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112 Cards in this Set
- Front
- Back
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OSI Model - purpose
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Purpose - increase interoperability between vendor products
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OSI Layers
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Application - Layer 7
Presentation - Layer 6 Session - Layer 5 Transport - Layer 4 Network - Layer 3 Data - Layer 2 Physical - Layer 1 |
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OSI memorization phrase
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Please Do Not Throw Sausage Pizza Away
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OSI Physical Layer (1)
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Bits into voltage
Coax, twisted pair (TP), fiber (FX), RJ45 Specifies how signals are transmitted Electrical Signaling Electrical & Mechanical interfaces Data sent over physical media Encoding scheme |
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OSI Data Layer (2)
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Rules of access the network media
switching breaks sending msg into frames formats frames (token ring, Ethernet, ATM, ) media access methods - collision/contention based - Token passing - FDDI ring architecture synchronization and error control |
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Ethernet standard
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802.3
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Token ring standard
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802.5
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Wireless Standard
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802.11
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OSI Network Layer 3
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** only one to provide confidentiality, authentication, and integrity with IPsec **
Routing and IP Fragments for dissimilar frame size Buffering Error control |
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OSI Transport Layer 4
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End to End ** HOST to HOST **
Protocols here are TCP, UDP, IPX Buffering Error Control Packet sequencing, segmenting, reassemble |
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OSI Layer 5 Session
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connection establish, maintenance, tear down
NFS, SQL, RPC Client/server Sychronization Half, Full Duplex and simplex here |
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OSI Layer 6 Presentation
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File level encryption, compression
translates into standard presentation Encoding (ASCII,EBCDIC) Binary negotiation Formatting - GIF, TIFF, JPEG |
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OSI Layer 7 Application
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File Transfer
E-mail (SMTP Gateway) telnet ,POP, Access Control Services Browsers (HTTP) Non-repudiation provide network for applications |
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Digital Signature provides
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Integrity, authentication, non-repudiation
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Protocols
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Rules to allow two or more computers to send/receive data
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OSI and DoD TCP/IP memory tool
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3112
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DoD TCP/IP suite
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Application (3)
Host to Host (1) Internet (1) Network Interface (2) |
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Well known TCP/UDP ports
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below 1024
(0-1023) |
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TCP
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connection oriented
reliable flow control SYN-SYN/ACK-ACK |
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UDP
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Connectionless
non-reliable no handshake "best effort" (Video Streaming) faster than TCP |
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IPv4 Class A
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0.0.0.0 - 126.0.0.0
16 million host addresses (16,777,214) |
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IPv4 Class B
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128.0.0.0 - 191.255.0.0
65 thousand host addresses (65,534) |
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IPv4 Class C
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192.0.0.0 - 223.255.255.0
254 host addresses |
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IPv4 Class D
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224..0.0.0 - 239.255.255.255
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IPv4 Class E
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240.0.0.0 - 255.255.255.255
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2^8
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256
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2^16
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65,536
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2^24
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16,777,216
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# IP host address
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Always 2^N - 2
one reserved for broadcast (255) one reserved for the network (0) |
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IPv6
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128 bit addresses (8 blocks)
64 bits network 64 bits hosts hosts component can be based on MAC |
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Global addresses
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1st 48 bits are global routing prefix
Next 16 are subnet ID |
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Synchronous Signaling Transmission
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Stream
No start and stop synchronizes before sending data - clocking mechanism Large amounts of data |
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Asynchronous Signaling Transmission
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Bits sent sequentially
start and stop bits small amounts of data Modems |
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Bus Network
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Linear
Single cable traffic received by all devices (ignored) if one computer has a problem affects all |
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Ring Network
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unidirectional transmission link
closed loop one computer has a problem affects all |
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Star Network
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connected to a central device (hub)
central device single point of failure |
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Tree
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bus topology but branches of cables
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Mesh
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all computers connected to each other
no single point of failure more expensive |
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Coax Thinnet
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10base-2
185 (200) meters RG-58 10 mbps 50 ohm |
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Coax Thicknet
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10base-5
500 meters RG-8 RG-11 10 mbps 50 ohm |
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Coax cabling
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higher performance than twisted pair
one way networks cable tv |
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Twisted pair cabling
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LAN media
cheap easy to work with residential telephone |
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10base-T
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Unshielded twisted pair
10 Mbps |
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100base-TX fast ethernet
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Unshielded twisted pair
100 Mbps |
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1000base-TX fast ethernet
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Unshielded twisted pair
1000 Mbps (gig) |
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1000base-X
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Fiber
1000 Mbps (gig) |
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Fiber
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Fast
less attenuation expense single mode 2000 meter multi mode 500 meter most secure |
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Cable Fire issues use:
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Plenum cable do not release toxic fumes
fluoropolymers |
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Transmission Method (Unicast)
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one to one relationship
"Client/Server" |
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Transmission Method (Multicast)
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One to many relationship
"Streaming" |
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Transmission Method (Broadcast)
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One to all relationship
usually just on a network (to locate) |
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ARP (Address Resolution Protocol)
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maps IP address (layer 3) to the media access control (MAC) address (layer 2)
ARP translates so they can talk ARP broadcast out ip gets MAC back |
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Masquerading Attack
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altering ARP table to a different MAC address
ARP Poisoning |
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RARP (Reverse Address Resolution Protocol)
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Has MAC, broadcasts to get IP
succeeded by BOOTP - provides for diskless workstations - more functionality |
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DHCP Leasing Process (DORA) 4 steps
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DHCP Discover
DCHP Offer DHCP Request DHCP pAck |
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ICMP
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message protocol for IP
PING - ICMP ECHO request/reply Can be used to trick routers into changing table Loki attack |
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SNMP Port
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161-162
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SMTP Port
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25
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SSH port
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22
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FTP port
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20-21
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Telnet port
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23
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HTTPs port
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443
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Router
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Layer 3
security through packet filtering and ACL's |
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Distance vector routing (RIP)
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does not look at bandwidth
distance = # of hops entire routing table sent to neighbors Noisy Max of 16 hops |
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Link state routing (OSPF - open shortest path first)
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more intelligence
topology map all routers establish topology database using DR Link State Advertisements used to check topology |
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Layer 7 Application Gateway
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Links networks (SMTP(
Translator |
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If they are talking proxy then its...
