Safety in Community Design: Key Concerns from a Community Architect’s Perspective


This visitor put up was authored by Cisco Designated VIP Daniel Dib, CCIE #37149, CCDE #20160011.

Just lately I used to be describing on Twitter the superb colleagues I’m attending to work with on a venture, with CCIE certifications in Enterprise Infrastructure, Information Middle, Wi-fi, and a CCDE certification. Somebody responded to me, “Who’s liable for safety?” My response was, “All of us are.”

Whereas we nonetheless undoubtedly want individuals who specialise in safety (there is no such thing as a doubt about that), it’s now the job of everybody to think about safety of their community designs. You must take into account safety inside all community architectures. It’s not sufficient to place a firewall on the perimeter and name it a day.

Key issues for safety in community design

No matter whether or not it’s a LAN, information heart, or WAN, what are among the key issues for safety in community design? Let’s take a look on the CCDE v3.0 Written examination blueprint.

Below network safety design and integration, we’ve: 

  • Segmentation 
  • Community entry management
  • Visibility 
  • Coverage enforcement 
  • CIA triad 
  • Regulatory compliance 

Earlier than we begin diving into these CCDE examination subjects, let me describe the method of designing a community—and the way safety can by no means be an afterthought. So, what differentiates community design from a nasty one? Is it how redundant it’s? Is it the variety of firewalls? Is it the variety of segments? Is it how briskly it converges?

No. The one factor that differentiates community design from a nasty one is whether or not it meets the necessities. A community design should at all times meet the necessities. Not assembly the community’s necessities is clearly unhealthy. However overdelivering can be unhealthy, and is typically known as “gold plating.”

So, how have you learnt what the community necessities are? Usually, step one in a community design (and maybe an important one!) is gathering the necessities. As soon as the necessities are gathered, I usually doc them in what is called a Buyer Necessities Doc (CRD). The doc contains solutions to a myriad of questions masking enterprise necessities, purposeful necessities, technical necessities, and operational necessities.

When creating this doc, you will need to perceive what kind of group I’m coping with. What’s a typical consumer? What kind of visitors flows have they got? How do they use the web? What kind of VPNs have they got? Already, at this section, I would like to grasp what the shopper and community appear like to outline what the safety necessities are. Now let’s return to the CCDE blueprint and dive into every space of community safety design and integration, in addition to how they have an effect on a community’s design. 

Community Segmentation 

Community segmentation is sweet, or so that you’ve heard. However what is segmentation? Is it sufficient to have completely different VLANs? Whereas utilizing completely different VLANs can present advantages corresponding to smaller flooding and failure domains, segmentation often is used to explain two networks that don’t have direct entry to one another.  There are two types of segmentation; macro segmentation and micro segmentation.


Macro-segmentation is used to explain networks which might be walled off from one another. For instance, (1) a visitor community that’s separate from the enterprise customers’ community, (2) a administration community that’s separate from the enterprise customers, and (3) an IoT community that’s remoted from every part else. Macro-segmentation is usually applied utilizing Digital Routing and Forwarding (VRFs) and/or firewalls.  


There may be additionally micro-segmentation, which describes tips on how to filter inside a macro section. For instance, possibly customers shouldn’t have the ability to talk with one another. Ought to a printer have the ability to talk with one other printer? Ought to one air flow system have the ability to talk with one other? Usually they will, since they belong to the identical section, however you could wish to limit it, which might require micro segmentation. This is able to usually be applied utilizing some type of Software program Outlined Networking (SDN) know-how or by putting in a shopper on computer systems and servers, and so forth. 

There are additionally in fact many different forms of segments, corresponding to a Demilitarized Zone (DMZ), the place you host public companies which might be reachable from the web. 

