Some basic network troubleshooting commands

Below are some every day, useful commands to use when troubleshooting your own device and network issues

ipconfig /all

This command shows the current TCP/IP configurations for all adapters. This can be both logical and physical addresses. Below is a simple screenshot with the results. Notice the default gateway is shown, this is the router address on the same network as the device. Without the default gateway being configured we will not be able to communicate remotely or with other networks. 

show ip interface brief

This is a router command it shows all IPv4 interface configurations and their current status

ping

Ping verifies IP connectivity to another networked device by sending Internet Control Message Protocol (ICMP) echo Request messages. When a successful ping happens you get the below pieces of information. In the example 127.0.0.1 is a loopback address to check if the local PC's TCP/IP address is configured correctly. If an IP address is not available you will get a timed out message.

tracert

Trace route will diagnose the path taken to a destination. Again ICMP is used, and echo requests are feedback when a different network is identified. This is used to pinpoint where network failures occur

These are just some small examples of commands that can be used at a fundamental level. Microsoft have published a detailed list of commands here

AAA - Authentication, Authorisation, Accounting

802.1X authentication

802.1X authentication involves ensuring something is what its saying it is.

Features

Supplicant - (client-end user) - Devices that are trying to connect to an 802.1X need to have software installed on them and this is known as a supplicant. The supplicant initiates the connection by activating EAP (Extensible Authentication Protocol) between the device and switch

Authenticator - A device on a network that connects a client to a network. It blocks and allows traffic. A switch is an example of an authenticator.

Authentication Server - deals with requests for access to the network. The server tells the authenticator to allow or deny the traffic. Authentication servers usually run on the RADIUS protocol.

AAA

AAA is a requirement of network security. It is a process from start to finish of network access and monitoring

Authentication: uses challenge and response methodology for granting access. This identifies users by username and password

Authorisation: After initial authentication, authorisation uses the RADIUS protocol to allow access to resources based on permission levels

Accounting: After access users can be be monitoring for billing, reporting and auditing. You can observe what users do after they have been authenticated and authorised for example when they log in and when they log out.

The next steps are to look at a practical scenario using the AAA methodology.

Topology addressing:

Server: 192.168.2.2

G/0/0/1: 192.168.2.1

G/0/0/0: 192.168.1.1

PC0: 192.168.1.2 (Default Gateway 192.168.1.1)

Configure IP addressing on the router:

Assign a valid IP address to your Radius Server:

Turn on AAA on the services tab, add the the router details for the network the server is on ands specify a passkey - here I have used "hello"

Configuring AAA on the router, specify the server address and the passkey you used. (note the passkey I used is not very secure so something with multiple characters, number etc may be better)

Enable remote login:

Assign an IP address for your PC:

Test the telnet connection:

Note here: To use the more secure SSH connection you would need to add the ssh configurations into the router and it is also good practice to enable passwords on your router which was discussed in previous posts. 

Using Group Policy to deploy wallpaper to domain machines

On the server open up internet explorer, go to the website bing.com ( google may run slow ) . Search for an image of your choice

Right click on the image - and save it to the Pictures folder on the server as a bmp file 

Right click on the pictures folder and click share with specific people

Ensure everyone is added if not click the drop down box and add tick read/write and click share

Do the same for the file you want to use for example here I have right clicked on burnley2 and clicked share with specific people

Ensure Everyone + Read/write is selected and click share

You should see the below screen with the file name location listed. Mine is 

\\SERVER1\Users2\Administrator\Pictures\Burnley2.bmp

On server manager, click tools then Group policy management 

Right click Group Policy Objects - Click New 

Type Wallpaper then click ok

Now right click Wallpaper in the Group Policy Objects folder and click edit

Expand user configuration -> policies -> administrative templates then click desktop and on the right hand side click desktop wallpaper

Click enabled - type the full file path into the Wallpaper name , and select style as center or fill ( however you want the logo to appear. Click apply 

Go back to the group policy management console and right click your domain name - click Link an existing GPO

Select wallpaper

On the Windows 10 machine open cmd prompt 

Type gpupdate /force 

You should see the below message that is has been successfully update. Close the command prompt window and restart the windows 10 machine

Login with a user and you should see your logo if you have been successful :) 

Connect a Windows 10 machine to a domain

 

Select the Windows 10 machine and click start

Enter your password at the login screen

Press the Windows + X key and select system

Select rename this PC

Change the name to PC1

Click restart now

Press the windows + s key and type firewall and select the Windows defender firewall

Select turn windows defender on or off

Turn off both private and public settings

Press the Windows + X key and select system

Select Remote Desktop

Turn Remote Desktop On 

Click confirm

Press the Windows + X key and select network connections 

Click Change adapter options

Double click on the ethernet icon

Click properties

Uncheck IPv6 

Double click on Ipv4

Enter the IP address of your server from previous instructions below is my server's address . click ok 

Press the Windows + X key and select settings 

Select accounts

Select access work or school 

Select connect 

Select join this device to a local Active Directory domain 

Type your domain name

Type .\ ( then the username for which you made an administrator and the password )

Skip the below step and restart the PC

When the computer restarts you should see your domain name at the Sign in 

Type the user logins and press enter

New user has joined 👏

Close tabs down and shutdown the Windows 10 machine.