Download Networking

Networking
Kevin Cunningham, Ray, Stephan,
Norman, Phil
History
- ARPANET (Advanced Research Projects Agency
Network)
- World's first operational packet-switching
network
- Became the core network of what composes
the global Internet
- Originally consisted of terminals in UCLA,
Standford, UCSB, and the University of Utah
- DoD was concerned about our ability to
survive a nuclear strike due to lack of a
Outline
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Kevin – Network
Ray – IP'S and Packets
Kelvin – Sockets
Stephan – Security
Norman – Hardware
Phil - Conclusion
Networks As We Know Them Today
• A collection of computers and devices
interconnected by communications channels
that facilitate communications among users
and allows user to share resources
• Source:
http://en.wikipedia.org/wiki/Computer_netw
ork
Purposes of a Modern Network
• Facilitates communications
– E-mail, IM’s, chat rooms
• Sharing hardware
– A set of printers to be used by a whole office
• Sharing data
• Sharing software
– Running programs via a remote connection
IP addresses
And
Packets
IP’S And Macs
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NIC has unique Mac address(physical address)
•
IP address is logical
•
IPv4 and IPv6
Packets
•
All info on networks travel in packets
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Data in broken up and sent
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Each packet can take a different bath
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Allows for best path
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Put back together when received
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Click to edit Master text style
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Second level
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Third level
•
Fourth level
– Fifth level
Packet structure
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Fixed length and varying length
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Three main parts
•
o
Header(most inportant)
o
Data
o
Trailer
Have error checking
Header
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Contains all information about data being sent
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Packet length
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Packet number
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Destination and origination
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Every packet contains header
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Can vary in size
Other parts
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Data contains the data
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Trailer identifies end
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Check sum error checking
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All words in the message are XOR
Receiving end preforms same opertaion and
includes orginal XOR
If not all zeros error occured
Sockets
What are sockets?
- Used for client/server interaction
- Mechanism for transfer of data
- Socket API is provided by the OS
- Interface between applications and networking
and transfer protocols
How do sockets work?
- Server process waits for client
- Server accepts and binds client
- Server waits for client request
- Server replies to request
- Close
How do sockets work?
(Diagram)
Link:
http://publib.boulder.i
bm.com/infocenter/i
series/v5r4/topic/rza
b6/rxab6500.gif
Accepting connections
- Usually threaded to listen on many ports
- Client sends a connection request
- Server binds the client using IP and port
number
- Analogous to telephone/ext
Transferring Data
- Sockets are identified by socket identifier, aka
socket number
- OS decodes packets to determine socket
number, then forwards payload to application
- Sockets are bidirectional
- Different kinds of sockets use different
protocols (TCP/UDP/etc.)
Security
What is it?

Protection

Layers of security

Administrator privileges
How does it work

Authentication of user

Firewall enforced policies

What about worms and viruses?

Need IPS or IDS

Encryption
IPS and IDS

Intrusion Detection System(IDS)
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Network Intrusion Detection System
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Host-based Intrusion Detection System
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NIDS HIDS
IPS and IDS cont...

Intrusion Prevention System(IPS)
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Improvement of IDS

Classifications

NIPS – Network-based Intrusion Prevention

WIPS – Wireless-based Intrusion Prevention

NBA – Network Behavior Analysis

HIPS – Host-based Intrusion Prevention
Detection Methods

Signature-based Detection

Statistical Anomaly-Based Detection

Stateful Protocol Analysis Detection
Hardware
Network Interface Card
• Simply an I/O device
• Sends and receives data to the network in the
form of packets
• Will do DMA reads/writes directly to/from
main memory
• Can generate headers, but this is usually done
by the CPU
Network Interface Card
• After creating the frame or packet, the OS will
create a buffer descriptor which will tell where
and how large the data is
• After creating the buffer descriptor, the OS will
notify the NIC that it is ready
• The NIC will then do a DMA read for the
descriptor and then for the actual frame
• The frame is then sent out to the network
Network Interface Card
• OS will also have the NIC keep buffer
descriptors pointing to free space in main
memory
• When a frame is received, it will do a DMA
write to main memory
• It will then modify the descriptor to reflect the
received data, DMA write it to memory, and
notify the OS that a frame is ready
Drivers
• Handles the translation from standard I/O
function calls to the hardware’s specific
required software in order to run
• Can run in both kernel and user mode
• Kernel mode used mainly for speed
• User mode used mainly for stability
Hub
• Sends all packets to all other systems
connected to it
• High tendency to cause data collisions
– Collisions refer to when two or more systems send
data over the network, requiring the nowfragmented data to be retransmitted
Switch
• Like a hub, connects multiple systems
together to form a new network
• Operates by forwarding data to specific
systems on the network
• May be able to be piggy-backed, but may also
require crossover cables
• Have unmanaged and managed modes where
unmanaged refers to plug-and-play
Switch
• Avoids data collisions by sending data only to
its intended destination as a full-duplex
machine
• Keeps track of MAC addresses of each
connected system (nodes) in a table
Router
• Connects networks together and forwards
traffic between them
• Most have built-in switches
• Performs the job of a computer which acts as
a gateway (much cheaper than the computer)
Router
Computer
Internet
Computer
Switch
Computer
Computer
Computer
Internet
Router
Switch
Computer
Computer
Computer
Internet
Modern Router
Computer
Computer
Conclusion
What did we learn?