Network security challenges for remote access

Effective network security is most successful when it is built up using a layered approach. Here we review common technologies and challenges for secure remote access, and examine one commercial device-based approach.

02/26/2009


Security considerations are always a major issue when deploying a remote access solution, and the difficulties are compounded when solutions must include support for embedded systems. Successful implementations must provide effective authentication and access control, and care must also be taken to ensure that data is secured during transport over the network.

Additional considerations arise when target devices are hosted as guests on remote networks administered by others. In such cases particular care must be taken to ensure that your systems do not open the hosting network to outside threats.

Effective network security is not based on any one technology or component; it is most successful when it is built up using a layered approach, following the OSI Seven Layer Networking Model, with multiple defenses contributing to the overall solution. Here we review some common technologies for developing secure remote access solutions, along with some of the real-world challenges faced. We will also examine one commercial offering that addresses these challenges in an innovative and cost-effect way.

Network-based access controls

Network-based access controls are used to ensure that only authorized hosts are allowed to establish connections to your networked devices. Such access control usually takes the form of Firewalls that may work at Layer 2 (also referred to as the data link layer in the OSI Seven Layer Networking Model) or Layer 3 (the network layer).

Layer 2 solutions are sometimes described as “stealth firewalls”– they do not appear as a router hop to the network layer. Instead they provide a filtering capability on top of a transparent bridging connection between two network end points.

A layer 2 firewall may have Access Control Lists that allow the operator to control connections to or from specific devices or to prevent traffic for specific network protocols. For example, you may configure such a system to block IP-based traffic to a specific host while permitting Novell Netware IPX-based traffic.

Layer 3 firewalls, also known as port-based firewalls, operate at the TCP layer. When setting up a layer 3 firewall, the administrator configures Access Control Lists that enable or block connections based upon specified source and destination IP addresses and ports. Some so-called “Layer 3/Layer 4” firewalls function by examining the contents of layer 3 packets for additional information to help make their decisions.

Significant Issues with network layer access controls

The success of firewall technology in addressing external network threats did not come without a price - universal deployment of firewalls has greatly aggravated the difficulty of providing remote access to network devices.

Although effective and usually offering good performance, firewalls are complex to set up and administer and require network administrative privileges on the protected network. When setting up a layer 3 firewall it is common practice to enable connections to a device only on those ports that you know will be used. This can often lead to problems when a new service is enabled and the required port is being blocked.

The networking industry’s initial response to the growing remote access challenge was the virtual private network (VPN). As its name implies, a VPN replaces dedicated leased lines, cellular links or other costly physical connections with a secure mechanism over which traffic from a remote device can be tunneled to the target network using an existing network connection.

As with firewalls, installing and operating your own VPN requires network administrator privileges. Both IPSec and SSL VPNs are “IT-oriented” solutions, used by network administrators to control access into their networks. Thus, installing such a device at each remote location is usually not an option for enabling remote access to devices on other people’s networks. Another issue for SSL VPN solutions is the challenge of maintaining large numbers of user-level security credentials for each support technician when accessing equipment at a large number of locations.

A final significant issue for VPNs when used to grant guest access is that once a VPN connection is established, the remote host essentially becomes another node on the remote network. This can be a problem when the goal is to grant limited access privileges to specific hosts.

One solution is to group guest devices onto their own local area network (LAN), but this is often not possible when your equipment is being hosted on networks outside your own administrative control.

Machine-to-machine remote management

One commercial offering that addresses these challenges is a machine-to-machine remote management device capable of providing easy yet secure remote Internet access to IP-enabled equipment– even when such equipment is located behind remote firewalls or a VPN. Readily adaptable to a wide range of management tasks, such devices are suited for accessing and managing embedded systems located on remote customer networks. They are also appropriate where support staff do not have administrator privileges on the remote network.

The ManageLinx management platform from Lantronix is one example. Its patent-pending ManageLinx VIP Access component provides transparent Layer 3 network access to any piece of remote equipment without specialized client software or network reconfiguration. Because it is able to work with any TCP/IP-enabled application running on any host or operating system, ManageLinx VIP Access is particularly useful for embedded systems deployments where dedicated VPN clients or specialized networking configuration changes are not an option.

ManageLinx works over conventional Internet connections with as little as one open port to the WAN and requires no reconfiguration of the target network’s firewall settings. Because it can use existing Internet connections, ManageLinx VIP Access eliminates the need for dedicated analog phone lines or cellular coverage.

Because the ManageLinx VIP Access operates at the Network layer and communication between VIP address and the endpoint device is fully automated, it is easy to integrate embedded devices into the system. No dedicated clients or specialized software is needed to access the system. Embedded systems programmers utilize traditional TCP/IP programming mechanisms:

With multiple defenses contributing to the overall solution, effective network security is attainable. Investigate the layered approach. With care, it is possible to provide effective, secure network access to remote access deployments, enabling new service models and increasing customer capabilities.

Errett Kroeter is director of corporate & channel marketing for Lantronix in Irvine, CA. errett.kroeter@lantronix.com . Additional information on the new ManageLinx VIP Access remote access solution, including a security white paper and a remote product services case study, are available at the Lantronix website .

Remote Control: Get Behind firewalls securely.

Renee Robbins , senior editor
Control Engineering News Desk
Register here and scroll down to select your choice of eNewsletters free .





No comments
The Engineers' Choice Awards highlight some of the best new control, instrumentation and automation products as chosen by...
Each year, a panel of Control Engineering editors and industry expert judges select the System Integrator of the Year Award winners.
Control Engineering Leaders Under 40 identifies and gives recognition to young engineers who...
Learn more about methods used to ensure that the integration between the safety system and the process control...
Adding industrial toughness and reliability to Ethernet eGuide
Technological advances like multiple-in-multiple-out (MIMO) transmitting and receiving
Virtualization advice: 4 ways splitting servers can help manufacturing; Efficient motion controls; Fill the brain drain; Learn from the HART Plant of the Year
Two sides to process safety: Combining human and technical factors in your program; Preparing HMI graphics for migrations; Mechatronics and safety; Engineers' Choice Awards
Detecting security breaches: Forensic invenstigations depend on knowing your networks inside and out; Wireless workers; Opening robotic control; Product exclusive: Robust encoders
The Ask Control Engineering blog covers all aspects of automation, including motors, drives, sensors, motion control, machine control, and embedded systems.
Join this ongoing discussion of machine guarding topics, including solutions assessments, regulatory compliance, gap analysis...
News and comments from Control Engineering process industries editor, Peter Welander.
IMS Research, recently acquired by IHS Inc., is a leading independent supplier of market research and consultancy to the global electronics industry.
This is a blog from the trenches – written by engineers who are implementing and upgrading control systems every day across every industry.
Anthony Baker is a fictitious aggregation of experts from Callisto Integration, providing manufacturing consulting and systems integration.
Integrator Guide

Integrator Guide

Search the online Automation Integrator Guide
 

Create New Listing

Visit the System Integrators page to view past winners of Control Engineering's System Integrator of the Year Award and learn how to enter the competition. You will also find more information on system integrators and Control System Integrators Association.

Case Study Database

Case Study Database

Get more exposure for your case study by uploading it to the Control Engineering case study database, where end-users can identify relevant solutions and explore what the experts are doing to effectively implement a variety of technology and productivity related projects.

These case studies provide examples of how knowledgeable solution providers have used technology, processes and people to create effective and successful implementations in real-world situations. Case studies can be completed by filling out a simple online form where you can outline the project title, abstract, and full story in 1500 words or less; upload photos, videos and a logo.

Click here to visit the Case Study Database and upload your case study.