cisco introduction to networking. part 2

To move directly from one (subconfiguration) mode to another

(subconfiguration) mode command Switch(config-line)# interface FastEthernet 0/1 Switch(config-if)#

Some of the differences between various types of media include

- Distance the media can successfully carry a signal - Environment in which the media is to be installed - Amount of data and the speed at which it must be transmitted - Cost of the media and installation

naming guidelines for hosts

- 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

A CLI-based network operating system enables:

- Use a keyboard to run CLI-based network programs - Use a keyboard to enter text and text-based commands - View output on a monitor

GUI based PC operating system enables:

- Use a mouse to make selections and run programs - Enter text and text-based commands - View output on a monitor

Password Guidelines

- Use passwords that are more than eight characters in length. - Use a combination of upper and lowercase letters, numbers, special characters, and/or numeric sequences. - Avoid using the same password for all devices. - Do not use common words because they are easily guessed.

the command syntax

- boldface Boldface text indicates commands and keywords that you enter literally as shown. -italics Italic text indicates arguments for which you supply values. [x] Square brackets indicate an optional element (keyword or argument). {x} Braces indicate a required element (keyword or argument). [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.

two system files that store the device configuration

- startup-config - running-config to save configurations copy running-config startup-config

Manual configuration an IPv4 address

1) Control Panel > Network Sharing Center > Change adapter settings 2) choose the adapter 3) right-click and select Properties to display the Local Area Connection Properties 4) click Properties to open the Internet Protocol Version 4 (TCP/IPv4) Properties window. 5) configure the IPv4 address and subnet mask information, and default gateway.

To restore a configuration file to a device:

1) Enter global configuration mode on the device. 2) Copy and paste the text file into the terminal window connected to the switch. The text in the file will be applied as commands in the CLI and become the running configuration on the device. This is a convenient method of manually configuring a device.

Capture Configuration to a Text File

1) Open terminal emulation software, such as PuTTY or Tera Term, that is already connected to a switch. 2) Enable logging in to the terminal software and assign a name and file location to save the log file. 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. 4) Disable logging in the terminal software. The text file created can be used as a record of how the device is currently implemented.

administrative access to network devices

All networking devices should limit administrative access by securing privileged EXEC, user EXEC, and remote Telnet access with passwords. all passwords should be encrypted and legal notifications provided

global config mode

CLI configuration changes are made that affect the operation of the device as a whole From global config mode, the user can enter different subconfiguration modes. Switch(config)#

running-config (system file that store the device configuration)

Command (privileged EXEC): show 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.

startup-config (system file that store the device configuration)

Command (privileged EXEC): show 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 not lose its contents when the device is powered off.

Kernel

Communicates between the hardware and software of a computer and manages how hardware resources are used to meet software requirements

Tab (hotkey)

Completes a partial command name entry.

devices that must have IP addresses

Computers (work stations, laptops, file servers, web servers) Network printers VoIP phones Security cameras Smart phones Mobile handheld devices (such as wireless barcode scanners)

This table lists commands used to exit out of an operation.

Ctrl-C When in any configuration mode, ends the configuration mode and returns to privileged EXEC mode. When in setup mode, aborts back to the command prompt. Ctrl-Z When in any configuration mode, ends the configuration mode and returns to privileged EXEC mode. Ctrl-Shift-6 All-purpose break sequence used to abort DNS lookups, traceroutes, pings, etc.

Automatic IP Address Configuration for End Devices

DHCP select Obtain an IP address automatically and Obtain DNS server address automatically

Enter Key (hotkey) when prompt --More-- displayed

Displays the next line.

Space Bar (hotkey) when prompt --More-- displayed

Displays the next screen.

Any other key * (hotkey) when prompt --More-- displayed

Ends the display string, returning to previous prompt. *Except "y", which answers "yes" to the --More-- prompt, and acts like the Space bar

Backspace (hotkey)

Erases the character to the left of the cursor.

type of Cisco IOS command structure

Hierarchical command structure

Alter(change) the Running Configurations

If changes made to the running config do not have the desired effect and the running-config has not yet been saved, you can restore the device to its previous configuration. To do this you can: - Remove the changed commands individually. - Reload the device using the reload command in privilege EXEC mode(: This will cause the device to briefly go offline, leading to network downtime.)

