IPv4 Addresses A Quick Guide

What is an IPv4 Address 32 bits separated by 4 groupings of bits 11111111 11111111 11111111 11111111 32 bits = 2^32 possible = 4.2 Million IPv4 Addresses Each octet can be up to 255 IP stands for Internet Protocol IP is the primary set of rules that transport data Network numbers are managed by ICANN

Where do you use IP addresses? Everywhere Computers, phones, light bulbs, even toothbrushes Hunting Finding the bad guy Being the bad guy Setting up networks Technical exams

Classful IP Range

Special addresses Class Start Finish Class A Private 10.0.0.0 10.255.255.255 Class B Private 172.16.0.0 172.32.0.0 Class C Private 192.168.0.0 192.168.255.255 Loopback 127.0.0.1 127.255.255.255 APIPA 169.254.0.1 169.254.255.254

Private IP address Reusable Specific to individual networks Companies, homes, and devices all have these same addresses

Loopback Often used for testing Can send signals back to the device Allows an administrator to act as if the local machine was remote

APIPA Automatic Private IP Addressing Ability to assign an IP address to a machine without an internet connection Assigns default class B subnet Computer can only communicate with nodes using APIPA range Occurs when devices use DHCP (Dynamic Host Configuration Protocol) and no DHCP is available

What address are private? 5.8.128.5 127.0.0.1 172.32.0.1 192.160.5.24 10.1.0.100 226.35.75.124 172.16.256.10 169.254.0.1 192.168.0.1 172.14.252.5

Private IP address Class Start Finish Comment Class A 10.0.0.0 10.255.255.255 Class B 172.16.0.0 172.32.0.0 Class C 192.168.0.0 192.168.255.255 Loopback 127.0.0.1 127.255.255.255 Common 127.0.0.1 APIPA 169.254.0.1 169.254.255.254

Default Gateway Routers IP address The destination gateway of all traffic Connects different networks 10.10.10.0/24 172.16.25.0/24 This Photo by Unknown Author is licensed under CC BY-ND

Subnetting Separates Network from host IP Address Subnet Mask 192.168.1.1 255.255.255.0 Subnetting Separates Network from host Network ID: identifies the network Host ID: identifies the computer or device on the network Series of flags that indicate the segmented network or LAN (Local Area Network) that contains the IP addresses If the subnet mask has a 255 in the octet Than the IP address must start contain the corresponding fields Example: 255.255.255.0 has 3 sets of 255. For an IP address to be in the same subnet or segmented network, the IP address must start with 192.168.1.1

Does the traffic stay or go? IP Address Subnet LAN Range 192.168.1.0 255.255.255.0 192.168.1.X IP Address LAN Gateway 192.168.1.1 X 10.25.36.54 172.18.94.35 192.168.1.252 192.167.1.45 IP Address LAN Gateway 192.168.1.1 10.25.36.54 172.18.94.35 192.168.1.252 192.167.1.45

Changing Subnet The left side of the LAN Range is Networks IP Address Subnet LAN Range 192.168.1.1 255.255.255.0 192.168.1.X 255.255.0.0 192.168.X.X 255.0.0.0 192.X.X.X The left side of the LAN Range is Networks The right side of the LAN Range is Hosts Changing the subnet mask increases or decreases the size of your subnet

Binary A bit is a 1 or a 0 Octet 1 = On 0 = Off 00000000 = 0 11111111 = 255

Does 192 go into 128? Yes, Put a 1 in the 128 network column Try 5 and 2 on your own. 192-128=64 Does 64 go into 64? Yes Put a 1 in network 64 64-64=0 The rest of the division will result in zeros IP to Binary 192.168.5.2 128 64 32 16 8 4 2 1 Network Class A Class B Class C 1100000000 10101000 00000101 00000010 Does 168 go into 128? Yes, Put a 1 in Class A 168-128=40 Does 64 go into 40? No, put a zero in Class A under 64. Does 32 go into 40? Yes Place a 1 in Class A 32/ 40-32=8 The only place 8 fits is 8. Base Exponent: In binary, you can determine number if

Try 5 and 2 on your own. Binary to IP In the network row find your ones. The ones are located in field 128 and 64 128+64=192 1100000000 10101000 00000101 00000010 128 64 32 16 8 4 2 1 Network Class A Class B Class C 192.168.5.2 In the Class A rown find your ones. The ones are located in field 128, 32, 8 128+32+8= 168 Base Exponent: In binary, you can determine number if

Subnetting Example Both IPs and Subnets are 32 characters 192 168 1 12 11000000 10101000 00000001 X 255 11111111 00000000 Both IPs and Subnets are 32 characters Ways to write 192.168.1.12/24 192.168.1.12 255.255.255.0

CIDR Classless Inter-Domain Routing Problem with Classful Why Class A: 16,777,214 Hosts Class B: 65,534 Hosts 254 Hosts Why Need smaller or larger networks What if you needed a network for 1000 hosts, you would was 64,534 addresses Or have 5 smaller networks Easy to organize networks

VLSM Variable Length Subnet Mask Using Binary you can choose where to separate the network from the hosts Draw a line and choose your network, you are no longer restricted to 0 and 255 11111111 11111111 11111111 11111000 255 255 255 248 255 7 _____ 248

