Module 2: Basic Switch and End Device Configuration
IPv6 Addresses - Explained
- 128 bits in length and written as a string of hexadecimal values - Every four bits is represented by a single hexadecimal digit; for a total of 32 hexadecimal values - Groups of four hexadecimal digits are separated by a colon
Privileged EXEC Mode
- Allows access to all commands and features - Identified by the CLI prompt that ends with the # symbol
User EXEC Mode
- Allows access to only a limited number of basic monitoring commands - Identified by the CLI prompt that ends with the > symbol
VTY Lines
- Enable remote access using Telnet or SSH to the device. - Many Cisco switches support up to 16 VTY lines that are numbered 0 to 15
Securing Privileged EXEC mode access
- First enter global configuration mode - Next, use the enable secret password command
There are Several Terminal Emulation Programs
- PuTTY - Tera Term - SecureCRT
Alter the Running Configurations - Restore: Not Saved
- Remove the changed commands individually - Reload the device using the reload command in privilege EXEC mode: device briefly goes offline = network downtime.
Guideline for naming devices
- Start with a letter - Contain no spaces - End with a letter or digit - Use only letters, digits, and dashes - Be less than 64 characters in length
Configuration Files - Two System Files that Store the Device Configuration
- Startup-config - Running-config
Configuration Files - Running-Config
- This is stored in Random Access Memory (RAM) - It reflects the current configuration. - Modifying a running configuration affects the operation of a Cisco device immediately - RAM is volatile memory - It loses all of its content when the device is powered off or restarted
Configuration Files - Startup-Config
- This is the saved configuration file that is stored in NVRAM - It contains all the commands that will be used by the device upon startup or reboot - Flash does no lose its contents when the device is powered off
Types of Network Media
- Twisted-pair copper cables - Fiber-optic cables - Coaxial cables - Wireless
CLI-based Network Technician to do the Following:
- Use a keyboard to run CLI-based network programs - Use a keyboard to enter text and text-based commands - View output on a monitor
PC Operating System Enables a User to do the Following:
- Use a mouse to make selections and run programs - Enter text and text-based commands
Primary Command Modes
- User EXEC Mode - Privileged EXEC Mode
GUI Examples
- Windows - macOS - Linux KDE - Apple iOS - Android
IPv4 Subnet Mask
A 32-bit value that differentiates the network portion of the address from the host portion.
Banner Messages
A banner message is important to warn unauthorized personnel from attempting to access the device
Device Names - Default
All devices are assigned a factory default name - For example, a Cisco IOS switch is "Switch"
Password Guidelines - Limit Administrative Access
All networking devices should limit administrative access by securing privileged EXEC, user EXEC, and remote Telnet access with passwords.
Password Guidelines - Encryption
All passwords should be encrypted and legal notifications provided
Hot Keys and Shortcuts - Ctrl-Shift-6
All-purpose break sequences used to abort DNS lookups, traceroutes, pings, etc
Password Guidelines - Avoid
Avoid using the same password for all devices
IOS Command Syntax Check - [x {y | z}]
Braces and vertical lines within square brackets indicate a required choice within an optional element. Spaces are used to clearly delineate parts of the command.
IOS Command Syntax Check - {x}
Braces indicate a required element (keyword or argument)
The Structure of an IPv4 address
Called doted decimal notation and is represented by four decimal numbers between 0 and 255
Commands and Keywords Shortened
Can be shortened to the minimum number of characters that identify a unique selection.
CLI
Command Line Interface
Kernel
Communicates between the hardware and software of a computer and manages how hardware resources are used to meet software requirements
Hot Keys and Shortcuts - Tab
Completes a partial command name entry
Capture Configuration to a Text File
Configuration files can also be saved and archived to a text document
Capture Configuration to a Text File - Step 4
Disable logging in the terminal software
"--More--" Prompt Hot Keys and Shortcuts - Enter Key
Displays the next line
"--More--" Prompt Hot Keys and Shortcuts - Space Bar
Displays the next screen
Differences Between Various Types of Media - Distance
Distance the media can successfully carry a signal
Password Guidelines - Common Words
Do not use common words because they are easily guessed
Capture Configuration to a Text File - Step 2
Enable logging in to the terminal software and assign a name and file location to save the log file
Securing User EXEC Mode Access - Third
Enable user EXEC access using the login command
Context-Sensitive Help
Enables you to quickly find answers to these questions: - Which commands are available in each command mode? - Which commands start with specific characters or group of characters? - Which arguments and keywords are available to particular commands?
