About • How to use • Practice and Evaluation • Subnet • Contributing • License

ABOUT

This is a practical networking exercise aimed at exploring the fundamentals of networking. In this project, I configured a small-scale network and delved into the world of TCP/IP addressing. The goal is to complete 10 levels, each designed to challenge and enhance my networking knowledge.

• Subject PDF
• References GitHub

HOW TO USE

1º - Change directory

cd netpractice/netpractice/exercises/

2º - Open the index.html file

It doesn't work well in Firefox.

open -a "Google Chrome" index.html

PRACTICE AND EVALUATION

UTILITY

This utility will help us understand more about Address Manipulation:

brew install ipcalc
ipcalc 172.30.0.69/30

COMPLETE ALL 10 LEVELS

There will be a practice and evaluation mode:

• Practice mode - Insert your 42 intra username. You will do all 10 levels.
• Evaluation mode - 3 random levels from level 6 to level 10. You only have 15 minutes for all.

Warning

Before moving to the next level, don’t forget to export your configuration using the Get My Config button so you can put it in your Git repository.

BUTTONS

There will be 2 buttons on the top left corner (3 if you completed a level):

• Check again - Verify whether your configuration was correct or not.
• Get my config - Download your configuration. It will be needed to turn in your assignment.
• Next level - Click on this button to get to the next level.

SUBNET

A subnet or subnetwork is a network inside a network. Subnets make networks more efficient.

Subnetting is the process of stealing bits from the HOST part of an IP address to divide the large network into smaller ones called subnets. After subnetting, we end up with NETWORK SUBNET HOST fields, and we always reserve an IP address to identify the subnet and another one to identify the broadcast subnet address, and through subnetting, network traffic can travel a shorter distance without passing through unnecessary routes to reach its destination.

CALCULATE SUBNET MASK FROM IP ADDRESS

1º - Find Subnet Number (we are gonna use the IP address 10.20.4.13/29 for this example):

Subtract prefix number from /32
32 - 29 = 3

Calculate Subnet Mask:
8 bits - 3 bits = 5 bits (Network bits turned on)

You might be asking why 8 bits, 8 bits are required for each octet.

|-------|-------|-------|-------|-------|-------|-------|-------|
| 128   | 64    | 32    | 16    | 8     | 4     | 2     | 1     |
|-------|-------|-------|-------|-------|-------|-------|-------|
| 1     | 1     | 1     | 1     | 1     | 0     | 0     | 0     |
|-------|-------|-------|-------|-------|-------|-------|-------|
| 128 + | 64 +  | 32 +  | 16 +  | 8     | =       248           |
|-------|-------|-------|-------|-------|-------|-------|-------|

Subnet Mask = 255.255.255.248

2º - Find Subnet Size:

Raise 2 to the power of deduction (8 - 3 = 5) -> Let's call it n.

2 ** n    = Subnet Size.
2 ** 3    = Subnet Sizes for each subnet.
2 * 2 * 2 = 8

NOTE: 8 is the block size for the subnet, so for example:
the increments will now be 0 8 16 24 32 and so on (we add 8 each time)

3º - Find Broadcast Address:

Subnet size - 1
(2 ** n) - 1  = Broadcast Address
(2 ** 3) - 1  = (8 - 1) = 7

4º - Locate IP Address Subnet:

Identify subnet block for IP address:
-> Where in each increment is the address 10.20.4.13/29 located (0 8 16 32 40)?

13 falls between 8 and 16 and therefore the address is in the valid host range of the subnet 10.20.4.8/29

5º - Calculate The Valid Hosts:

Subnet size - 2
(2 ** n) - 2 = Valid Host Range
(2 ** 3) - 2 = (8 - 2) = 6

And from these steps, we can know 4 important things:

Subnet Address    -> 10.20.4.8/29
Min Host Address  -> 10.20.4.9/29
Max Host Address  -> 10.20.4.14/29
Broadcast Address -> 10.20.4.15/29

SUBNET MASK TABLE

Here is a quick reference table for help when subnetting.

Subnet Mask	CIDR	Binary Notation	Network Bits	Host Bits	Available Addresses
255.255.255.255	/32	11111111.11111111.11111111.11111111	32	0	1
255.255.255.254	/31	11111111.11111111.11111111.11111110	31	1	2
255.255.255.252	/30	11111111.11111111.11111111.11111100	30	2	4
255.255.255.248	/29	11111111.11111111.11111111.11111000	29	3	8
255.255.255.240	/28	11111111.11111111.11111111.11110000	28	4	16
255.255.255.224	/27	11111111.11111111.11111111.11100000	27	5	32
255.255.255.192	/26	11111111.11111111.11111111.11000000	26	6	64
255.255.255.128	/25	11111111.11111111.11111111.10000000	25	7	128
255.255.255.0	/24	11111111.11111111.11111111.00000000	24	8	256
255.255.254.0	/23	11111111.11111111.11111110.00000000	23	9	512
255.255.252.0	/22	11111111.11111111.11111100.00000000	22	10	1024
255.255.248.0	/21	11111111.11111111.11111000.00000000	21	11	2048
255.255.240.0	/20	11111111.11111111.11110000.00000000	20	12	4096
255.255.224.0	/19	11111111.11111111.11100000.00000000	19	13	8192
255.255.192.0	/18	11111111.11111111.11000000.00000000	18	14	16384
255.255.128.0	/17	11111111.11111111.10000000.00000000	17	15	32768
255.255.0.0	/16	11111111.11111111.00000000.00000000	16	16	65536
255.254.0.0	/15	11111111.11111110.00000000.00000000	15	17	131072
255.252.0.0	/14	11111111.11111100.00000000.00000000	14	18	262144
255.248.0.0	/13	11111111.11111000.00000000.00000000	13	19	524288
255.240.0.0	/12	11111111.11110000.00000000.00000000	12	20	1048576
255.224.0.0	/11	11111111.11100000.00000000.00000000	11	21	2097152
255.192.0.0	/10	11111111.11000000.00000000.00000000	10	22	4194304
255.128.0.0	/9	11111111.10000000.00000000.00000000	9	23	8388608
255.0.0.0	/8	11111111.00000000.00000000.00000000	8	24	16777216

CONTRIBUTING

If you find any issues or have suggestions for improvements, feel free to fork the repository and open an issue or submit a pull request.

LICENSE

This project is available under the MIT License. For further details, please refer to the LICENSE file.