Problems that you encounter during password recovery often occur because you are not sure about what the break key sequence is for the (non-Cisco) software you use. For software not listed in the table, and for additional information, refer to the documentation of the individual software packages. Control Break on a Switch (packet tracer 5.3) hi everyone! I m trying to get into ROMMON in a switch Cisco WS-C2950T-24 (using PT) but the Ctrl+C is not working (as at the router) also i tried Ctr+Pause and Ctrl+Alt+6, Ctrl +Supr. Tambien se usa para realizar uno de los pasos del password recovery de los routers de cisco. Cuado se reinicia el router con reload, se le da ctrl+break y despues de esto carga el romon. Si se usa todavia y si es en los Routers de cisco, pues si que tiene utilidad.
Cisco switches can be used as plug-and-play devices out of the box but they also offer an enormous amount of features. Although the main purpose of the switch is to provide inter-connectivity in Layer 2 for the connected devices of the network, there are myriad features and functionalities that can be configured on Cisco Switches.
In the following Cisco Switch Commands Cheat Sheet, I have tried to include the most important and frequently-used CLI commands that Cisco professionals encounter in real world networks. I know that the list is not exhaustive but I believe that the most useful commands are included. Make sure to download the whole commands cheat sheet in PDF format below so you can print it or save it on your computer for future reference.
NOTE: Other Cisco Command Cheat Sheet Posts:
The following commands will work on most Cisco switch models such as 4500, 3850, 3650, 2960, 3560 etc.
[Displays software and hardware information]
[Displays currently running configuration in DRAM]
[Displays configuration in NVRAM which will be loaded after reboot]
[Displays Flash memory information]
[Displays boot path and image]
[Displays the system clock]
[Displays all interfaces configuration and status of line]
[Displays vlan number, name, status and ports associated with it]
TestSwitch#show vtp status
[Displays VTP mode, Number of existing vlans and config revision]
TestSwitch#show interface status
[Displays interface status, vlan, Duplex, Speed and type]
[Displays etherchannel information]
TestSwitch#show cdp neighbors
[Displays information of connected devices]
TestSwitch#show cdp neighbors detail
[Displays detailed information of connected devices]
TestSwitch#show mac address-table
[Displays current MAC address forwarding table and which MAC is learned on each switch port]
[Displays spanning-tree state information, which interfaces are in active or blocking state etc]
Resetting the Switch
[Deletes vlan database from flash memory so you can start adding new VLANs from scratch]
[Delete start-up file from NVRAM]
[Reboot the Switch]
Setting Host Names
Control Break Key Cisco
[Entering into Global Configuration Mode]
[Enter the hostname of the switch]
Setting login credentials:
MySwitch(config)#username admin password csico1234
[create username and password for logging in to the switch]
MySwitch(config)#enable secret test1
[Sets encrypted secret password using MD5 algorithm. This is the enable password that you will be asked to enter when trying to enter into “enable” mode]
[Encrypt all the passwords using MD5]
MySwitch(config)#line con 0
[Enter into line console mode]
[Set password on console]
[Enable password checking on console]
Control Break On Mac Cisco
SSH/Telnet Access to the switch:
MySwitch(config)#line vty 0 4
[Enters line vty mode for all five virtual ports]
MySwitch(config-line)#transport input ssh
MySwitch(config-line)#transport input telnet
Setting IP Address (To allow remote access to the switch):
[Enters vlan1, the native vlan]
MySwitch(config-if)#ip address 192.168.1.2 255.255.255.0
[Set IP address for management]
MySwitch(config)#ip default-gateway 192.168.1.1
[Exit path for the switch – gateway IP]
MySwitch(config-if)#description TO SERVER
Duplex and Speed Settings
[Force 10Mbps Speed]
[Force 100Mbps Speed]
[Enable auto speed configuration]
[Enable auto duplex configuration on switch port]
[Enable full duplex configuration on switch port]
[Enable half duplex configuration on switch port]
Setting Web-based interface for configuration (GUI):
MySwitch(config)#ip http server
[Enable HTTP server]
MySwitch(config)#ip http port 80
[Set port number for HTTP]
[Enter the interface to set port-security]
[Enable port security on the interface]
MySwitch(config-if)#switchport port-security mac-address sticky
[Interface converts all MAC addresses to sticky secure addresses]
MySwitch(config-if)#switchport port-security maximum 1
[Only one MAC address will be allowed for this port]
MySwitch(config-if)#switchport port-security violation shutdown
[Port will shut down if violation occurs]
[Verifying Port security]
Save current configuration
MySwitch(config)#copy running-config startup-config
“Portfast” bypasses the Spanning Tree states and brings the port up as quickly as possible. Use it only if you connect a regular host (e.g Computer) on the port. Do not use this command when the port is trunk or if you connect other switches on the specific port.
