cis 81 fundamentals of networking chapter 2: configuring a network operating system rick graziani...

CIS 81 Fundamentals of NetworkingChapter 2: Configuring a Network

Operating System

Rick Graziani

Cabrillo College

[email protected]

Fall 2013

Chapter 2 - Objectives

Explain the purpose of Cisco IOS.Explain how to access and navigate Cisco IOS to configure

network devices.Describe the command structure of Cisco IOS software.Configure hostnames on a Cisco IOS device using the CLI.Use Cisco IOS commands to limit access to device

configurations.Use Cisco IOS commands to save the running

configuration.Explain how devices communicate across network media.Configure a host device with an IP address.Verify connectivity between two end devices.

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Cisco IOSOperating Systems

All networking equipment depend on operating systems: End users (PCs, laptops, smart phones, tablets) Switches Routers Wireless access points Firewalls

Cisco Internetwork Operating System (IOS) Collection of network operating systems used on Cisco devices

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Cisco IOS

Operating Systems

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Cisco IOS

Purpose of OS

PC operating systems (Windows 8, Linux & OS X) perform technical functions that enable • Use of a input and output devices• Manage processes and programs• Manage file systems, security, hardware, etc.

Switch or router IOS provides options to • Same functions as host operating systems• Configure interfaces• Enable routing and switching functions

All networking devices come with a default IOS (switches, routers, firewalls)

Possible to upgrade the IOS version or feature set 5

Cisco IOS

Location of the Cisco IOS

IOS stored in Flash Non-volatile storage – not lost when power is lost Can be changed or overwritten as needed Can be used to store multiple versions of IOS IOS copied from flash to volatile RAM when booted Quantity of flash and RAM memory determines IOS that

can be used 6

Cisco IOS

IOS FunctionsMajor functions performed or enabled by Cisco routers and switches include:

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Router/Switch Bootup Process (more in later course)

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Bootup Process

running-config

IOS (running)

startup-config IOS

ios (partial)Bootup program

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running-config

IOS (running)

startup-config IOS


Where is the permanent configuration file stored used during boot-up? NVRAM (B)

Where is the diagnostics software stored executed by hardware modules? ROM (D)

Where is the backup (partial) copy of the IOS stored? ROM (D)

Where is IOS permanently stored before it is copied into RAM? FLASH (C)

Where are all changes to the configuration immediately stored? RAM (A)

A B C D

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running-config

IOS (running)

startup-config IOS


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?

?

?

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?

?

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running-config

IOS (running)

startup-config IOS


startup-config

IOS

Bootup program

ios (partial)

running-config

IOS (running)

A B C D

B A D

C D A

Cisco IOS

CCO Account Benefits and IOS Files

This video introduces Cisco Connection Online (CCO). CCO has a wealth of information available regarding Cisco products and services. 13

http://www.youtube.com/watch?feature=player_embedded&v=28fTWnjPm_U

Accessing a Cisco IOS DeviceConsole Access Method

Most common methods to access the Command Line Interface Console Telnet or SSH AUX port

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Accessing a Cisco IOS Device

Console Access Method

Console portDevice is accessible even if no networking services have been configured (out-of-band)Need a special console cable (aka rollover cable)Allows configuration commands to be enteredShould be configured with passwords to prevent unauthorized accessDevice should be located in a secure room so console port can not be easily accessed

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Establishing a HyperTerminal session (next week)

Connect PC using the RJ-45/mini-USB to Serial/USB rollover cable. Configure the terminal or PC terminal emulation software for:

9600 baud 8 data bits no parity 1 stop bit no flow control

Rollover cable

Console port

Com1 or Com2 serial port Or USB port with USB-to-Serial adapter

Terminal or a PC with terminal emulation software

Router

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Terminal (Serial) Settings)

Configure the terminal or PC terminal emulation software for: 9600 baud 8 data bits no parity 1 stop bit no flow control.

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Establishing a Terminal/Serial/Console session

Important: A console connection is not the same as a network connection!

=

• PuTTY• Tera Term• SecureCRT• HyperTerminal• OS X Terminal• Zoc

Dumb Terminal


Telnet, SSH, and AUX Access MethodsTelnet Method for remotely accessing the CLI over a network Require active networking services and one active interface that

is configured

Secure Shell (SSH) – Preferred over Telnet Remote login similar to Telnet but utilizes more security Stronger password authentication Uses encryption when transporting data

Aux Port (not used too much) Out-of-band connection Uses telephone line Can be used like console port

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C:\> ssh

C:\> ping

Ethernet ConnectionNetwork connection needed

When can you use a network connection to connect to the router?

What software/command do you need?

What cable and ports do you use?

