Remote access technologies enable secure connectivity to corporate networks from outside locations, with VPNs serving as the dominant solution alongside alternatives such as SSH, VNC, remote desktop, VDI, and HTTPS-based applications.
Remote Access
We have a huge remote work population now. There are a lot of people that need remote access into our networks, more so than ever before, and so it's really important that we have mechanisms in place that allow secure connection into our network.
Dial-in is one of the original ways that we had remote access connections. Let's take a look at just what dial-in would look like. You would have some sort of server, and perhaps it was connected to a bank of modems, and those modems were then connected into phone lines in here. Somebody at home would get onto their computer, which also had a modem, and that modem would dial in to one of these modems, one of these lines, and then make a connection to this server right here. That server then would make a connection to the rest of the network. Therefore somebody who had a dial-in connection then could have access to the rest of the network.
Dial-in had such prevalent use because you really didn't have a lot of other options; the internet didn't exist. But as the internet developed, and as more and more people got the internet, then it allowed us to create some sort of connectivity without using dial-in. You had faster connections. But the one big problem with the internet is that all of the communication that would go across the internet would be insecure, so we needed some sort of mechanism in place to create a secure connection across this internet.
Because most companies and most users now have internet, there's a way to make a cheaper connection and a faster connection between an end user and the rest of the company and get them connected in. But the problem is the privacy part of it: it's going across public lines. So you create something called a virtual private network. It's virtually private, which means that it really isn't private, it's going across these public lines, but you encrypt it, so really only the end devices know what the actual message is going to be. You do this through encryption: it gets encrypted on one side, sent across, and then decrypted on the other side. That creates what we call a tunnel. A tunnel is a connection between these two devices, acting like this device now is sitting on the network along with everything else.
VPNs are not the only way to make these connections, though. You can use something like secure shell. Secure shell uses commands; there's no graphical user interface with it. So it's for if you're remoting into things like servers. If you're remoting in from a machine, you can remote into a server, maybe a switch, something that you'd typically be programming with a command line anyway. So you would SSH into it. A lot of times they're like a Linux box, or like I say switches or routers or something like that, that you would typically be entering commands into, but now you're entering it through secure shell.
VNC, or virtual network computing, is another way to make a remote connection. That could use a graphical interface, so if I'm remoting into a machine I could use a VNC, and then I'd have to encrypt that data to make that connection secure.
Virtual desktop connections are very similar to VNC, it's just a different protocol. Once again, you can use virtual desktop connections to remote into a machine and manage it, and this is built into Microsoft Windows systems, so the virtual desktop is largely used around Windows systems.
What's great about VNC or remote desktop connection is that then you can use something called a jump box. That is, you have a machine on your network that you utilize to gain access to the rest of the network. You'd use one of these remote connections to connect into this box and control it, giving you access to the rest of the network. But what's great is that your machine never actually touches the network. It is only going through to this machine right here, and it creates an extra level of security that way. You're not opening up things like servers to your outside world; you're just opening it up to maybe an internal resource, that's controlled by an internal resource.
Another thing that's grown in popularity is this virtual desktop infrastructure, or VDI. You would have a server and it would be running a lot of different virtual machines, so you'd have these different virtual machines, and then what you would do with VDI is you would remote into one of these virtual machines, which would be on the network, and now you have access to all of the other network resources. It uses things like VNC or remote desktop connection or certain protocols to make that connection, so you can have access to the rest of the network. Now what's great about this is that your machine is never really directly on the network at all, creating an extra level of security. It's really just this machine which is already on the network, and then you have access to control that machine.
One that I think gets often overlooked, and probably is the most popular method, is an HTTPS connection. That is, a lot of apps nowadays just use an HTTPS connection to establish a connection and transfer data. You have a lot of apps that are up in the cloud now, you have a lot of ways of connecting, and you're just doing it through a web app, through a browser. An example of this might be email: we make a lot of connections nowadays through email by bringing up a web browser and connecting that way. So I don't want to overlook that a lot of our services are just hosted through some sort of web application, or making some sort of connection through an HTTPS connection, and we can still get the data without ever touching that network at all. So that's a great way to do it and secure that network at a greater level.
Since I mentioned HTTPS, I might as well mention that there are other protocols as well. There's secure copy, SCP. There's FTPS and SFTP, which is a form of file transfer protocol that is secure; those are actually two different mechanisms of securing file transfer protocol. So there are other protocols as well that can be used. We don't see that as much; HTTPS is one of the most popular.
Because VPNs are so prevalent nowadays and you see them in a lot of businesses out there, I just want to cover a few concepts when it comes to VPNs.
Let's first of all talk about site-to-site. The idea behind a site-to-site VPN is that you've got two networks that you're connecting together, so to make it more like a single network. An example of this is maybe we have our main headquarters over here and then we have some satellite campus. So what we would do is create a site-to-site VPN between these two. Perhaps this has a firewall and this site over here has a firewall, and it's between those two firewalls. So now if somebody came and sat on this network over here and made a connection, they would now have connection to all the resources over here. They wouldn't need to do something separate, they wouldn't need to pull up a client on their machine and make a connection; it would just all be automatic.
The alternative is to have something like a client-to-site VPN, where rather than having another site you actually just have a client that's making a connection. Perhaps this firewall is still the VPN concentrator, that's still what you're connecting to, but you're doing it from this machine right here. You probably have some sort of process that you need to go through to authenticate yourself and make the connection between this client and the server before it considers you on the network, before it actually allows you onto the network.
Most of the time I see this done with some sort of client on the machine. That means that this client machine has client software, a separate program that you get up and running to make the connection and then authenticate through that connection. So this might be like Cisco's AnyConnect or OpenVPN or some sort of VPN software that then creates this tunnel to your firewall. So that would be a client based.
But there is also a clientless base, and that uses other connections. It uses like SSL, or technically it's TLS, to make that connection to the firewall, and you probably do it through some sort of browser to make that connection. The thing with that is it's much more limited with the type of things that you can do. If you install a full client, it's like you're sitting on the network, versus a clientless only allows you to do certain tasks that you could do through a browser. So that is a difference between a client versus a clientless VPN.
One other concept when it comes to VPNs is this idea of split tunnel. So maybe I make a VPN connection into this network right here, so it's like I'm sitting on this network right here. Well then the question is, what happens if I want to access some sort of server or resource that's not on this network right here? A typical VPN would actually send the traffic over to here, and then from this firewall right here it would send it out to make the request of that server or service that I'm trying to access. But a split tunnel allows the traffic that's going to this network to be sent through the VPN, versus the traffic that's going to other resources that are outside of that network to take a more direct path. So it splits the tunnel into the traffic that's going to go to here versus the traffic that's going to go to the rest of the world.
So we really started out largely using dial-in to get into networks, to make a connection into a network. Of course, with the internet coming out, that made it much easier and much faster to connect through the internet, but of course connecting through the internet required some sort of level of security, so we created VPNs to create that security when making that connection. VPNs are not the only way we can make that connection, though. We can use secure shell, we can use VNC, virtual desktop connections, we can use VDI: different ways that we can actually establish that connection. I also don't want to overlook the use of HTTPS. We use a lot of applications nowadays and never have to actually connect into a network; for a lot of services we just use HTTPS. And then because VPNs have such prevalence out there, we also talked about some specific ideas around VPNs, such as site-to-site VPNs versus client-to-site VPNs, the client versus clientless VPN, and then also the split tunnel. So that is remote access: much more prevalent nowadays, but there are many ways that we could go about actually implementing this.
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