The Brief How & Why of ISCS

Copyright (c) 2003-2004 John A. Sullivan III, Nexus Management. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License".

The Integrated Secure Communications System (ISCS) provides an integrated, GUI management console for a collection of related communications security tools such as firewalls and VPN gateways. It uses a Security Policy Manager (SPM) to create abstract, high-level policies for securing network communication, translate them into low-level rules needed by Security Policy Enforcement Points (PEPs, e.g., firewalls or VPN gateways) and automatically distribute these rules to the PEPs.

The SPM is not a centralized GUI rule configurator as other proprietary "policy enabled" network security tools are. It is a radically different approach to viewing network security. By both integrating the management of previously separate security tools and abstracting the rules and configurations into high-level policies, the SPM produces an approximate 90% reduction in the time needed to administer complex secure communications environments. This is not a speculated reduction. Nexus Management, the original sponsor fo the ISCS project, has done exactly this in the real world with proprietary tools and now wishes to achieve the same results with entirely original Open Source tools.

The current development version uses iptables, *swan, OpenCA, Linux Advanced Routing, OpenSSH, the ISC DHCP server and the Strongsec DHCP relay. The design is extensible to support other products as the ISCS community writes those modules. The SPM will eventually include QoS/CoS, Intrusion Detection, Content Filtering and Virus Scanning and should manage devices from most major security hardware manufacturers.

As previously mentioned, the SPM is different from existing firewall GUI's. It is a completely different way of looking at network security. The most obvious distinction is the integration of many technologies into one management console but the most efficient and important distinction is the abstraction.

We answer the simple security question of WHO has ACCESS to WHAT. Unlike traditional firewalls that attempt that in a single rule, the SPM divides it into three - separate rule processing for evaluating WHO, ACCESS and WHAT. That sounds like more complexity rather than less but the result of such modularity is the opposite. We can create a series of definitions for WHO and a series of definitions for WHAT. We can then freely mix and match them in a building block fashion. The reusability leads to the need to define far fewer WHO's and WHAT's than are required by a traditional firewall.

Besides reusability, we also implement hierarchy and inheritance. We place Accessors (typically users) into Access Groups and arrange those groups in a hierarchical tree with inheritance, i.e., if a right is granted at one level, that right flows down or, in other words, is inherited, by all the levels below that level. We place Resources (a combination of a server and a service as a unique object - a slight but critical departure from typical firewall use) in Resource Groups and arrange those groups in a hierarchical tree with inheritance, i.e., if a right is granted at one point in the Resource Group tree, the Access Group also has rights to all levels below it. Policies are created by establishing relationships between the two trees. Thus we not only reduce the number of WHO's and WHAT's but by a judicious use of inheritance reduce even the number of policies that must be created. Hundreds, even thousands of rules can be described in just one policy which then automatically creates those hundreds or thousands of rules and distributes them to the enforcement points. This is one of the most important ways, although not the only way, in which we achieve such astonishing efficiency.

We use this powerful access control paradigm and combine it with robust user authentication (dynamic iptables rules are now created based upon IP address and X.509 certificate DN values and soon by LDAP, Active Directory, e-Directory, RADIUS and SecureID) to control access into and out of the tunnel. We add the VPN with automated creation of SA's to facilitate the creation of full meshes and secure the traffic during transmission. We also provide an out-of-band means of automatically communicating routing changes to ease deployments, mergers and acquisition and system reconfigurations.

The need for this efficient security administration is driven by four major changes to the current computing environment:

  1. New forms of security exploits such as phishing, spam planted trojans and malicious spyware which give the attacker an internal rather than an external attack posture.

  2. Mobile, hand held, embedded and wireless computing - now neither the network media nor the computing devices themselves are in a physically secure environment. Our organizations are directly exposed to the world at thousands of points and our computing devices are regularly exposed to theft. Worse yet, the stolen device can connect to our internal networks.

