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Cumulus Linux

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User Accounts

By default, Cumulus Linux has two user accounts: cumulus and root.

The cumulus account:

  • Uses the default password cumulus. You must change the default password when you log into Cumulus Linux for the first time.
  • Is a user account in the sudo group with sudo privileges.
  • Can log in to the system through all the usual channels, such as console and SSH.
  • Includes permissions to run NVUE nv show, nv set, nv unset, and nv apply commands.

The root account:

  • Has the default password disabled by default and prevents you from using SSH, telnet, FTP, and so on, to log in to the switch.
  • Has the standard Linux root user access to everything on the switch.

Add a New User Account

You can add additional user accounts as needed.

  • You control local user account access to NVUE commands by changing the group membership (role) for a user. Like the cumulus account, these accounts must be in the sudo group or include the NVUE system-admin role to execute privileged commands.
  • You can set a plain text password or a hashed password for the local user account. To access the switch without a password, you need to boot into single user mode.
  • You can provide a full name for the local user account (optional).

Default Roles

Cumulus Linux provides the following default roles:

Role
Permissions
system-adminAllows the user to use sudo to run commands as the privileged user, run nv show commands, run nv set and nv unset commands to stage configuration changes, and run nv apply commands to apply configuration changes.
nvue-adminAllows the user to run nv show commands, run nv set and nv unset commands to stage configuration changes, and run nv apply commands to apply configuration changes.
nvue-monitorAllows the user to run nv show commands only.
Role
Permissions
sudoAllows the user to use sudo to run commands as the privileged user.
nvshowAllows the user to run nv show commands only.
nvsetAllows the user to run nv show commands, and run nv set and nv unset commands to stage configuration changes.
nvapplyAllows the user to run nv show commands, run nv set and nv unset commands to stage configuration changes, and run nv apply commands to apply configuration changes.

To add a new user account and assign the user a default role:

The following example:

  • Creates a new user account called admin2 and sets the role to system-admin.
  • Sets a plain text password. NVUE hashes the plain text password and stores the value as a hashed password. To set a hashed password, see Hashed Passwords, below.
  • Adds the full name FIRST LAST. If the full name includes more than one name, either separate the names with a hyphen (FIRST-LAST) or enclose the full name in quotes ("FIRST LAST").
cumulus@switch:~$ nv set system aaa user admin2 role system-admin
cumulus@switch:~$ nv set system aaa user admin2 password
Enter new password:
Confirm password:
cumulus@switch:~$ nv set system aaa user admin2 full-name "FIRST LAST"
cumulus@switch:~$ nv config apply

You can also run the nv set system aaa user <user> password <plain-text-password> command to specify the plain text password inline. This command bypasses the Enter new password and Confirm password prompts but displays the plain text password as you type it.

If you are an NVUE-managed user, you can update your own password with the Linux passwd command.

The following example:

  • Creates a new user account called admin2, creates a home directory for the user, and adds the full name First Last.
  • Securely sets the password for the user with passwd.
  • Sets the group membership (role) to sudo and nvapply (permissions to use sudo, nv show, nv set, and nv apply).
cumulus@switch:~$ sudo useradd admin2 -m -c "First Last"
cumulus@switch:~$ sudo passwd admin2
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully
cumulus@switch:~$ sudo adduser admin2 sudo
cumulus@switch:~$ sudo adduser admin2 nvapply

When you use Linux commands to add a new user, you must create a home directory for the user with the -m option. NVUE commands create a home directory automatically.

Only the following user accounts can create, modify, and delete other system-admin accounts:

  • NVUE-managed users with the system-admin role.
  • The root user.
  • Non NVUE-managed users that are in the sudo group.

You can also create custom roles and assign a custom role to a user. See Role-based Access Control.

Hashed Passwords

Instead of a plain text password, you can provide a hashed password for a local user.

You must specify the hashed password in Linux crypt format; the password must be a minimum of 15 to 20 characters long and must include special characters, digits, lowercase alphabetic letters, and more. Typically, the password format is set to $id$salt$hashed, where $id is the hashing algorithm. In GNU or Linux:

  • $1$ is MD5
  • $2a$ is Blowfish
  • $2y$ is Blowfish
  • $5$ is SHA-256
  • $6$ is SHA-512

To generate a hashed password on the switch, you can either run a python3 command or install and use the mkpasswd utility:

