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Shadow Cipher

Networking Services - Best practice and Technologies

  • IP address

  • Subnet mask

  • Gateway

  • Name server

  • Dyanamic Host Configuration Protocol (DHCP) An application layer protocol that automates the configuration process of hosts on a network

  • Dyanamic Allocation A range of IP addresses is set aside for client devices and one of these IPs is issued to these devices when they request one

  • Automatic Allocation a range of IP addresses is set aside for assigment purposes

  • Fixed allocation Requires a manually specified list of MAC address and their corresponding IPs

  • Netwrok time protocol(NTP) servers Used to keep all computers on a network synchronized in time

DHCP in Action

  • DHCP discovery The process by which a client confihured to use DHCP attempts to get network configuration information

  • DHCP lease

Basics of NAT

  • Netwrok Address Translation A technologies that allows a gateway, usually a router or firewall, to rwrite the source IP of an outgoing IP datagram while retaining the original Ip in order to rewrite it into the response

  • IP masquerading

  • One-to-many NAT

NAT and the Transport Layer

  • Port preservation A technique where the source port chosen by a client is the same port used by the router

    • Port Forwarding A technique where specific destination ports can be configured to always be delivered to speicific nodes

NAT, Non-Routable Address Space and the Limits of IPv4

  • Regionnal internet registries

  • AFRINIC serves the continent of Africa

  • ARIN serves the United States, Canada, and parts of the Caribbean

  • APNIC is responsible for most of Asia, Australia, New Zealand and Pecific Island nations

  • LACNIC covers central Central and South america and any parts of the Carribbean not covered by ARIN

  • RIPE serves Europe, Russia, the Middle East portions of Central Asia

  • The IANA assigned the last unallocated/8 network blocks to the various RORs on February 3, 2011

  • Then in April 2011, APNIC ran out of addresses

  • RIPE was exit, in september of 2012v

  • LACNIC ran out of addresses to assign in June 2014, and ARIN did the same in September 2015

  • Only AFRINIC has some IPs letf, but those are predicted to be depleted by 2018

  • Non-routable address space

  • EFC1918

  • Virtual Private Netwroks (VPN) A technology that allows for the extension of a private or local network to hosts that might not be on that local network

  • Remote Client -> VPN Tunnel(Internet) - > Router -> VPN server

  • Two-factor authentication A technique where more than just a username and password are used to authenticate

  • VPN server -> router -> VPN tunnel(Internet) -> Router -> VPN Server

Proxy Services

A server that acts on behalf of a client in order to access another services

  • Anonymity

  • Security

  • Content filtering

  • Increased performance

  • Web proxies

  • Reverse proxy A service that might appear to be a single server to external clients, but actually represents many servers living behind it