AWS Directory Service
Administration Guide (Version 1.0)

Manually Join a Linux Instance

In addition to Amazon EC2 Windows instances, you can also join certain Amazon EC2 Linux instances to your AWS Directory Service for Microsoft Active Directory directory. The following Linux instance distributions and versions are supported:

  • Amazon Linux AMI 2015.03

  • Red Hat Enterprise Linux 7.2

  • Ubuntu Server 14.04 LTS

  • CentOS 7

Note

Other Linux distributions and versions may work but have not been tested.

Join an Instance to Your Directory

Before you can join either an Amazon Linux, CentOS, Red Hat, or Ubuntu instance to your directory, the instance must first be launched as specified in Seamlessly Join a Windows EC2 Instance.

Important

Some of the following procedures, if not performed correctly, can render your instance unreachable or unusable. Therefore, we strongly suggest you make a backup or take a snapshot of your instance before performing these procedures.

To join a linux instance to your directory

Follow the steps for your specific Linux instance using one of the following tabs:

Amazon LinuxCentOSRed HatUbuntu
Amazon Linux
  1. Connect to the instance using any SSH client.

  2. Configure the Linux instance to use the DNS server IP addresses of the AWS Directory Service-provided DNS servers. You can do this either by setting it up in the DHCP Options set attached to the VPC or by setting it manually on the instance. If you want to set it manually, see How do I assign a static DNS server to a private Amazon EC2 instance in the AWS Knowledge Center for guidance on setting the persistent DNS server for your particular Linux distribution and version.

  3. Make sure your Amazon Linux - 64bit instance is up to date.

    $ sudo yum -y update
  4. Install the required Amazon Linux packages on your Linux instance.

    Note

    Some of these packages may already be installed.

    As you install the packages, you might be presented with several pop-up configuration screens. You can generally leave the fields in these screens blank.

    Amazon Linux 1
    $ sudo yum -y install sssd realmd krb5-workstation
    Amazon Linux 2
    $ sudo yum -y install sssd realmd krb5-workstation samba-common-tools
  5. Join the instance to the directory with the following command.

    $ sudo realm join -U join_account@example.com example.com --verbose
    join_account@example.com

    An account in the example.com domain that has domain join privileges. Enter the password for the account when prompted. For more information about delegating these privileges, see Delegate Directory Join Privileges for AWS Managed Microsoft AD.

    example.com

    The fully-qualified DNS name of your directory.

    ... * Successfully enrolled machine in realm
  6. Set the SSH service to allow password authentication.

    1. Open the /etc/ssh/sshd_config file in a text editor.

      sudo vi /etc/ssh/sshd_config
    2. Set the PasswordAuthentication setting to yes.

      PasswordAuthentication yes
  7. Start the SSSD service.

    $ sudo systemctl start sssd.service

    Alternatively:

    $ sudo service sssd start
  8. Restart the instance.

  9. After the instance has restarted, connect to it with any SSH client and add the AWS Delegated Administrators group to the sudoers list by performing the following steps:

    1. Open the sudoers file with the following command:

      $ sudo visudo
    2. Add the following to the bottom of the sudoers file and save it.

      ## Add the "AWS Delegated Administrators" group from the example.com domain. %AWS\ Delegated\ Administrators@example.com ALL=(ALL:ALL) ALL

      (The above example uses "\<space>" to create the Linux space character.)

CentOS
  1. Connect to the instance using any SSH client.

  2. Configure the Linux instance to use the DNS server IP addresses of the AWS Directory Service-provided DNS servers. You can do this either by setting it up in the DHCP Options set attached to the VPC or by setting it manually on the instance. If you want to set it manually, see How do I assign a static DNS server to a private Amazon EC2 instance in the AWS Knowledge Center for guidance on setting the persistent DNS server for your particular Linux distribution and version.

  3. Make sure your CentOS 7 instance is up to date.

    $ sudo yum -y update
  4. Install the required CentOS 7 packages on your Linux instance.

