Telecommunications and Network Security Flashcards
IPv6
39-digit number in decimal larger and simpler than IPv4.
Does IPv6 hosts needs a DHCP
no, because IPv6 hosts can statelessly autoconfigure a unique IPv6 address, omitting the need for static addressing or DHCP. It takes the host’s MAC address and uses it to configure the IPv6 address.
What is RFC 1918 addresses?
* 10.0.0.0–10.255.255.255 (10.0.0.0/8)
- 172.16.0.0–172.31.255.255 (172.16.0.0/12)
- 192.168.0.0–192.168.255.255 (192.168.0.0/16)
Three new TCP flags were added
CWR (Congestion Window Reduced)
ECE (Explicit Congestion Notification Echo),
NS (Nonce Sum)
These flags are used to manage congestion (slowness) along a network path.
SNMP agents use what port?
UDP port 161
coaxial network cable
has an inner copper core separated by an insulator from a metallic braid or shield. The outer layer is a plastic sheath.
Fiber Optics
made from a very narrow glass or plastic fiber that is surrounded by and the cladding in turn is covered by a protective sheath. Fiber optics emit extremely small amounts of energy from the cable, data cannot be as easily intercepted. Fiber optics are more difficult to wiretap.
FDDI (Fiber Distributed Data Interface)
legacy LAN technology, running a logical network ring (token-passing ) via a primary and secondary counter-rotating fiber optic ring.
The secondary ring was typically used for fault tolerance. Runs at 100 MBPS speed using light Not effected by EMI
FDDI-2 allows for fixed bandwidth to be assigned unlike FDDI and not affected by EMI.
T1
a 1.544-megabit circuit that carries 24 64-bit DS0 (DigitalSignal0) channels.
T3
28 bundled T1s, forming a 44.736-megabit circuit.
E1
is a dedicated 2.048-megabit circuit that carries 30 channels.
E3
16 bundled E1s, forming a 34.368-megabit circuit.
SONET
carries multiple T-carrier circuits via fiber optic cable. SONET uses a physical fiber ring for redundancy.
X.25
is an older packet-switched WAN protocol.
Transmit data over long distances in the 1970s though early 1990s via analog modem.
Separate from the global IP-based Internet.
Performs error correction that can add latency on long links and can carry TCP/IP.
It uses virtual circuits instead of dedicated ones.
Frame Relay
a Layer 2 WAN protocol, no error recovery and focuses on speed.
Frame Relay multiplexes multiple logical connections over a single physical connection to create Virtual Circuits; this shared bandwidth model is an alternative to dedicated circuits such as T1s.
Frame Relay can carry TCP/IP.
Like X.25, it uses virtual circuits instead of dedicated ones.
Asynchronous Transfer Mode (ATM)
Not a packet-switch based network. Reliable network comparing to Ethernet
Multiprotocol Label Switching (MPLS)
forward WAN data via labels through a shared MPLS cloud network, such as ATM, Frame Relay and IP.
A technical solution for the QoS, speed, and security problems facing the Internet.
Improved routing performance. gives service providers the ability to create VPNs without the need of end user applications.
Synchronous Data Link Control (SDLC) is
synchronous Layer 2 WAN protocol that uses polling to transmit data. Polling is similar to token passing; the difference is that a primary node polls secondary nodes, which can transmit data when polled.
High-Level Data Link Control (HDLC)
the successor to SDLC. HDLC adds error correction and flow control, as well as two additional modes (ARM and ABM). Three modes: NRM, ARM, and ABM
Normal Response Mode (NRM)
Secondary nodes can transmit when given permission by the primary.
Asynchronous Response Mode (ARM
Secondary nodes may initiate communication with the primary.
Asynchronous Balanced Mode (ABM)
Combined mode where nodes may act as primary or secondary, initiating transmissions without receiving permission.
Routing protocols come in two basic varieties:
o Interior Gateway Protocols (IGPs) such as RIP and OSPF used by Private network. o Exterior Gateway Protocols (EGPs), such as BGP are used on public networks.
Distance vector routing protocols
uses metrics, which is hop count prone to routing loops, where packets loop between two routers. Ex. RIP and OSPF
RIP
a distance vector routing protocol that uses hop count as it’s metric.
It does not have a full view of a network: It can only “see“directly connected routers.
Convergence is slow.
RIP sends routing updates every 30 seconds regardless of routing changes.
RIP’s maximum hop count is 15; 16 is considered “infinite.”.
Disadvantage of RIP
increases network congestion
Only works with classful network, and there is no way for a router to verify the trustworthiness of a route update from its neighbors.
Hold-down timers, split horizon, and poison reverse are small fixes that do not compensate for RIP’s weaknesses.
RIP uses split horizon to help avoid routing loops.
RIP uses a hold-down timer to avoid flapping (repeatedly changing a route’s status from up to down).
RIPv2
used in a network with different subnet masks and authenticate with other routers using MD5. RIPv2 added support for CIDR.
What RIP can do to avoid routing loop?
RIP can use split horizon to help avoid routing loops
Poison reverse
Distance vector routing protocol safeguard that sets a bad route to infinity. Can be used in addition to split horizon
Link-state routing protocols
additional metrics for determining the best route, including bandwidth, latency and QoS. Ex. OSPF
o Open Shortest Path First (OSPF)
an open link-state routing protocol. It learns the entire network topology for their area the lowest cost paths to a destination. OSPF routers send event-driven updates. If a network is converged for a week, the OSPF routers will send no updates.
Stateful matching IDS`
scans for attack signatures in the context of a stream of traffic or overall system behavior rather than the individual packets.
Statistical anomaly-based IDS
Analyzes event data by comparing it to typical, known, or predicted traffic profiles by analyzing event data and identifying patterns of entries that deviate from a predicted norm. Very effective and, at a very high level. It can detect unknown attacks. Tuning the IDS can be challenging and, if not performed regularly, the system will be prone to false positives. Not suitable in large enterprises.
Protocol anomaly-based IDS
identifies any unacceptable deviation from expected behavior based well-known or well-defined protocols within an environment. Ex: HTTP session Specific protocol analysis modules may have to be added or customized to deal with unique or new protocols or unusual use of standard protocols.
Traffic anomaly-based IDS
dentifies any unacceptable deviation from expected behavior based on actual traffic structure. When a session is established between systems, there is typically an expected pattern and behavior to the traffic transmitted in that session. That traffic can be compared to expected traffic conduct based on the understandings of traditional system interaction for that type of connection.
Land attack
It uses a spoofed SYN packet that includes the victim’s IP address as both source and destination.