Сброс конфигурации на роутерах, коммутаторах и устройствах безопасности CIsco, возврат к заводским настройкам
Этот метод использует команду config-register 0x2102 в режиме глобальной конфигурации.
- Проверьте конфигурационный регистр на роутере, выполнив команду show version.
- Настройка конфигурационного регистра находится в последней линии вывода show version и должна быть выставлена в значение 0x2102. Если это не так, выполните следующую последовательность команд, чтобы это исправить.
router#configure terminal router(config)#config-register 0x2102 router(config)#end router# - Теперь, если снова посмотреть show version, то к предыдущему выводу добавится «will be 0x2102 at next reload» в конце.
- Сотрите существующую конфигурацию роутера, используя команду write erase или erase startup-config (идентичны)
- Перезагрузите роутер, используя команду reload. Когда Вам будет предложено сохранить конфигурацию — НЕ ДЕЛАЙТЕ ЭТОГО!
router#reload System configuration has been modified. Save? [yes/no]: no Proceed with reload? [confirm] - Когда устройство перезагрузится, Вам будет предложено начать процесс начальной конфигурации (System Configuration Dialog).
--- System Configuration Dialog --- Would you like to enter the initial configuration dialog? [yes/no]: Вы можете согласиться или отказаться, так или иначе — устройство сброшено в заводские настройки.
Метод №2
Этот метод использует команду config-register 0x2142 в режиме глобальной конфигурации.
router(config)#config-register 0x2142- Это заставит роутер игнорировать загрузочную (start-up) конфигурацию при следующей перзагрузке. Если Вы выполните команду show version, то в последней строчке вывода Вы увидите запись «will be 0x2142 at next reload«, добавленную сразу после существующей настройки конфигурационного регистра.
- Перезагрузите роутер, используя команду reload. Сохранять конфигурацию, когда это будет предложено, не нужно.
router#reload System configuration has been modified. Save? [yes/no]: no Proceed with reload? [confirm] - После перезагрузки, Вам будет предложено начать процесс начальной конфигурации (System Configuration Dialog).
- Откажитесь от него, ответив no на вопрос «Would you like to enter initial configuration dialog?«
- Измените значение конфигурационного регистра обратно на 0x2102, введя команду config-register 0x2102 в режиме глобальной конфигурации.
- Выполните команду write memory или copy running-config startup-config (идентичны), чтобы перезаписать загрузочную конфигурацию на пустую.
- Перезагрузите роутер, используя команду reload.
- После перезагрузки, Вам будет предложено начать процесс начальной конфигурации (System Configuration Dialog).
--- System Configuration Dialog --- Would you like to enter the initial configuration dialog? [yes/no]:Ваше устройство сброшено в заводские настройки.
How to Reset a Cisco Router or Switch to Factory Default
What if we forget the login credentials of our Cisco routers or switches and we are not able to log in to make changes in configuration? To reset the Cisco router or switch is one of the quickest ways to resolve the issue. It will make a new and blank startup configuration file, and it will show you the setup wizard for a quick configuration of the router.
But what if we want to retain the existing configuration on the router? Another solution is to perform a password recovery on the router. We will discuss how to restore our Cisco routers and switches to the factory defaults and also how to implement password recovery on them.
Factory Reset on Cisco Router or Switch IOS
The following procedure is the steps when we are going to factory reset a Cisco router.
1. In the global configuration mode, create a hostname first on the router as we will use it for verification if the router is already reset into the factory settings.
Router(config)#hostname Router 1
2. Verify the configuration by using one of the following commands.
Router 1#sh running-config Building configuration. Current configuration: 526 bytes ! version 15.1 no service timestamps log datetime msec no service timestamps debug datetime msec no service password-encryption ! hostname Router 1 ! !
3. Save the configuration using the ‘copy running-config startup-config’ command.
Router 1#copy running-config startup-config Router 1#write
4. Resetting the Cisco router to factory default involves erasing the NVRAM.
Router 1#write erase Erasing the nvram filesystem will remove all configuration files! Continue? [confirm]y[OK] Erase of nvram: complete %SYS-7-NV_BLOCK_INIT: Initialized the geometry of nvram
5. Reload the Cisco router to complete resetting to the factory defaults, and the startup wizard or initial system configuration dialog will appear.
6. Verify if the Cisco router is reset to factory default by checking if “hostname Router 1” is disappeared and changed to default.
Router#sh running-config Building configuration. Current configuration: 584 bytes ! version 15.1 no service timestamps log datetime msec no service timestamps debug datetime msec no service password-encryption ! hostname Router ! !
Password Recovery on Cisco IOS
Before we proceed with password recovery, we will take a look first at the configuration register. We can use the ‘show version’ command to check the configuration register setting on our device. Configuration Register is a special 16 bits value that can be configured in Cisco routers. It is mainly used to determine how the router boots, to determine boot options, and to set console speed. The following are the most commonly used configuration register settings:
- config-register 0x2102 – boot normally (default configuration register setting)
- config-register 0x2120 – boot into ROM Monitor (ROMMON)
- config-register 0x2142 – ignore contents of NVRAM (startup-configuration)
The following procedure is the steps when we are going to recover the forgotten enable password or enable secret command configured in our Cisco router or switch.