    Note

    Some of these packages may already be installed.

    As you install the packages, you might be presented with several pop-up configuration screens. You can generally leave the fields in these screens blank.

    $ sudo yum -y install sssd realmd krb5-workstation samba-common-tools
  5. Join the instance to the directory with the following command.

    $ sudo realm join -U join_account@example.com example.com --verbose
    join_account@example.com

    An account in the example.com domain that has domain join privileges. Enter the password for the account when prompted. For more information about delegating these privileges, see Delegate Directory Join Privileges for AWS Managed Microsoft AD.

    example.com

    The fully-qualified DNS name of your directory.

    ... * Successfully enrolled machine in realm
  6. Set the SSH service to allow password authentication.

    1. Open the /etc/ssh/sshd_config file in a text editor.

      sudo vi /etc/ssh/sshd_config
    2. Set the PasswordAuthentication setting to yes.

      PasswordAuthentication yes
  7. Start the SSSD service.

    $ sudo systemctl start sssd.service

    Alternatively:

    $ sudo service sssd start
  8. Restart the instance.

  9. After the instance has restarted, connect to it with any SSH client and add the AWS Delegated Administrators group to the sudoers list by performing the following steps:

    1. Open the sudoers file with the following command:

      $ sudo visudo
    2. Add the following to the bottom of the sudoers file and save it.

      ## Add the "AWS Delegated Administrators" group from the example.com domain. %AWS\ Delegated\ Administrators@example.com ALL=(ALL:ALL) ALL

      (The above example uses "\<space>" to create the Linux space character.)

Red Hat
  1. Connect to the instance using any SSH client.

  2. Configure the Linux instance to use the DNS server IP addresses of the AWS Directory Service-provided DNS servers. You can do this either by setting it up in the DHCP Options set attached to the VPC or by setting it manually on the instance. If you want to set it manually, see How do I assign a static DNS server to a private Amazon EC2 instance in the AWS Knowledge Center for guidance on setting the persistent DNS server for your particular Linux distribution and version.

  3. Make sure the Red Hat - 64bit instance is up to date.

    $ sudo yum -y update
  4. Install the required Red Hat packages on your Linux instance.

    Note

    Some of these packages may already be installed.

    As you install the packages, you might be presented with several pop-up configuration screens. You can generally leave the fields in these screens blank.

    $ sudo yum -y install sssd realmd krb5-workstation samba-common-tools
  5. Join the instance to the directory with the following command.

    $ sudo realm join -U join_account@example.com example.com --verbose
    join_account@example.com

    An account in the example.com domain that has domain join privileges. Enter the password for the account when prompted. For more information about delegating these privileges, see Delegate Directory Join Privileges for AWS Managed Microsoft AD.

    example.com

    The fully-qualified DNS name of your directory.

    ... * Successfully enrolled machine in realm
  6. Set the SSH service to allow password authentication.

    1. Open the /etc/ssh/sshd_config file in a text editor.

      sudo vi /etc/ssh/sshd_config
    2. Set the PasswordAuthentication setting to yes.

      PasswordAuthentication yes
  7. Start the SSSD service.

    $ sudo systemctl start sssd.service

    Alternatively:

    $ sudo service sssd start
  8. Restart the instance.

  9. After the instance has restarted, connect to it with any SSH client and add the AWS Delegated Administrators group to the sudoers list by performing the following steps:

    1. Open the sudoers file with the following command:

      $ sudo visudo
    2. Add the following to the bottom of the sudoers file and save it.

      ## Add the "AWS Delegated Administrators" group from the example.com domain. %AWS\ Delegated\ Administrators@example.com ALL=(ALL:ALL) ALL

      (The above example uses "\<space>" to create the Linux space character.)

Ubuntu
  1. Connect to the instance using any SSH client.

