ISC2 SSCP Systems Security Certified Practitioner Exam Practice Test

Answer : C

Port Address Translation (PAT), is an extension to network address translation (NAT) that permits multiple devices on a local area network (LAN) to be mapped to a single public IP address. The goal of PAT is to conserve IP addresses or to publish multiple hosts with service to the internet while having only one single IP assigned on the external side of your gateway.

Most home networks use PAT. In such a scenario, the Internet Service Provider (ISP) assigns a single IP address to the home network's router. When Computer X logs on the Internet, the router assigns the client a port number, which is appended to the internal IP address. This, in effect, gives Computer X a unique address. If Computer Z logs on the Internet at the same time, the router assigns it the same local IP address with a different port number. Although both computers are sharing the same public IP address and accessing the Internet at the same time, the router knows exactly which computer to send specific packets to because each computer has a unique internal address.

Port Address Translation is also called porting, port overloading, port-level multiplexed NAT and single address NAT.

Shon Harris has the following example in her book:

The company owns and uses only one public IP address for all systems that need to communicate outside the internal network. How in the world could all computers use the exact same IP address? Good question. Here's an example: The NAT device has an IP address of 127.50.41.3. When computer A needs to communicate with a system on the Internet, the NAT device documents this computer's private address and source port number (10.10.44.3; port 43,887). The NAT device changes the IP address in the computer's packet header to 127.50.41.3, with the source port 40,000. When computer B also needs to communicate with a system on the Internet, the NAT device documents the private address and source port number (10.10.44.15; port 23,398) and changes the header information to 127.50.41.3 with source port 40,001. So when a system responds to computer A, the packet first goes to the NAT device, which looks up the port number 40,000 and sees that it maps to computer A's real information. So the NAT device changes the header information to address 10.10.44.3 and port 43,887 and sends it to computer A for processing. A company can save a lot more money by using PAT, because the company needs to buy only a few public IP addresses, which are used by all systems in the network.

As mentioned on Wikipedia:

NAT is also known as Port Address Translation: is a feature of a network device that translate TCP or UDP communications made between host on a private network and host on a public network. I allows a single public IP address to be used by many host on private network which is usually a local area network LAN

NAT effectively hides all TCP/IP-level information about internal hosts from the Internet.

The following were all incorrect answer:

IP Spoofing - In computer networking, the term IP address spoofing or IP spoofing refers to the creation of Internet Protocol (IP) packets with a forged source IP address, called spoofing, with the purpose of concealing the identity of the sender or impersonating another computing system.

Subnetting - Subnetting is a network design strategy that segregates a larger network into smaller components. While connected through the larger network, each subnetwork or subnet functions with a unique IP address. All systems that are assigned to a particular subnet will share values that are common for both the subnet and for the network as a whole.

A different approach to network construction can be thought of as subnetting in reverse. Known as CIDR, or Classless Inter-Domain Routing, this approach also creates a series of subnetworks. Rather than dividing an existing network into small components, CIDR takes smaller components and connects them into a larger network. This can often be the case when a business is acquired by a larger corporation. Instead of doing away with the network developed and used by the newly acquired business, the corporation chooses to continue operating that network as a subsidiary or an added component of the corporation's network. In effect, the system of the purchased entity becomes a subnet of the parent company's network.

IP Distribution - This is a generic term which could mean distribution of content over an IP network or distribution of IP addresses within a Company. Sometimes people will refer to this as Internet Protocol address management (IPAM) is a means of planning, tracking, and managing the Internet Protocol address space used in a network. Most commonly, tools such as DNS and DHCP are used in conjunction as integral functions of the IP address management function, and true IPAM glues these point services together so that each is aware of changes in the other (for instance DNS knowing of the IP address taken by a client via DHCP, and updating itself accordingly). Additional functionality, such as controlling reservations in DHCP as well as other data aggregation and reporting capability, is also common. IPAM tools are increasingly important as new IPv6 networks are deployed with larger address pools, different subnetting techniques, and more complex 128-bit hexadecimal numbers which are not as easily human-readable as IPv4 addresses.

Reference(s) used for this question:

STREBE,

Matthew and PERKINS, Charles, Firewalls 24seven, Sybex 2000, Chapter 1: Understanding Firewalls.

Schneiter, Andrew (2013-04-15). Official (ISC)2 Guide to the CISSP CBK, Third Edition : Telecommunications and Network Security, Page 350.

Harris, Shon (2012-10-25). CISSP All-in-One Exam Guide, 6th Edition (Kindle Locations 12765-12774). Telecommunications and Network Security, Page 604-606

http://searchnetworking.techtarget.com/definition/Port-Address-Translation-PAT

http://en.wikipedia.org/wiki/IP_address_spoofing

http://www.wisegeek.com/what-is-subnetting.htm

http://en.wikipedia.org/wiki/IP_address_management

Answer : C

Port 119 is normally used for the Network News Transfer Protocol. It is thus not need for a mail server, which would normally listen to ports 25 (SMTP), 110 (POP3) and 143 (IMAP).

Source: STREBE, Matthew and PERKINS, Charles, Firewalls 24seven, Sybex 2000, Chapter 1: Understanding Firewalls.

Answer : C

Firewalls can protect a network at multiple layers of the OSI models, however most of the firewalls do not have the ability to monitor the payload of the packets and see if an application level attack is taking place.

Today there are a new breed of firewall called Unified Threat Managers or UTM. They are a collection of products on a single computer and not necessarily a typical firewall. A UTM can address all of the layers but typically a firewall cannot.

Firewalls are security checkpoints at the boundaries of internal networks through which every packet must pass and be inspected, hence they create bottlenecks between the internal and external networks. But since external connections are relatively slow compared to modern computers, the latency caused by this bottleneck can almost be transparent.

By implementing the concept of border security, they centralize security services in machines optimized and dedicated to the task, thus relieving the other hosts on the network from that function.

Source: STREBE, Matthew and PERKINS, Charles, Firewalls 24seven, Sybex 2000, Chapter 1: Understanding Firewalls.

Answer : D

Source: TIPTON, Harold F. & KRAUSE, MICKI, Information Security Management Handbook, 4th Edition, Volume 2, 2001, CRC Press, NY, Pages 166-167.

Answer : A

Source: TIPTON, Harold F. & KRAUSE, MICKI, Information Security Management Handbook, 4th Edition, Volume 2, 2001, CRC Press, NY, Pages 166-167.

Answer : D

AH provides integrity, authentication, and non-repudiation. AH does not provide encryption which means that NO confidentiality is in place if only AH is being used. You must make use of the Encasulating Security Payload if you wish to get confidentiality.

IPSec uses two basic security protocols: Authentication Header (AH) and Encapsulation Security Payload.

AH is the authenticating protocol and the ESP is the authenticating and encrypting protocol that uses cryptographic mechanisms to provide source authentication, confidentiality and message integrity.

The modes of IPSEC, the protocols that have to be used are all negotiated using Security Association. Security Associations (SAs) can be combined into bundles to provide authentication, confidentialility and layered communication.

Source:

TIPTON, Harold F. & KRAUSE, MICKI, Information Security Management Handbook, 4th Edition, Volume 2, 2001, CRC Press, NY, page 164.

also see:

Shon Harris, CISSP All In One Exam Guide, 5th Edition, Page 758

Answer : C

Infrared is generally considered to be more secure to eavesdropping than multidirectional radio transmissions because infrared requires direct line-of-sight paths.

Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, John Wiley & Sons, 2001, Chapter 4: Cryptography (page 173).