CHAPTER 6 Flashcards
Hackers can intercept incoming and outgoing calls, carry out DoS attacks, spoof phone calls, and eavesdrop on sensitive conversations. Many of the countermeasures to these types of attacks are the same ones used with traditional data-oriented networks:
- Keep patches updated on each network device involved with VoIP transmissions:
The terms “IP telephony” and “Voice over IP” are used interchangeably:
- The term “VoIP” is widely used to refer to the actual services offered: caller ID, QoS, voicemail, and so on.
- IP telephony is an umbrella term for all real-time applications over IP, including voice over instant messaging (IM) and videoconferencing.
Characteristics of circuit-level proxy firewalls:
- Do not require a proxy for each and every protocol.
- Do not provide the deep-inspection capabilities of an application layer proxy.
- Provide security for a wider range of protocols.
Network interface cards and drivers convert bits into electrical signals and control the physical aspects of data transmission, including optical, electrical, and mechanical requirements. The following are some of the standard interfaces at this layer:
- EIA-422, EIA-423, RS-449, RS-485
- 10BASE-T, 10BASE2, 10BASE5, 100BASE-TX, 100BASE-FX, 100BASE-T, 1000BASE-T, 1000BASE-SX
- Integrated Services Digital Network (ISDN)
- Digital subscriber line (DSL)
- Synchronous Optical Networking (SONET)
Secure Sockets Layer (SSL):
- Works at the transport layer and protects mainly web-based traffic
- Granular access control and configuration are available
- Easy deployment since SSL is already embedded into web browsers
- Can only protect a small number of protocol types, thus is not an infrastructure-level VPN solution
This technology transmits data by “spreading” it over a broad range of frequencies:
- FHSS moves data by changing frequencies.
- DSSS takes a different approach by applying sub-bits to a message and uses all of the available frequencies at the same time.
The protocols at the data link layer convert data into LAN or WAN frames for transmission and define how a computer accesses a network. This layer is divided into the Logical Link Control (LLC) and the Media Access Control (MAC) sublayers. Some protocols that work at this layer include the following:
- Address Resolution Protocol (ARP)
- Reverse Address Resolution Protocol (RARP)
- Point-to-Point Protocol (PPP)
- Serial Line Internet Protocol (SLIP)
- Ethernet
- Token Ring
- FDDI
- ATM
The services of the presentation layer handle translation into standard formats, data compression and decompression, and data encryption and decryption. No protocols work at this layer, just services. The following lists some of the presentation layer standards:
- American Standard Code for Information Interchange (ASCII)
- Extended Binary-Coded Decimal Interchange Mode (EBCDIC)
- Tagged Image File Format (TIFF)
- Joint Photographic Experts Group (JPEG)
- Motion Picture Experts Group (MPEG)
- Musical Instrument Digital Interface (MIDI)
This chapter presents the following:
- OSI and TCP/IP models
- Protocol types and security issues
- LAN, WAN, MAN, intranet, and extranet technologies
- Cable types and data transmission types
- Network devices and services
- Communications security management
- Telecommunications devices and technologies
- Remote connectivity technologies
- Wireless technologies
- Threat and attack types
The following lists some important characteristics of a stateful-inspection firewall:
- Maintains a state table that tracks each and every communication session
- Provides a high degree of security and does not introduce the performance hit that application proxy firewalls introduce
- Is scalable and transparent to users
- Provides data for tracking connectionless protocols such as UDP and ICMP
- Stores and updates the state and context of the data within the packets
Several types of devices are used in LANs, MANs, and WANs to provide intercommunication among computers and networks. We need to have physical devices throughout the network to actually use all the protocols and services we have covered up to this point. The different networking devices vary according to their functionality, capabilities, intelligence, and network placement. We will look at the following devices:
- Repeaters
- Bridges
- Routers
- Switches
The protocols at the transport layer handle end-to-end transmission and segmentation of a data stream. The following protocols work at this layer:
- Transmission Control Protocol (TCP)
- User Datagram Protocol (UDP)
- Secure Sockets Layer (SSL)/Transport Layer Security (TLS)
- Sequenced Packet Exchange (SPX)
The responsibilities of the network layer protocols include internetworking service, addressing, and routing. The following lists some of the protocols that work at this layer:
- Internet Protocol (IP)
- Internet Control Message Protocol (ICMP)
- Internet Group Management Protocol (IGMP)
- Routing Information Protocol (RIP)
- Open Shortest Path First (OSPF)
- Internetwork Packet Exchange (IPX)
