With more focus being placed on rapid recovery times for disaster recovery (DR) operations, much of the design, strategy, and practice work done for DR in the past has shifted more toward the high availability (HA) concept. For many businesses, an “always on, 24/7/365″ concept is key, so a recovery time of 48 hours is simply too long, and a data loss of an entire week would be catastrophic and considered a definite disaster in its own right. So, availability is now king–how do we achieve it? See my article on Virtualization, Replication, Storage and High Availability for introductory concepts on replication and how storage requirements increase, and on the general ideas behind clusters and replication.

Many of you here are from a Microsoft Exchange and therefore a Windows Server environment. While much has changed in the capabilities for Windows server clustering, especially in the Exchange area, many of the core concepts are the same regardless of what the latest features and options are. For example, block-level replication across drives on a SAN solution such as EMC’s SRDF/CE option is specifically designed to assist in replication of Windows databases such as SQL and Exchange, but the block-level replication works in essentially the same manner as DRBD does on Linux.

Continue reading Considerations for High Availability Designs Used for Disaster Recovery

As companies and organizations grow in size, departments internally supporting the business grow as well. IT of course is one that must scale to accommodate business needs. If your department is small, it’s very likely that you know how all the components in your IT infrastructure are configured, what they are, what they do, and so forth. You know not only which servers host what resources, but know about the configuration of users in Active Directory, you may be responsible for provisioning those users, and for setting them up with VPN access, server access, and other actions unrelated to configuring the user in Exchange or giving them a mailbox as well as a login. You may be thinking, “Of course, Clemmer, but doesn’t everyone know about all the elements in a network and how the interrelate with email?”

Well, in larger organizations both operational responsibilities and security policies make the separation of duties for IT staff a reality. What does this mean? Well, the person who manages the firewalls and configures rules to allow email traffic between company sites or business units is very likely not the same email admin who is going to configure the SMTP connector or inter-site replication. The staff member that gets information from human resources and provisions accounts is likely not the same staff member that builds out hardware for servers, or configures desktops or notebooks for the new users. The security staff that manage proxies, load balancers, network anti-virus solutions and other security solutions are not the ones that will perform tuning and regular maintenance to your email servers, in most all cases. If you have backup and storage managed by a separate group in the IT staff, they may or may not know the specifics of backing up an Exchange database or server.

Continue reading Is Separation of Duties in IT a Help or a Hindrance?

As tightly integrated as modern email systems such as Exchange are, with the advanced features of the operating system, the enterprise directory, and the client systems, even small patches, changes and upgrades have the potential to wreak havoc. Large changes can be Herculean undertakings. If proper preparation, deployment and testing procedures are not followed, disasters are quite possible.

So consider that a seemingly simple upgrade to your mail servers, or a client security patch could result in significant downtime and give you and your IT organization a “black eye” due to the failure. We don’t want that. So, how can we avoid it?

Well, you may be thinking, “I’ve got backups, and even snapshots and images of the systems I’m altering, so if things go wrong, we can roll-back to the previous state almost instantly.” That’s great, and I hope you do have good backups, and even better restore procedures in place for when things do go wrong, as they will sometimes.

But how do we ensure that we are successful, so that we don’t need to quickly restore to yesterday’s configuration? After all, if we can’t get the changes and improvements in place, that will start to look bad as well. The question is, how do you test your changes, improvements, and upgrades? How do you ensure that when you roll the changes out into your live production environment that things will work properly and as expected?

Continue reading The Importance of a Testing Environment

One of the great benefits for us in IT is that as hardware and storage prices have come down, and performance has increased, we are more able to offer services that in the past was prohibitively expensive to deliver. Rapid deployment and expansion of service, redundancy, and very high availability are all possible now for a fraction of the cost of a few years ago. Granted, it still costs more to provide such high quality service. Let’s take a look at how virtualization, replication and high availability, impact storage requirements and costs.

Virtualization allows us to deploy servers without tying resources to a single specific hardware system. The images can be moved from one system to another, cloned, made redundant and thereby easily allow expansion of particular applications and services. Virtual servers are a foundation for simple, rapid, consistent scalability. Having several or many identical instances allows us to deliver high availability far more easily. Virtual images do take space, and must run on a base platform, so clearly a single VM takes more space and resources that the same service running on dedicated hardware.

