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Transmission Control Protocol / Internet Protocol and Network Utilities

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

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Transmission Control Protocol / Internet Protocol and Network Utilities

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  1. Transmission Control Protocol / Internet Protocol and Network Utilities Colin Jamison University of Ulster

  2. 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 Internet • then • TCP represents one of many specialised dialects

  3. 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

  4. Allocation of IP addresses • Network Information Centre (NIC) • NIC handles the administration of IP address allocation to an organisation • 5-types of IPv4 IP addresses can be allocated • Class A, Class B, Class C, Class D, Class E • These allow the internet address to be broken into blocks of small, medium and large networks

  5. To 255.255.255.255 IP Address Format Represented by a string of 4-bytes separated by full-stops Each byte contains 8 bits - so each byte ranges from 0 to 255 decimal or 0000 0000 to 1111 1111 binary From 000.000.000.000

  6. Start-Bits Netid Hostid Total Class A Class B Class C Breakdown of the IP Address • The IP address consists of 2 parts which are, a netid and a hostid 1 + 7 + 24 = 32 2 + 14 + 16 = 32 3 + 21 + 8 = 32

  7. 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 multicast • Class E reserved

  8. Breakdown of IP Address Classes • Class A 1.0.0.0 - 126.0.0.0 • Class B 129.0.0.0 - 191.255.0.0 • Class C 192.0.0.0 - 223.255.255.0 • Class D 224.0.0.0 - 239.255.255.0 • Class E 240.0.0.0 - 255.255.255.0

  9. 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

  10. 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

  11. 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 • and • 255 which is the broadcast address • e.g. 194.23.12.255

  12. 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

  13. 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, and • 2) subnet • When you AND an IP address and a subnet mask the result is an address that contains everything but the hostid

  14. Resolving IP Addresses Binary Class B Class B netid hostid 1000 1100 . 1100 1100 . 0001 1011 . 0001 1011 Decimal Class B Class B netid hostid IP Address 131 .204 .27 .27 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

  15. Network Utilities • netstat • route • arp • ifconfig • ping • traceroute

  16. 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

  17. 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

  18. 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

  19. 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

  20. 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

  21. 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

  22. Questions?

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