CIDR with VLSM 192 168 1 12 11000000 10101000 00000001 X 255 252 11111111 11111100 00000000 You may not always want to use a full range of address Note the 1’s all belong to the subnet and must match other IPs in the network Ways to write 192.168.1.12/22 192.168.1.12 255.255.252.0 There are two zeros at in the 3rd column separating network bits from host bits.. Take the last two digits of your IP address: 00 to 11 and calculate your range Numbers Binary 3rd column Conversion Minimum 00000000 Maximum 00000011 3

Speed Run The Magic Box

Dotted Decimal Notation Quick Draw IP Address Network bits This is the total number of networks you can have per CIDR or Dotted Decimal Networks per Subnet 2 4 8 16 32 64 128 256 Dotted Decimal Notation 192 224 240 248 252 254 255 Hosts Per Subnet: Class C 1 Class A /9 /10 /11 /12 /13 /14 /15 /16 Class B /17 /18 /19 /20 /21 /22 /23 /24 Class C /25 /26 /27 /28 /29 /30 /31 /32 Dotted Decimal Notation From the host bit take the Left most value, put it in dotted decimal spot, than take that number add it to the next host bit ex 128+64= 192, than add 192+32=224 and so on HOST Bits Double Numbers from right to left starting at 1 CIDR Each row represents 8 binary bits, allowing you to see the Class breakdown Base Exponent: In binary, you can determine number if 9 Columns by 6 Rows

Host bits start in the second Octet Default Subnet Masks Networks per Subnet 2 4 8 16 32 64 128 256 Dotted Decimal Notation 192 224 240 248 252 254 255 Hosts Per Subnet 1 11111111.00000000.0000000.0000000 Network.Host____.Host____.Host 255.0.0.0 Class A /9 /10 /11 /12 /13 /14 /15 /16 11111111.11111111.00000000.0000000 Network.Network.Host______.Host 255.255.0.0 Class B /17 /18 /19 /20 /21 /22 /23 /24 11111111.11111111.11111111.00000000 Network.Network.__Network.Host 255.255.255.0 Class C /25 /26 /27 /28 /29 /30 /31 /32 The First Octet is Reserved for the Network Only Class A, Class B, and Class C have subnets The host bits start on the 9th bit

How to Find CIDR Notation Find the intersection between the subnet and Class. The point of intersection is the CIDR How to Find CIDR Notation Networks per Subnet 2 4 8 16 32 64 128 256 Dotted Decimal Notation 192 224 240 248 252 254 255 Hosts Per Subnet 1 Class A /9 /10 /11 /12 /13 /14 /15 /16 Class B /17 /18 /19 /20 /21 /22 /23 /24 Class C /25 /26 /27 /28 /29 /30 /31 /32 If the octet is all 1s. Is this is a network bit You are given a subnet mask of 255.255.240.0, What is the CIDR Notation? 255.255.240.0 11111111.1111111.11110000.00000000 Network_.___A___.___B_____.___C____ Network_.Network.HostBits Class A is the 2nd Octet Class B is the 3rd Octet Class C is the 4th Octet

How to Find Dotted Decimal /14 is in the 6th Row, this means 6 bits are turned on 11111100 Networks per Subnet 2 4 8 16 32 64 128 256 Dotted Decimal Notation 192 224 240 248 252 254 255 Hosts Per Subnet 1 Class A /9 /10 /11 /12 /13 /14 /15 /16 Class B /17 /18 /19 /20 /21 /22 /23 /24 Class C /25 /26 /27 /28 /29 /30 /31 /32 CIDR /14 is in the Class A Range If you are given a CIDR (Classless Inter-domain Routing) of /14, what is the subnet mask? Find /14 Find the intersection of Dotted Decimal and the CIDR # Network bits are always the 1st 8 bits 11111111.11111100.00000000.0000 255.252.0.0 2nd Octet is Class A, The /14 is class A, place intersection in Class A octet. If the CIDR was class B you would use the 3rd octet and 4th for C

Hosts Networks per Subnet A 2 4 8 16 32 64 128 256 Dotted Decimal Notation 192 224 240 248 252 254 255 Hosts Per Subnet: Class A 8,388,608 4,194,304 2,097,152 1,048,574 524,286 262,144 131,072 65,536 Hosts Per Subnet: Class B 32,768 16,384 8,192 4,096 2,048 1,024 512 Hosts Per Subnet: Class C 1 Class A /9 /10 /11 /12 /13 /14 /15 /16 Class B /17 /18 /19 /20 /21 /22 /23 /24 Class C /25 /26 /27 /28 /29 /30 /31 /32 Base Exponent: In binary, you can determine number if /8=16,777,216

Exercise Use the box to determine Dotted Decimal Notation for /19? What is the CIDR notation for 252? How many hosts are in a /30? If you have 4,096 hosts what is your CIDR notation? If you have 32 networks what is your class B CIDR? 224 A=/14, B=/22, C=/30 C=4, B=1024, A=262,144 C=/28, B=/20, A=/12 21

Questions