IP address

IP Address Functions and Versions - An IP address serves two main functions: network interface identification and location addressing. - It identifies the host's network interface and provides the location of the host in the network. - The IP address is essential for establishing a path to the host. - The header of each IP packet contains the IP address of the sending and destination hosts. - Two versions of the Internet Protocol are in common use: IPv4 and IPv6. - IPv4, the original version, uses a 32-bit address, while IPv6 uses a 128-bit address. - IPv6 was standardized in 1998 due to the depletion of IPv4 addresses. - IPv6 deployment started in the mid-2000s. - IPv4 addresses are still prevalent, but IPv6 is gradually being adopted. IPv4 Addressing and Subnetting - An IPv4 address is 32 bits in size, allowing for 4,294,967,296 addresses. - Some addresses are reserved for special purposes like private networks and multicast addressing. - IPv4 addresses are represented in dot-decimal notation, with four decimal numbers ranging from 0 to 255. - Each part of the address represents an octet of 8 bits. - IPv4 addresses can also be presented in hexadecimal, octal, or binary representations. - In the early stages of IP development, the network number was the highest order octet. - Classful network architecture was introduced in 1981 to allow for more network assignments. - Classful addressing had three classes (A, B, and C) for unicast addressing. - Classful design reduced the number of hosts in higher-order classes. - Classful network design was replaced by Classless Inter-Domain Routing (CIDR) in 1993. Private IP Addresses and Address Assignment - Initially, IP addresses were intended to be globally unique. - Private networks, not connected to the internet, do not require globally unique IP addresses. - Private networks use IP addresses from three non-overlapping ranges. - Network address translation (NAT) is used to connect private networks to the internet. - Private networks conserve public address space. - IP addresses assigned dynamically or persistently. - Dynamic IP addresses assigned using DHCP. - DHCP avoids administrative burden and allows address sharing. - DHCP lease has an expiration period, address may be reassigned. - Static addressing used for network infrastructure equipment. - Sticky IP addresses seldom change. - Used in IPv4 and IPv6 configurations. - Maximizes chance of assigning the same address each time. - Provides stability in home or small-office setups. - Different from static configurations which are used indefinitely. - Link-local addressing for IPv4 networks in block 169.254.0.0/16. - Link-local addresses automatically assigned in IPv6 block fe80::/10. - Valid only on the local network segment or point-to-point connection. - Not routable and cannot be the source or destination of internet packets. - Automatic Private IP Addressing (APIPA) used for IPv4 address autoconfiguration. IP Address Classification and Geolocation - IP addresses are classified into several classes of operational characteristics: unicast, multicast, anycast, and broadcast addressing. - Unicast addressing is the most common concept and refers to a single sender or receiver. - Broadcast addressing is an addressing technique in IPv4 that sends data to all possible destinations on a network. - Multicast addressing is associated with a group of interested receivers and uses specific address ranges in both IPv4 and IPv6. - Anycast addressing is a one-to-many routing topology where data is transmitted to the closest receiver in the network. - Geolocation is used to deduce the geographic position of a communicating peer. - It helps determine the location of a host based on its IP address. - Geolocation can have various applications in services and targeting specific regions. - It provides valuable information for network analysis and security purposes. Public IP Addresses, Firewalling, and Address Translation - A public IP address is globally routable and not reserved for private networks. - It allows communication between hosts on the global Internet. - Public IP addresses assigned to home networks are visible by logging into the router configuration. - Most public IP addresses are dynamic and change relatively often. - Dynamic IP addresses prevent abuse and enhance security for home networks. - Network administrators use firewall software to restrict public Internet traffic within private networks. - IP addresses are used to discriminate traffic and apply IP address blocking or tailored responses. - Blacklists and whitelists are used to maintain databases of restricted and permissible traffic. - Firewalling is crucial for security and privacy considerations in network management. - Multiple client devices can share an IP address using techniques like NAT or proxy servers. - NAT masks the real originating IP address from the server receiving a request. - NAT maps different IP addresses on a private network to different port numbers on the public network. - Residential networks commonly use NAT implemented in a residential gateway. - Address translation enables multiple devices in a private network to share a single public IP address.