IP Addressing, Subnetting, and Network Protocols

Introduction to IP Addressing and Subnetting

• Classful and classless addressing is used.
• Subnetting and Variable Length Subnet Masking (VLSM) are used.

Network Layer Protocols

• Protocols implemented at the Network layer that carry user data include Internet Protocol version 4 (IPv4).
• Internet Protocol version 6 (IPv6) is a network layer protocol.
• Novell Internetwork Packet Exchange (IPX) is a network layer protocol.
• AppleTalk is a network layer protocol.
• Connectionless Network Service (CLNS/DECNet) is a network layer protocol.

Internet Protocol (IP)

• IPv4 and IPv6 are the most widely-used Layer 3 data carrying protocols and is the focus of study.
• Network layer services implemented by the TCP/IP protocol suite use IP.
• Version 4 of IP (IPv4) is currently the most widely-used version of IP.
• IPv4 is the only Layer 3 protocol that is used to carry user data over the Internet.
• IP version 6 (IPv6) is being developed and implemented, will operate alongside IPv4, and may replace it.

IPv4 Basic Characteristics

• IPv4 is connectionless, meaning no connection is established before sending data packets.
• IPv4 uses best effort delivery so no overhead is used to guarantee packet delivery.
• IPv4 is media independent, operating independently of the medium carrying the data.

Introduction to IP Addressing

• An IP address is a numeric identifier assigned to each machine on an IP network.
• IP addresses designate a specific location of a device on the network.
• An IP address is a software address, not a hardware address.
• IP addressing allows hosts on one network to communicate with hosts on different networks, regardless of LAN type.

IP Terminology

• A bit is a one digit, either a 1 or a 0.
• A byte is 8 bits.
• An octet consists of 8 bits and is used interchangeably as a byte.
• A network address designates where to send packets to a remote network; examples include 10.0.0.0, 172.16.0.0 and 192.168.10.0.
• Broadcast addresses are used by applications and hosts to send information to all nodes on a network.
• 255.255.255.255 is a broadcast address that reaches all networks and all nodes.
• 172.16.255.255 is a broadcast address for all subnets and hosts on network 172.16.0.0.
• 10.255.255.255 broadcasts to all subnets and hosts on network 10.0.0.0.
• An IP address consists of 32 bits of information, divided into four octets or bytes, each containing 8 bits.
• IP addresses can be expressed in Dotted-decimal such as 172.16.30.56, Binary such as 10101100.00010000.00011110.00111000, or Hexadecimal, as in AC.10.1E.38.
• A 32-bit IP address is a structured or hierarchical address.
• A network address uniquely identifies each network and is shared by every machine on the same network.
• In the example IP address 172.16.30.56, 172.16 is the network address.
• The node address is assigned to and uniquely identifies each machine on a network.
• A node address identifies a particular machine, not a group and it can also be referred to as a host address.
• In the sample IP address 172.16.30.56, 30.56 is the node address.
• Classes of networks based on network size exists because Internet designers created them.
• Class A networks have a very large number of nodes.
• Class C networks are reserved for a small number of nodes.
• Class B networks have a size between Class A and Class C networks.
• Subdividing an IP address into a network and node address is determined by the class of network.

IP Address Classification

• Subdividing an IP address into a network and node address is determined by the class designation of one’s network.
• Class A: has 8 bits for Network, and 8 bits each for Host, Host, Host
• Class B: has 8 bits each for Network, Network, and 8 bits each for Host, Host
• Class C: Has 8 bits each for Network, Network, Network and 8 bits for Host
• Class D: is designated for Multicast
• Class E: is designated for Research

Network Address Range - Class A

• The first bit of the first byte in a Class A network address is always OFF, meaning that it must be between 0 and 127, inclusive.
  • Consider the network address 0xxxxxxx.
    • If other 7 bits are all OFF the network address is 00000000 = 0
    • If other 7 bits are all ON the network address is 01111111 = 127

Network Address Range - Class B

• The first bit must always be ON but the second bit must always be OFF, to find the range for a Class B network.

Network Address Range Classes D and E

• Addresses from 224 to 255 are reserved for Class D and E networks.
• Class D (224-239) is used for multicast addresses.
• Class E (240-255) are for scientific purposes.

Special Purpose IP Addresses

• Some IP addresses are reserved for special purposes and cannot be assigned to nodes.

Class A Addresses

• The first byte is assigned to the network address and the three remaining bytes are used for the node addresses network.node.node.node
• 1 Byte is used for the network address with the first bit of that byte reserved and the 7 remaining bits available for addressing.
• Maximum number of Class A networks is 128, with 7 bit positions that can be either a 0 or a 1, thus 2^7, or 128.
• All 0s (00000000) are reserved to designate the default route and address 127 has been reserved for diagnostics.
• Numbers 1 to 126 to designate Class A network addresses.
• The actual number of usable Class A network addresses is 128 - 2 = 126.
• Each Class A address has three bytes (24-bit positions) for the node address of a machine.
• With 24-bit positions, there are 2^24 or 16,777,216 unique combinations .
• Usable number of nodes for a Class A network is 2^24 - 2 = 16,777,214 because node addresses with the two patterns of all 0s and all 1s are reserved.
• Class A Valid Host IDs
  • Use these steps to figure out the valid host IDs in a Class A network address:
    • All Host bits OFF is the network address: 10.0.0.0.
    • All Host bits ON is the broadcast address: 10.255.255.255.
  • Valid hosts are the numbers in between the network & the broadcast address: 10.0.0.1 through 10.255.255.254.
  • Remember that the host bits cannot be turned OFF or turned ON at the same time.

