65 terms

linux --8

The TCP/IP protocol suite operates at four layers and has many protocols at each layer
what are the layers
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)
transfer layer examples
Scalable TCP
internet layer examples
IP (Internet Protocol) and IPv6
ICMP (used by the ping utility)
many routing protocols including RIP, OSPF and BGP
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 netmask broadcast
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
quickly obtain the IP address to domain name
ping www.bbc.co.uk
a program to query Internet domain name servers
nslookup (in english)
name servers look up
IPv4 how many bit
IPv6 how many bits
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 to, to to
reserved for what
private use.
IPv6 3FFE:0000:0000:0000:0200:f8FF:FE21:67CF
can be shortened , how ?
IPv6 address is hexadecimal and uses
16 digits from 0 to F (0123456789ABCDEF).
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)
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 to any port 80
lspci -(in english )
list all PCI devices
Ethernet 0 wired or wireless network interface
wireless local area network 0 wireless network interface
Atheros 0 wireless network interface that uses the Atheros chipset
personal area network 0 allows Bluetooth devices to form an ad hoc network
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
Media Access Control
command to apply wireless-specific settings to the card
manually configure a default gateway
route add default gw {IP address of gateway device}{network card}
route del default gw ath0
remove the default gateway,
route del default gw ath0
DNS server addresses can be manually configured by using a text editor
the /etc/resolv.conf

eg add
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
network address translation
Interactive Colorful IP LAN Monitor
A combination of an IP address and a port number is known as a
a socket uniquely identifies an application on a specific system