Isa tarafından yazılmıştır.
Hi, I will be sharing my learnings from various CCNA documents. Hoping for a productive course for everyone.
In the transportation of the data to reach from somewhere to another, an addressing process is needed. IP Address is a must, let me put it this way. We need a mouth to speak, the mouth here is the IP address. We can’t communicate with our devices without an IP address.
ISPs are the corporations that provide internet to us.
Packet-Tracer-Image 1
For instance, these devices can’t communicate for not having an IP address
How IP addresses are written is as:
IP Address: 192.168.1.2
You see IPs in your home network like this but the last part switches. Routers are 192.169.1.1 because they are the first device in the network. Apart from the router, devices are given addresses with the last parts increasing from 2.
MACs, carry the address for network adapters. IP addresses are changeable but MAC addresses aren’t, because they are physical hardware addresses, they are written on the network adapter inside the computer.
Sample MAC address: 49:4c:4a:c9:e9:51
A MAC address is made up of 6 octets, first three of them represent the manufacturer. The last three octets represent the device itself.
Network Adapter
You can view your MAC address by typing ipconfig all to CMD
These values are given with a device with an IP
We can enter these ourselves but we have DHCP for doing that. The process of entering these parameters by servers or machines is called Dynamic Routing, and DHCP takes the charge of it.
DHCP Diagram
DHCP requests are firstly initiated by Client. “Gimme an IP address,” he says and the server passes an IP. For every IP to be unique, DHCP checks up on IP addresses that it will give soon.
In terms of a home network, the network router takes charge of DHCP. Client, the user requests an IP address from the router to give one.
To understand the good of DHCP, let’s think of a network with a thousand computers. Every device will need an IP but it’s a hell of labor work to do so. DHCP arrives in the field and undertakes this.
How to enable dynamic routing though?
The window when you do “Control Panel > Network and Internet > Network and Sharing Center > Change adapter settings > IPv4 Properties” is as:
Dynamic Confuguration
If the circled options are ticked, DHC Protocol is working. Otherwise, You will assign IP addresses manually if the ones below them are ticked.
Works in the Client-Server way. Is used to the Hostnames to IP. Hostnames have to become IP because devices can’t communicate with hostnames.
We encounter DNS on websites. What we use on websites “www.pwnlab.me” is a domain. When you type this domain in a web browser, DNS resolves this and turns them into IP addresses.
DNS names have to be unique as IP addresses do. But for they are unique, there would be chaos.
DNS-Diagram EN
A diagram that practically represents the main idea.
The client initiates the request. Request reaches to DNS server, gives the IP address we need.
DNS Diagram
The route how domain “www.pwnlab.me” is built:
First, Top Level Domain(TLD) which looks like “.com, .me”. We go to TLD “.me” and ask for a “pwnlab”, TLD says, yes, so that we have a “pwnlab.me” now. We are at Second Level Domain(SLD) now. Lastly, we go to the next stop and ask for a “www”. If there is one, our domain completely is.
In conclusion, we don’t just take the domain from just one place. And this route doesn’t repeat every time, cache steps in, helps to save some internet usage.
To see the DNS of the device we are in, use CMD. DNS Server information is seen when ipconfig /all is typed:
ipconfig all
I will show few ways to see if our DNS is working.
Pinging:
Pinging
As you can see, there is a response. Yet another toll is nslookup:
nslookup
This command affirms that the domain address has turned into an IP address.
HTTP works as client-server way too. It is in charge of defining the communication rules between the web client and the web server. The client requests something, and the server responds to us.
HTTP_diagram
I didn’t include ISPs in this diagram even though they exist. We could do nothing without ISPs. As the client, we request “pwnlab.me homepage”; it returns the index.html as a response. If there is no such page, it will respond a 404 error.
The difference between HTTP and HTTPS is pretty visual without an abbreviation.
HTTP = Hyper Text Transport Protocol
HTTPs = Secure Hyper Text Transport Protocol
Why HTTPs is secure is because every data you send gets encrypted. At HTTP, if someone catches a response in the air, (Burp Suite) they can screen everything so clear.
Both of them are protocols to check up on the device remotely. Telnet works as client-server. There is a verification process when client requests connecting. Logs in if affirmative.
While Telnet sends data as clear text, ssh encrypts the whole traffic.
Works as client-server. Adjusts the rules of file sending between FTP client and FTP server.
The client initiates the FTP request, the FTP server confirms, sends the files to local.
We can connect to FTP by going by “ftp” on CMD. “?” Will list the usable commands.
FTP
To can see detailed information on NAT, see Salih Öztürk’s post.
You have probably heard that addresses on IPv4 are limited. NAT ensures that the public IP addresses of devices are the same in a home network. That way fewer IP addresses are used.
