SSL VPNs ease the burden of securing large-scale Internet applications
For several years, federal agencies have used virtual private networks (VPNs) to reliably secure online information exchanges with remote workers and trading partners. Yet, deploying systems based on the IP Security (IPSec) protocol — the main method until now — is not always as easy or flexible as agencies would like.
In the past year, an alternative has emerged that is taking the market by storm: VPNs based on the Secure Sockets Layer (SSL) protocol. Boasting several attractive features — such as simpler installation, more device flexibility and lower maintenance costs — SSL VPN products are quickly reaching government information technology shops that want to expand the user base for e-government applications without breaking the bank.
In fact, market research firms Gartner Inc. and META Group Inc. both expect SSL VPNs to be the primary way to connect remote users to enterprise networks as soon as next year.
As the SSL VPN market mushrooms, the supplier base also has diversified. Initially, start-ups Aventail Corp., Neoteris Inc., NetSilica Inc. and SafeWeb Inc. dominated the space. Not wanting to miss the action, networking heavyweight Nortel Networks Ltd. has begun promoting its Alteon 2424-SSL, while Cisco Systems Inc. plans to unveil its SSL VPN wares by year's end. In all, about two-dozen vendors now offer the products.
To understand the surging interest in SSL VPNs, it's important to grasp how the approach differs from IPSec VPNs. Both techniques share a goal: Encrypt transactions to ensure data is secure as it passes over Internet connections. They achieve this in different ways (see "How it works," below). As a result, each option has strengths and weaknesses.
IPSec has become popular because it rides on top of the standard TCP/IP stack, whereas previous security mechanisms relied on proprietary network protocols. Although IPSec makes it simple to connect two computers, it poses installation and maintenance challenges.
For one, agency officials have to ensure that their end-user devices use the same encryption technique as their central servers. This typically involves installing IPSec software on PCs. "In a large [organization] with thousands of employees at various remote locations, it can become quite cumbersome to maintain the IPSec software," said Sarah Daniels, Aventail's vice president of product management and marketing.
Typically, users can't install the software themselves, so the IT department is responsible for deploying and testing the security functions. If an agency upgrades its IPSec software, it often has to make the changes on all end-user devices.
By comparison, with SSL VPNs, a device only needs a generic Web browser that has SSL functionality, something found in almost every case. So the initial installation requires minimal manpower. To upgrade an SSL connection, a company usually only has to change its server software.
"Because there is so much less administrative [work] required, organizations can realize dramatic manpower savings by moving to an SSL VPN," said Jason Matlof, Neoteris' vice president of marketing and business development.
Easier maintenance appeals to the U.S. Naval Medical Information Management Center in Bethesda, Md. In early 2002, officials explored ways to provide its 55,000 users with secure access to medical data via its IP-based intranet.
After evaluating its options, they selected SafeWeb's secure extranet appliance Tsunami SSL VPN system to give its users access to health industry information, such as medical benefits, newsletters, reservist duties and e-mail.
"The client security functions have been quite simple to install and easy to manage," said Ariel Echano, a network security engineer at the naval center.
Because IPSec requires both ends of a connection to use compatible software — almost always from a single vendor — it may not be a viable option for all applications, such as those involving outside organizations.
"IPSec has never been a fit choice with extranet applications, because it can be difficult to set up and maintain connections to a large number of trading partners," said Jim Slaby, a senior network analyst at Forrester Research Inc., a market research firm.
IPSec's requirement of special client software can also create problems for nomadic employees. "With IPSec, employees can't use a kiosk, a terminal at a customer's site or a handheld device to access a corporate network, because they lack the appropriate client software," said Anthony Daley, senior vice president and general manager at Westcon Inc., a computer and network products distributor.
Also, IPSec VPNs can run into problems with firewalls, which operate at the same network level as the encryption software. For example, if a government employee is at a contractor's site and tries to download data from his or her agency's enterprise application, the firewall likely will block the transaction because the request comes from outside the organization. Firewalls typically ignore SSL connections because they know security functions operate at another level.
The Case Against SSL VPNs
Although SSL VPNs include enticing features, they are not a cure-all. Because they require Web browsers, most SSL VPN solutions only provide access to Web-based applications. Vendors have to add special software so their systems are compatible with mainframes, client/ server applications, file transfer systems and terminal server applications.
"When they first came out, the SSL solutions supported only a couple of applications," such as e-mail, said Jim Jones, chief technology officer at systems integrator Science Applications International Corp.
Cost is another area where SSL VPNs can come up short. "The initial price for installing an SSL VPN can be three times higher than that of an IPSec VPN," said Kyle Klassen, a product marketing manager at Nortel. SSL software is more complicated than IPSec software and the SSL products are at an earlier stage of development, so vendors have been unable to reduce costs yet via volume shipments.
Typically, management functions are one of the last components added to a nascent technology, and that has been the case with SSL products. Vendors are focusing on improving their systems' graphical user interfaces and widening the range of management information their products can collect.
Initially, the IPSec and SSL VPNs were positioned as an either/or scenario. "SSL vendors started out talking about their products as IPSec replacements, but there has been a growing realization that neither option is perfect for every application" so vendors now view the technology as complementary to IPSec VPNs, Westcon's Daley said.
Korzeniowski is a freelance writer in Sudbury, Mass., specializing in technology issues. He can be reached at firstname.lastname@example.org.
How it works
To secure information, an agency must encrypt data as it moves from the sender to the receiver. IP Security (IPSec) virtual private networks (VPNs) operate and encrypt information at the network layer — Layer 3 of the seven-layer network model, to be precise. This protocol does not pay attention to what type of information (e-mail message, file transfer) may be moving from place to place. It is more concerned about locking down the network transport (e.g., TCP/IP).
Secure Sockets Layer (SSL) VPNs function at the application layer, the top layer of the seven-layer model. This technique does not take the network layer into account but instead focuses on the application layer. In most cases, an SSL session assumes the person is connecting to a Web service, although special vendor add-ons make it possible for users to work with other systems, such as mainframe and client/server systems.
By the Numbers: Ideal for mobile users
If you have a small (say, half a dozen), stable set of locations that you want to connect securely, chances are that a Secure Sockets Layer (SSL) virtual private network (VPN) may not be the best option. The initial hardware can cost $25,000 to $50,000, significantly more than IP Security (IPSec) VPN switches, which are priced in the $15,000 to $25,000 range.
However, because an SSL VPN requires little setup — only a standard Web browser — on the end user's computer, it typically costs about half as much to manage those connections as it would with IPSec, which requires that special software be loaded and maintained on all client computers. Therefore, SSL usually makes the most sense when a company has a large number of mobile employees who work from different locations and use a wide variety of devices (hotel computers, handhelds, customer systems, etc.) to connect to an enterprise network.
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