Run the following command on the switch or Linux host. When prompted, enter the plain text password you want to hash:

cumulus@switch:~$ python3 -c "import crypt; import getpass; print(crypt.crypt(getpass.getpass(), salt=crypt.METHOD_SHA512))"                    
Password:                                                                                                                                                                 
$6$MIDE.sdxwxuAMGHd$XFXSpHV4NRJymUpeCKz.SYEMUfGGEtLbcqK0fBw3d96ZzegP3sw6ppl5Atx9xLS3UHLLTWS/BOwjkeBJJaRx10
  1. Install the mkpasswd utility on the switch or Linux host:
cumulus@switch:~$ sudo -E apt-get update
cumulus@switch:~$ sudo -E apt-get install whois

  1. To generate a hashed password for SHA-512, SHA256, or MD5 encryption, run the following command. When prompted, enter the plain text password you want to hash:

    SHA-512 encryption:

    cumulus@switch:~$ mkpasswd -m SHA-512
Password:
$6$bQcjKuWgKC0vdwT5$.ZlRgmS44geDH/HsCIttldsaxJ7Y/NidicXwR0FarwXq74uA/yJHxQXGHZwNviY/cG412i7Grzl6Wk8mStJwD0

    SHA256 encryption:

    cumulus@switch:~$ mkpasswd -m SHA-256
Password:
$5$SJsPU8bjl2F$.fzRpTGxwGw82RDdFPwhIermSSh6g2ZCYzPeNpeDrgC

    MD5 encryption:

    cumulus@switch:~$ mkpasswd -m MD5
Password:
$1$/ETjhZMJ$P73qhBZEYP20mKnRkhBol0

To set the hashed password for the local user:

Run the nv set system aaa user <username> hashed-password <password> command:

cumulus@switch:~$ nv set system aaa user admin2 hashed-password '$1$/ETjhZMJ$P73qhBZEYP20mKnRkhBol0'
cumulus@switch:~$ nv config apply

cumulus@switch:~$ sudo useradd admin2 -c "First Last" -p '$1$/ETjhZMJ$P73qhBZEYP20mKnRkhBol0'

Hashed password strings contain characters, such as $, that have a special meaning in the Linux shell; you must enclose the hashed password in single quotes (').

Delete a User Account

To delete a user account:

Run the nv unset system aaa user <user> command. The following example deletes the user account called admin2.

cumulus@switch:~$ nv unset system aaa user admin2
cumulus@switch:~$ nv config apply

Run the sudo userdel <user> command. The following example deletes the user account called admin2.

cumulus@switch:~$ sudo userdel admin2

Show User Accounts

To show the user accounts configured on the system, run the NVUE nv show system aaa command or the linux sudo cat /etc/passwd command.

cumulus@switch:~$ nv show system aaa user
Username          Full-name                           Role     enable  Summary
----------------  ----------------------------------  -------  ------  -------
_apt                                                  Unknown  system         
_lldpd                                                Unknown  system         
backup            backup                              Unknown  system         
bin               bin                                 Unknown  system         
cumulus           cumulus,,,                          Unknown  on             
daemon            daemon                              Unknown  system         
dnsmasq           dnsmasq,,,                          Unknown  system         
frr               Frr routing suite,,,                Unknown  system         
games             games                               Unknown  system         
gnats             Gnats Bug-Reporting System (admin)  Unknown  system         
irc               ircd                                Unknown  system         
list              Mailing List Manager                Unknown  system         
lp                lp                                  Unknown  system         
mail              mail                                Unknown  system         
man               man                                 Unknown  system         
messagebus                                            Unknown  system         
news              news                                Unknown  system         
nobody            nobody                              Unknown  off            
ntp                                                   Unknown  system         
nvue              NVIDIA User Experience              Unknown  system         
proxy             proxy                               Unknown  system         
root              root                                Unknown  system         
snmp                                                  Unknown  system         
sshd                                                  Unknown  system         
sync              sync                                Unknown  system         
sys               sys                                 Unknown  system         
systemd-coredump  systemd Core Dumper                 Unknown  system         
systemd-network   systemd Network Management,,,       Unknown  system         
systemd-resolve   systemd Resolver,,,                 Unknown  system         
systemd-timesync  systemd Time Synchronization,,,     Unknown  system         
user1                                                 OSPF     on             
user2                                                 IFMgr    on             
uucp              uucp                                Unknown  system         
uuidd                                                 Unknown  system

To show information about a specific user account, run the NVUE nv show system aaa user <user> command:

cumulus@switch:~$ nv show system aaa user cumulus
                    operational  applied
------------------  -----------  -------
role                Unknown             
full-name           cumulus,,,          
hashed-password     *                   
ssh                                     
  [authorized-key]                      
enable              on

Enable the root User

The root user does not have a password and cannot log into a switch using SSH. This default account behavior is consistent with Debian.