Privileged EXEC Mode

Mode allows access to all commands and features. The user can use any monitoring commands and execute configuration and management commands. Switch# Router#

User EXEC Mode

Mode allows access to only a limited number of basic monitoring commands. It is often referred to as "view-only" mode. Switch> Router>

Left Arrow or Ctrl+B (hotkey)

Moves the cursor one character to the left.

Right Arrow or Ctrl+F (hotkey)

Moves the cursor one character to the right.

Up Arrow or Ctrl+P (hotkey)

Recalls the previous command in the history buffer, beginning with the most recent command.

Securing privileged EXEC mode access:

Sw-Floor-1# configure terminal Sw-Floor-1(config)# enable secret class Sw-Floor-1(config)# exit Sw-Floor-1# 1)First enter global configuration mode. 2)Next, use the "enable secret" password command.

commands to change(create) password

Sw-Floor-1# configure terminal Sw-Floor-1(config)# line console 0 Sw-Floor-1(config-line)# password cisco Sw-Floor-1(config-line)# login (enables user EXEC access) Sw-Floor-1(config-line)# end (exit) Sw-Floor-1# 1)Enter line console configuration mode using the line console 0 command in global configuration mode. 2)Next, specify the user EXEC mode password using the password password command. 3)Finally, enable user EXEC access using the login command.

Securing VTY (Virtual Tele tYpe) access:

Sw-Floor-1# configure terminal Sw-Floor-1(config)# line vty 0 15 Sw-Floor-1(config-line)# password cisco Sw-Floor-1(config-line)# login Sw-Floor-1(config-line)# end Sw-Floor-1# 1)First enter line VTY configuration mode using the line vty 0 15 command in global configuration mode. 2)Next, specify the VTY password using the password password command. 3)Finally, enable VTY access using the login command.

verify that the passwords on the device are encrypted

Sw-Floor-1# show running-config

Secure the privileged EXEC access with the password Cla55.

Sw-Floor-1(config)# enable secret Class Sw-Floor-1(config)#

Secure the console line. Use the password Cisc0 and allow login

Sw-Floor-1(config)# line console 0 Sw-Floor-1(config-line)# password Cisc0 Sw-Floor-1(config-line)# login SW-Floor-1(config-line)# exit Sw-Floor-1(config)#

Secure the first 16 VTY lines. Use the password Cisc0 and allow login.

Sw-Floor-1(config)# line vty 0 15 Sw-Floor-1(config-line)# password Cisc0 Sw-Floor-1(config-line)# login Sw-Floor-1(config-line)# end Sw-Floor-1#

To return the switch to the default prompt(name)

Sw-Floor-1(config)# no hostname Switch#

Encrypt all passwords.

Sw-Floor-1(config)# service password-encryption Sw-Floor-1(config)#

SVI

Switch Virtual Interface lets you remotely manage a switch over a network using IPv4 and IPv6

command to name device

Switch# configure terminal Switch(config)# hostname Sw-Floor-1 Sw-Floor-1(config)#

Basic IOS Command Structure

Switch>ping 192.168.10.5 Switch>ping ip protocols 1)Switch> is a Prompt 2)ping is a command 3)space between command and keyword 4)192.168.10.5 is a KEYWORD(s) of argument(s) 4)ip protocols is a keyword(s) of ARGUMENT(s)

Cisco Internetwork Operating System (IOS)

The family of network operating systems used on many Cisco devices Each device router or switch type uses a different version of Cisco IOS.

Hardware

The physical parts of a computer including underlying electronics

IPv4

The structure of an IPv4 address is called dotted decimal notation and is represented by 4 decimal numbers between 0 and 255. An IPv4 subnet mask is a 32-bit value that differentiates the network portion of the address from the host portion. Coupled with the IPv4 address, the subnet mask determines to which subnet the device is a member.

