Domain 4: Communication and Network Security 14% Flashcards
Baseband
networks have on channel, and can only send one signal at a time. Ethernet is baseband.
Broadband
networks have multiple channels and can send and receive multiple signals at a time.
Extranet
is a connection between private Intranets, often connecting business partners Intranets.
Circuit switching
Expensive, but always available, used less often. A dedicated comm channel through the network, guarantees the full bandwidth.
Packet switching
cheap, but no capacity guarantee, very widely used today.
QOS (Quality of Service)
gives specific traffic priority over other traffic. Most commonly VOIP, or other UDP traffic needing close to real time comm.
GAN (Global area network)
A global area network, is a network used for supporting mobiles users across a number of wireless LANs, satellite coverage areas, the transition from one to the next can be seamless
OSI (Open Systems Interconnect)
7 layers. 1. Physical, 2. Data Link, 3. Network, 4 Transport, 5. Session, 6. Presentation, 7. Application
7-1 All people seem to need data processing
PDU (Protocol Data Units)
Data-567, Segments-4, Packets-3, Frames-2, Bits-1
Layer 2: Data Link Layer
Transports btw 2 nodes connected to same network. LLC - Logical Link Control-error detection.
MAC address (BIA)
a unique identifier on the network card. Can be spoofed very easily. Threats - MAC Spoofing, MAC Flooding.
ARP (Address Resolution Protocol)
Layer 2/3
CSMA/CD (Collision Detection)
Ethernet - minimized with switches vs hubs.
CSMA/CA (collison Avoidence)
Wireless
Token passing
Similar to the talking stick, not really used anymore
Layer 3: Network Layer
Expands to many different nodes (IP) - The Internet is IP based. Isolates traffic into broadcast domains. Threats = Ping of Death, Ping Floods, Smurf - spoof source and directed broadcast, IP modifications, DHCP attacks
Only IMAP is layer 7 all other I protocols are Layer 3.
Layer 4: Transport Layer
SSL/TLS Layer 4 to 7
UDP (User Datagram Protocol)
Connectionless protocol, unrealiable, VOIP, Live video, gaming, “real time” Timing is more important than delivery confirmation Attack: Fraggle attack
TCP (Transmission Control Protocol)
Reliable, connection oriented, guaranteed delivery, 3 way handskake, slower/more overhead, data reassembled. Attacks: SYN floods - half open TCP sessions, client sends 1,000’s of SYN requests, but never the ACK
3-Way handshake
SYN, SYN/ACK, ACK
TCP Flags (9 bits 1-bit flags)(Control bits)
SYN= synch sequen numbers ACK= indicates that the Acknowledgment field is significant. RST= Rest the connection. FIN= Last package from sender
Layer 5: Session Layer
Establishes connection between 2 applications: Setup > Maintenance>Tear down
Layer 6: Presentation Layer
Only layer with no protocols. Formatting, compressing, encryption (file level)
Layer 7: Application Layer
Presents data to user (applications/websites. HTTPS, FTP, SNMP, IMAP, POP, AD integration
The higher up the layers
the slower it is, speed traded for intelligence
Threats to level 5-7
virus, worms, trojans, buffer overflow, app or OS vulner
TCP/IP Model (Internet protocol suite)
A conceptual model that provides end-to-end data comm. It has four layers which are used to sort all related protocols according to the scope of networking involved.
TCP/IP link layer
equals OSI Layers 1/2
TCP/IP Internetwork layer
equals OSI Layer 3
TCP/IP Transport layer
equals OSI Layer 4, TCP/UDP. port number
TCP/IP Application layer
equals OSI Layers 5-7
48bit MAC’s in IPv6
modified into 64-bit MAC’s by adding FF:FE to the device identifier
IPv4
1st deployed for production in the ARPANet in 1984, ARPANet later became the Internet. IP was developed in 1970’s for secure closed networks DARPA. Security was not built in, but was bolted on later. It is a connectionless protocol for use on packet-switched networks. It operates on a best effort delivery model, it does not guarantee delivery, it also does not assure proper sequencing or avoidance of duplicate delivery. We have added protocols (TCP) on top of IP to ensure those.
IPv6
moving here mainly because we are running out of IPv4 address
A Socket
1 set of IP and Port. UDP only uses 1 socket (connectionless), TCP uses 2 in a pair
Socket Pairs (TCP)
2 sets of IP and Port (Source and Destination)
IANA (Internet Assigned Numbers Authority)
governs the IP’s address allocation. Is a department of ICANN (Internet Corporation for Assigned Names and Numbers)
Unicast
1-1 traffic (Client to Server) we can capture all unicast traffic on a network by using promiscuous mode on a NIC (Network IDS’/IPS’)
Multicast
one to many (predefined)
Broadcast
one to all (on a LAN Network) The traffic is sent to everyone
Limited L3 Broadcast:
Use the 255.255.255.255 broadcast IP address, router do not pass
Limited L2 Broadcast:
Uses FF:FF:FF:FF:FF:FF broadcast MAC address, routers do not pass.