  2. Configure the Linux instance to use the DNS server IP addresses of the AWS Directory Service-provided DNS servers. You can do this either by setting it up in the DHCP Options set attached to the VPC or by setting it manually on the instance. If you want to set it manually, see How do I assign a static DNS server to a private Amazon EC2 instance in the AWS Knowledge Center for guidance on setting the persistent DNS server for your particular Linux distribution and version.

  3. Make sure your Ubuntu - 64bit instance is up to date.

    $ sudo apt-get update $ sudo apt-get -y upgrade
  4. Install the required Ubuntu packages on your Linux instance.

    Note

    Some of these packages may already be installed.

    As you install the packages, you might be presented with several pop-up configuration screens. You can generally leave the fields in these screens blank.

    $ sudo apt-get -y install sssd realmd krb5-user samba-common packagekit adcli
  5. Join the instance to the directory with the following command.

    $ sudo realm join -U join_account@example.com example.com --verbose

    Note

    If you are using Ubuntu 16.04, you must enter the domain name portion of the username with all capital letters. For example, join_account@EXAMPLE.COM example.com --verbose.

    join_account@example.com

    An account in the example.com domain that has domain join privileges. Enter the password for the account when prompted. For more information about delegating these privileges, see Delegate Directory Join Privileges for AWS Managed Microsoft AD.

    example.com

    The fully-qualified DNS name of your directory.

    ... * Successfully enrolled machine in realm
  6. Set the SSH service to allow password authentication.

    1. Open the /etc/ssh/sshd_config file in a text editor.

      sudo vi /etc/ssh/sshd_config
    2. Set the PasswordAuthentication setting to yes.

      PasswordAuthentication yes
  7. Start the SSSD service.

    $ sudo systemctl start sssd.service

    Alternatively:

    $ sudo service sssd start
  8. Restart the instance.

  9. After the instance has restarted, connect to it with any SSH client and add the AWS Delegated Administrators group to the sudoers list by performing the following steps:

    1. Open the sudoers file with the following command:

      $ sudo visudo
    2. Add the following to the bottom of the sudoers file and save it.

      ## Add the "AWS Delegated Administrators" group from the example.com domain. %AWS\ Delegated\ Administrators@example.com ALL=(ALL:ALL) ALL

      (The above example uses "\<space>" to create the Linux space character.)

Restricting Account Login Access

Since all accounts are defined in Active Directory, by default, all the users in the directory can log in to the instance. You can allow only specific users to log in to the instance with ad_access_filter in sssd.conf. For example:

ad_access_filter = (memberOf=cn=admins,ou=Testou,dc=example,dc=com)
memberOf

Indicates that users should only be allowed access to the instance if they are a member of a specific group.

cn

The canonical name of the group that should have access. In this example, the group name is admins.

ou

This is the organizational unit in which the above group is located. In this example, the OU is Testou.

dc

This is the domain component of your domain. In this example, example.

dc

This is an additional domain component. In this example, com.

You must manually add ad_access_filter to your /etc/sssd/sssd.conf. After you do this, your sssd.conf might look like this:

[sssd] domains = example.com config_file_version = 2 services = nss, pam [domain/example.com] ad_domain = example.com krb5_realm = EXAMPLE.COM realmd_tags = manages-system joined-with-samba cache_credentials = True id_provider = ad krb5_store_password_if_offline = True default_shell = /bin/bash ldap_id_mapping = True use_fully_qualified_names = True fallback_homedir = /home/%u@%d access_provider = ad ad_access_filter = (memberOf=cn=admins,ou=Testou,dc=example,dc=com)

In order for the configuration to take affect you need to restart the sssd service:

$ sudo systemctl restart sssd.service

Alternatively, you could use:

$ sudo service sssd start

Connect to the Instance

When a user connects to the instance using an SSH client, they are prompted for their username. The user can enter the username in either the username@example.com or EXAMPLE\username format. The response will appear similar to the following:

login as: johndoe@example.com johndoe@example.com's password: Last login: Thu Jun 25 16:26:28 2015 from XX.XX.XX.XX