What is a Network?. Public, private, and internet explained… | by Sam Writes Security | Apr, 2022

Public, private, and internet explained for non-techies.

Image by svilen001 from Freeimages.com

Networks are things connected, you and your friends, family members, computers, and mobile devices in one way or another are all connections.

In a private network (which we’ll define later on) computers are connected, and to prove such a connection computers usually share similar IPs where only certain numbers vary from others. This is because an IP is divided into two parts the Network ID and the Host ID, furthermore because each computer should have its unique identifying number.

192.123.0.5

if the above IP address was the unique IP of your computer device other devices in the same network would have similar IPs but each with its own unique identifying number for example 192.123.0.3, 192.123.0.4, 192.123.0.2, and 192.123.0.1 where 0 is reserved for your networkID. The numbers in bold help you distinguish one device from another. No devices in a network should have the same IP address that would make communication a pain in the … so, that sort of thing in networking is not acceptable.

More on networking …

A network can be formed from as little as two devices to as many as necessary. So, connected devices form a network. You don’t need expensive equipment to make yourself a network. Sharing my mobile device connection using tethering/hotspot with two or more devices is an example of a network diagram.

Should you decide to do this look up the IP addresses attributed to each connected device at home and you’ll realize each of those IPs lead back to the device sharing the connection acting as a modem (Network ID).

The Internet

The internet is a network, not a simple public network but a giant network with many private networks within its domain. I doubt you’ll find a network bigger than the internet Good luck!

Private and Public Networks

The internet is made of small networks these are what we call private Networks. This can be your home setup, school, or work. Networks connecting these private networks are called public networks. We can consider a private network as any network to which access is restricted public networks are the exact opposite. The best example of a public network is the internet.

Identifying devices on a network

Humans have names and individual fingerprints, one can use a fake ID here and there but, (and I don’t condone this of course) the same doesn’t apply to fingerprints. We can compare IP addresses to names and Mac Addresses to Fingerprints since these don’t change.

So, within a network to find who is connected and where just like you’d need a name and fingerprints to prove that I am, who I say I am a valid IP and Mac address will work on computers.

Public and Private IP addresses

Let us forget the comparison for a while because we don’t have private and public names, not officially anyway. Public IP addresses are used to identify devices on the internet whereas private IP addresses are used to identify devices amongst other devices.

Find yours, lookup on Google, and write “what is my IP address” note that down, close your browser and use your terminal this time and use the command “IP config on Windows/ifconfig or Mac and Linux ” and hit enter. For what it’s worth those won’t match.

Ping

Ping is very easy to use but very important and available on most Operating Systems by default like “IP/If config depending on your Operating System. Easy or not we won’t go deep into using the tool but only the basic command to help us with our networking journey.

Ping uses Internet Control Message Protocol (ICMP) which can help us detect whether a connection is reliable or if it even exists in the first place.

Here’s an example;

ping -c 4 8.8.8.8
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data
64 bytes from 8.8.8.8: icmp_seq=1 ttl=56 time=8.21 ms
64 bytes from 8.8.8.8: icmp_seq=1 ttl=56 time=9.90 ms
64 bytes from 8.8.8.8: icmp_seq=1 ttl=56 time=9.88 ms
64 bytes from 8.8.8.8: icmp_seq=1 ttl=56 time=8.43 ms
— — 8.8.8.8 ping statistics — –
4 packets transmitted, 4 received, 0% packet loss, time 4006ms

This is a good result it means whatever site behind that IP is alive and well (online). by the way, you should know that (8.8.8.8) is Google’s DNS server.

You can find that out yourself by using whois

who is 8.8.8.8

# start

NetRange: 8.8.8.0–8.8.8.255
CIDR: 8.8.8.0/24
NetName: LVLT-GOGL-8–8–8
NetHandle: NET-8–8–8–0–1
Parent: LVLT-ORG-8–8 (NET-8–0–0–0–1)
NetType: Reallocated
OriginAS:
Organization: Google LLC (GOGL)
RegDate: 2014–03–14
Updated: 2014–03–14
Ref: https://rdap.arin.net/registry/ip/8.8.8.0

OrgName: Google LLC
OrgId: GOGL
Address: 1600 Amphitheatre Parkway
City: Mountain View
StateProv: CA
PostalCode: 94043
Country: US
RegDate: 2000–03–30
Updated: 2019–10–31
Comment: Please note that the recommended way to file abuse complaints are located in the following links.
Comment:
Comment: To report abuse and illegal activity: https://www.google.com/contact/
Comment:
Comment: For legal requests: http://support.google.com/legal
Comment:
Comment: Regards,
Comment: The Google Team
Ref: https://rdap.arin.net/registry/entity/GOGL

OrgAbuseHandle: ABUSE5250-ARIN
OrgAbuseName: Abuse
OrgAbusePhone: +1–650–253–0000
OrgAbuseEmail: network-abuse@google.com
OrgAbuseRef: https://rdap.arin.net/registry/entity/ABUSE5250-ARIN

OrgTechHandle: ZG39-ARIN
OrgTechName: Google LLC
OrgTechPhone: +1–650–253–0000
OrgTechEmail: arin-contact@google.com
OrgTechRef: https://rdap.arin.net/registry/entity/ZG39-ARIN

# end
# Copyright 1997–2022, American Registry for Internet Numbers, Ltd.

Just in case you’re lost;

IP= Internet Protocol
Mac= Media Access Control (unique single mac for every device)
Using the ping comand= #ping IP/website
Note:
Since the ping command doesn’t stop ever on Mac type Command + C and on Windows type Ctrl + C. Alternatively you can add the letter (C ) and the number of counts to stop pinging after a count the same way I did.

ARP protocol

Address Resolution Protocol is the technology that makes it possible for devices to identify themselves on a network using a Mac and IP address.
The devices within a network store information and have the help of cache which helps identify each other and match mac addresses to the correct IP addresses.

To match a Mac Address to an IP address a broadcast is sent by a device and is read by every device on the network and this is called an ARP request. The device to which the IP in question matches sends back a message and this is called an ARP reply. Device (A) sends a request and device (B) the match sends a reply.

Leave a comment let me know what your thoughts are, and make every day a Cyber Security awareness day!

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