That was the background information for what I will be mentioning soon.
Packet Tracer is an application that is developed by Cisco Networking Academy to help students learn networks. You can prepare for the CCNA exam with this software.
This is the login screen you’ll see after installation(clicking next constantly). Sign up to the Cisco Networking Academy to log in.
Packet Tracer Login
Logged in interface:
Packet-Tracer-Image-1
I’ll briefly explain the interface, though you can just find out about them hovering around.
We have some tools we will need. First part is Network Devices. Things like router, switch, hub goes in here.
Network-devices
The second part is End Devices. requests’ last stop are these devices. Computers, tablets, etc.
End-Devices
And Connections, here we have the cable types for connecting devices to each other.
Connections EN
We can drag all of them to the space.
We need components to make two device communicate:
We could put just one device. But it wouldn’t count as communication.
Now we’ll form a communication channel between two computers. First, drag PC from toolbar down there, End Devices. Now we have Source but Destination. Drag another computer to let there be a Destination.
Packet Tracer named the computers PC0, PC1.
To computers without a connection.
Now we have two devices without a connection. These processes will remain in network adapter because there isn’t a network media. The wireless adapter is required for sending packets wirelessly. Anyway, let’s whether these computers have wireless adapter or not
Double-click a computer to do that:
PC Network Adapter Check
As you can see from the circled part, this computer uses cabled network adapter. Firstly you’ll need to turn off this computer to change this.
Turn off computer
Then drag the cabled network adapter to the menu left there, add the wireless network adapter.
Removing the cabled network card in the computer
Install wifi cable to computer
PC with wireless NWA
You can mount various modules and network adapters from the left bar there. Let’s put back the cabled network adapter (1CFE) now.
Assembling the Cabled Network Adapter
You’ll need to restart this computer.
Now let’s connect the networking cable. For that, choose the Automatic Choose Connections Type from Connections, then click the two computers. Normally there are various cabling methods for devices in the network, but I won’t refer to them in this first episode.
Choosing Cable
Connection Successful
Successfully connected if there are green arrows.
That’s it for the very first chapter of this series. Later.
[EN] CCNA Study Notes – 1
Hi, I will be sharing my learnings from various CCNA documents. Hoping for a productive course for everyone.
Preliminary
What is IP(Internet Protocol)?
In the transportation of the data to reach from somewhere to another, an addressing process is needed. IP Address is a must, let me put it this way. We need a mouth to speak, the mouth here is the IP address. We can’t communicate with our devices without an IP address.
ISPs are the corporations that provide internet to us.
Packet-Tracer-Image 1
For instance, these devices can’t communicate for not having an IP address
How IP addresses are written is as:
IP Address: 192.168.1.2
You see IPs in your home network like this but the last part switches. Routers are 192.169.1.1 because they are the first device in the network. Apart from the router, devices are given addresses with the last parts increasing from 2.
MAC (Media Access Control)
MACs, carry the address for network adapters. IP addresses are changeable but MAC addresses aren’t, because they are physical hardware addresses, they are written on the network adapter inside the computer.
Sample MAC address: 49:4c:4a:c9:e9:51
A MAC address is made up of 6 octets, first three of them represent the manufacturer. The last three octets represent the device itself.
Network Adapter
You can view your MAC address by typing ipconfig all to CMD
DHCP (Dynamic Host Configuration Protocol)
These values are given with a device with an IP
- IP Address
- Subnet Mask
- Default Gateway
- DNS Server Adress
We can enter these ourselves but we have DHCP for doing that. The process of entering these parameters by servers or machines is called Dynamic Routing, and DHCP takes the charge of it.
DHCP Diagram
DHCP requests are firstly initiated by Client. “Gimme an IP address,” he says and the server passes an IP. For every IP to be unique, DHCP checks up on IP addresses that it will give soon.
In terms of a home network, the network router takes charge of DHCP. Client, the user requests an IP address from the router to give one.
To understand the good of DHCP, let’s think of a network with a thousand computers. Every device will need an IP but it’s a hell of labor work to do so. DHCP arrives in the field and undertakes this.
How to enable dynamic routing though?
The window when you do “Control Panel > Network and Internet > Network and Sharing Center > Change adapter settings > IPv4 Properties” is as:
Dynamic Confuguration
If the circled options are ticked, DHC Protocol is working. Otherwise, You will assign IP addresses manually if the ones below them are ticked.
DNS (Domain Name Server)
Works in the Client-Server way. Is used to the Hostnames to IP. Hostnames have to become IP because devices can’t communicate with hostnames.
We encounter DNS on websites. What we use on websites “www.pwnlab.me” is a domain. When you type this domain in a web browser, DNS resolves this and turns them into IP addresses.