2. Press the break sequence (ctrl-Break) while the router is initializing to break into ROMMON prompt.
3. Follow this command, confreg 0x2142, to ignore the startup-configuration and reset or reload the router.
rommon 1 > confreg 0x2142 rommon 2 > reset
4. After reboot, it will not ask you the secret password and will proceed to the setup wizard or initial system configuration dialog, as it booted up with a blank configuration.
5. The startup-configuration is still there with the full configuration, including the unknown enable secret, but the router does not use it when it boots. Enter a new enable secret in global configuration mode to overwrite the old one. This will go into the running-config.
Router(config)#enable secret cisco12345
6. In the global configuration mode, configure the configuration register back to default by entering the ‘config-register 0x2102’ router command, so the router will boot normally on the next restart.
Router(config)#config-register 0x2102
7. Save the configuration. This will merge the new enable password into the existing startup-configuration.
Router#copy running-config startup-config
8. Reboot the router using the ‘reload’ command and see that the secret password is changed to the one we configured earlier.
Download our Free CCNA Study Guide PDF for complete notes on all the CCNA 200-301 exam topics in one book.
We recommend the Cisco CCNA Gold Bootcamp as your main CCNA training course. It’s the highest rated Cisco course online with an average rating of 4.8 from over 30,000 public reviews and is the gold standard in CCNA training:
- IOS Basic Commands
- Configure an IP Address on a Switch
- Configure Descriptions
- Interface Range Command
- Power on a Cisco Device
- Half Duplex and Full Duplex
- Configure Speed and Duplex
- Link Layer Discovery Protocol (LLDP)
- Cisco Discovery Protocol (CDP) overview
- show Command
- show interfaces status Command
- Interface Status Codes
- show version Command
- OSPF Overview
- Differences Between OSPF and EIGRP
- Cisco Bandwidth Command vs Clock Rate and Speed Commands
- OSPF Cost — OSPF Routing Protocol Metric Explained
- OSPF Configuration
- Designated & Backup Designated Router
- OSPF Passive Interface — Configuration and Why it is Used
- OSPF Default-Information Originate and the Default Route
- OSPF Load Balancing — Explanation and Configuration
- OSPF Summarization
- Troubleshooting OSPF and OSPF Configuration Verification
- OSPF Network Types — Point-to-Point and Broadcast
- OSPF Summary
- Cisco Three-Layer Hierarchical Model
- Collapsed Core and Three-Tier Network Architectures
- What is Spine and Leaf Network Architecture?
- What is a VLAN?
- Frame Tagging
- Configuring VLANs
- Access and Trunk Ports
- Inter-Switch Link (ISL)
- IEEE 802.1Q
- Configuring Access & Trunk Ports
- Configuring Voice VLANs
- Configuring Allowed VLANs
- Cisco Dynamic Trunking Protocol (DTP) Explained
- What is VTP?
- VTP Modes
- VTP Configuration
- What is STP?
- Network Bridge Explained
- How STP Works
- Electing the Root Switch in STP
- Spanning Tree Priority: Root Primary and Root Secondary
- Selecting STP Root Port
- Selecting STP Designated Port (DP)
- Spanning Tree Modes: MSTP, PVST+, and RPVST+
- What is RSTP?
- How RSTP Works
- Configuring RSTP
- Cisco HSRP and Spanning Tree Alignment Configuration
- Spanning Tree Portfast, BPDU Guard, Root Guard Configuration
- What is IPv6?
- IPv6 Address Format
- IPv6 Interface Identifier
- Differences Between IPv4 and IPv6
- Types of IPv6 Addresses
- How to Configure IPv6
- IPv6 SLAAC — Stateless Address Autoconfiguration
- IPv6 Routing — Static Routes Explained and Configured
- IPv6 Default Static Route and Summary Route
- IPv6 Routing Protocols
- Neighbor Discovery Protocol — NDP Overview
- Telnet & SSH
- Setting Up Telnet
- Setting Up SSH
- Cisco Console Port Security
- exec-timeout Command
- Encrypt Local Usernames and Passwords
- Cisco Privilege Levels — Explanation and Configuration
- What is AAA? Authentication, Authorization, & Accounting
- Configuring AAA on Cisco Devices – RADIUS and TACACS+
- Configuring a Cisco Banner: MOTD, Login, & Exec Banners
- Configure Timezone and Daylight Saving Time (DST)
- NTP (Network Time Protocol)
- Configure NTP on a Cisco Router
- What is Network Automation and Why We Need It?
- Network Programmability — Git, GitHub, CI/CD, and Python
- Data Serialization Formats — JSON, YAML, and XML
- SOAP vs REST: Comparing the Web API Services
- Model-Driven Programmability: NETCONF and RESTCONF
- Configuration Management Tools — Ansible, Chef, & Puppet
- Cisco SDN — Software Defined Networking Explained
- Cisco DNA — Digital Network Architecture Overview
- Cisco IBN — Intent-Based Networking Explained
- Cisco SD-Access (Software-Defined Access) Overview
- Cisco SD-WAN (Software-Defined WAN) Overview & Architecture