42-net-practice

🪧 Overview

🌐 NetPractice is a general practical exercise to let you discover networking.

📷 Preview

🕹️ Usage

1. There are 10 levels available for training.
2. Complete the empty fields and click on button Check again to verify whether your configuration is correct or not.
3. Once the exercise is successful, click on button Get my config to download your configuration.
4. When you have successfully completed a level, click on button Next level.
5. Click here to start training.

🧠 Networking Basics

What is IP?

IP is a connectionless protocol that operates at the network layer of the OSI model. IP enables communication between hosts by carrying data within packets. Each host is assigned an IP address which is used to ensure that traffic is sent to the correct destination, synonymous in many ways to a postal address that we place on a letter.

An IP address (in the case of v4) is built upon 32-bits, expressed in four numbers known as octets. Each octet is 8 bits i.e one byte.

• Network - the network the IP address belongs to. For example the street name.
• Host - the host identifier of the device for the network. For example the house number.

What is Subnet Mask?

A subnet mask is a 32-bit number created by setting host bits to all 0s and setting network bits to all 1s. In this way, the subnet mask separates the IP address into the network and host addresses.

The “255” address is always assigned to a broadcast address, and the “0” address is always assigned to a network address. Neither can be assigned to hosts, as they are reserved for these special purposes.

Subnet Mask Chart

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

Example

Address:   192.168.0.1           11000000.10101000.00000000 .00000001
Netmask:   255.255.255.0 = 24    11111111.11111111.11111111 .00000000
Wildcard:  0.0.0.255             00000000.00000000.00000000 .11111111
=>
Network:   192.168.0.0/24        11000000.10101000.00000000 .00000000 (Class C)
Broadcast: 192.168.0.255         11000000.10101000.00000000 .11111111
HostMin:   192.168.0.1           11000000.10101000.00000000 .00000001
HostMax:   192.168.0.254         11000000.10101000.00000000 .11111110
Hosts/Net: 254                   (Private Internet)

🧰 Tools

IP Calculator - ipcalc takes an IP address and netmask and calculates the resulting broadcast, network, Cisco wildcard mask, and host range.

📚 References

• techtarget.com - How to calculate a subnet mask from hosts and subnets

• softwaretestinghelp.com - Guide to Subnet Mask (Subnetting) & IP Subnet Calculator

• avinetworks.com - Glossary Subnet mask

• packetcoders.io - A Beginners Guide to Subnetting

📝 License

Distributed under the MIT License. See LICENSE for more information.