Every day we surf the internet from our computer but we know exactly what happens when you connect your PC to the rest of the world "> Computer dictionary for the Internet and Networks with the meaning of the main terms The websites all have an address such as www.microsoft.com or www.google.it which are now familiar names to everyone and which are called URLs (Uniform Resource Locator)
However, this common form of addresses that we use, with recognizable and easily remembered letters and names, is not actually the type of address used by computers.
Human memory needs words that have a certain meaning to be remembered, but computers don't need that help and use sets of numbers called IP addresses to identify websites .
The most common IP address format is that made up of 4 numeric segments, each separated by a dot.
The numbers must vary from 0 to 255 (eight bits for each, therefore 32 bits in total), so the real Microsoft web address is 64.4.11.37 .
Since that IP address format, called IPv4, is limited in possible combinations, there are new IPv6 addresses that use 128-bit representation.
The IPv4 system will be gradually replaced by this new 128-bit system, known as IPv6 necessary to host the huge increase in connected devices that has been occurring in recent years due to the spread of smartphones and tablets.
It is necessary to know that not only websites are represented on the internet by an IP address, but also computers and every device that accesses the network has one.
The 128-bit IPv6 address is made up of eight 16-bitch blocks that become 4-digit hexadecimal numbers.
The blocks are separated by colons (e.g. 2001: 0: 4137: 9e76: 8f0: 202c: b9c0: 2f05 )
To keep order and coordinate addresses on the Internet before there was an organization under the protection of the United States government (the Internet Assigned Numbers Authority or IANA) while now a private company called ICANN thinks about it (The Internet Corporation for Assigned Names and Numbers).
The formats that are used for URLs are standards proposed and agreed upon since the beginning of the Internet.
The schematic form of a URL is as follows :
//: @: /
where the parentheses indicate particular individual components and are not part of the real URL. Taking into consideration each of these parts we have:
1) Protocol indicates how information is transmitted and retrieved.
Protocol is the language used by computers to communicate with each other and exchange information of a certain type.
Protocols are established by international agreements that guarantee that computers all over the world can communicate with each other.
The main internet protocols are:
- TCP / IP explained in the article on how computers talk to each other via TCP / IP
- Email protocols to transfer Email: SMTP to send and POP to receive.
See also the meaning and difference between POP and IMAP
SMTP and POP3 use TCP to manage the transmission and delivery of e-mail over the Internet.
- Hypertext Transfer Protocol (HTTP) is the protocol used by websites that refers to the format of hypertext links encoded in various versions of Hypertext Markup Language (HTML) that our browser downloads and converts into web pages with a graphic format pleasing to the eye .
The only other protocol that a user can encounter on the internet is FTP (File Transfer Protocol) which indicates the connection to a file server to download.
2) The " : @ " part is never seen, but would allow you to enter your username and password on the sites where it is requested.
This section can also be used to obscure a URL: For example, // foo: works like //www.navigaweb.net (try it).
3) host is the computer we want to connect to.
The host can be an IP address or a URL like www.navigaweb.net
Often the hostname is made up of three words separated by periods.
The first part is a name for a specific computer which is often " www " (World Wide Web), but it can also be different and which lately is also omitted.
The second part (" Navigaweb ") is the local network where the computer resides, while the third part (" net ") is one of the so-called generic top-level domains .
For some time these domains have been limited to com, edu, org, net, mil, gov and int .
Com, net and org are domains available to people and companies all over the world.
Originally, they should have been descriptive therefore as indicated commercial site, net network service, non profit organization org.
However, these meanings have been lost over time and anyone can request a .net or an .org.
Other top-level domains are reserved such as .edu for schools and universities and .gov for public administration sites.
In recent years, ICANN has added or proposed many new domains including .info, .biz and many others (also .xxx).
Each country then has its own top-level domain such as .it for Italy.
Each country manages this national domain as it wishes, some reserving it only for those who live in that country, others instead selling it at high prices for their combination of words such as the .io (British Indian Ocean Territory), .am (armenia ) or .ly (Libya).
