is that just like with apache

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too we can also look in our var directory or ww directory as well as html and if i do an ls we

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can actually see here i do have an engine x file this is like my index dot html in fact let me just

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remove my index dot php that was what i had for my apache server and i'll just move this one and

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just call this index dot html is so you'll notice here we have a bunch of html this has got some

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default formatting relating to engine x nothing special here again it's just plain html but notice

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now with this actually installed if i say sudo system ctl start engine x and i say sudo system ctl

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status engine x we can see the web server engine x is running what i can do is i can go to my web

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browser so i'll type in my local ip address of 192.1680.44 and we are now accessing our default

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engine x html page now one thing you might actually notice is that depending on your system as opposed

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to looking in this directory here for this particular file instead your engine x server

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may actually be configured by default to point to this location here which would be the user share

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engine x and in here you may have an index dot html file within here so just understand that depending

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on the installation there might be a little bit of variation there but now like i say engine x can

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be a web server as we see here but we can also configure it to act as a reverse proxy now the

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configuration for the reverse proxy is actually very very simple and that is the good news so what

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i'm going to do here is i'm going to try to clear my screen and i'm going to go into that

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configuration file i talked about earlier so that's etsy engine x and i'll go into engine x.conf in fact

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i need to go in and use an editor there we go engine x.conf hit enter and what i'm going to do here

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is if i scroll on down i'm just going to add some new configurations so i'll just use my

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hashtag to just maybe give a description just say my reverse proxy settings again this is just a

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comment nothing special here and i will go in and i will use the keyword server and then a curly brace

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and then within the curly braces i'm going to say lesson on port 80 and then i will have my semi colon

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so then i'm going to see a location and then i'll say forward slash the point to the root

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directory and then i'll open my curly braces and then i'm going to use this very particular keyword

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proxy underscore pass this is something you want to be remembering and all i'm going to do here

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is to specify the location of the remote ip where i'm actually going to be acting as a proxy for

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so i could just say http and then whatever the ip address may be of who i'm actually proxying with

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let's just maybe say 192 168 0.100 or this could be a domain name such as ipv0 blah blah

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dot com whatever it may be whatever the server happens to be so i'll just add in some

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address of some non-existent server let's just say 192 168 0.133 and then i want to close my

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curly brace and then again one final curly brace oh and i've just noticed something very very important

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after you specify your proxy pass server you absolutely want to be ending that statement

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with the semicolon once again and really that is all there is to it it's just this small little

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section here that you see right here that can allow us to set a reverse proxy configuration now of

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course there are way way way more things that we can modify and configure and do with our engine x

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server but for the purposes of the objectives within the lp2 examination a very simple configuration

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as we see here is all we have to understand and recognize for the purposes of the examination

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ok doc so that is us for our introduction into reverse proxies and engine x i hope this has

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been informative for you and i'd like to thank you for viewing