Why do we need IP addresses

The use of IP addresses is the primary means of enabling devices to locate one another and establish end-to-end communication on the internet. The default gateway address is the IP address of the router that the host will use to access remote networks, including the internet.

Shell

The user interface that allows users to request specific tasks from the computer. These requests can be made either through the CLI of GUI interfaces

Keyword

This is a specific parameter defined in the operating system (ip protocols).

Argument

This is not predefined; it is a value or variable defined by the user (192.168.10.5).

Interface Configuration Mode (subconfiguration mode)

Used to configure a switch port or router network interface. Switch(config-if)#

Line Configuration Mode (subconfiguration mode)

Used to configure console, SSH, Telnet, or AUX access. Switch(config-line)#

Context-sensitive help

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? To access enter "?" at the CLI (different at different prompts)

DHCP

a network server that automatically provides and assigns IP addresses DHCP enables automatic IPv4 address configuration for every end device that is DHCP-enabled.

Console method of switch configuration

a physical management port used to access a device in order to provide maintenance, such as performing the initial configurations The advantage of using a console port is that the device is accessible even if no networking services are configured, such as performing the initial configuration A computer running terminal emulation software and a special console cable to connect to the device are required for a console connection. out-of-band access

IPv6

are 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 ":" IPv6 addresses are not case-sensitive and can be written in either lowercase or uppercase.

To move in and out of (global configuration) mode

configure terminal

Switch Virtual Interface (SVI) Configuration

configure terminal interface vlan 1 ip address 192.168.1.20 255.255.255.0 no shutdown (enabling the virtual interface) exit

Interfaces and Ports

connect n end user device interfaces and networking device interfaces

To move from (user EXEC) mode to (privilege EXEC) mode and back

enable/disable ------------ Switch> enable Switch# ------------- Switch# disable Switch>

To move from any (subconfiguration) mode to the (privileged EXEC) mode

end or key combination Ctrl+Z. ----------------- Switch(config-line)# end Switch#

Secure shell (SSH) method of switch configuration

establishes a secure remote CLI connection to a device, through a virtual interface over a network SSH connections require active networking services on the device, including an active interface configured with an address Best practice - to use SSH (version 2) instead of Telnet whenever possible in-of-band access

Telnet method of switch configuration

establishes as insecure remote CLI connection to a device over the network. Telnet does not provide a secure, encrypted connection and should only be used in a lab environment. User authentication, passwords, and commands are sent over the network in plaintext. in-of-band access

To move out of any (subconfiguration) mode to get back to (global configuration) mode

exit -------------- Switch(config)# line console 0 Switch(config-line)# exit Switch(config)#

To move from (global configuration) mode to (privilege EXEC)

exit ----------------- Switch(config)# Switch(config)#exit Switch#

Types of network media

include twisted-pair copper cables, fiber-optic cables, coaxial cables, or wireless.

Banner Messages

is important to warn unauthorized personnel from attempting to access the device Sw-Floor-1(config)# banner motd #Authorized Access Only#

Alter(change) the Startup-config

it may be necessary to clear all the configurations using the "erase startup-config" command in privilege EXEC mode. After erasing the startup-config, reload the device to clear the running-config file from RAM.

AUX method of switch configuration

legacy auxiliary port that was used to establish a CLI session remotely over a telephone connection using a modem. does not require networking services to be configured or available. out-of-band access

To move in and out of (line configuration) mode

line --------------- Switch(config)#line console 0 Switch(config-line)#exit Switch(config)#

GUI (graphical user interface)

such as Windows, macOS, Linux KDE, Apple iOS, or Android allows the user to interact with the system using an environment of graphical icons, menus, and windows. more user-friendly and requires less knowledge of the underlying command structure that controls the system. may not always be able to provide all the features available with the CLI. can also fail, crash, or simply not operate as specified.

PuTTY, Tera Term, SecureCRT

terminal emulation programs you can use to connect to a networking device either by a serial connection over a console port, or by an SSH/Telnet connection.

ipconfig

to display the IP configuration settings on a Windows PC

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 - if it discovers an error, the IOS generally provides feedback such as "ambiguous command", "incomplete command", "incorrect command"