Noteworthy is the example of a small country like the small Pacific island, Tuvalu, which collects a lot of money in the sale of expensive .tv domains for obvious reasons widely used by online television sites.
SEE ALSO: How many things you can do with a custom domain
4) door is the segment that specifies the door.
To understand the meaning of the door, you can think of the IP address as a street address such as Via Dante and the door as the house number.
Although the computer can only have one IP address on the internet, there are several programs that take advantage of the connection.
For example, you connect to the internet to receive e-mails, send emails, surf the internet, chat etc.
Each of these activities is carried out by software which, in order to be able to carry out these functions in a systematic way, needs "doors" that complete the local addresses.
These ports have no physical existence and are not as real as the USB ports, they are simply numbers that complete the address of a type of activity on the internet so that the computer knows how to receive and with what program to process a packet of data received.
In practice, if you send a request to an IP address, the program to which this request is addressed is specified with the port.
Thinking of a postman who has to deliver letters, the IP address corresponds to the street address of the house while the doors to the house number.
The port number is often hidden in a network address.
For example, the browser the port number 80 is assigned by convention to the http protocol so each website has an address like www.navigaweb.net:80 (by convention, since it is always the same port, it is not put and not She sees).
The doors are numbered from 0 to 65536 .
The port numbers, however, are not randomly assigned, but conform to the standards of the Internet Assigned Numbers Authority (IANA) so we have: Ports 0-1023 reserved for the main system processes; Ports 1, 024-49, 151 are called "registered ports", the remaining ports 49, 152-65, 535 are called "dynamic" and / or "private doors" and are not regulated.
Among the main and most used doors are:
20 FTP File transfer
22 SSH Secure Shell
25 SMTP Sending email
53 DNS Domain Name Service
80 HTTP Reading web pages
110 POP3 Receiving e-mails
119 NNTP News groups
Since the ports are used to exchange information between a computer and the Internet, they are also a gateway for hackers trying to break into private and secure networks.
If a port remains open (i.e. a computer program or software is running on the computer that leaves the port listening and waiting for information), it is vulnerable to intrusion.
This is where a firewall comes into play, to control system access and block unauthorized ones.
In another article it is written how to see connections, ports and use of the internet on the PC by programs and sites.
READ ALSO: Programs for scanning a network to find connected computers
5) URL path
The last part of the network address is the path or url-path which is the path on the host computer where there is a particular page or file that we want to download.
This part will often have the name of a directory with subdirectories, often ending with an .html file or generated by other programs such as .asp or .php .
For example, taking this address, //www.navigaweb.net/2013/06/garantire-computer-senza-mai-errori.html, URL path is all that is after .net /, made from the 2013 folder that contains the folder 06 which contains the guarantee-computer-without-never-errors.html hypertext file
To finish this brief manual to internet addresses, we must also talk about DNS .
When the browser sends a request to the Internet service provider (ISP) to connect to the www.microsoft.com site, there is a Telecom or Fastweb computer that checks what those letters that make up the word microsoft.com mean.
The ISP uses a special server called DNS server (DNS stands for " Domain Naming System ") which has databases to associate numeric IP addresses with names.
These translation processes are important and can take a certain amount of time if the name servers used by your ISP are busy.
Another article explains how to optimize the internet by changing DNS servers
Note that every computer including ours must have an IP address when connected to the Internet.
On the way in which IP addresses are assigned, I refer to reading: How do we connect to the internet and why with the same Public IP address? .
In conclusion, to make a summary :
Any device on a network or the Internet must have an address.
In order for computers around the world to communicate with each other, there must be well-defined and secure methods that are called protocols.
Protocols provide a universal way of doing things that computers around the world are capable of understanding.
A computer connected to the Internet can then do several operations at the same time, therefore, to use the Internet from various programs, there are sub-addresses called ports.
For any questions, please contact your trusted technician (i.e. me) and write a comment below!
