Secure Network Design: Designing a DMZ & VPN

Transcription

1 Secure Network Design: Designing a DMZ & VPN DMZ : VPN : pet.ece.iisc.ernet.in/chetan/.../vpn- PPTfinal.PPT 1 IT352 Network Security Najwa AlGhamdi

2 Introduction DMZ stands for DeMilitarized Zone. A network added between a protected network and an external network in order to provide an additional layer of security A DMZ is sometimes called a Perimeter network or a Three-homed perimeter network. A DMZ is an example of the Defense-in-Depth principle. no one thing, no two things, will ever provide total security. It states that the only way for a system to be reasonably secured is to consider every aspect of the systems existence and secure them all. A DMZ is a step towards defense in depth because it adds an extra layer of security beyond that of a single perimeter

3 Introduction A DMZ separates an external network from directly referencing an internal network. It does this by isolating the machine that is being directly accessed from all other machines. Most of the time the external network is the Internet and what is in the DMZ is the web server but this isn t the only possible configuration. A DMZ can be used to isolate a particular machine within a network from other machines.

4 Introduction This might be done for a branch office that needs its own Internet access but also needs access to the corporate network. In DMZ terminology, an internal connection is generally thought of as having more secret or valuable information than an external network. An easy way to understand which is the external and internal network is to ask yourself which network am I protecting from the other.

5 Introduction DMZ is designed to support the principle of separation. Any system should have its important applications separated. This acts as system of checks and balances to make sure that if any one area goes bad that it cannot corrupt the whole. A DMZ s separation will degrade performance. If configured correctly the degradation in performance is usually minimal and seldom noticeable. However, it does exist and you need to be aware of it. This effect on performance must be calculated in the total cost of implementing a DMZ. 5 IT352 Network Security Najwa AlGhamdi

6 DMZ Architecture DMZ is used to protect nodes that provide services to the external network: web, mail, ftp servers. DMZ use a firewall to Restrict access from Internet to the DMZ to protect servers from DMZ to intranet to protect against compromises Example Allow connections from Internet to mail server on port 25 (SMTP) Allow connections from intranet to mail server on port 993 (secure IMAP) Two of the most basic DMZ design architecture 1. with a single firewall 2. with dual firewalls.

7 Single firewall A single firewall with at least 3 network interfaces can be used to create a network architecture containing a DMZ. 1 st firewall interface : The external network ( Interent) 2 nd firewall interface: the internal network 3 rd firewall interface : DMZ. The firewall will handle all of the traffic going to the DMZ as well as the internal network. purple for LAN green for DMZ red for Internet 7 IT352 Network Security Najwa AlGhamdi

8 Dual firewall A more secure approach is to use two firewalls to create a DMZ. The first firewall (also called the "front-end" firewall) must be configured to allow traffic destined to the DMZ only. The second firewall (also called "back-end" firewall) allows only traffic from the DMZ to the internal network. purple for LAN green for DMZ red for Internet 8 IT352 Network Security Najwa AlGhamdi

9 Dual firewall There is even more protection if the two firewalls are provided by two different vendors, because it makes it less likely that both devices suffer from the same security vulnerabilities. The practice of using different firewalls from different vendors is sometimes described as is an example of defense in depth" security strategy purple for LAN green for DMZ red for Internet 9 IT352 Network Security Najwa AlGhamdi

10 VIRTUAL PRIVATE NETWORKS (VPN)

11 Traditional Connectivity [From Gartner Consulting]

12 What is VPN? Virtual Private Network is a type of private network that uses public telecommunication, such as the Internet, instead of leased lines to communicate. Became popular as more employees worked in remote locations.

13 Private Networks vs. Virtual Private Networks Employees can access the network (Intranet) from remote locations. Secured networks. The Internet is used as the backbone for VPNs Saves cost tremendously from reduction of equipment and maintenance costs. Scalability

14 Remote Access Virtual Private Network (From Gartner Consulting)

15 Brief Overview of How it Works Two connections one is made to the Internet and the second is made to the VPN. Datagrams contains data, destination and source information. Firewalls VPNs allow authorized users to pass through the firewalls. Protocols protocols create the VPN tunnels.

16 Four Critical Functions Authentication validates that the data was sent from the sender using digital signature. Access control limiting unauthorized users from accessing the network. Confidentiality preventing the data to be read or copied as the data is being transported. Using public key cryptography. Data Integrity ensuring that the data has not been altered

17 Tunneling A virtual point-to-point connection made through a public network. It transports encapsulated datagram's. Original Datagram Encrypted Inner Datagram Datagram Header Outer Datagram Data Area Data Encapsulation [From Comer] Two types of end points: Remote Access Site-to-Site

18 Four Protocols used in VPN PPTP -- Point-to-Point Tunneling Protocol L2TP -- Layer 2 Tunneling Protocol IPsec -- Internet Protocol Security SOCKS is not used as much as the ones above

19 VPN Encapsulation of Packets

20 Types of Implementations What does implementation mean in VPNs? 3 types Intranet Within an organization Extranet Outside an organization Remote Access Employee to Business

21 Virtual Private Networks (VPN) Basic Architecture

22 Device Types What it means 3 types Hardware Firewall Software

23 Device Types: Hardware Usually a VPN type of router Pros Highest network throughput Plug and Play Dual-purpose Cons Cost Lack of flexibility

24 Device Types: Firewall More security? Pros Harden Operating System Tri-purpose Cost-effective Cons Still relatively costly

25 Device Types: Software Ideal for 2 end points not in same org. Great when different firewalls implemented Pros Flexible Low relative cost Cons Lack of efficiency More labor training required Lower productivity; higher labor costs

26 Advantages VS. Disadvantages

27 Advantages: Cost Savings Eliminating the need for expensive long-distance leased lines Reducing the long-distance telephone charges for remote access. Transferring the support burden to the service providers Operational costs Cisco VPN Savings Calculator

28 Advantages: Scalability Flexibility of growth Efficiency with broadband technology

29 Disadvantages VPNs require an in-depth understanding of public network security issues and proper deployment of precautions Availability and performance depends on factors largely outside of their control Immature standards VPNs need to accommodate protocols other than IP and existing internal network technology

30 Applications: Site-to-Site VPNs Large-scale encryption between multiple fixed sites such as remote offices and central offices Network traffic is sent over the branch office Internet connection This saves the company hardware and management expenses

31 Site-to-Site VPNs

32 Applications: Remote Access Encrypted connections between mobile or remote users and their corporate networks Remote user can make a local call to an ISP, as opposed to a long distance call to the corporate remote access server. Ideal for a telecommuter or mobile sales people. VPN allows mobile workers & telecommuters to take advantage of broadband connectivity. i.e. DSL, Cable

33 Industries That May Use a VPN Healthcare: enables the transferring of confidential patient information within the medical facilities & health care provider Manufacturing: allow suppliers to view inventory & allow clients to purchase online safely Retail: able to securely transfer sales data or customer info between stores & the headquarters Banking/Financial: enables account information to be transferred safely within departments & branches General Business: communication between remote employees can be securely exchanged

34 Some Businesses using a VPN CVS Pharmaceutical Corporation upgraded their frame relay network to an IP VPN ITW Foilmark secured remote location orders, running reports, & internet/intranet communications w/ a 168-bit encryption by switching to OpenReach VPN Bacardi & Co. Implemented a 21-country, 44- location VPN

35 Where Do We See VPNs Going in the Future? VPNs are continually being enhanced. Example: Equant NV As the VPN market becomes larger, more applications will be created along with more VPN providers and new VPN types. Networks are expected to converge to create an integrated VPN Improved protocols are expected, which will also improve VPNs.