Network Communications Depend On
End user device interfaces, networking device interfaces, and the cables that connect them
"--More--" Prompt Hot Key Commands - Any Other Key
Ends the display string, returning to privileged EXEC mode
Securing User EXEC Mode Access - First
Enter line console configuration mode using the line console 0 command in global configuration mode
Hot Keys and Shortcuts - Backspace
Erases the character to the left of the cursor
Secure Shell (SSH)
Establishes a secure remote CLI connection to a device, through a virtual interface, over a network. - Note: This is the recommended method for remotely connecting to a device
Telnet
Establishes an insecure remote CLI connection to a device over the network - Note: User authentication, passwords and commands are sent over the network in plaintext
Capture Configuration to a Text File - Step 3
Execute the show running-config or show startup-config command at the privileged EXEC prompt. - Text displayed in the terminal window will be placed into the chosen file
GUIs Can
Fail, crash, or simply not operate as specified. For these reasons, network devices are typically accessed through a CLI
Securing VTY Line Access - Third
Finally, enable VTY access using the login command
Securing VTY Line Access - First
First enter line VTY configuration mode using the line vty 0 15 command in global configuration mode
GUI
Graphical User Interface
IPv6 Addresses - Case-Sensitivity
IPv6 addresses are not case-sensitive and can be written in either lowercase or uppercase
Command Syntax - Italics
Indicates arguments for which you supply values
IOS Command Syntax - Boldface
Indicates commands and keywords that you enter literally as shown
Hot Keys and Shortcuts - Left Arrow or Ctrl+B
Moves the cursor one character to the left
Hot Keys and Shortcuts - Right Arrow or Ctrl+F
Moves the cursor one character to the right
Sub-Configuration Modes - Move out
Of any sub-configuration mode, use the exit command. - To return to privilege EXEC mode, use the end command or key combination Ctrl +z
Capture Configuration to a Text File - Step 1
Open terminal emulation software, such as PuTTY or Tera Term, that is already connected to a switch
Hot Keys and Shortcuts - Up Arrow or Ctrl+P
Recalls the commands in the history buffer, beginning with the most recent commands
Securing VTY Line Access - Second
Specify the VTY password using the password password conmmand
Securing User EXEC Mode Access - Second
Specify the user EXEC mode password using the password password command
Command Syntax Check - [x]
Square brackets indicate an option element (keyword or argument)
Banner Messages - Delimiting Character
The "#" in the command syntax is called the delimiting character. It is entered before and after the message
Hot Keys and Shortcuts
The IOS CLI provides hot keys and shortcuts that make configuring, monitoring, and troubleshooting easier
IOS Help Features
The IOS has two forms of help available: - Context-sensitive help - Command syntax check
When a Command Output Produces more Text than can be Displayed in a Terminal Window
The IOS will display a "--More--" prompt
Default Gateway Address
The IP address of the router that the host will use to access remote networks, including the internet
Banner Messages - Display
The banner will be displayed on attempts to access the device
Commands and Keywords Shortened - Example
The configure command can be shortened to conf because configure is the only command that begins with conf
Device Names
The first configuration command on any device should be to give it a unique hostname
Command Syntax Provides
The pattern, or format, that must be used when entering a command
Hardware
The physical part of a computer including underlying electrons
The Use of IP Addresses
The primary means of enabling devices to locate one another and establish end-to-end communication on the internet
Encrypt Passwords - Startup-Config and Running-Config
The startup-config and running-config files display most passwords in plaintext
IPv4 Subnet Mask - Coupled with the IPv4 Address
The subnet mask determines to which subnet the device is a member
Password Guidelines - Security Concern
The use of weak or easily guessed passwords
Shell
The user interface that allows users to request specific tasks from the computer. These requests can be made either through the CLI or GUI interfaces
Command - ping and traceroute
The user-defined argument is the ip-address of the destination device
Basic IOS Command Structure - Keyword
This is a specific parameter defined in the operating system
Basic IOS Command Structure - Argument
This is not predefined; it is a value or variable defined by the user
Banner Messages - Creation
To create a banner message of the day on a network device, use the banner motd # the message of the day # global config command
Encrypt Passwords - Encryption
To encrypt all plaintext passwords, use the service password-encryption global config command
Sub-Configuration Modes - Move to Another
To move directly from one sub-configuration mode to another, type in the desired sub-configuration mode command.
Navigation Between IOS Modes - Privileged EXEC Mode
To move from user EXEC mode to privilege EXEC mode, use the enabled command
Navigation Between IOS Modes - Global Configuration Mode
To move in and out of global configuration mode, use the configure terminal command. To return to privilege EXEC mode, use the exit command.
Navigation Between IOS Modes - Line Configuration Mode
To move in and out of line configuration mode, use the line command followed by the management line type. To return to global configuration mode, use the exit command
Configuration Files - Save Changes
To save changes made to the running configuration to the startup configuration file, use the copy running-config startup-config privileged EXEC mode command
Password Guidelines - Characters
Use a combination of upper and lowercase letters, numbers, special characters, and/or numeric sequences
Password Guidelines - Length
Use passwords that are more than eight characters in length
Alter the Startup Configuration - Restore: Saved
Use the erase startup-config command in privilege EXEC mode - Reload the device to clear he running-config from RAM
To Return the Switch to the Default Prompt
Use the no hostname global config command
Encrypt Passwords - Verify
Use the show running-config command to verify that the passwords on the device are now encrypted
Global Configuration Mode
Used to access configuration options on the device
Interface Configuration Mode
Used to configure a switch port or router interface
Line Configuration Mode
Used to configure console, SSH, Telnet or AUX access
Terminal Emulation Programs
Used to connect to a network device by either a console port or by an SSH/Telnet connection
The GUI Allows
User to interact with the system using an environment of graphical icons, means, and windows
A GUI is More
User-friendly and requires less knowledge of the underlying command structure that contacts the system
Command Syntax Check
Verifies that a valid command was entered by the user: - If the interpreter cannot understand the command being entered, it will provide feedback describing what is wrong with the command
Hot Key and Shortcuts - Ctrl-C
When in any configuration mode, ends the configuration mode and returns to privileged EXEC mode
Hot Key and Shortcuts - Ctrl-Z
When in any configuration mode, ends the configuration mode and returns to privileged EXEC mode