NetPractice

Project made to learn basics of networking Pretty simple but you have to be confortable with some concept like IP address and mask

IP address

allows elaboration and transport of IP datagrams (data packet) WITHOUT ENSURING THE DELIVERY
process packets independently of each other by defining their representation, routing and forwarding

Composed of 4 bytes, each composed of 8 bits

a part reserved for the machine | part of the network
Two IP addresses belong to the same subnet if they have the subnet mask bits in common.
There are unavailable addresses:
- From 10.0.0.0 to 10.255.255.255.
- From 172.16.0.0 to 172.31.255.255
- From 192.168.0.0 to 192.168.255.255 They are not unique: they are reserved for naming machines in a local network. Most of the time, the first machine connected to a Box will have the address 192.168.0.1. It is therefore not a routable address on the Internet at all.

Special feature: the masks include a sequence of bits of 1 then 0
Number of machines that can be put on a network are defined by mask (right part or upper part)

Example :

IP address: 192.168.0.0
Subnet mask: 255.255.255.0
Takes the upper part: image above, represents a byte which is 0. Can go from 0 to 255, or 256 numbers.
Can code 256 addresses, but 2 addresses are reserved (0 and 255)
0: identifies the network (see image: 192.168.0.0)
255: broadcast address -> used to send a message to all network addresses (see image: 192.168.0.255)
256 - 2 = 254 usable addresses

= Classless Inter-Domain Routing

Another way to describe a mask
gives the network number followed by a slash (or slash, “/”) and the number of bits at 1 in the binary notation of the subnet mask.
/32 designates a network that has only one IP address, ie an individual IP address.
Example: The mask 255.255.224.0, equivalent in binary to 11111111.11111111.11100000.00000000, will therefore be represented by /19 (19 bits at the value 1, followed by 13 bits 0).

network path selection mechanism for routing data from a sender to one or more recipients

= data structure used by a router or networked computer

associates prefixes with ways to route packets to their destination
In NetPractice, the use of routes is mainly used to direct unwanted packets (default or 0.0.0.0/0) to the nearest interface. Or direct incoming packets from the internet to the nearest interface