Directed broadcast:
Sent to anyone logically connected to the same network, regardless if it is physically behind the same router or not.
IPv4 Private Addresses
RFC 1918 - Not routable on the Internet
- 0.0.0 10.255.255.255
- 16.0.0 172.31.255.255
- 168.0.0 192.168.255.255
- 0.0.0/8 Loopback IP’s
- 254.0.0/16 Link-Local
- 255.255.255 Broadcast
NAT (Network Address Translation)
Static NAT Translates 1-1, not practical.
Pool NAT Also still 1-1, but a pool was available to all clients not assigned to specific clients
PAT (Port Address Translation)
It uses IP and Port number. Also called One-to-Many or NAT Overload since it translates One public IP to Many private IP’s. This is what is used today.
Classful IP Networks
were used early on the Internet for public address networks were very large. It was very inefficient use of IP Addresses.
CIDR (Classless Inter-Domain Routing, also called slash notation)
it breaks our addresses into smaller logical segments, thus saving addresses.
IP Headers contain
Version: IP v4 IHL: Length of the IP header QoS (Quality of Service) Id, Flags, Offset: used for IP fragmentation TTL (Time to live): to prevent routing loops. Protocol: Protocol number for TCP/UDP Source/Destination IP Addresses Optional: Options and padding
MTU (Maximum Transmission Unit)
normally 1500 bytes in Ethernet usage. If packet exceeds that size a router along the path may fragment into smaller packets.
IPv6
is 128bit in hexadecimal numbers (uses 0-9 and a-f). IPSec is built in, not bolted on like with IPv4.
IPv6 MAC Address
It is a EUI-48 address we add “ffee” to convert for EUI-64. This is added to the middle of the EUI-48 address.
IPv6 Header contains
Version: IP v6 (4bits) Traffic Class/Priority (8bits) Flow label/QoS management (20bits) Payload length in bytes (16bits) Next Header (8bits) Time to live (TTL)/Hop Limit Source IP add Destination IP address
ARP
translates IP address into MAC addresses. OSI 2/3 layer. Is simple and trusting protocol, anyone can respond to an ARP request.
ARP (cache) Poisoning
an attacker sends fake responses to ARP requests, often done repeatedly for critical AP entries (default gateway)
RARP (Reverse ARP)
is used by diskless workstations to get IP’s.
ICMP (Internet Control Message Protocol)
used to help IP, often used for troubleshooting. If we do not get a ping response it does not mean that it is down. Firewalls and routers can block ICMP replies.
Traceroute
Uses ICMP to trace a network route. Sends message with TTL until it reaches the destination. Max 30 hops.
Telnet
remote access over a network. Uses TCP port 23 everything is transmitted in plaintext so it is easy to sniff
SSH (Secure Shell)
Designed to replace or add security to unsecure protocols Telnet, FTP, HTTP. CIA and NSA can decrypt SSH and SSL traffic/data. No longer secure.
FTP (File Transfer Protocol)
Transfer files to and from servers. No confidentiality or Integrity checks. Should not be used. Uses TCP port 21 for sending command/ control collection. Uses TCP port 20 for sending the data
SFTP (SSH/Secure File Transfer Protocol)
Uses SSH to add security to FTP
FTPS (FTP Secure)
Uses TLS and SSL to add security to FTP
TFTP(Trivial FTP)
uses UDP port 69. No authentication or directory structure, files are written and read from one directory /tftpboot. Used for “Bootstrapping” - Downloading an OS over the network for diskless workstations. Used for saving router configuration.
DNS (Domain Name System)
Translates server names into IP Address, uses TCP/UDP port 53. Uses UDP for most requests and natively has no authentication
Authoritative name servers
The authority for a given name space
Recursive name server
Tries to resolve names it does not already know
Cache name server
Keeps previously resolved names in a temporary cache
DNS Poisoning
is similar to ARP poisoning, an attacker sends a fake address/name combo to another DNS server when asked and the server keeps it in its DNS record until it expires
DNSSEC (DNS Security Extensions)
Provides Authentication and Integrity using PKI Encryption
SNMP (Simple Network Management Protocol)
Mostly used to monitor devices on our network (routers, switches, servers, HVAC, UPS) An SNMP client agent is enabled or installed on the client. SNMPv1/v2 send data in cleartext and should be avoided.
SNMPv3
uses encryption to provide CIA. This should be the standard across any organization.