1980 – Creation of IPv4 (RFC 791)
1980 – 1990 – BOOM Internet (Exponential increase)
IPv4 – 4.3 billion (or 232) addresses
IPv4 quickly finds itself in short supply of IP
Creation of the NAT / PAT.
Creating a new IP addressing system (IPv6).
The IPv4 address is still the most used in the world, any company and any internet BOX uses the NAT.
The IPv6 address is being deployed.
NAT – Network Address Translation
The NAT is a protocol that allows you to change the source IP address of a package to another IP address.
Creating two zones:
– PRIVATE (Private address)
Class A – from 10.0.0.0 to 10.255.255.255
Class B – from 172.16.0.0 to 172.31.255.255
Class C – from 192.168.0.0 to 192.168.255.255
– PUBLIC (Public address)
Managed by the Internet Assigned Numbers Authority (IANA)
The NAT allows several devices in a private network to use the same public IP address.
We can see in this diagram that our router will replace the IP address of the post in the LAN with its own.
The IP address on our post will never be seen from the outside world.
There are three ways to operate for the NAT:
– Static NAT
– Dynamic NAT
– NAT Overlay (PAT)
The Static NAT makes it possible to make 1 for 1
1 private IP for a public IP
interface f 0/1 LAN description ip address 192.168.1.254 255.255.255.0 ip nat inside ! interface f 0/2 WAN description ip address 220.127.116.11 255.255.255.0 ip nat outside ! ip nat inside source static 192.168.1.1 18.104.22.168 ip nat inside source static 192.168.1.2 22.214.171.124 ip nat inside source static 192.168.1.3 126.96.36.199 etc...
interface f 0/1 LAN description ip address 192.168.1.254 255.255.255.0 ip nat inside ! interface f 0/2 WAN description ip address 188.8.131.52 255.255.255.0 ip nat outside ! ip nat pool BUT 184.108.40.206 220.127.116.11 netmask 255.255.255.0 ip nat inside source list 10 pool BUT ! access-list 10 permit 192.168.1.1 access-list 10 permit 192.168.1.2 etc...
PAT (NAT overlay)
PAT – Port Address Translation.
Allow multiple private IP addresses to be matched to a single public address.
To do this, our router will play on the port numbers.
Post 1 sends a package to Google
– IP Source: 192.168.0.1 / Source Port 1234
– The router receives this package, puts its IP WAN address in place of the IP Source and will choose a new dynamic port (4567).
– He stays tuned on port 4567.
– If he receives a package on this port, he will transmit it to post 192.168.0.1 and then he will stop listening on that port.
FastEthernet0/1 interface LAN description ip address 192.168.1.254 255.255.255.0 ip nat inside ! FastEthernet0/2 interface WAN description ip address 18.104.22.168 255.255.255.0 ip nat outside ! ip nat inside source list 10 interface FastEthernet0/2 overload ! access-list 10 permit 192.168.1.0 0.0.0.0.255 etc...
All Internet BOXEs work in PAT. So the posts in your home network use your BOX's public IP address.
They are not directly reachable from the internet.
If you want to set up a server that is accessible from the outside behind your BOX, you're going to have to do Port-Forwarding. (Port direction)
A port redirection allows you to tell your BOX to stay tuned to a particular port. If he receives something on the latter, he will always pass it on to the specified user.
Hoping this article has been helpful to you! Don't hesitate to let me know!!
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