Why do we’d like segmentation, although? Properly, do you? What did the necessities say? Why we create segmentation comes from the necessities. For instance, a community requirement might state, “Visitor customers could solely use the web and should not have entry to any inner networks.” With a requirement like that, you would want to create segments as a result of visitor customers ought to be separated from enterprise customers. If there may be one other requirement, corresponding to, “Enterprise customers should not have entry to one another,” then more than likely you want some type of micro segmentation. The aim of segmentation is to have the ability to management what visitors is allowed between segments.  

From a safety perspective, it is usually necessary to limit lateral motion. If somebody hacks one among our net servers, we don’t need them to have entry to, for instance, our area controller. That’s the reason we don’t enable any visitors from the DMZ to our larger safety zones, corresponding to the place we maintain the area controller. 

Community Entry Management 

Let’s say you plug in your pc to a swap port. With no authentication, you could have full entry to different customers, your administration community, and the web. Is that this good safety? We might argue that it’s unhealthy, however what did the necessities say? When implementing community entry management, we should in fact take into account the safety necessities, but additionally the benefit of use. If the community turns into too sophisticated and sophisticated to make use of, and error-prone, then our design has failed, even when we met the necessities. What’s community entry management? 

Many types of community entry management come to thoughts. The obvious one maybe is to implement 802.1X in your LAN. It is a mechanism that authenticates customers, and optionally their pc, earlier than permitting them entry to the LAN. This may be within the type of offering credentials, and/or utilizing certificates. Relying on the consumer, they might get completely different ranges of entry to the community. This may for instance leverage Dynamic ACLs (DACL). 

There are in fact many different strategies, corresponding to utilizing firewalls to implement guidelines for what visitors can circulate between segments. The community could use a proxy, corresponding to Umbrella Safe Web Gateway (SIG), to implement what’s allowed to be used on the web. This may be enforced within the community or on the shopper itself.  

There may be issues which might be so apparent that you just didn’t even take into account them. What about placing community gear in a locked room to forestall folks from accessing them or shutting down switchports so that individuals can’t hook up with random ports? Community entry management might be something from bodily safety, to coverage, and rather more. 


What does visibility should do with safety? Rising up within the ’80s and being named Daniel, The Karate Child was one among my favourite films. In The Karate Child Half III, there may be this quote from Terry Silver, the primary antagonist in that film. He says, “A person can’t see, he can’t battle.” In case your group is blind to what’s going on within the community, how are you going to stop any threats? You possibly can’t! You want visibility to grasp visitors flows and what’s moving into your community. 

How do you get visibility? That’s one large and sophisticated matter! Do you know that the majority visitors, not less than to the web, is encrypted? Because of this it’s getting increasingly more troublesome to see what visitors we’ve in our networks and therefore, tips on how to defend towards potential threats. What can we do? We are able to attempt to glean data from the packets by taking a look at DNS requests (if not encrypted), IP addresses (the place the packets are going), what ports the packet is utilizing, patterns within the packet, corresponding to measurement and frequency, and different issues. There are well-known prefixes, corresponding to when utilizing Microsoft 365 for instance, the place we will make a certified guess about what the visitors is that if we acknowledge the prefix. To get visibility, we regularly want some type of third-party product that may take data from the community, for instance, within the type of Deep Packet Inspection (DPI), NetFlow, packet faucets, packet mirroring, and so forth. 

To get full visibility, more than likely, you’ll have to set up one thing on the shopper. The shopper is the one place the place you’ll be able to see unencrypted packets — except you might be decrypting the customers’ packets utilizing Transport Layer Safety (TLS) inspection, in fact. 

There are numerous different methods of getting visibility, corresponding to utilizing proxies, firewalls, community entry management, and Syslog. Essentially the most troublesome half, contemplating the wealth of knowledge, is knowing what is definitely occurring and how one can stop assaults such because the exfiltration of your information. If somebody logs in from a location the place you don’t have any workplace and so they switch a lot of information, wouldn’t you wish to learn about it? Ideally, visibility ought to get you insights into incidents corresponding to these. 

