Introduction

By Campbell Taylor - Global

Recently I attended a presentation by Lynx Technology in London . The presentation was about the complimentary use of Cisco and Microsoft technology for network security. The title of the presentation was “End-to-end SecurityBriefing” and it set out to show the need for security within the network as well as at the perimeter. This document is an overview of that presentation but focuses on some key areas rather than covering the entire presentation verbatim. The slides for the original presentation can be found at http://www.lynxtec.com/presentations/.

The presentation opened with a discussion about firewalls and recommended a dual firewall arrangement as being the most effective in many situations. Their dual firewall recommendation was a hardware firewall at the closest point to the Internet. For this they recommended Cisco's PIX firewall. The recommendation for the second firewall was an application firewall. such as Microsoft's Internet Security and Acceleration server (ISA) 2004 or Checkpoint's NG products.

The key point made here is that the hardware firewall will typically filter traffic from OSI levels 1 – 4 thus easing the workload on the 2nd firewall which will filter OSI levels 1 – 7.

To elaborate, the first firewall can check that packets are of the right type but cannot look at the payload that may be malicious, malformed HTTP requests, viruses, restricted content etc.

This level of inspection is possible with ISA.

Figure 1. Dual firewall configuration
Provides improved performance and filtering for traffic from OSI levels 1 – 7.

You may also wish to consider terminating any VPN traffic at the firewall so that the traffic can be inspected prior to being passed through to the LAN. End to end encryption is creating security issues, as some firewalls are not able to inspect the encrypted traffic. This provides a tunnel for malicious users through the network firewall.

Content attacks were seen as an area of vulnerability, which highlights the need to scan the payload of packets. The presentation particularly made mention of attacks via SMTP and Outlook Web Access (OWA)

Network vendors are moving towards providing a security checklist that is applied when a machine connects to the network. Cisco's version is called Network Access Control (NAC) and Microsoft's is called Network Access Quarantine Control (NAQC) although another technology called Network Access Protection (NAP) is to be implemented in the future.

Previously NAP was to be a part of Server 2003 R2 (R2 due for release end of 2005). Microsoft and Cisco have agreed to develop their network access technologies in a complementary fashion so that they will integrate. Therefore clients connecting to the Cisco network will be checked for appropriate access policies based on Microsoft's Active Directory and Group Policy configuration.

The following is taken directly from the Microsoft website: http://www.microsoft.com/windowsserver2003/techinfo/overview/quarantine.mspx

Note: Network Access Quarantine Control is not the same as Network Access Protection, which is a new policy enforcement platform that is being considered for inclusion in Windows Server "Longhorn," the next version of the Windows Server operating system.

Network Access Quarantine Control only provides added protection for remote access connections. Network Access Protection provides added protection for virtual private network (VPN) connections, Dynamic Host Configuration Protocol (DHCP) configuration, and Internet Protocol security (IPsec)-based communication. For more information about Network Access Protection, see the Network Access Protection Web site.