Network ProtocolDefines rules and conventions for communication betweennetwork devices. ● Ethernet ● ARP ● IP ● UDP ● TCP ● CAN ● SSH
UDP Protocol Used to communicate (unreliable) between applicationprograms in a network.UDP header. Source port and destination port identifies the process thatsends a receives the data in the UDP packet.The IP protocol needs network address to send the data to thecorrect host in the network and needs a port number to sendthe data to the correct program application.
Well-known portsTheres a list of currently assigned ports to some services, sowhen you need to use a port number you must remember toavoid those numbers. Port number Name 22 SSH 23 Telnet 88 Kerberos 80 HTTP 194 IRC
UDP PropertiesDoes not need acknowledge.Its not a reliable network protocol, thats why the messagescan be: ● lost ● arrive out of order ● duplicatedDoes not provide feedback to control the rate at whichinformation flows between the machines.
TCP Protocol TCP is a reliable connection oriented protocol, which meansthat: ● data its received in the same order that was send. ● detects duplicated data. ● retransmits lost data.TCP header
Planning practical implementationNachos already send packets in order but its protocol is notreliable.So with that in mind we propose build a protocol similar to TCPin top of the nachos one.The program for testing the new protocol will be a ping or achat.
Network SecurityConfidence information and services available on a networkcannot be accessed by unauthorized users.Theres two fundamental techniques that form the basis for theinternet security: ● Perimeter security ● encryptionPerimeter security allows an organization to determine theservices and networks it will make available to outsiders andthe extend to which outsiders can use resources.
Aspects of information security ● Data Integrity ● Data Availability ● Privacy Or Confidentiality ● Authorization ● Autentication ● Replay Avoidance
Internet Security Source authentication (accepts requests from computers on aauthorized list) is a weak security method.Stronger authentication requires encryption.
IPsec Provides a set of security algorithms and a general frameworkthat allows a security communication .
FirewallBlocks all unauthorized communication between computers inthe organization and computers outside the organization.Monitoring: ● a firewall notifies a manager whenever an incident occurs (active monitoring). ● a firewall logs a record of each incident in a file on disk (passive monitoring).
Planning practical implementation Some security in nachos programs execution andcomunication: ● Implement a list of nachos machines authorized to communicate with. ● Implement a list of users (ids) authorized to execute useprog programs.
DHCPThe Dynamic Host Configuration Protocol (DHCP) serviceenables devices on a network to obtain IP addresses andother information from a DHCP server. This service automatesthe assignment of IP addresses, subnet masks, gateway andother IP networking parameters.
Static Assignment of AddressesWith a static assignment, the network administrator mustmanually configure the network information for a host, asshown in the figure. At a minimum, this includes enteringthe host IP address, subnet mask, and default gateway.
Dynamic Assignment of AddressesDHCP enables the automatic assignment of addressinginformation such as IP address, subnet mask, defaultgateway, and other configuration information.
DNSDomain Name Service Protocol (DNS) is used to resolveInternet names to IP addresses.
DNS protocol communications use a single format called amessage. This message format is used for all types of clientqueries and server responses, error messages, and thetransfer of resource record information between servers.