Coverage Enforcement 

How can we implement our insurance policies, just like the requirement that customers can’t speak to one another? How is coverage enforcement completely different from community entry management? Community entry management pertains extra to giving entry to the community itself whereas coverage enforcement is about stopping entry when you have already got entry.

There’s fairly some overlap right here, although. Let’s break the phrase down into its elements. Coverage is the intent of our community; the interpretation of our necessities right into a algorithm. Enforcement is to make sure that our coverage will get adhered to. To have the ability to implement one thing, packets should cross by a tool that may determine if the packet adheres to the coverage or not.

What we’d like are choke factors. Whenever you journey to a different nation, they’ve a border. In addition they management your passport earlier than admitting you. That is coverage enforcement at a choke level. This is similar factor that we do in our networks. Historically, all our visitors went to some sort of headquarters or information heart and handed by a giant fats firewall. Most organizations moved away from this design, because it created a less-than-optimal consumer expertise. However what are among the chokepoints or potential coverage enforcement nodes that we’ve right now? There are numerous, so let me listing just a few of them. 

  • Firewalls 
  • Proxies 
  • IDS/IPS (usually built-in with the FW) 
  • Switches 
  • Routers 
  • Wi-fi LAN controllers 
  • Purposes on shoppers and servers 

There are numerous locations we will implement insurance policies. The principle problem is most frequently on getting visibility, although. You possibly can’t implement a coverage should you don’t know what’s within the packet.

The opposite problem is usually round implementation. When you’ve got a firewall in each department, and you’ve got 1000 branches, how straightforward is it to handle this? It might come all the way down to how standardized your design is. This is the reason many organizations are actually utilizing cloud proxies to have fewer choke factors and make it extra manageable. The opposite factor I usually see in community design is organizations don’t know what their coverage is, what apps and methods they’ve, or what ports they use and the visitors circulate. You possibly can’t write a coverage should you don’t have sufficient data to categorise what’s allowed or not. 

CIA Triad 

The CIA triad feels like some bizarre mixture of the US Central Intelligence Company and a Japanese mafia. The excellent news is that this isn’t in any respect what it’s.

CIA in a community design is: 

  • C – Confidentiality 
  • I – Integrity 
  • A – Availability

Confidentiality is about preserving the group’s information non-public or secret. All information ought to be non-public, proper? What did the necessities say? A visitor community at Starbucks may have completely different necessities than the Division of Protection (DoD) extremely categorized networks. This is sensible, proper? 

Integrity is about making certain the integrity of the info. How have you learnt the data I despatched you actually got here from me? What if my packet was altered earlier than it reached you? 

My information could also be safe and personal, and we ensured the packets couldn’t be tampered with, but when my packet doesn’t attain you, what good does it do? A safe system should even be accessible. 

Let’s take a better take a look at the elements of the CIA triad. Then I’ll allow you to in on how this all ties collectively. 

CIA Triad in Network Design

Confidentiality is about preserving information non-public or secret. There are numerous potential threats right here, corresponding to accessing information in transit if it’s not encrypted, utilizing weak algorithms, key loggers, attackers shifting laterally after taking up an IoT gadget, and so forth. The principle instruments for preserving the info secret are having correct entry controls, corresponding to utilizing sturdy passwords, implementing Multi-Issue Authentication (MFA), utilizing least privilege entry, and encrypting the info — at relaxation and in transit. There are additionally different measures, corresponding to avoiding shoulder browsing, locking the pc, and stopping USB-device entry to the pc. 

Integrity is about making certain that the info has not been tampered with. This might occur to information that’s in transit or at relaxation. Having unauthorized entry to information is unhealthy sufficient, however what in the event that they have been additionally in a position to alter the info? Think about somebody will get entry to the system that manages your payments and redirects a fee to themselves. The principle safety mechanisms, past entry management, are digital signatures corresponding to certificates, checksums, and message digests (additionally known as hashes). Certificates are used to confirm the identification of the sender. Checksums and message digests are used to confirm, utilizing cryptography, that the info has not been altered. 

