在Oracle云上使用cloud-init脚本创建初始用户

Oracle Cloud 上创建实例的时候，默认都是设置公钥登录，但是如果密钥没输入正确，就白瞎这台虚拟机了，登不上呀。

可以临时创建 Console Connection ，上传新的公钥，但是进去之后发现，还TM要输入帐号和密码，默认根本没密码呀。。。woc！！

这里使用 cloud-init 脚本，在虚拟机创建的时候，创建一个可以用来从console connection登录、且可sudo的帐号。

  1. 创建 instance，配置主要参数后，点击“Create”按钮上面的“Show Advanced Options”
  2. Management 》Paste cloud-init script
    ~~~
    #cloud-config
    users:
    • default

    • name: backdoor
      sudo: ALL=(ALL) NOPASSWD:ALL
      lock_passwd: false
      passwd: $6$MFhXlUHt$JG.sn2M4ReeZ.V/TDs8AWJzhA1anX0iUbE0WvfR8v/8d4eGv8v6EwhyiKO.6VixMaC8/dG.YQce01QV8w1.dZ0
      ~~~
      以上脚本，创建了一个名为 backddor 的用户，密码为 1LoveOracle!!，但是他没有公钥，所以他没法通过ssh登录。

    • passwd 密文的生成方法： 
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        yay -S mkpasswd
  mkpasswd --method=SHA-512 --salt=MFhXlUHt
  # 输入密码后回车，会生成密文

      以上例子中的密文开头部分 $6$MFhXlUHt$ ，6 表示加密方法是 SHA-512，当然可以换其他加密方法，例如，SHA-265 对应 5，详情可查看 mkpasswd 的帮助文档。MFhXlUHt 就是执行mkpasswd时，传入的salt参数。

  3. 点击 create ，创建实例
  4. 实例详情页面，左侧导航 Resources 》Console Connection
  5. 点击 Create local Connection ，上传当前linux电脑的 public key
  6. 创建完成后，点击 connection 对应的三个竖排点，出现的菜单中选择 Copy serial console connection for Linux/Mac
  7. 将拷贝好的命令，在当前linux电脑执行。就可以通过Oracle的代理连上虚拟机了。
  8. 这时候输入用户名和密码就能进去操作了。
  9. sudo -i 可以提权到root

cloud-init 脚本 users 配置参考

Cloud config examples
Including users and groups

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#cloud-config
# Add groups to the system
# The following example adds the ubuntu group with members 'root' and 'sys'
# and the empty group cloud-users.
groups:
  - ubuntu: [root,sys]
  - cloud-users

# Add users to the system. Users are added after groups are added.
# Note: Most of these configuration options will not be honored if the user
#       already exists. Following options are the exceptions and they are
#       applicable on already-existing users:
#       - 'plain_text_passwd', 'hashed_passwd', 'lock_passwd', 'sudo',
#         'ssh_authorized_keys', 'ssh_redirect_user'.
users:
  - default
  - name: foobar
    gecos: Foo B. Bar
    primary_group: foobar
    groups: users
    selinux_user: staff_u
    expiredate: '2032-09-01'
    ssh_import_id:
      - lp:falcojr
      - gh:TheRealFalcon
    lock_passwd: false
    passwd: $6$j212wezy$7H/1LT4f9/N3wpgNunhsIqtMj62OKiS3nyNwuizouQc3u7MbYCarYeAHWYPYb2FT.lbioDm2RrkJPb9BZMN1O/
  - name: barfoo
    gecos: Bar B. Foo
    sudo: ALL=(ALL) NOPASSWD:ALL
    groups: users, admin
    ssh_import_id:
      - lp:falcojr
      - gh:TheRealFalcon
    lock_passwd: true
    ssh_authorized_keys:
      - <ssh pub key 1>
      - <ssh pub key 2>
  - name: cloudy
    gecos: Magic Cloud App Daemon User
    inactive: '5'
    system: true
  - name: fizzbuzz
    sudo: False
    ssh_authorized_keys:
      - <ssh pub key 1>
      - <ssh pub key 2>
  - snapuser: joe@joeuser.io
  - name: nosshlogins
    ssh_redirect_user: true

