Switch and Router

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Configure hostname

Cisco IOS
Switch# configure terminal
Switch(config)# hostname S1
S1(config)# exit

Set the minimal length for all passwords

Cisco IOS
Switch# configure terminal
Switch(config)# security passwords min-length 10
Switch(config)# !* for a 10 password length

Set privileged mode password

Cisco IOS
Switch> enable
Switch# configure terminal
Switch(config)# enable password class
Switch(config)# exit

Set encrypted privileged mode password

Cisco IOS
Switch> enable
Switch# configure terminal
Switch(config)# enable secret class
Switch(config)# exit

Set password for console access

Restricted access to the console port.

Cisco IOS
Switch(config)# line console 0
Switch(config-line)# password cisco
Switch(config-line)# logging synchronous
Switch(config-line)# !* Prevent console messages from aborting commands
Switch(config-line)# login !* Impose the use of the password

Set password for virtual terminal (telnet) access

Password must be set to access device through telnet.

Cisco IOS
Switch(config)# line vty 0 4 !* or 0 15
Switch(config-line)# password cisco
Switch(config-line)# logging synchronous
Switch(config-line)# !* Prevent console messages from aborting commands
Switch(config-line)# login !* Impose the use of the password

Set encryption for plain text password such as enable and line

Cisco IOS
Switch(config)# service password-encryption

Set a banner

Format

Cisco IOS
Switch(config)# banner motd # Your message #

Example:

Cisco IOS
Switch(config)# banner motd #
Enter TEXT message.  End with the character '#'.
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@                                                  @
@             This is a secure network !           @
@               No access authorized !             @
@                                                  @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
#

Switch(config)#

Set date and time

RQ: it won't be saved with the config !!!

Cisco IOS
Switch# clock set 12:06:30 29 November 2016
Switch# show clock
12:6:33.623 UTC Tue Nov 29 2016
Switch#

Prevent unwanted DNS lookups

Disables the default behavior of the device of attempting to resolve the invalid command into an IP address.

Cisco IOS
Switch(config)# no ip domain-lookup

Configure SSH

To use SSH, IOS has to be a 'K9' version. That means that the cryptography is taken over.

Checking SSH support:

This command is accessible from the User and Privileged Modes.

Cisco IOS
Switch> show ip ssh 
                ^
% Invalid input detected at '^' marker.
    
Switch>
Cisco IOS
Switch> show ip ssh 
SSH Disabled - version 1.99
%Please create RSA keys (of atleast 768 bits size) to enable SSH v2.
Authentication timeout: 120 secs; Authentication retries: 3
Switch>
Cisco IOS
Switch> show ip ssh
SSH Enabled - version 1.99
Authentication timeout: 75 secs; Authentication retries: 2
Switch>

Configuration

Configuration of the IP domain name

Cisco IOS
Switch(config)# ip domain-name myDomain

Example:

Cisco IOS
Switch(config)# ip domain-name CCNA-Lab.com

Creation of the username and the password for authentification

Cisco IOS
Switch(config)# username myName (privilege 0-15) secret myPass

Example:

Cisco IOS
Switch(config)# username admin privilege 15 secret sshadmin

SSH protocole activation on the VTY lines (required)

Cisco IOS
Switch(config)# line vty 0 15
Switch(config-line)# transport input ssh
Switch(config-line)# login local

RSA Encryption Key generation

Here we'll choose a modulus of 1024 bits

Cisco IOS
Switch(config)# crypto key generate rsa
The name for the keys will be: S1.CCNA-Lab.com
Choose the size of the key modulus in the range of 360 to 2048 for your
  General Purpose Keys. Choosing a key modulus greater than 512 may take
  a few minutes.

How many bits in the modulus [512]: 1024
% Generating 1024 bit RSA keys, keys will be non-exportable...[OK]

Switch(config)#

To make sure that the SSH version 2 is used

Cisco IOS
Switch(config)# ip ssh version 2

Change authentication timeout

Cisco IOS
Switch(config)# ip ssh time-out 75

Change authentication retries

Cisco IOS
Switch(config)# ip ssh authentication-retries 2

Display the SSH configuration

Cisco IOS
Switch# show ip ssh
SSH Enabled - version 2.0
Authentication timeout: 75 secs; Authentication retries: 2

Verify the SSH conections towards the peripheral

Cisco IOS
Switch# show ssh
%No SSHv2 server connections running.
%No SSHv1 server connections running.

Access the device from a PC through a SHH connection

Format

Cisco IOS
SSH -l username IPAddress

Example:

The used password is sshadmin.

Cisco IOS
C:\>SSH -l admin 172.16.99.11
Open
Password: 



S1>sh ip ssh
SSH Enabled - version 2.0
Authentication timeout: 75 secs; Authentication retries: 2
S1>exit

[Connection to 172.16.99.11 closed by foreign host]
C:\>

Get a summary of the interfaces

Cisco IOS
Switch# show ip interface brief

Activate the full duplex mode on interface

Options:

Cisco IOS
Switch(config)# interface FastEthernet 0/1
Switch(config-if)# duplex full
Switch(config-if)# end

Set the speed of an interface

Options:

Cisco IOS
Switch(config)# interface FastEthernet 0/1
Switch(config-if)# speed 100
Switch(config-if)# !* the speed is 100 Mbps
Switch(config-if)# end

Activate auto-MDIX

RQ: To use this option, the speed and the duplex have to be auto.

Cisco IOS
Switch(config)# interface FastEthernet 0/1
Switch(config-if)# duplex auto
Switch(config-if)# speed auto
Switch(config-if)# mdix auto
Switch(config-if)# end

Get the informations of an interface (like its MAC address)

The MAC address is 0060.3e71.9902.

Cisco IOS
Switch# show interfaces GigabitEthernet 0/1
GigabitEthernet0/1 is up, line protocol is up (connected)
  Hardware is CN Gigabit Ethernet, address is 0060.3e71.9902 (bia 0060.3e71.9902)
  Internet address is 172.16.99.1/24
  MTU 1500 bytes, BW 1000000 Kbit, DLY 100 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 100Mb/s, media type is RJ45
  output flow-control is unsupported, input flow-control is unsupported
  ARP type: ARPA, ARP Timeout 04:00:00, 
  Last input 00:00:08, output 00:00:05, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0 (size/max/drops); Total output drops: 0
  Queueing strategy: fifo
  Output queue :0/40 (size/max)
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     0 packets input, 0 bytes, 0 no buffer
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
     0 watchdog, 1017 multicast, 0 pause input
     0 input packets with dribble condition detected
     0 packets output, 0 bytes, 0 underruns
     0 output errors, 0 collisions, 1 interface resets
     0 unknown protocol drops
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier
     0 output buffer failures, 0 output buffers swapped out

Switch#

Additional source

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