MySwitch(config)#interface FastEthernet 0/1
[Create a Layer2 VLAN with id 20]
MySwitch(config-vlan)# name testvlan
[Enter a name for the vlan]
MySwitch#show vlan brief
[Verify the vlan database]
Assigning access ports to a vlan
MySwitch(config-if)#switchport mode access
[Set the interface in switch access mode]
MySwitch(config-if)#switchport access vlan 20
[Assign the port to vlan 20]
The following commands will select a range of interfaces (from 1 to 24) and add all of them to vlan20
MySwitch(config)#interface range gigabitEthernet 0/1-24
MySwitch(config-if)#switchport mode access
MySwitch(config-if)#switchport access vlan 20
Configuring trunk port
MySwitch(config-if)#switchport trunk encapsulation dot1q
[Configure the port to support 802.1Q Encapsulation (default is negotiate)]
MySwitch(config-if)#switchport mode trunk
[Set the interface in permanent trunking mode]
MySwitch(config-if)#switchport trunk native vlan 20
[Specify native vlan for 802.1q trunks – OPTIONAL]
MySwitch(config-if)#switchport trunk allowed vlan 2-5
[vlans 2 to 5 are allowed to pass through the trunk]
MySwitch(config-if)#switchport trunk allowed vlan add 7
[add also vlan 7 in the allowed vlans]
MySwitch(config-if)#switchport trunk allowed vlan remove 3
[remove vlan 3 from the allowed vlans in the trunk]
MySwitch#show interface g0/2 trunk
[Verify the trunk ports and associated vlans on the specific interface]
DOWNLOAD THE CHEAT SHEET AS PDF FILE
For whatever historical reason (I used to know, but I’ve forgotten ) the break character for Cisco IOS command line is Ctrl-Shift-6 and X. Now, that is a pain to type and I often makes mistakes because it takes four fingers in coordinated fashion (lets face it, I’m not a world class athlete, and using four fingers is beyond my physical capability). So I have a habit of repeating it about five times …just to make sure.
Most importantly, when you are using a Cisco terminal server to access a router on a test bench (or study rack) and you hit the break sequence, the session snaps back to terminal server as if you had issued the command there. Annoying right ?
So now I have connected over to a neighboring router, and foolishly attempted to ping something that doesn’t exist:
Now I hit the break key because I’m impatient and
That right, I have shifted the console back to the first router.
My solution on my test bench has been to change the escape character on the routers (but not on the terminal server).
Works for Telnet/SSH too
A common practice when making routing changes is to telnet to the nearest router, then jump to to remote router and make the routing changes. This way, if the routing doesn’t work exactly right you still have a console session running.
This has the same problem. If you hit break to shut out a ping command, or interrupt a DNS lookup, your console will snap back to the original router.
Control Break Cisco Webex
There are two ways to change the escape sequence / break character on Cisco IOS.
Change the break character for the current session
This sequence changes it only for current SSH/Telnet session that you are using. Changes are lost when you exit the session.
See that? My personal choice is Ctrl-W because it’s easy to type and doesn’t conflict with much else in the ASCII characters
Change the break permanently
Changing it back
For those people who will rush off and test this on a live router (oh yes, Elizabeth, they do exist):
Generally, I wouldn’t recommend making this a default, because other people will have to work on your network eventually and this is the sort of thing that can have unexpected problems. But the settings for the current session is a neat trick and can save a lot of time in complex networks.
CCIE Mendicants may choose to use this also, but you need to be consistent about putting into your configuration across all devices. Might be a bit tricky.
Hope it’s useful.