8 - 1.1: TCP/IP Networking Flashcards
TCP/IP
A set of networking protocols, stands for Transmission Control Protocol / Internet Protocol
Main roles of IP
Providing an addressing scheme to uniquely identify computers on a network and deliver information
Packets
Chunks of information sent over networks
IP is a ______ layer protocol
Network
Two main transport layer protocols
Transmission Control Protocol (TCP) and User Datagram Protocol (UDP)
TCP is defined as
A connection-oriented protocol, guarantees delivery through acknowledgment
Three-way handshake
A TCP process for creating a connection before data is transmitted..
TCP packet flags role
Special flags that identify packets used in the handshaking process
TCP packet flag names
SYN, FIN, ACK
SYN flags
open a connection
FIN flags
close a connection
ACK flags
acknowledge a SYN or FIN
Three steps of handshake
1) originating system sends SYN 2) destination receives, sends a SYN + ACK packet set 3) originating system sends an ACK packet
UDP is defined as
Lightweight connectionless protocol that doesn’t send acknowledgments or guarantee delivery
OSI model
Open Systems Interconnection model
OSI layers
1) physical 2) data link 3) network 4) transport 5) session 6) presentation 7) application
Physical layer
Sending bits with wires, radio waves, fiber optics, etc.
Data link layer
Transfers data between nodes on the same physical network
Network layer
expands networks to different nodes
Transport layer
Creates connections between systems and reliably transfers data
IP works at the ______ layer
Network
TCP and UDP work at the _____ layer
Transport
Session layer
Manages exchange of communication between systems
Presentation layer
translates data for network transmission, describes how to represent a character in terms of bits, performs cryptography
Application layer
Determines how users interact with data using software
IP addresses
Uniquely identifying numbers for internet locations
Dotted quad notation
Four numbers, ranging between 0 - 255, separated by dots
Why 255?
Each number in the IP quad is represented by eight binary bits. 2 to the eight is 256, but we start at 0 so 255
NAT
Network Address Translation: there are only so many IP addresses that can possibly be made, so your home/org uses repeated one other places also do. Routers translate those private IPs into publicly facing ones
IP address portions
Network portion and host address
Network portion
Identifies the network that a system is connected to
Host address
Uniquely identifies a system/device on that network
Subnetting
Subdividing IP addresses beyond the normal 4 numbers
IP addresses in network communication
Source address and destination address
Source address
Indicates the system sending information
Destination address
Destination address indicates system receiving information
IPv4
32-bits, four numbers
IPv6
128 bits, using eight groups of four hexadecimal digits
IP address assignment
Static or Dynamic Host Configuration Protocol
Static address assignment
Manually specify IP addresses, requires fitting within the network range
Dynamic Host Configuration Protocol
Configures a pool of IP addresses, then automatically assigns from that pool as systems join
Domain Name System / servers
Translates the names of web locations into addresses computers use, operating over UDP port 53
DNS Resolution
1) Enter domain name in browser 2) computer sends DNS query to local DNS server 3) DNS server responds with an IP address 4) computer contacts server at that address
DNS is a ____ system
Hierarchical. If one local DNS server doesn’t know the answer, it will contact others that do
DNS poisoning
Inserting false DNS records to redirect users to malicious sites or locations
DNSSEC
Adds an extra signature to DNS records for verification
Network ports
A sub-address within IP address locations to specify applications
Network port numbers
16-bit binary numbers, ranging between 216 or 65,536 possible values. Starting at 0, that makes the maximum 65,535
Network port ranges
0 to 1,023: Well-known ports
1024 to 49,151: Registered ports
Above 49,151: Dynamic ports
Well-known ports
Reserved for common applications issued by internet authorities; web servers, email servers, etc.
Registered ports
Vendors may reserve these for their applications, such as Microsoft’s SQL databases on 1433 and Oracle’s on 1521
Dynamic ports
Reserved for use on a temporary basis
Internet Control Message Protocol
The “housekeeping” protocol of the network
Ping command
Sending an “are you there,” echo command to another system
Traceroute
More detailed troubleshooting, including status and messages, network path taken, and performance
