linux --8

Created by gringo9 

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The TCP/IP protocol suite operates at four layers and has many protocols at each layer
what are the layers

Application
Transport
Internet
Link

what does the application layer do

Supports the communication between operating system supported applications (email, chat, web browser), which depend on user interaction. The protocols are diverse and are continuously developed.

what does the Transport layer do

Manages the 'end-to-end' reliability of each communication. .
tcp udp

The TCP protocol supports

resending of traffic

UDP (User Datagram Protocol) is based on

'best effort' and is designed for communication which does not benefit from resends, such as voice or video traffic.

what does the Internet layer do

Provides the unique address for each system and supports the internetwork routing of packets

what does the link layer do

Looks after the physical network connection, this may be the Ethernet cable, wireless connection, 3G or Bluetooth amongst many other systems.

At this layer each 'interface' or connection has a unique physically encoded address (called a MAC address).

application layer examples

SMTP (email)
HTTP
FTP

transfer layer examples

TCP
UDP
STCP

STCP

Scalable TCP

internet layer examples

IP (Internet Protocol) and IPv6
ICMP (used by the ping utility)
many routing protocols including RIP, OSPF and BGP

ICMP

Internet Control Message Protocol

link layer examples

wireless (802.11a, b, g, n)

Ethernet (802.3)

displays settings on the 'first' Ethernet card, eth0

ifconfig eth0

displays information on all active and inactive interfaces on system

ifconfig -a

starts up the eth0 interface

ifconfig eth0 up

shuts down the eth0 interface

ifconfig eth0 down

sets up an IP address with subnet mask and broadcast address

ifconfig eth0 192.168.0.1 netmask 255.255.255.0 broadcast 192.168.0.255

ifconfig (in english)

interface configuration

DHCP (Dynamic Host Configuration Protocol) and DNS (Domain Name System)

both manage the allocation and the association of IP addresses to devices and domains.

DHCP request the client will In most cases (your local operating system) will receive:

a unique, currently unused IP address
the subnet mask
the default gateway (the address of the local router)
the address of the DNS server (or servers).

command to renew the IP address

dhclient

quickly obtain the IP address to domain name

ping www.bbc.co.uk

a program to query Internet domain name servers

nslookup

nslookup (in english)

name servers look up

IPv4 how many bit

32

IPv6 how many bits

128

IPv4 address are divided into what classes, and what are they used for

Classes A, B, and C are used to allocate addresses on public and private networks. Class D is used for multicast communication traffic (such as routing protocols) and Class E is reserved.

IPv4 address is divided into four

octets

10.0.0.0 to 10.255.255.255,
172.16.0.0 to 172.31.255.255
192.168.0.0 to 192.168.255.255
reserved for what

private use.

IPv6 3FFE:0000:0000:0000:0200:f8FF:FE21:67CF
can be shortened , how ?

3FFE::0200:f8FF:FE21:67CF

IPv6 address is hexadecimal and uses

16 digits from 0 to F (0123456789ABCDEF).

Subnetworking

feature of IPv4 where the IP address is followed by a binary mask which is used by routers as well as Linux systems to describe what network an IP address may be a member of.

port 7

Echo (ping)

port 20 ,21

File Transfer Protocol (FTP)

port 25

Simple Mail Transfer Protocol (SMTP)

port 53

Domain Name System (DNS)

port 80

Hypertext Transfer Protocol (HTTP)

port 443

Secure Sockets Layer (SSL)

ufw

Uncomplicated Firewall

start,stop ufw

ufw enable, ufw disable

Allow a port,block a port

ufw allow 80,ufw deny 80

Allow remote entry to system or computer

ufw allow proto tcp from 192.168.0.99 to any port 80

lspci -(in english )

list all PCI devices

eth0

Ethernet 0 wired or wireless network interface

wlan0

wireless local area network 0 wireless network interface

ath0

Atheros 0 wireless network interface that uses the Atheros chipset

pan0

personal area network 0 allows Bluetooth devices to form an ad hoc network

lo

loopback 0 internal logical interface used by TCP/IP

make permanent changes to your network interfaces by

modify the contents of the /etc/network/interface file

start theNetworkManager Tool from cli

nm-tool

MAC

Media Access Control

command to apply wireless-specific settings to the card

iwconfig

manually configure a default gateway

route add default gw {IP address of gateway device}{network card}
route del default gw 192.168.5.254 ath0

remove the default gateway,

route del default gw 192.168.5.254 ath0

DNS server addresses can be manually configured by using a text editor

the /etc/resolv.conf

eg add
nameserver 208.67.222.22

display the kernel IP routing table

route -n

The Dynamic Host Configuration Protocol (DHCP) was developed to

provide network address information to host devices

force your system's network interface to contact the DHCP server and renew its IP address

ifconfig eth0 down
dhclient eth0

ping three times

ping -c 3 www.google.com
c = count

what is ping

an Internet Control Message Protocol (ICMP): it is a combination of an ICMP echo request, and an ICMP echo reply

a command displays each step (router) along the path

mtr www.google.com

NAT

network address translation

iptraf

Interactive Colorful IP LAN Monitor

A combination of an IP address and a port number is known as a

socket
a socket uniquely identifies an application on a specific system

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