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Application Gateway
Proxy - better security |
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Circuit level proxy
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Looks only at the header packet information
wider range than application but not the detailed level makes decisions based on address and port Session Layer (5) |
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SOCKS
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circuit level proxy
clients must be SOCKs-ified with client software VPN and outbound internet VPN like but not tradition VPN protocol |
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Kernel Proxy
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most advanced
faster than application proxy (done in kernel) one network stack for each packet does NATing Application Layer (7) |
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Dual-Homed Firewall
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single system with two nics, one to trusted network, one to untrusted network
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Screened Host Firewall
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Router between the internet and the firewall screening traffic
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Screened Subnet Firewall
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External router filters traffic before DMZ, then goes thru firewall and another router
Provides more protection that Dual Homed and Screened Host |
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Directory services ISO standard
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X.500
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Static NAT
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Each internal system has its own external IP
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Hiding NAT
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All internal systems have same external IP
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Port Address Translation (PAT)
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uses port in url to get to specific system internally
https://www.abc.com:8080 |
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Circuit switching
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connection oriented link
virtual connection acts like dedicated link voice phone calls packets in order |
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Packet switching
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packets use dynamic paths and can arrive out of order
carries data |
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Multiplexing
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device that combines two or more channels
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Frequency division multiplexing (FDM)
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assigning separate portions of an available spectrum
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Time- Division Multiplexing (TDM)
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assigning discrete time intervals in sequence to individual channels
more secure - reassembles by time |
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Asynchronous Transmission Mode (ATM)
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CELL based
switching and multiplexing 53 byte CELLS instead of frames |
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Session Initiation Protocol (SIP) for VOIP
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emulates phone like features (dial tone, ringing, busy signals, etc)
uses User Agents (Client and Server) |
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Vishing
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Phishing over VOIP
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ISDN BRI (Basic Rate Interface)
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uses 2 B channels for data (64k each)
uses 1 D channel for signaling (16k) data 128k signaling 16k total pipe 144k |
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ISDN PRI (Primary Rate Interface)
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23 B Channels
1 D Channel at 64k Total bandwidth = to T1 (1.544 Mbps) |
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Point to Point Protocol (PPP) Authentication mechanisms
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PAP - clear text
CHAP- not credentials across the wire EAP - extensible (external) |
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Point to Point Tunneling Protocol (PPTP)
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Layer 2
Data layer protocol for point to point connections Data is encrypted ** negotiation information in clear text ** only IP traffic (need L2TP to do other than IP) |
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IPSec
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works at network layer (3)
encrypts just the payload or payload and header Tunnel mode (payload and header protected) Transport mode (payload protected) |
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Password Authentication Protocol (PAP)
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creds sent in clear text
vulnerable to man in the middle, sniffing and replay attacks |
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Challenge Handshake Authentication Protocol (CHAP)
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challenge response
user's password used to encrypt challenge value periodically challenges for pw to prevent man in the middle attack password not sent over the wire |
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Extensible Authentication Protocol (EAP)
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802.1x
Supports: Token cards Kerberos OTP |
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Lightweight Extensible Authentication Protocol (LEAP)
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Cisco proprietary
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EAP-TLS
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very secure
uses certs on both client and server (PKI) |
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EAP-TTLS
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Only server side certs
can have client certs doesn't have to |
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PEAP (Protected Extensible Authentication Protocol)
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Joint venture with Cisco, Microsoft, RSA
Protected EAP server side certs only |
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WLAN 802.11a
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more channels
high speed less interference |
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WLAN 802.11b
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de facto standard
11 mb/sec |
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WLAN 802.11g
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like 802.11b
54 mb/sec |
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WLAN 802.11i
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Adds WPA II
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WLAN 802.11n
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450 Mbps
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WLAN 802.16
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Long-distance wireless infrastructure
WIMAX |
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What is the backward compatible wireless encryption
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WPA
WPA II is NOT |
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Access points modes
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Infrastructure
Peer to Peer |
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WEP (Wired Equivalent Privacy)
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based on RC4 encryption
Single shared key (symmetric) |
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WPA
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uses TKIP
48 bit Initialization Vector different session key for each packet Pre shared key |
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WPA2
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802.11i
CCMP (Counter mode with Cipher Block Chaining (CBC) Message Authentication Code (MAC) protocol) AES based encryption stronger than TKIP AES uses variable strength encryption (128,192,256 bit) |
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WAP (Wireless Application Protocol)
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set of older protocols
low overhead allows wireless device to access internet |
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Stateful Firewall
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network layer
looks at the state and context of packets keeps track of each conversation in state table |
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Packet filtering firewall
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network layer
looks at source and dest addresses, ports and services Routers using ACL's to monitor network traffic |
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Application level firewall
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Application layer
looks deep into packets, makes granular decisions on access control one proxy per protocol |
