Junhwan Heo

AWS Rack Decom Datatech

1 분 소요

1. 서론

    오늘은 Router와 Switch의 Console에 연결하여 Enable Password를 초기화 하는 법과 IOS를 업데이트 및 백업, 복구하는 방법을 배워보았다.

2. 본론

1. Cisco IOS

1. Router
Configuration register value is a special register that is used to control the booting process. You can check current configuration register value with "show version" command from exec mode.
It is a four characters hexadecimal value, that can be changed from privileged mode.
Default value is 0x2102.
"0x" indicates that the characters that follow are in hexadecimal.
The third character in the configuration register can modify how the router loads the configuration file.
The fourth character in the configuration register is known as the boot field. Changing this value, will change booting process.
Setting of 0x2100 will always boot router in ROMMON mode.
Setting of 0x2101 will always boot router in RXBOOT mode. (Mini IOS in ROM)
Setting of 0x2102 to 0x210F will always load first valid IOS from flash.
values of 2 through F for the fourth character specify other IOS image files in flash.
Router keeps password in startup-config file that is stored in NVRAM.
The setting of 0x2142 causes the router to ignore the startup-config file in NVRAM and proceed without a configuration. Thus the setting of 0x2142 is used for password recovery process of router.
So far in this tutorial we have learned router booting components. In next section we will learn how these components are involved in router booting process.

//Reset Enable Password
Ctrl + Pause -> ROMMON
> confreg 0x2142
> reset
!
# en
# show version
!
# conf t
# enable password cisco
!
# config-register 0x2102
!
# copy r s
!
# reload

//Restore IOS
# show version
System image file is "blabla"
!
# delete flash:/blabla //IOS 날아간 상황 만들기
!
# dir
!
ctrl + pause -> ROMMON
> IP_ADDRESS=192.168.100.254 //자동으로 장비의 첫 인터페이스에 할당
> IP_SUBNET_MASK=255.255.255.0
> DEFAULT_GATEWAY=192.168.100.1
> TFTP_SERVER=192.168.100.1
> TFTP_FILE=[파일명]
> tftpdnld

//공장초기화
# erase startup-config
# reload

2. Switch

//암호 초기화
: flash_init
: dir flash:/ //config.text파일이 없으면 암호설정 안된것
: cat >> flash:/config.text
: rename flash:/config.text flash:/backup
: boot
> en
# copy backup config.text
!
# conf t
# enable password cisco
# dir flash:/
# copy r s

3. 결론

    오늘은 중요하지만 되도록 쓸일이 없었으면 하는 부분들에 대해 배워보았다.

4. 참고자료

1. Cisco Docs

  1. ARP
  2. CDP / VLAN
  3. Frame Relay
  4. Static Routing
  5. VLAN
  6. VTP
  7. Routed Port
  8. AD
  9. Route Selection
  10. FHRP
  11. HSRP
  12. DHCP
  13. DNS
  14. STP
  15. NAT
  16. EtherChannel
  17. DTP
  18. RIP
  19. NTP
  20. Offset List
  21. Password Encryption
  22. ACL
  23. CAR Attack
  24. Broadcast
  25. Port Assignments
  26. IPv6 Static Routing
  27. HSRP for IPv6
  28. Clock Rate
  29. DHCPv6 Guard
  30. EIGRP
  31. Express Forwarding
  32. Routing and Switching
  33. Load Balancing
  34. Ping, Traceroute
  35. Load Balancing
  36. Fast Switching
  37. CEF
  38. DNS
  39. SSH
  40. Regular Expression
  41. OSPF
  42. EIGRP’s SIA
  43. NSSA
  44. AAA
  45. Understand the Zone-Based Policy Firewall Design
  46. The Cisco SD-WAN Solution
  47. Understand the Zone-Based Policy Firewall Design
  48. ASA cli
  49. Defining Strategies to Protect Against TCP SYN Denial of Service Attacks
  50. Configuring Firewall TCP SYN Cookie
  51. ASA 방화벽에서 NAT 및 ACL 구성
  52. Configuring Network Object NAT
  53. Configuring Twice NAT
  54. 모든 라우터의 컨피그레이션 레지스터 사용 이해
  55. Storing Data In USB

2. Linux

  1. rhel9’s docs
  2. Linux Directory Structure
  3. File Types in Linux
  4. fstab
  5. Vim Cheat Sheet
  6. Protecting GRUB with a password
  7. SELinux
  8. DNS
  9. Samba as a server
  10. DHCP
  11. NFS
  12. SSH
  13. VNC
  14. heredoc
  15. docker vs podman + buildqh + skopeo
  16. Docker란?
  17. Linux 컨테이너란?
  18. Container vs VM
  19. 컨테이너화란?
  20. container
  21. 컨테이너 오케스트레이션이란?
  22. 쿠버네티스란?
  23. 쿠버네티스 아키텍처 소개
  24. 쿠버네티스 기본 사항 학습
  25. 쿠버네티스 클러스터란?
  26. Ansible과 Puppet: 알아야 할 사항

3. Docker / k8s

  1. nextcloud
  2. cadvisor
  3. Dangling Image
  4. Swarm
  5. Install Docker Engine on Ubuntu
  6. Install kubdadm
  7. container-runtimes
  8. kubectl cheat sheet

4. Web

  1. HTML’s Elements
  2. Emmet
  3. JavaScript
  4. Anchor Tag
  5. Post, Get
  6. Block, Inline Elements
  7. Semantic Web
  8. Semantic Elements
  9. CSS
  10. Viewport_meta_tag
  11. Media_queries
  12. JavaScript

5. DB

  1. MySQL
클라우드 엔지니어를 꿈꾸며 공부를 시작한 초보 엔지니어입니다. 틀린점 또는 조언해주실 부분이 있으시면 친절하게 댓글 부탁드립니다. 방문해 주셔서 감사합니다 :)

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