Class B Addresses

• The first 2 bytes in a Class B network address are for the network address and the remaining 2 bytes for node addresses network.network.node.node
• 2 bytes (16 bits) would lead to 2^16 combinations , but all Class B network addresses should start with the binary digits 10.
• Class B network addresses leaves 14 bit positions to manipulate, therefore 16 384 (That is , 2^14) unique Class B network addresses.
• A Class B address uses 2 bytes for node addresses which leads to 2^16 which you then subtract the two reserved patterns( All 0s and 1s) for a total of 65, 534 possible node address for each Class B network.
• Class B Valid Host IDs
  • Use these steps to figuring out the valid host in class B network :
  • All host bits OFF is the network address: 172.16.0.0
  • All host bits ON is the broadcast address: 172.16.255.255
  • This means that valid hosts range between the network & the broadcast address: 172.16.0.1 through 172.16.255.254

Class C Addresses

• The first 3 bytes are dedicated to the network portion of the address, with only 1 byte remaining for the node address network.network.network.node
• In a Class C network address, the first three bit positions are always the binary 110, 3 bytes of 24 bits.
• Minus 3 reserved position leaves 21 position.
• There are 2^21 ot 2,097,152 possible Class C networks.
• There is 1 byte to use for node addresses.
• This leads to 2^8 or 256, minus the two reserved patterns of all 0s and all 1s, for a total of 254 node addresses for each Class C network.

Class C Valid Host IDs

• Here is how to find a valid host in a Class C network:
  • All host bits turned OFF is the network ID: 192.168.100.0.
  • All host bits turned ON is the broadcast address: 192.168.100.255.
  • The valid hosts range between: 192.168.100.1 through 192.168.100.254.

Private IP Addresses

• Private IPs can be used on a private network, but is not routable through the internet.
• Private IP addresses creates great measure of much needed security and valuable address space.
• All hosts on every network has real routable IP addresses so IP's don't run out.

Subnetting and Variable Length Subnet Masking (VLSM)

• Subnetting is dividing one large network into a bunch of smaller networks.
• Subnetting is beneficial because it is reduces network traffic, optimizes network performance, and streamlines management.
• Taking bits from the host portion of the IP address and reserve to define subnet address to create subnetworks.
• Less bits for hosts because the more subnets, the fewer bits available for defining hosts.
• A subnet mask is a 32-bit value that allows the recipient of IP packets to distinguish the network ID portion of the IP address from the host ID portion of the IP address.
• A network administrator creates a 32-bit subnet mask composed of 1s and os.
• The 1s in the subnet mask represent the positions that refer to the network or subnet addresses.
• Not all networks need subnets, and they use the default subnet mask, or don't have a subnet address.
• These default masks cannot change.

Default Subnet Mask

• Class Format Default Subnet Mask
  • A network.node.node.node 255.0.0.0
  • B network.network.node.node 255.255.0.0
  • C network.network.network.node 255.255.255.0

Classless Inter-Domain Routing (CIDR)

• When receiving a block of address from a IPS something like 192. 168.10.32/28 indicates what a subnet mask is.
• The slash notation (/) or CIDR, means how many bits are turned on (1s).
• The maximum could only be /32 because a byte is 8 bits and there are 4 bytes in an ip address (4 x 8 = 32).
• The largest subnet mask available (Regardless of the class of address) can only be / 30 keep at least 2 bits for host bits.
• /8 through /15 can only be used with Class A network addresses.
• /16 through /23 can be used by Class A and B network addresses.
• /24 through /30 can be used by Class A, B, and C network addresses.
• There are 8 bits are available for defining the hosts, for Class C addresses. Start at the left and got to the right, without skipping bits.
• This means that only Class C subnet masks can only be :
  • 00000000 = 0 (/24)
  • 10000000= 128/25
  • 11000000 = 192(/26)
  • 11100000= 224(/27)
  • 11110000= 240(/28)
  • 11111000= 248(/29)
  • 11111100 = 252(/30)
• At least 2 host bits are needed so /31 or /32 can't be used for assigning IP addresses to hosts.
• When a possible subnet mask is chosen need to determine five Simple Questions in order to know ,valid hosts, an all broadcast address of a subnet.
• How many subnets does the chosen subnet mask produce?
• How many valid hosts per subnet are available?
• What are the valid subnets?
• What's the broadcast address of each subnet
• What are the valid hosts in each subnet.
• number of subnets = 2X ,X is number of Market bit or the 15.
• For Example in 11000000 number of (1s) give to (2²)= subnets so there are 4 subnets.

