v.10 - Introduction to iSessions
Amongst the wave of new features that came out in Version 10 of TMOS is a nifty little feature called iSessions. This being the first release of iSessions, there is a lot of curiosity and not as much documentation as we’d like yet. So I’ll walk you through what is available, why you’d want to use it, and what benefits it offers in this blog post. As time goes on we will expand our coverage of iSessions to more fully discuss all of the options and challenges they present. The concept of iSessions in v.10 is pretty straight-forward… A secure tunnel between two BIG-IP systems to share in load-balancing and failover. The extension is that those BIG-IPs can be (and generally should be) geographically remote. Indeed, the whole point of iSessions is to make WAN communications faster, but we’ve got enough experience to know that some of you will find a use for them inside the datacenter. iSessions only require that the BIG-IPs be able to route between each other, not that they be geographically remote. Since optimization of traffic over an iSessions link is built in, you get both secure and accelerated WAN communications. The type of optimization is configurable, as are several other things about the tunnels. While this post isn’t intended to be a step-by-step How-To document, it will give you an overview of the steps necessary to get your BIG-IPs talking on the “back channel”, and offer some points of interest for you to be aware of. Much like some vendors have a remote office solution that is simply an optimizing proxy for their data center products, iSessions will forward requests to a remote BIG-IP. Unlike those solutions, if the connection the iSessions communicate over is down, the BIG-IP can be configured to handle the request locally if you have the servers in-place. For this blog post we will refer to the “Data Center BIG-IP” and the “Remote BIG-IP” note that the “Remote BIG-IP” could be configured in an alternate data center, and thus could be fulfilling both the role of the Data Center BIG-IP in some instances and that of the Remote BIG-IP in others. For simplicity’s sake, we will not explore that configuration here, simply note that it’s possible. For this blog post, the “Remote BIG-IP” is the device that the user’s requests will come in through, the “Data Center BIG-IP” is the one that will ultimately service requests. That should be all the background we need to cover, now on with the overview. The best way to think of iSessions (for me at least) is like a fibre optic cable. iSessions are turned on at both Remote and Data Center BIG-IPs, and that creates the sheath that holds the fibres. When connections are requested on the Remote BIG-IP, an individual fiber (connection) is created in the sheath (tunnel). Depending upon your settings, that connection could exist for a long time, servicing repeated requests from different clients, or it could exist only so long as the requesting connection is live. At its simplest, the iSessions configuration is easy. On the Remote BIG-IP, you configure a forwarding Virtual Server to forward requests to the Data Center BIG-IP. The Data Center BIG-IP has a Virtual Server configured for iSessions that either maps to a server or forwards to another Virtual Server on the same BIG-IP. Either way, the Data Center BIG-IP services the request, and sends the response along the same iSession connection, assuming the request is for the same target Virtual Server. Note that re-use has some drawbacks in every implementation out there, and you might want to consider their use carefully if you have very bursty traffic patterns. Also note that in this first implementation of iSessions, the longevity of a connection is 10 minutes and cannot be changed. Note that the iSession Forwarding Virtual Server is different than most Forwarding Virtual Servers – it is configured as a standard Virtual Server with address/port translation turned off and no Pool object associated with it. A destination is then set that is the Data Center BIG-IP’s address. The Virtual Server on the Remote BIG-IP requires a TCP profile to be selected for both the client and server side contexts, and a client SSL profile must be selected so that iSessions info can be decrypted when the other BIG-IP sends responses. This Virtual Server on the Remote BIG-IP also requires an iSession Profile to be selected so that tells the BIG-IP how to handle tunnel creation when communicating with the Data Center BIG-IP. The iSession profile specifically tells the BIG-IP about mappings to the Data Center BIG-IP, Session re-use, optimizations of the tunnel, and other general connection options like de-duplication (not currently available even if enabled… Check back for more info) and port transparency. Note that while the Endpoint Pool is slipped in at the bottom of the configuration screen, you need it set to a pool of one node that is the forwarding point for iSession Tunnels to the Data Center BIG-IP. The Data Center BIG-IP has the same iSession Profile, and your choices for tunnel-specific configurations are compared when a tunnel is initiated, and only those settings that are enabled on both sides are used for this tunnel. On the Data Center side, you must configure the iSession Profile such that it knows what to do with incoming connections – are they simply routed, or do they get sent to Virtual Servers for additional processing, etc. These options are at the bottom of the iSession Profile configuration. For Target Virtual type, your early implementations can probably use Match All, which will match to any Virtual that fits, and route the request on if none matches. Okay, that’s a ton of info. We’ll call that the quick overview. The salient points are: iSessions create an encrypted, optimized tunnel over the WAN between two BIG-IPs. Both BIG-IPs must be v.10 When configuring client and server profiles remember to think of traffic direction… Where the traffic comes in from the client (regardless of which BIG-IP you’re on) is the client side, where it flows back toward the client is the server side. iSessions are always encrypted but you have options for which and how much compression to use (and the ability to choose “adaptive” if you are uncertain which is best for you). Just because this blog post used “Remote BIG-IP” doesn’t mean it can’t also be in a data center, and in some instances it may even be the “Data Center BIG-IP” in highly distributed environments. Session re-use saves the overhead of renegotiating for each connection, but comes with a price of long-lived connections between the two BIG-IPs. That’s it for now. I’ll be posting soon about how and why this is important if you’re considering using a cloud provider. Check with your SE if you’re interested in more implementation-specific details. Don.Not On My VM. Step One In Secure Cloud Usage.