  3. Increased connectivity of small offices and home workers via VPN.

  4. The growth of collaborative computing between separate organizations.

Consider the dramatic impact of VPN technology on traditional security paradigms - particularly the use of VPN as a WAN replacement. In the traditional firewall paradigm, an organization might have 200 offices and 3 Internet access points in hub offices. These were complex, difficult to administer devices but that was acceptable because of their static configuration. Changes were rare.

VPN's turn the world of firewalls upside down. Now instead of 200 offices with 3 Internet access points, there are 200 offices with 200 Internet access points. That allows the great advantage of permitting direct Internet access in each office and not having to haul Internet traffic across the private WAN just to be screened by the corporate firewall. This also makes possible the implementation of inter-office security. If we have firewalls in each office, we can protect an office from malicious intrusion from another office. That allows us to finally begin to address the issue that 70% of security breaches are internal.

In fact, inter-office security is not only made possible by putting a VPN/firewall in each office but the presence of the VPN makes the need for inter-office security greater. Now we have 200 potential points of intrusion instead of 3. If we do not implement inter-office security, a breach in any one of those offices opens the door to the entire WAN.

Worse yet, the low cost of VPN WAN's frequently imply that smaller offices that could never afford to be on the WAN can now join the WAN. It is likely that physical security is not as good in some of those small offices. If some intruder calls on that small office in the middle of nowhere disguised as the telephone repairman, walks into the kitchen and plugs his laptop into the hub under the kitchen sink, they have full access to corporate headquarters across the VPN!

So, we have this great opportunity to create direct Internet access in every office and keep local web browsing off the hub office network. We have the great chance to finally implement inter-office security. We have got 200 hundred offices with 200 VPN/firewall gateways. How are we going to manage the configuration of 200 firewalls?

Not only do we have to manage a far greater number of security devices but the number of configuration changes is vastly greater. In the past, we typically let all Internet traffic out (or at least the most commonly used ports) and only let Internet traffic in to our public devices. Changes to the firewall rules were rare. With inter-office security, every time a new server or new service comes on line, we need to make changes. Every time a new office comes on line, we need to make changes. Every time there is a merger or acquisition, we need to make major changes. Suddenly, we are not putting through a few changes per quarter but perhaps several per day - on 200 devices! We have got to find a way to make managing and distributing all those changes easier.

The situation is further compounded when we add external partners, e-commerce and service providers. In a multi-client environment, any security breach from one client to another is intolerable. Managing that kind of complex security can be a nightmare fraught with the opportunity for human error unless we integrate the management of the disparate components that make up that security and automate the security rule creation process by abstracting the minute rule creation into abstract, high-level policies that automatically translate themselves into the minute rules and distribute themselves to the enforcement points.

We also need to do something about SA creation and topology changes. VPN WANs give us the ability to implement fully meshed networks without the per circuit charges of traditional WAN technologies. This is perfect as work flow changes from central and hierarchical to distributed and flattened. Best-of-breed applications may now be housed outside of "headquarters". Peer-to-peer applications from instant messaging to VOIP to desktop video-conferencing are completely disruptive to the traditional hub-and-spoke WAN. But the hidden cost of managing SA creation for a meshed VPN is astounding. The example 200 office network we have been using requires 19,900 SA's to fully mesh! Manually creating that is sheer torment and subject to much human error. The SPM automatically creates and distributes the SAs needed to fully mesh the VPN WAN.

The SPM also coordinates all topology changes and automatically distributes these topology changes to all PEPs. This is certainly helpful when one adds a network to an existing office - all PEPs automatically know about the new network rather than having to manually change the VPN routes on 200 devices. It becomes indispensable during the migration from a traditional leased-line WAN to a VPN WAN or when combining large numbers of networks as in a merger or acquisition.

We have used the number of 200 offices for illustrative purposes. The SPM is designed to be highly scalable in both directions. It can handle thousands of gateways but is also useful for installations of only a few offices.

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