When should you not use a network connection to configure the router?

When there is a network connection to the router (telnet).

TCP/IP, Terminal prompt (DOS), Tera Term, etc.

PC & Router: Ethernet NICEthernet straight-through cable

When the change may disconnect the telnet connection.

NIC


Terminal Emulation Programs

Software available for connecting to a networking device (usually same as terminal/serial/console connection):PuTTYTera TermSecureCRTHyperTerminalOS X TerminalZoc

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Navigating the IOSCisco IOS Modes of Operation

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Navigating the IOS

Cisco IOS Modes of Operation

enable

configure terminal

interface < >router < >line < >

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Navigating the IOS

Primary Modes

enableenable

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Navigating the IOS

Global Configuration Mode and Submodes

Global configuration mode and interface configuration modes can only be reached from the privileged EXEC mode. 25

Navigating the IOS

Navigating between IOS Modes

Similar IOS commands for switches and routers26

Navigating the IOS

Navigating between IOS Modes (cont.)Switch> user mode

Switch> enable go to privilege mode

Switch# configure terminal go to global configuration mode

Switch(config)# interface vlan 1 go to interface mode

Switch(config-if)# exit

Switch(config)# exit

Switch# config t Shortened commands and parameters

Switch(config)# vlan 1 go to VLAN configuration mode

Switch(config-vlan)# end go to privilege-EXEC mode

Switch# disable

Switch> enable

Switch# config t

Switch(config)# line vty 0 4 go to interface (line) mode

Switch(config-line)# exit

Switch(config)#

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Common Commands for Switches and RoutersSwitch> user mode

Switch> enable

Switch# privilege mode

Switch# configure terminal

Switch(config)# exit

Switch# config t

Switch(config)# hostname name

Switch(config)# enable secret password privilege passwordSwitch(config)# line console 0 console passwordSwitch(config-line)# password passwordSwitch(config-line)# loginSwitch(config)# line vty 0 4 telnet passwordSwitch(config-line)# password passwordSwitch(config-line)# login

Switch(config)# banner motd # message # banner

Switch(config)# interface type number configure interface

Switch(config-if)# description description

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Making your life easier!

Switch# enableSwitch(config)# line console 0 Console portSwitch(config-line)# logging synchronous IOS will notSwitch(config-line)# exec-timeout 0 0 passwordSwitch(config)# no ip domain-lookup passwordSwitch(config-line)# login

Switch(config)# banner motd # message # banner

Switch(config)# interface type number configure interface

Switch(config-if)# description description

Navigating the IOS

Navigating between IOS Modes

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http://www.youtube.com/watch?feature=player_embedded&v=SKvZDCL-zh8

The Command StructureIOS Command Structure

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The Command Structure

Cisco IOS Command Reference

IOS Command Conventions

The general syntax for a command is the command followed by any appropriate keywords (defined) and arguments (undefined).

An argument is generally not a predefined word.

An argument is a value or variable defined by the user.

Switch(config-if)# description string

Boldface text indicates commands and keywords that are typed as shown Italic text indicates an argument for which you supply the value. For the description command, the argument is a string value. The string value can be any text string of up to 80 characters.Example:

Switch(config-if)# description MainHQ Office Switch

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Cisco IOS Command Reference For the ping command:

Switch> ping IP-address

Switch> ping 10.10.10.5

The command is ping and the user defined argument is the 10.10.10.5.

Similarly, the syntax for entering the traceroute command is:

Switch> traceroute IP-address

Switch> traceroute 192.168.254.254

The command is traceroute and the user defined argument is the 192.168.254.254.

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Context Sensitive Help

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Command Syntax Check

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Hot Keys and Shortcuts Tab - Completes the remainder of a partially typed command or

keyword Ctrl-R - Redisplays a line Ctrl-A – Moves cursor to the beginning of the line Ctrl-Z - Exits configuration mode and returns to user EXEC Down Arrow - Allows the user to scroll forward through former

commands Up Arrow - Allows the user to scroll backward through former

commands Ctrl-Shift-6 - Allows the user to interrupt an IOS process such

as ping or traceroute. Ctrl-C - Aborts the current command and exits the configuration

mode

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IOS Examination Commands

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The show version Command

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Navigating the IOS

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HostnamesWhy the Switch

Let’s focus on Creating a two PC network connected via a switchSetting a name for the switchLimiting access to the device configurationConfiguring banner messages Saving the configuration

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Hostnames

Device NamesHostnames allow devices to be identified by network administrators over a network or the Internet.

Some guidelines for naming conventions are that names should:Start with a letterContain no spacesEnd with a letter or digitUse only letters, digits, and dashesBe less than 64 characters in length

Without names, network devices are difficult to identify for configuration purposes.