Enable Console Access

To log into the switch using root from the console, you must set the password for the root account:

cumulus@switch:~$ sudo passwd root
Enter new password:
...

Enable SSH Access

To log into the switch using root with SSH, either:

  • Install an SSH authorized key; refer to Install an Authorized SSH Key.

  • Follow these steps to set a password and enable password authentication for root in sshd:

    1. Run the following command:

      cumulus@switch:~$ sudo passwd root

    2. In the /etc/ssh/sshd_config file, change the PermitRootLogin setting from without-password to yes:

      cumulus@switch:~$ sudo nano /etc/ssh/sshd_config
...
# Authentication: 
LoginGraceTime 120 
PermitRootLogin yes 
StrictModes yes
...

    3. Restart the ssh service:

      cumulus@switch:~$ sudo systemctl reload ssh.service

Password Security

A user password is the key credential that verifies the user accessing the switch and acts as the first line of defense to secure the switch. The complexity of the password, replacement capabilities, and change frequency define the security level of the first perimeter of the switch. To further improve and harden the switch, Cumulus Linux enables a password security option that enforces password policies that apply to all users on the switch; user passwords must include at least one lowercase character, one uppercase character, one digit, one special character, and cannot be usernames. In addition, passwords must be a minimum of eight characters long, expire in 365 days, and provide a warning 15 days before expiration.

You can change these password security policies; see Configure Password Policies below.

Disable Password Security

The password security option is enabled by default. To disable password security, run the nv set system security password-hardening state disabled command:

cumulus@switch:~$ nv set system security password-hardening state disabled
cumulus@switch:~$ nv config apply

To re-enable password security, run the nv set system security password-hardening state enabled command.

Configure Password Policies

The following table describes the password policies that Cumulus Linux provides and shows the default settings when password security is enabled. You can change these settings with NVUE commands.

PolicyDescriptionDefault Setting
LowercasePasswords must include at least one lowercase character. You can specify enabled or disabled.enabled
UppercasePasswords must include at least one uppercase character. You can specify enabled or disabled.enabled
DigitsPasswords must include at least one digit. You can specify enabled or disabled.enabled
Special charactersPasswords must include at least one special character. You can specify enabled or disabled.enabled
Password lengthThe minimum password length. You can specify a value between 6 and 32 characters.8 characters
Expiration in daysThe duration in days after which passwords expire. You can set a value between 1 and 365 days.180 days
Password expiration warningThe number of days before a password expires to send a warning. You can set a value between 1 and 30 days.15 days
Prevent usernames as passwordsPasswords cannot be usernames. You can specify enabled or disabled.enabled
Password reuseThe number of times you can reuse the same password. You can set a value between 1 and 100.10

The following example commands disable enforcement of lowercase and uppercase characters, digits, and special characters:

cumulus@switch:~$ nv set system security password-hardening lower-class disabled
cumulus@switch:~$ nv set system security password-hardening upper-class disabled
cumulus@switch:~$ nv set system security password-hardening digits-class disabled
cumulus@switch:~$ nv set system security password-hardening special-class disabled

Special characters include ` ~ ! @ # $ % ^ & * ( ) - _ + = | [ { } ] ; : ' , < . > / ? and white space.

The following example commands set the minimum password length to 10 characters, the password expiration to 30 days, and the expiration warning to 5 days before expiration.

cumulus@switch:~$ nv set system security password-hardening len-min 10
cumulus@switch:~$ nv set system security password-hardening expiration 30
cumulus@switch:~$ nv set system security password-hardening expiration-warning 5

The following example commands allow usernames as passwords and sets the number of times you can reuse a password to 20:

cumulus@switch:~$ nv set system security password-hardening reject-user-passw-match disabled
cumulus@switch:~$ nv set system security password-hardening history-cnt 20

Show Password Policies

To show the currently configured password policies, run the nv show system security password-hardening command:

cumulus@switch:~$ nv show system security password-hardening
                         operational  applied 
-----------------------  -----------  --------
state                    enabled      enabled 
reject-user-passw-match  disabled     disabled
lower-class              enabled      enabled 
upper-class              enabled      enabled 
digits-class             disabled     disabled
special-class            disabled     disabled
expiration-warning       15           15      
expiration               180          180     
history-cnt              20           20      
len-min                  8            8

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