Configuring Local user management

RBFS allows you to create privileges that are configurable for user-defined and pre-defined roles. RBFS supports a combination of permit and deny regular expressions and a configurable default privilege to support both blacklisting and whitelisting of users. If both permit and deny command regular expressions match, the allow regular expression takes precedence.

Creating Roles

To create a role, you need to configure the following:

Configure role-based access control (RBAC) privilege for the role
Configure the command privilege for the role

It is important to have secure management enabled when granting any type of privilege, whether it is RBAC or command-based, to any user. Without secure management, privileges will not have the desired impact.

Configuring the RBAC Privilege

You need to configure the RBAC privilege for both table and object.

set system authorization global role <name> rbac-permission ( object | table ) <resource> <permission-type>

Command arguments

<name>

Authorization role name

Represents resources in the RBFS (table/object)

<permission-type>

Permissions to create, read and delete. The following are the supported RBAC permission types:
-/-/-
-/-/delete
-/read/-
-/read/delete
create/-/-
create/-/delete
create/read/-
create/read/delete

Configuring the Command Privilege

set system authorization global role <name> cmd-permission ( allow-cmds <allow-cmds> | deny-cmds <deny-cmds> )

<role>

Authorization role name

<allow-cmds>

List of allow commands regular expression

<deny-cmds>

List of deny commands regular expression

If you configure a privilege for any of the pre-defined roles (supervisor, operator, reader), then it replaces the default privilege.
If you delete the configured privilege for a pre-defined role, then it will revert to the default privilege of the role.
Priority of privilege rules is as follows: explicit deny, explicit permit, default privilege.

The example below shows the new role named "support" which has RBAC permission to read any table and objects. Also, the user is denied everything except the allowed commands (ping, set, show, traceroute, and watch-mode).

{
  "ietf-restconf:data": {
    "rtbrick-config:system": {
      "authorization": {
        "global": {
          "role": [
            {
              "name": "support",
              "rbac-permission": [
                {
                  "permission": "-/read/-",
                  "resource-type": "object",
                  "resource": ".*"
                },
                {
                  "permission": "-/read/-",
                  "resource-type": "table",
                  "resource": ".*"
                }
              ],
              "cmd-permission": {
                "allow-cmds": [
                  "ping .*",
                  "set .*",
                  "show .*",
                  "traceroute .*",
                  "watch .*"
                  ],
                "deny-cmds": ".*"
              }
            }
          ]
        }
      }
    }
  }
}

Linux pre-configured users, roles and privileges

User Name	Role Name	Default Privileges
supervisor	supervisor	Allow all actions
operator	operator	Allow all actions
reader	reader	All commands will be denied other than the commands which match any of the below regular expressions. "color.", "date.", "exit.", "history.", "paging.", "ping.", "show.", "traceroute.", "watch-mode.*"

User Name

Role Name

Default Privileges

supervisor

Allow all actions

operator

Allow all actions

reader

All commands will be denied other than the commands which match any of the below regular expressions.

"color.*",
"date.*",
"exit.*",
"history.*",
"paging.*",
"ping.*",
"show.*",
"traceroute.*",
"watch-mode.*"

Creating New Users

The new users created through local user management will always have a primary group with the same name and ID of the created user. The new user’s ID will be allocated within the range of 3000 and 3999.

You cannot use usernames such as root, wheel, admin, sudo or any of the SMP Linux pre-configured users and groups such as supervisor, operator, reader. Also, a username cannot start with “rtbrick_”. If a Linux user with the same username already exists but has an ID outside of the 3000-3999 range then the user creation through the RBFS configuration will fail.

To create a new user, enter the following command:

set system user <username>

Command arguments

Name of the local user

Assigning Roles to Users

A "role" is an RBFS RBAC construct and it is mapped to a Linux group. The list of user roles from the RBFS configuration becomes the list of additional Linux groups that the Linux user belongs to. You can create new users and assign “roles” to the new users. The supervisor, operator, and reader are the pre-defined and pre-configured roles both in Linux and RBFS.

When a user is configured in RBFS under “system users”, RBFS/confd validates that the list of user roles only contain roles that are pre-defined or that are configured under “system authorization”.

Do not create role names that start with “rtbrick_”. In addition, "root", "wheel", "admin", and "sudo" are not acceptable role names.

To assign a role to a new user, enter the following command:

set system user <username> role <role>

Command arguments

Name of the user

<role>

Role of the user (not the primary role)

Example: Assigning Roles to Users

{
  "ietf-restconf:data": {
    "rtbrick-config:system": {
      "user": [
        {
          "username": "bob",
          "role": [
            "operator"
            ],
          "shell": "/usr/local/bin/cli",
          "password-hashed-text": "$6$uTE4OYn0iRq.Vppe$JBVMQ5DZHfuCuUP5yTnfl9IJsRLQAXqTLlLMKRO8bCz9WDlB2ele8puwMrT4/QDF2nNOcoHtqYqFljly4B.Vu0"
        }
      ]
    }
  }
}

Configuring Authentication for a New User

There are two ways in which you can create a password for a new user in RBFS:

Configuring hashed password
Configuring plain-text password

Configuring Hashed Password

You can verify the integrity of your password using hashed passwords. When a user is present in the configuration but a "password hashed text" is not present, the password authentication is considered disabled for that specific user.