# Valid Values:
#   name: The user's login name
#   expiredate: Date on which the user's account will be disabled.
#   gecos: The user name's real name, i.e. "Bob B. Smith"
#   homedir: Optional. Set to the local path you want to use. Defaults to
#           /home/<username>
#   primary_group: define the primary group. Defaults to a new group created
#           named after the user.
#   groups:  Optional. Additional groups to add the user to. Defaults to none
#   selinux_user:  Optional. The SELinux user for the user's login, such as
#           "staff_u". When this is omitted the system will select the default
#           SELinux user.
#   lock_passwd: Defaults to true. Lock the password to disable password login
#   inactive: Number of days after password expires until account is disabled
#   passwd: The hash -- not the password itself -- of the password you want
#           to use for this user. You can generate a safe hash via:
#               mkpasswd --method=SHA-512 --rounds=4096
#           (the above command would create from stdin an SHA-512 password hash
#           with 4096 salt rounds)
#
#           Please note: while the use of a hashed password is better than
#               plain text, the use of this feature is not ideal. Also,
#               using a high number of salting rounds will help, but it should
#               not be relied upon.
#
#               To highlight this risk, running John the Ripper against the
#               example hash above, with a readily available wordlist, revealed
#               the true password in 12 seconds on a i7-2620QM.
#
#               In other words, this feature is a potential security risk and is
#               provided for your convenience only. If you do not fully trust the
#               medium over which your cloud-config will be transmitted, then you
#               should use SSH authentication only.
#
#               You have thus been warned.
#   no_create_home: When set to true, do not create home directory.
#   no_user_group: When set to true, do not create a group named after the user.
#   no_log_init: When set to true, do not initialize lastlog and faillog database.
#   ssh_import_id: Optional. Import SSH ids
#   ssh_authorized_keys: Optional. [list] Add keys to user's authorized keys file
#   ssh_redirect_user: Optional. [bool] Set true to block ssh logins for cloud
#       ssh public keys and emit a message redirecting logins to
#       use <default_username> instead. This option only disables cloud
#       provided public-keys. An error will be raised if ssh_authorized_keys
#       or ssh_import_id is provided for the same user.
#
#       ssh_authorized_keys.
#   sudo: Defaults to none. Accepts a sudo rule string, a list of sudo rule
#         strings or False to explicitly deny sudo usage. Examples:
#
#         Allow a user unrestricted sudo access.
#             sudo:  ALL=(ALL) NOPASSWD:ALL
#
#         Adding multiple sudo rule strings.
#             sudo:
#               - ALL=(ALL) NOPASSWD:/bin/mysql
#               - ALL=(ALL) ALL
#
#         Prevent sudo access for a user.
#             sudo: False
#
#         Note: Please double check your syntax and make sure it is valid.
#               cloud-init does not parse/check the syntax of the sudo
#               directive.
#   system: Create the user as a system user. This means no home directory.
#   snapuser: Create a Snappy (Ubuntu-Core) user via the snap create-user
#             command available on Ubuntu systems.  If the user has an account
#             on the Ubuntu SSO, specifying the email will allow snap to
#             request a username and any public ssh keys and will import
#             these into the system with username specifed by SSO account.
#             If 'username' is not set in SSO, then username will be the
#             shortname before the email domain.
#

# Default user creation:
#
# Unless you define users, you will get a 'ubuntu' user on ubuntu systems with the
# legacy permission (no password sudo, locked user, etc). If however, you want
# to have the 'ubuntu' user in addition to other users, you need to instruct
# cloud-init that you also want the default user. To do this use the following
# syntax:
#   users:
#     - default
#     - bob
#     - ....
#  foobar: ...
#
# users[0] (the first user in users) overrides the user directive.
#
# The 'default' user above references the distro's config:
# system_info:
#   default_user:
#     name: Ubuntu
#     plain_text_passwd: 'ubuntu'
#     home: /home/ubuntu
#     shell: /bin/bash
#     lock_passwd: True
#     gecos: Ubuntu
#     groups: [adm, audio, cdrom, dialout, floppy, video, plugdev, dip, netdev]