High Availability (HA) is the IT goal of having continuously available service for a particular application, connection or resource. Sometimes this is done via fail-over from a primary to a secondary connection or resource. It is also possible via load balancing. The load balancing can be accomplished at the application layer, at a gateway layer, or via an appliance. Load balancing is also possible at the name lookup level. For the purposes of this discussion we are considering application, gateway, and appliance types of load balancing and fail-over. Application layer mail gateway routing is often built-in to the system, whereby the gateway has alternate choices to try if its primary gateway is unavailable. This may be implemented in different ways depending on the vendor and the service. For SMTP there are underlying standards and requirements for gateway and routing behavior.

Continue reading Virtualization, Replication, Storage and High Availability

Certificates and encryption utilizing them play a critical role in modern systems and network security. Even if none of your email users has a client certificate in their email application, and they’re not using PKI for a VPN connection, they’re using certificates in more than a couple of places on a Windows network with Active Directory and Microsoft Exchange. You say, “Clemmer, I know all this, so what?”

Certificate Import Wizard

As I discovered recently, the need to renew certificates only once every year, two years, or more, can make for some hair-pulling troubleshooting with turnover with IT departments often shorter than that time period and likely sparse internal documentation for the many “set it and forget it” configuration components of the CA infrastructure.

Continue reading Microsoft Certification Authority, Certificates, Your AD forest, and More

My recent posts have discussed identifying commonalities in new occurrences of spam, and concerns to keep in mind regarding indirect attacks using email as a vector. A strong perimeter defense and solid virus protection, along with an effective anti-spam solution can lull us into a false sense of security. The seemingly constant stream of unwanted mail begins to look like little more than an annoyance and not a continuing threat. In this post let’s examine technically other methods of attack, how to recognize them, and ways and means to defend against them.

Attacks against email servers, systems, and infrastructure are in many ways similar to attacks against other Internet-facing services, but are different in several important ways. Just as a concerted attack that brings down your Web servers stops communication with customers, vendors, and others on the Internet, the same is true for email communication attacks.

Continue reading Email Attacks and Defense Against Them

Sometimes spam, viruses, and other malware filtering at your email gateway isn’t enough. It’s important to keep your host anti-virus signatures up to date, and if you don’t have anti-virus protection at your firewall or on your network at the Internet gateway you should seriously consider it.

Here’s why these items are critical. Some recent malware attacks have used malware embedded in video and audio streams as a transfer. They can gain an initial foothold, so to speak, by managing to get a link to your users in a spam email. If your spam filter doesn’t block the message, a link in the email appears to be a video or audio link, but in fact the destination contains a trojan that is embedded in the content stream.

This method of attack isn’t exactly new. For example, the ZLOB Trojan began making rounds in 2005, and began gaining traction in 2006. Some attacks with it simply involved downloading other viruses or malware. Using a video link, however, for users that have their ActiveX controls set to download codecs automatically means that those users with poor virus protection would automatically download the virus and become infected.

Continue reading Malware Threats from Unexpected Sources: Trojans Embedded in Streaming Video Links

Despite the generally excellent performance of most modern, well-tuned anti-spam engines, some spam is going to get through. We may be lulled into a false sense of superiority when for a period of time our anti-spam tools and techniques have borne fruit, and we see that we have more-than-just-excellent results; we have no spam in our inboxes for an entire day, week, whatever. Then, it returns. We’ve all seen it happen. Some strangely formatted message that you or I can surely tell is garbage, a bizarre attempt to sneak through your heuristics that has surprisingly succeeded.

Lately it has been some rather clever nonsense. I’ve been getting these spam emails with a particularly peculiar twist. Many of them have what appear to be at first glance meaningful, but “non-spam” sentences. On closer look, the sentences are strange, and not quite sensible. For some reason they consistently were getting through the spam filtering. What was strangest to me was the lack of any marketing content or attempt to sell whatsoever. They did have a link in the message, and the link was not ever to the same web destination or even clearly directed to an obvious undesirable site. This may have been one of the reasons this set of spam got by; to the filters, it looked really no different than a sentence or two sent by a friend describing some link they thought I would be interested in.

Continue reading The Latest Spam Getting Through Your Filtering – and What to Do About It