You can also disable password authentication for any of the predefined supervisor, operator and reader users by adding a "system users supervisor" configuration section without any "password hashed text" and thus disabling password authentication for the supervisor user.

SSH public keys can still be configured even if "password hashed text" is not present.

To create a password hashed text and authenticate the new user, perform the following steps:

Generate hash password on any Linux server.
mkpasswd --method=SHA-512
Configure authentication using a password hashed text and an SSH public key.
set system user <username> password-hashed-text <password-hashed-text>
set system user <username> ssh-pub-key <ssh-pub-key>

Command arguments

Name of the user.

<password-hashed-text>

Password string.

<ssh-pub-key>

public keys of a user. You can specify multiple ssh-pub-keys.

It is possible to change shell, password-hash and ssh-pub-keys for supervisor, reader, and operator roles.
The password string provided as part of the RBFS configuration needs to be a compatible password hashed text as defined by the shadow manual page: https://manpages.debian.org/buster/passwd/shadow.5.en.html and by the crypt https://manpages.debian.org/buster/manpages-dev/crypt.3.en.html.

Example

{
  "ietf-restconf:data": {
    "rtbrick-config:system": {
      "user": [
        {
          "username": "bob",
          "shell": "/usr/local/bin/cli",
          "password-hashed-text": "$5$L2DaOYYuddhBV$9RA5MX9RQzLC9fIKJzbnoFBb88w9rkSXl7GVrVJ9PY7",
          "ssh-pub-key": [
            "ssh-rsa AAAAB3NzaC1yc2EAAAADAQCBAAABAQCubg5sdDycPN5EViNkV6w7rfp2GAfKWuInfaL3xOXyvSNpsmaHILYmgrLUU0GKQH9gauPUJpDcvvYaMt0ZBuTbWHVMUc4cvhgbNDkTB2bG2cTZ5QzbicyXff3BlDWQThVp2LtVBiW2tf7JTTa9SnL4Lnm+CQcXsQ0rxqy2S6bJpsRYlFMyQl/hZ4QEWE153dw0HGvcG8mjfnPN4wvCc/omfD3ljxx+Gf4oFS0davX6pdphUKLvgL33VVG5xaK71imv2l3897LIJZaHxy7FbB+CjSYT6QNq1XksX8omrbRjiP3enEQi/bANtzTNnGDnIm1KHf3xuKpoKw+B5fhDZogx"
            ]
        }
      ]
    }
  }
}

Configuring a Plain-Text Password

To configure a password with plain text password for a new user, enter the following command:

set system user <username> password-plain-text <password-plain-text>

Command arguments

Name of the user

<password-plain-text>

Specifies the plain-text password

Example for Configuring Plain Text Password

set system user bob password-plain-text bob123
set system user bob shell /usr/local/bin/cli
set system user bob role operator

Viewing Configuration of Plain Text Password

{
  "ietf-restconf:data": {
    "rtbrick-config:system": {
      "user": [
        {
          "username": "bob",
          "role": [
            "operator"
            ],
          "shell": "/usr/local/bin/cli",
          "password-hashed-text": "$6$uTE4OYn0iRq.Vppe$JBVMQ5DZHfuCuUP5yTnfl9IJsRLQAXqTLlLMKRO8bCz9WDlB2ele8puwMrT4/QDF2nNOcoHtqYqFljly4B.Vu0"
        }
      ]
    }
  }
}

Setting the User Shell

RBFS validates that the shell is one of the following 3 valid options:

/usr/sbin/nologin
/bin/bash
/usr/local/bin/cli

To configure user shell, enter the following command:

set system user <username> shell <shell>

Command arguments

Name of the user

<shell>

Name of the shell

Example

root@rtbrick: cfg> set system user smith shell /usr/local/bin/cli

Specifying the Display Name for User Names

The display name allows you to specify a preferred name so that you can easily identify the user. You can change your display name by entering the following command:

set system user <username> display-name <display_name>

Command arguments

Name of the user

<display_name>

Display name to easily identify the user

Example

set system user smith display-name primeuser

Enabling or disabling CLI access

You can control a user’s access to the CLI. By default, users will have access to the CLI.

set system user <username> no-cli-access < true | false >

Command arguments

Name of the user

When the no-cli-access is set to true, the user’s access to the CLI is disabled. When the no-cli-access is set to false, the user will be able access the CLI.

Example

set system user smith no-cli-access false

Configuring sudo Without Password

You can configure local system users to log in via passwords or using SSH keys. From a security perspective, it is desirable to allow authentication with SSH keys only. RBFS provides a configuration knob to disable the requirement for a 'sudo' password so that local users can authenticate with SSH keys only. This knob is configurable only if the user or one of its roles is supervisor.

You can enter the following command to enable or disable the 'sudo' password. By default, this is set to false which ensures that the supervisor must provide a password when using sudo.

set system user <user> no-sudo-password < true | false >

Command arguments

Name of the user

When the no-sudo-password is set to true, it indicates that a 'sudo' password is not required. When it is set to false, it indicates that the supervisor must provide a password when using sudo.

Example Configuration:

{
    "rtbrick-config:user": [
      {
        "username": "smith",
        "role": "supervisor",
        "shell": "/bin/bash",
        "ssh-pub-key": "ssh-rsa AAAAB3Nza<...>",
        "no-sudo-password": "true"
      }
    ]
 }

Note: If 'no-sudo-password' is set, you can log in with your SSH key.