Linux Networking Course

History

*Arpanet
*switched network
*TCP/IP
*spread in the 90's

TCP/IP

What is a protocol

*strict procedure how things are done
*communication between layers
*clearly defined interfaces
*data encapsulation
*example

TCP/IP protocol

*Application
*Transport
*Network
*Physical / Data link

Physical layer / Data link layer

*not much of a concern for us.
*different topologies (ethernet, wirless, DSL, modem etc)
*this is about the physical connection
*here the bits are shifted.
*how many Volt represent a 1, how many a 0
*ethernet address (HWaddr in Hex format)

Network layer

*IP ICMP
*IPv4 32bit written in dotted decimal notation
*65.212.180.178

*different classes

A starts with 0
B starts with 10
C starts with 110
D starts with 1110

*although outdated it roughly specifies the network and host part.
*Common now is the CIDR (Classless InterDomain Routing)

192.168.10.3/24

this actually stands for

11000000 10101000 00001010 00000011
11111111 11111111 11111111 00000000

private networks that are not routed
localhost 127.0.0.0/8
"network addresses" ending with 0
"broadcast addresses" ending with 255
routing
nat
configuration

Transport Layer

UDP (User Datagram Protocol)

connectionless
media-streaming

TCP (Transmission Control Protocol)

makes sure every packet arrives
if it didn't arrive, it will request it again
ftp-data-transfer

*connections through ports
*well known ports <1024 can be found in /etc/services