DNS names have to be unique as IP addresses do. But for they are unique, there would be chaos.
DNS-Diagram EN
A diagram that practically represents the main idea.
The client initiates the request. Request reaches to DNS server, gives the IP address we need.
DNS Diagram
The route how domain “www.pwnlab.me” is built:
First, Top Level Domain(TLD) which looks like “.com, .me”. We go to TLD “.me” and ask for a “pwnlab”, TLD says, yes, so that we have a “pwnlab.me” now. We are at Second Level Domain(SLD) now. Lastly, we go to the next stop and ask for a “www”. If there is one, our domain completely is.
In conclusion, we don’t just take the domain from just one place. And this route doesn’t repeat every time, cache steps in, helps to save some internet usage.
To see the DNS of the device we are in, use CMD. DNS Server information is seen when ipconfig /all is typed:
ipconfig all
I will show few ways to see if our DNS is working.
Pinging:
Pinging
As you can see, there is a response. Yet another toll is nslookup:
nslookup
This command affirms that the domain address has turned into an IP address.
HTTPS
HTTP works as client-server way too. It is in charge of defining the communication rules between the web client and the web server. The client requests something, and the server responds to us.
HTTP_diagram
I didn’t include ISPs in this diagram even though they exist. We could do nothing without ISPs. As the client, we request “pwnlab.me homepage”; it returns the index.html as a response. If there is no such page, it will respond a 404 error.
The difference between HTTP and HTTPS is pretty visual without an abbreviation.
HTTP and HTTPs
HTTP = Hyper Text Transport Protocol
HTTPs = Secure Hyper Text Transport Protocol
Why HTTPs is secure is because every data you send gets encrypted. At HTTP, if someone catches a response in the air, (Burp Suite) they can screen everything so clear.
Telnet & SSH
Both of them are protocols to check up on the device remotely. Telnet works as client-server. There is a verification process when client requests connecting. Logs in if affirmative.
While Telnet sends data as clear text, ssh encrypts the whole traffic.
FTP
Works as client-server. Adjusts the rules of file sending between FTP client and FTP server.
The client initiates the FTP request, the FTP server confirms, sends the files to local.
We can connect to FTP by going by “ftp” on CMD. “?” Will list the usable commands.
FTP
NAT
To can see detailed information on NAT, see Salih Öztürk’s post.
You have probably heard that addresses on IPv4 are limited. NAT ensures that the public IP addresses of devices are the same in a home network. That way fewer IP addresses are used.
Packet Tracer
That was the background information for what I will be mentioning soon.
Packet Tracer is an application that is developed by Cisco Networking Academy to help students learn networks. You can prepare for the CCNA exam with this software.
This is the login screen you’ll see after installation(clicking next constantly). Sign up to the Cisco Networking Academy to log in.
Packet Tracer Login
Logged in interface:
Packet-Tracer-Image-1
Packet Tracer Network Components
I’ll briefly explain the interface, though you can just find out about them hovering around.
We have some tools we will need. First part is Network Devices. Things like router, switch, hub goes in here.
Network-devices
The second part is End Devices. requests’ last stop are these devices. Computers, tablets, etc.
End-Devices
And Connections, here we have the cable types for connecting devices to each other.
Connections EN
We can drag all of them to the space.
First Networking Test (PC – PC)
We need components to make two device communicate:
- Source
- Destination
- Media
We could put just one device. But it wouldn’t count as communication.
Now we’ll form a communication channel between two computers. First, drag PC from toolbar down there, End Devices. Now we have Source but Destination. Drag another computer to let there be a Destination.
Packet Tracer named the computers PC0, PC1.
To computers without a connection.
Now we have two devices without a connection. These processes will remain in network adapter because there isn’t a network media. The wireless adapter is required for sending packets wirelessly. Anyway, let’s whether these computers have wireless adapter or not
Network Adapter Check
Double-click a computer to do that:
PC Network Adapter Check
As you can see from the circled part, this computer uses cabled network adapter. Firstly you’ll need to turn off this computer to change this.
Turn off computer
Then drag the cabled network adapter to the menu left there, add the wireless network adapter.
Removing the cabled network card in the computer
Install wifi cable to computer
PC with wireless NWA
You can mount various modules and network adapters from the left bar there. Let’s put back the cabled network adapter (1CFE) now.
Assembling the Cabled Network Adapter
You’ll need to restart this computer.
Now let’s connect the networking cable. For that, choose the Automatic Choose Connections Type from Connections, then click the two computers. Normally there are various cabling methods for devices in the network, but I won’t refer to them in this first episode.
Choosing Cable
Connection Successful
Successfully connected if there are green arrows.
That’s it for the very first chapter of this series. Later.
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