A few years ago, a gentleman created a video showing how quickly an unpatched, unprotected Windows XP machine was infected once connected to the public Internet (the linked video is worth a watch, and is short). That video took the business community pretty much by storm, but was old news to security administrators and most systems administrators. Things have improved on the operating systems side of the house, but so have the systems, attackers, and environment for hackers, meaning things aren’t much better today. In the confines of your enterprise, that’s all cool. Whether you are deploying a server or a desktop, you configure a machine, it follows the standards of the organization, and is protected by the organization’s security architecture. When you deploy an application to the cloud, though, far too often the fact of how hostile the Internet is to unprotected servers is not properly appreciated. Sometimes because it isn’t IT deploying the application, sometimes because it is “just a pilot to evaluate cloud”, sometimes because the environment is so different that the Standard Operating Procedure (SOP) and policy documents are close to useless. No matter what the reason, the end result can be a nightmare just the same as if it happened in your datacenter. The solution is, of course, to use the tools that virtualization offers, install and configure the VM and all applications internally, set up antivirus, lock down the operating system and the applications running in the VM, then either clone it and move the clone out to the cloud, or use VMotion to move it out to the cloud. Any other alternative approach, due to the nature of the cloud, will leave you exposed for a variable amount of time. The problem here is that the IP has to be publicly routable for you to get to the instance, so there really isn’t a good way to install the OS out there and then lock it down. Once the OS is installed, you’re potentially in for a rough ride. Some of you are going “Of course, this is common sense”. As usual, in some organizations it is indeed common sense. In others it absolutely is not, and often the nature of pilot programs makes “common sense” relative to “gaining knowledge”. So it is absolutely worth saying outright. And yes, this is the very tip of the iceberg, your application must provide its own security services or have access to the role-based architecture deployed in the datacenter, but seriously, cloud security at the OS/Application layer is no different than public-facing applications in the datacenter. In the end, both are going to have public IP addresses that must be protected from those lurking in the shadows. The next major sticking point is data connections back to the datacenter, but products like F5’s BIG-IPLTM can help in that department, offering tools like iSessions to provide secure, encrypted tunnels back to the datacenter. There are other products out there that can answer this same need, but recall that I’m an F5 employee. And recall that F5 is a market leader for a reason. But you won’t even get there if your server instances are infected before they’re even patched. So remember, protect your server instances before you deploy them. In fact, if you’re going to do more than one or two servers to the cloud, it might just be worth your while to create a specialized image and insist that all cloud images be clones of that image – that way you can build all the protections in once and be done with it, much as you likely do with desktops and servers today. Better to start with the known-to-be-locked-down image and loosen from there than to recreate lock-down code every time you build a new server. Safety first, it’s scary out there.Extreme Automation. Dynamic Control with or without the Cloud.
In the data center of the future, you are going to need to be able to bring up new instances of an application, have them fully functional without any user intervention, and when they’re no longer needed they should clean up after themselves and quietly go away. Five years ago this was fantasy talk, two years ago it was coming to the fore, and today we can see clearly that such adaptable infrastructure is going to be mandatory for any installation/application that has a highly variable rate of throughput. The drivers for this need for adaptability are varied, but the core ones that we have all heard an earful of are cloud – where you are charged for your usage, and leaving apps running when not needed is tantamount to throwing money away – and a highly virtualized environment where there are a lot of virtuals running per physical server and keeping an instance running that you do not need is tantamount to throwing CPU cycles away. Okay, the alliteration was good, but it really IS throwing CPU cycles away, nothing tantamount about it. The problem is/has been that there are a lot of complex pieces to put together when making such a system work. It is difficult to say “spin up an instance, give it access to all the resources it needs, and make it play well with the other instances of the same application while directing traffic to it.” Related Articles and Blogs iC2I: Introduction iC2I: Dumping a Node iC2I: Dumping iRules iC2I: Creating a Virtual Server iC2I: Creating Virtuals Simplified iC2I: What Virtuals Rely on This iRule? iC2I: What Pools Rely on This Server? iC2I: What Virtuals Rely on This Server? Introducing Long Distance VMotion With VMWare