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Hostnames

Configuring Hostnames

Switch(config)# hostname Sw-Floor-3

Sw-Floor3(config)#


Sw-Floor2(config)#


Sw-Floor1(config)#

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Limiting Access to Device ConfigurationsSecuring Device Access

The passwords introduced here are:

Enable password - Limits access to the privileged EXEC mode

Enable secret - Encrypted, limits access to the privileged EXEC mode

Console password - Limits device access using the console connection

VTY password - Limits device access over Telnet

Note: In most of the labs in this course, we will be using simple passwords such as cisco or class.

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Limiting Access to Device Configurations

Securing Privileged EXEC Access

use the enable secret command, not the older enable password command

enable secret provides greater security because the password is encrypted

class

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Securing User EXEC Access

Console port must be secured• reduces the chance of unauthorized personnel physically

plugging a cable into the device and gaining device access

vty lines allow access to a Cisco device via Telnet• number of vty lines supported varies with the type of

device and the IOS version47


Encrypting Password Display

service password-encryptionprevents passwords from showing up as plain text when viewing the configuration purpose of this command is to keep unauthorized individuals from viewing passwords in the configuration fileonce applied, removing the encryption service does not reverse the encryption

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Banner Messages

Important part of the legal process in the event that someone is prosecuted for breaking into a device

Wording that implies that a login is "welcome" or "invited" is not appropriate

Switch(config)# banner motd # This is a secure system Authorized Access Only!!! #

Sw-Floor3(config)#

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Saving Configurations

Configuration FilesSwitch# show running-config

Switch# copy running-config startup-config

<Changes made>

Switch# delete vlan.dat

Delete filename [vlan.dat]?

Delete flash:vlan.dat? [confirm]

Switch# erase startup-config

Switch# reload

System configuration has been modified. Save? [yes/no]: n

Proceed with reload? [confirm]

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Capturing Text

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Capturing Text

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Ports and AddressesIP Addressing in the Large Each end device on a

network must be configured with an IP address

Structure of an IPv4 address is called dotted decimal

IP address displayed in decimal notation, with four decimal numbers between 0 and 255

With the IP address, a subnet mask is also necessary

IP addresses can be assigned to both physical ports and virtual interfaces

IPv4 and IPv6 addresses will be discussed in more detail later 53

Ports and Addresses

Interfaces and Ports Terms are used interchangeably Some interfaces can be can be configured with an IP address such as:

NIC (Ethernet interface) on a host/computer Router’s Ethernet or Serial interfaces

Switches have ports (interfaces) but do not typically have IP addresses assigned to them

Used to connect devices on LANs that do have IP addresses such as hosts, routers, printers.

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Addressing Devices

Configuring a Switch Virtual Interface

Allows the network administrator to communicate (SSH, telnet, ping) with the switch.

It is OPTIONAL “Layer 2” switches do NOT need an IP address to forward Ethernet frames. IP address - together with subnet mask, uniquely identifies end device on

internetwork (more later) Subnet mask - determines which part of a larger network is used by an IP address

interface VLAN 1 - interface configuration mode ip address 192.168.10.2 255.255.255.0 - configures the IP address and subnet

mask for the switch no shutdown - administratively enables the interface Switch still needs to have physical ports configured and VTY lines to enable

remote management 55

Addressing Devices

Manual IP Address Configuration for End Devices

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More later!

Addressing Devices

Automatic IP Address Configuration for End Devices

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More later!

Addressing Devices

IP Address Conflicts

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More later!

In Class Lab

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Verifying ConnectivityTest the Loopback Address on an End Device

C:\> ping 127.0.0.1

Reply from 127.0.0.1: bytes=32 time<1ms TTL=128



Reply from 127.0.0.1: bytes=32 time<1ms TTL=128 60

Verifying Connectivity

Testing the Interface Assignment

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Verifying Connectivity

Testing End-to-End Connectivity

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Configuring a Network Operating System

Chapter 2 Summary

Services provided by the Cisco IOS accessed using a command-line interface (CLI)• accessed by either the console port, the AUX port, or through

telnet or SSH• can make configuration changes to Cisco IOS devices• a network technician must navigate through various hierarchical

modes of the IOS Cisco IOS routers and switches support a similar operating system Introduced the initial settings of a Cisco IOS switch device

• setting a name• limiting access to the device configuration• configuring banner messages • saving the configuration

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DEMO

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In Class Lab

CIS 81 Fundamentals of NetworkingChapter 2: Configuring a Network

Operating System

Rick Graziani

Cabrillo College

[email protected]

Fall 2013

cis 81 fundamentals of networking chapter 2: configuring a network operating system rick graziani...

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