How many hosts per subnet?

number of hosts per subnet = 2^y -2 ,Y is a the number of unmasked bits, or the Os.

What are the valid subnets?

• For example, in 11000000, the number of 0s gives us 26 - 2 hosts which is 62 hosts per subnet.
• Subtract 2 for the subnet address and for broadcast address, which are not valid hosts.
• 256- subnet mask = block size or increment number.
• Example 256 - 192 = 64, with the block Size and always a 64 mask , start counting zero of blocks of 64 until you reach the subnet mask Value which yields 0,64, 128, 192.
• The broadcast address is always the number right before the next subnet.
• The first subnet is zero, 64,128, and 192, and the broadcast address of 0 subnet is 63 , the 64 is next subnet.
• The 64 subnet and then broadcast address os, 127( because 128 is the next subnet). so the last and to remember is the broadcast address is always 255.
• Valid Hosts are the numbers between the subnets, with all 0's and 1's.
• For example 64 and 127 are is the subnet ,then 65-126 to get a valid host range.
• Always the numbers between the subnet address and the broadcast address.

Data Security and Integrity

• A security overview of secure networks, cryptography, encryption, privacy, authentication protocols firewalls, vpn and transport layer security is provided.

Security Overview

• The main points of security involves what, why and who.
• Dictionary.com gives the definition of security which includes the freedom from risk or danger safety.
• Freedom from doubt, anxiety or safety as well as providing measures to prevent suspicious behavior like acts espionage or crime, or attacks from external bodies.
• Security is needed to protect vital information while allowing access to authorized users.
• This includes Trade Secrets and medical records.
• Authentication ensures access to authorized resource.
• Guarantees the availability of resources with 99.99% reliability commonly known as 5 9s.
• Entities that are most vulnerable included financial institutions and banks, pharmaceutical companies, internet service providers, contractors/agencies, and anyone on the network. Computing in mobility is at a price.
• Risk increase for sensitive critical information
• All systems are under attack.
• Build a security system to know all about the enemy and vulnerability and prevention.
• This includes ( protection/ Detection/ Recovery)

Categories of Network Related Attacks

• Normal flow of information
• Interruption
• Interception
• Modification
• Fabrication

Overall security problems

• Confidentiality
• Integrity
• Availability
• Non-repudiation (trust)

Security Techniques and Algorithms

• Stream and block cipher
• Symmetric and asymmetric or public key cryptography
• Digital Signature
• DES, 3 Triple DES, AES ,Diffie-Hellman and RSA.
• Hashing Algorithm (MD5,SHA- l).
• Security Protocols (SSL, TLS AND WTLS).
• Multi Factor Security (what you know , what you have, what you are).
• Key Recovery, Security Models,.
• Frameworks and Digital Watermark. Categorizing Security Physical Access Technological- ( Hardware And Softwareapplication OS and Network) Social And Technological.

###Goals:

• Security.
• Prevents access to unauthorized users.
• Detection (What is).
• Is an active attack, like system monitoring.
• The common security attack involves; finding a way into the system by (firewalls), exploiting software bugs, such as buffer overflow, intrusion detection services.
• Defense against denial of service attacks involve ingression filtering and IDS.
• Tcp hijacking for use in IPsec.
• Packet sniffing through encryption( ssh and https).

Security Solutions :

• Involves the utilization of Firewalls, Intrusion Detection Systems (IDS) ,and cryptography.

###Firewall:

• A security software that helps monitors incoming and out going network traffic based on security rules that may have been pre defined.
• The firewall typically presents a barrier between internal network and a external untrusted networks such as the internet, through packet filtering, network address translation, dmz (De-militarized zones)

Network Firewalls:

-Filter traffic between two networks often in network hardware, vs. a host based firewall which runs host computers  traffic, as it comes in and out of computers intrusion detection system involves the implementation of a security system or  a  software that will assess the network activity malicious behavior, and policy violations ,and will report administrators and is often connected to SIEM ( security and event management system).
-Types of IDS system includes network vs host vs misuse vs anomaly based system.

Cryptography

• Is a science that uses mathematics in order to encrypt data, that is used on untrusted networks such as the internet where people other intended recipients.

Encryption:

• Is the process of decoding a message or some information in such a way that is assessed by authorized parties, using encryption algorithmic process.

###Plain:

• Text can be encrypted using an encryption or algorithm this becomes a ciphertext.
• Decryption is the process of decoding encrypted data into secret Format.
• Caesar Cipher( a older form of cipher).
• Security And Applications On The Layer: Security on Application Layer, which uses HTTPS, SFTP ,SSH, SSL ( Secuirty socket layers a. VPN ( Is a and encrypted connection over the internet. Is very widely in the work Place and Corporate Settings.
  • Extends the network.
  • Employee has to work .
  • Still securely connect.