Availability is usually ignored from a safety perspective. Having the info unavailable is a safety menace as effectively, although. Guaranteeing availability comes all the way down to having a correct design in place that meets the provision necessities. This includes having redundant methods and paths, however along with redundancy, you even have to think about resiliency. What if in case you have redundant switches, routers, and firewalls, however all of them use the identical energy supply? What occurs when you could have an influence outage? I’ve labored with environments the place they used each AC and DC energy in addition to UPS and diesel mills to forestall eventualities the place redundant elements go down with the opposite elements. You even have to think about this from a transport perspective. Having a single transport, such because the web, places you at larger threat of creating your methods unavailable.  

From an assault perspective, the primary menace to availability is that if your methods get attacked and the attacker crashes the methods. Extra generally although, you’d see one thing like a DDoS assault, the place your methods are flooded with visitors. Somebody might additionally attempt to ship large quantities of information into an utility, corresponding to a database, to have the system crash. Having your information encrypted by a crypto locker would even be a menace to your availability. 

Defending your self contains having design, the place you could have thought-about the provision necessities and what transports to make use of, in addition to applied safety methods that may filter out threats. Take IDS/IPS, for instance. Some threats, corresponding to DDoS, are troublesome to deal with by yourself. You could must depend on your ISP for defense in such eventualities.  

Regulatory Compliance 

What was it Huey Lewis and the Information stated? It’s HIPAA to be sq.? Resistance is futile; you’ll be assimilated. I don’t recall whether or not this was from Star Trek or my PCI auditor. Joking apart, regulatory compliance is essential, in fact. Regulatory compliance is there to make sure that organizations reside as much as the requirements which might be required to maintain our information protected. The 2 most well-known ones are in all probability Well being Insurance coverage Portability and Accountability Act (HIPAA) and the Cost Card Business Information Safety Customary (PCI DSS). HIPAA is used to assist maintain our medical information protected, for instance. PCI DSS is used to create protected funds, so our bank card numbers don’t get leaked. 

On the subject of regulatory compliance, there are a number of necessities that include them. You must fulfill the necessities, and there could also be auditing concerned to make sure that you’re doing so. The necessities could embrace issues like segmentation, encryption, entry management, and extra. Whereas working with regulatory compliance might be tedious, time-consuming, and typically really feel like you might be designing for issues that ought to be apparent, they’re there to make sure that organizations meet the minimal requirements when working with delicate issues corresponding to medical information and fee data. 

This weblog put up ended up slightly longer than I anticipated, however I wished to provide you perception into simply how a lot there may be to think about in community design, or any design on the subject of safety. Even should you don’t specialise in safety, it ought to nonetheless be high of thoughts in every part you do. Remember although, any design strives to satisfy the necessities, nothing extra, nothing much less. 
In case you take pleasure in speaking about community design or are finding out for the CCDE certification, be a part of me within the CCDE Certification Neighborhood on the Cisco Studying Community. Take a look at this CCDE: Ask about something dialogue, the place you will get your CCDE cert questions answered straight by Cisco. Thanks for sticking round and see you subsequent time!


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About Daniel Dib

Daniel Dib, CCIE #37149, CCDE #20160011, is a senior community architect at Conscia Netsafe. He works with creating scalable, modular, and extremely accessible community designs that meet enterprise wants. Daniel began out in implementation and operations and bought his CCIE in 2012. In Could 2016, he turned the second particular person in Sweden to get CCDE licensed.

He usually acts as a subject skilled for his clients with deep experience in routing, switching, multicast, and quick convergence. He’s an lively particular person within the networking neighborhood and believes in serving to folks attain their full potential. He writes technical articles, and blogs and holds member-led examine periods for the members of the Cisco Studying Community.

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