transmission control protocol / internet protocol and network utilities
DESCRIPTION
Transmission Control Protocol / Internet Protocol and Network Utilities. Colin Jamison University of Ulster. Network Protocols. Protocol - used by computers to exchange information over a network The most common is TCP/IP originated by the U.S department of Defence - PowerPoint PPT PresentationTRANSCRIPT
Transmission Control Protocol / Internet Protocol and Network Utilities
Colin JamisonUniversity of Ulster
Network Protocols
Protocol - used by computers to exchange information over a network
The most common is TCP/IP originated by the U.S department of Defence
If IP is the native language of the InternetthenTCP represents one of many specialised
dialects
Sockets
De facto portable standard for portable applications on TCP/IP
Sockets available on most PC OSs and Mainframes
Internet Address(IP) and Port Address
netid . hostid . portid
Allocation of IP addresses
Network Information Centre (NIC)NIC handles the administration of IP
address allocation to an organisation5-types of IPv4 IP addresses can be
allocatedClass A, Class B, Class C, Class D, Class EThese allow the internet address to be
broken into blocks of small, medium and large networks
IP Address Format
From 000.000.000.000
To 255.255.255.255
Represented by a string of 4-bytes separated by full-stops
Each byte contains 8 bits - so each byte ranges from 0 to 255 decimalor 0000 0000 to 1111 1111 binary
Breakdown of the IP Address
The IP address consists of 2 parts which are, a netid and a hostid
Class A
Class B
Class C
Start-Bits Netid Hostid Total
1 + 7 + 24 = 32
2 + 14 + 16 = 32
3 + 21 + 8 = 32
IP Address Classes
Class A for extremely large networks (up 16 million hosts) - no longer issued
Class B for medium sized networks (65534 hosts)
Class C for small networks (254 hosts)Class D reserved for multicastClass E reserved
Breakdown of IP Address Classes
Class A 1.0.0.0 - 126.0.0.0Class B 129.0.0.0 - 191.255.0.0Class C 192.0.0.0 - 223.255.255.0Class D 224.0.0.0 - 239.255.255.0Class E 240.0.0.0 - 255.255.255.0
Host Addresses (1)
Each computer network interface is identified by a unique IP address
If a computer has more than one interface then it uses multiple IP addresses - one for each interface
Host Addresses (2)
Each packet has a destination address
All hosts on the network examine each broadcast packet
If addressed to them then the host processes it - otherwise it is ignored
Limit to the Number of Hosts
2 IP addresses are reserved in each type of class,and these are 0
e.g. 194.23.12.0 which is the address of the network itself
and255 which is the broadcast addresse.g. 194.23.12.255
Subnets
Each host must determine if a broadcast packet is for it
For a large number of hosts each host must process many packets
To maintain efficiency in a network the network is split into sub-networks (subnets)
The network is divided by sub-netting to create self-contained broadcast domains
Subnet Masks
A subnet mask is a bit mask that allows you to determine which parts of an IP address correspond to the :-
1) network address, and2) subnetWhen you AND an IP address and a
subnet mask the result is an address that contains everything but the hostid
Resolving IP Addresses
Decimal
Class B Class B netid hostid IP Address 131 .204 .27 .27
Binary
Class B Class B netid hostid1000 1100 . 1100 1100 . 0001 1011 . 0001 1011
Subnet Mask 255 .255 .255 .0 1111 1111 . 1111 1111 . 1111 1111 . 0000 0000
1000 1100 . 1100 1100 . 0001 1011 . 0000 0000
Subnet Number 131 .204 .27 .0
Network Utilities
netstatroutearpifconfigpingtraceroute
netstat
Netstat prints information about the Linux networking subsystem
The type of information printed is controlled by the option given
-a displays both listening and non-listening sockets
-r displays the routing table/bin/netstat
route
Used to add or delete to the kernels IP routing table.
Its primary use is to setup static routes to specific hosts or networks
Without options it displays the current contents of the routing table
/sbin/route
arp
Manipulates the kernels address resolution protocol (ARP) cache in various ways
The main use is to setup and clear an address mapping entry
/sbin/arp -a
ifconfig
ifconfig is used to configure the kernels resident network interfaces
it is used at boot time to set up the computers interfaces
If no arguments are specified it displays the status of the given interface only
If -a is specified it displays the status of all interfaces
/sbin/ifconfig
ping
Used to send packets to a destination hostname or IP address and display the response from the destination
Useful to detect intermittent or non-existent network connectivity
ping destination
traceroute
Traces the path of packets through the local network or Internet to the specified destination
The destination can either be a hostname or IP address
Useful as a network debugging aid/usr/sbin/traceroute destination
Questions?