Copy Running Config Startup Config

Cisco IOS

The Cisco device stack uses the Internetwork operating system (IOS), which controls the device's performance and behavior. The Cisco IOS defines an interface called the Command Line Interface (CLI), which enables administrators to enter commands into a terminal emulation program. The CLI can be accessed through three methods: the panel, Telnet and Secure Shell (SSH).

Cisco Modes

Users tin exist logged in to a Cisco device using the following modes:

Exec mode (user mode) — Allows the user to look around but not alter annihilation. Accessing the CLI by whatever of the three methods logs the user into Exec
Enable mode (privileged mode or privileged exec fashion) — Allows the user to execute privileged commands, such every bit the reload command, which tells the switch to reboot the Cisco IOS. To enter this mode, the user runs the enable control fashion.
Global configuration mode — Allows users to enter nondisruptive commands and display some information. Unlike exec and enable mode, configuration way accepts configuration commands — commands that tell the switch the details of what to do and how to practice it. Commands entered in configuration mode update the active configuration file, but the bodily changes in configuration have place only after the device reboots. To enter configuration mode, a user executes the configure terminal (conf t) command.

Configuration way contains several sub-modes. Ane is interface configuration mode, which can be entered by running the interface FastEthernet 0/1 (int fa0/1) configuration command.

Basic CLI Commands

Evidence

The show command is one of the virtually helpful commands because you tin find the condition of virtually every feature of the Cisco IOS. It reads the current configuration from the Cisco device's RAM and lists the requested settings in the CLI. For example, the prove version command displays information about the Cisco IOS version currently loaded on a device.

Debug

Like the show control, debug reveals data well-nigh the device'due south settings. However, instead of simply listing the electric current status, the debug command asks the device to continue monitoring different processes in it and send letters to the user when different events occur, showing the status of settings over time. Equally a result, the debug command takes more CPU cycles, merely it lets you lot monitor what is happening in a switch in existent time. In short, bear witness is for reporting and debug is for monitoring.

Hostname

The hostname control assigns a network proper noun to the Cisco device.

?

Use the ? command to become answers to your questions nigh other commands, such as their syntax and description.

Where Configuration Files are Stored

A Cisco device needs to use the configuration file to do its work. Cisco devices have random-access retention (RAM) to shop data from the configuration file while Cisco IOS is using it, merely the RAM loses its contents when the device loses power. In order to load all configuration data back after the device loses ability, Cisco apply several types of more permanent memory. The post-obit list explains the four main types of memory establish in Cisco switches or Cisco routers, as well as the almost mutual utilize of each type:

RAM — RAM is used by a Cisco device for working storage. The running configuration file is stored
ROM — Read-just retention (ROM) stores a bootstrap programme that is loaded when the switch kickoff powers on. This program finds the full Cisco IOS image and loads it into RAM.
Wink memory — This memory can exist either inside the device or on a removable memory card. Flash retention stores fully functional Cisco IOS images and is the default location where the switch gets its Cisco IOS at boot time. Wink memory also can be used to shop other files, including fill-in copies of configuration files.
NVRAM — Nonvolatile RAM (NVRAM) stores the initial or startup configuration file that is used when the Cisco device is powered on or reloaded.

Copying, Erasing and Saving Running Config on Cisco Devices

To change the configuration of a Cisco device, you need to enter configure final mode and then use one or more of the following commands.

Rename a device

Use the command hostname newname to change the name of the device to the string y'all specify.

Save running config on Cisco device

Utilise the command copy running-config startup-config (copy run first) to overwrite the current startup config file with what is currently in the running configuration file.

Copy files

The copy command can be used to copy files on a Cisco device, such as a configuration file or a new version of the Cisco IOS. Files tin be copied between RAM, NVRAM and a TFTP server. The syntax for the copy commands is as follows:

re-create {tftp | running-config | startup-config} {tftp | running-config | startup-config}

The first set up of parameters in braces is the "from" location; the side by side set is the "to" location. When a file is copied into NVRAM or a TFTP server, the re-create command always overwrites the existing destination file with the new file. Even so, when the copy command copies a configuration file into the running config file in RAM, the configuration file in RAM is not replaced; information technology is merged instead.

Erase the contents of NVRAM

You lot can use three unlike commands to erase NVRAM: write erase, erase startup-config and erase nvram. All of them erase the contents of the NVRAM configuration file, and so if the device is and so reloaded, at that place is no initial configuration and you take to begin initial device configuration.

Note that Cisco IOS does not have a command that erases the contents of the running configuration file. To clear out the running config file, only erase the startup config file and then reload the device.

Securing Login to Cisco Devices

Cisco devices authenticate users as they log in, just the default configuration uses only simple password security and the enable password command defines the password for the current login. You tin can assist protect enable style by using the enable secret command instead. The older enable countersign control stores the password as clear text in the running configuration, and the merely manner to encrypt it is to use the weak service countersign-encryption command. The newer enable secret command automatically encodes the password using a Message Assimilate v (MD5) hash.

Initial Configuration of Cisco Devices

Cisco switches get out the manufacturing plant with the following default settings:

All interfaces are enabled.
Automobile-negotiation is enabled for ports that tin employ it (duplex machine and speed auto).
All interfaces are a part of VLAN ane.

All you have to do with a new Cisco switch is make all the concrete connections — Ethernet cables and a ability cord — and it starts working.

To configure the switch:

Enter VLAN one configuration style using the interface vlan one global configuration control.
Assign an IP accost and mask using the ip address ip-address mask
Enable the VLAN 1 interface using the no shutdown
Add the default gateway with ip default-gateway
Add together the DNS server using the ip name-server command to resolve names into IP addresses.

After the initial configuration, you tin can expect at the IP accost and mask information using the show interface vlan ten control, which shows detailed condition information about the VLAN interface. If yous utilize DHCP, employ the show dhcp lease control to see the leased IP address.

You tin see some of the details of the interface configuration using the show running-config command or the handy bear witness interfaces condition control, which lists each interface on a single line that shows the first part of the interface clarification and the speed and duplex settings.

The show port-security interface command lists the configuration settings for port security on an interface, forth with several important facts about the current operation of port security, including information near whatsoever security violations. The switch can exist configured to take one of three actions when a violation occurs using the post-obit command: switchport port-security violation {protect | restrict | shutdown}. All three options cause the switch to discard the offending frame, but some of the options make the switch take additional deportment, such equally sending syslog messages to the console, sending SNMP trap messages to the network direction station, or disabling the interface.

Determination

Equally you can see, it is very piece of cake to salvage the running config, copy information technology to a tftp server and perform the initial configuration for a Cisco device. Before changing the running config, be certain to make a backup.

Jeff is a quondam Director of Global Solutions Engineering at Netwrix. He is a long-time Netwrix blogger, speaker, and presenter. In the Netwrix blog, Jeff shares lifehacks, tips and tricks that tin can dramatically meliorate your system assistants experience.