Ho to configure Cisco Network Operating system

1. CIS 81 Fundamentals of Networking
Chapter 2: Configuring a Network
Operating System
Rick Graziani
Cabrillo College
graziani@cabrillo.edu
Fall 2013

2. 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.
2

3. Cisco IOS
Operating 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
3

4. Cisco IOS
Operating Systems
4

5. 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

6. 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

7. Cisco IOS
IOS Functions
Major functions performed or enabled by Cisco routers and switches
include:
7

8. 8
Router/Switch Bootup Process (more in later course)

9. 9
Bootup Process
running-config
IOS (running)
startup-config IOS
ios (partial)
Bootup program

10. 10
running-config
IOS (running)
startup-config IOS
ios (partial)
Bootup program
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

11. 11
running-config
IOS (running)
startup-config IOS
ios (partial)
Bootup program
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12. 12
running-config
IOS (running)
startup-config IOS
ios (partial)
Bootup program
startup-config
IOS
Bootup program
ios (partial)
running-config
IOS (running)
A B C D
B A D
C D A

13. 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

14. Accessing a Cisco IOS Device
Console Access Method
Most common methods to access the Command Line Interface
 Console
 Telnet or SSH
 AUX port
14

15. Accessing a Cisco IOS Device
Console Access Method
Console port
Device 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 entered
Should be configured with passwords to prevent
unauthorized access
Device should be located in a secure room so console
port can not be easily accessed
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16. 16
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

17. 17
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.

18. 18
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

19. Accessing a Cisco IOS Device
Telnet, SSH, and AUX Access Methods
Telnet
 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
19

20. 20
C:> ssh
C:> ping
Ethernet Connection
Network 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 NIC
Ethernet straight-through cable
When the change may
disconnect the telnet connection.
NIC

21. Accessing a Cisco IOS Device
Terminal Emulation Programs
Software available for
connecting to a networking
device (usually same as
terminal/serial/console
connection):
PuTTY
Tera Term
SecureCRT
HyperTerminal
OS X Terminal
Zoc
21

22. Navigating the IOS
Cisco IOS Modes of Operation
22

23. Navigating the IOS
Cisco IOS Modes of Operation
enable
configure terminal
interface < >
router < >
line < >
23

24. Navigating the IOS
Primary Modes
enable
enable
24

25. 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

26. Navigating the IOS
Navigating between IOS Modes
Similar IOS commands for switches and routers
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27. 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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28. 28
Common Commands for Switches and Routers
Switch> 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 password
Switch(config)# line console 0 console password
Switch(config-line)# password password
Switch(config-line)# login
Switch(config)# line vty 0 4 telnet password
Switch(config-line)# password password
Switch(config-line)# login
Switch(config)# banner motd # message # banner
Switch(config)# interface type number configure interface
Switch(config-if)# description description

29. 29
Making your life easier!
Switch# enable
Switch(config)# line console 0 Console port
Switch(config-line)# logging synchronous IOS will not
Switch(config-line)# exec-timeout 0 0 password
Switch(config)# no ip domain-lookup password
Switch(config-line)# login
Switch(config)# banner motd # message # banner
Switch(config)# interface type number configure interface
Switch(config-if)# description description

30. Navigating the IOS
Navigating between IOS Modes
30

31. The Command Structure
IOS Command Structure
31

32. 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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33. The Command Structure
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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34. The Command Structure
Context Sensitive Help
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35. The Command Structure
Command Syntax Check
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36. The Command Structure
Command Syntax Check
36

37. The Command Structure
Command Syntax Check
37

38. The Command Structure
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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39. The Command Structure
IOS Examination Commands
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40. The Command Structure
The show version Command
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41. The Command Structure
Navigating the IOS
41

42. Hostnames
Why the Switch
Let’s focus on
Creating a two PC network connected via a switch
Setting a name for the switch
Limiting access to the device configuration
Configuring banner messages
Saving the configuration
42

43. Hostnames
Device Names
Hostnames 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 letter
Contain no spaces
End with a letter or digit
Use only letters, digits, and dashes
Be less than 64 characters in length
Without names, network
devices are difficult to
identify for configuration
purposes.
43

44. Hostnames
Configuring Hostnames
Switch(config)# hostname Sw-Floor-3
Sw-Floor3(config)#
Switch(config)# hostname Sw-Floor-2
Sw-Floor2(config)#
Switch(config)# hostname Sw-Floor-1
Sw-Floor1(config)#
44

45. Limiting Access to Device Configurations
Securing 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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46. 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
46

47. Limiting Access to Device Configurations
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 version
47

48. Limiting Access to Device Configurations
Encrypting Password Display
service password-
encryption
prevents
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
file
once applied,
removing the
encryption service
does not reverse the
encryption
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49. Limiting Access to Device Configurations
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)#
49

50. Saving Configurations
Configuration Files
Switch# 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]
50

51. Saving Configurations
Capturing Text
51

52. Saving Configurations
Capturing Text
52

53. Ports and Addresses
IP 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

54. 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.
54

55. 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

56. Addressing Devices
Manual IP Address Configuration for End Devices
56
More later!

57. Addressing Devices
Automatic IP Address Configuration for End Devices
57
More later!

58. Addressing Devices
IP Address Conflicts
58
More later!

59. In Class Lab
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60. Verifying Connectivity
Test 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
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

61. Verifying Connectivity
Testing the Interface Assignment
61

62. Verifying Connectivity
Testing End-to-End Connectivity
62

63. 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
63

64. 64
DEMO

65. 65
In Class Lab

66. CIS 81 Fundamentals of Networking
Chapter 2: Configuring a Network
Operating System
Rick Graziani
Cabrillo College
graziani@cabrillo.edu
Fall 2013