Skip to content

Guide to the Secure Configuration of Alibaba Cloud Linux 3

Rules, Groups, and Values defined within the XCCDF Benchmark

  • Configure Dovecot if Necessary

    If the system will operate as an IMAP or POP3 server, the dovecot software should be configured securely by following the recommendations below.
    Group
  • Allow IMAP Clients to Access the Server

    The default iptables configuration does not allow inbound access to any services. This modification will allow remote hosts to initiate connection...
    Group
  • Support Only the Necessary Protocols

    Dovecot supports the IMAP and POP3 protocols, as well as SSL-protected versions of those protocols. Configure the Dovecot server to support only ...
    Group
  • Disable Cyrus IMAP

    If the system does not need to operate as an IMAP or POP3 server, the Cyrus IMAP software should be removed.
    Group
  • Disable Dovecot

    If the system does not need to operate as an IMAP or POP3 server, the dovecot software should be disabled and removed.
    Group
  • Kerberos

    The Kerberos protocol is used for authentication across non-secure network. Authentication can happen between various types of principals -- users,...
    Group
  • LDAP

    LDAP is a popular directory service, that is, a standardized way of looking up information from a central database. Alibaba Cloud Linux 3 includes ...
    Group
  • Configure OpenLDAP Clients

    This section provides information on which security settings are important to configure in OpenLDAP clients by manually editing the appropriate con...
    Group
  • Configure OpenLDAP Server

    This section details some security-relevant settings for an OpenLDAP server.
    Group
  • Install and Protect LDAP Certificate Files

    Create the PKI directory for LDAP certificates if it does not already exist: <pre>$ sudo mkdir /etc/pki/tls/ldap $ sudo chown root:root /etc/pki/tl...
    Group
  • Configure SSL Certificates for Use with SMTP AUTH

    If SMTP AUTH is to be used, the use of SSL to protect credentials in transit is strongly recommended. There are also configurations for which it ma...
    Group
  • Mail Server Software

    Mail servers are used to send and receive email over the network. Mail is a very common service, and Mail Transfer Agents (MTAs) are obvious target...
    Group
  • The Postfix package is installed

    A mail server is required for sending emails. The <code>postfix</code> package can be installed with the following command: <pre> $ sudo yum instal...
    Rule Medium Severity
  • Enable Postfix Service

    The Postfix mail transfer agent is used for local mail delivery within the system. The default configuration only listens for connections to the de...
    Rule Unknown Severity
  • Configure SMTP For Mail Clients

    This section discusses settings for Postfix in a submission-only e-mail configuration.
    Group
  • Postfix Network Interfaces

    The setting for inet_interfaces in /etc/postfix/main.cf
    Value
  • Postfix relayhost

    Specify the host all outbound email should be routed into.
    Value
  • Postfix Root Mail Alias

    Specify an email address (string) for a root mail alias.
    Value
  • Configure System to Forward All Mail For The Root Account

    Make sure that mails delivered to root user are forwarded to a monitored email address. Make sure that the address <xccdf-1.2:sub idref="xccdf_org....
    Rule Medium Severity
  • Configure System to Forward All Mail From Postmaster to The Root Account

    Verify the administrators are notified in the event of an audit processing failure. Check that the "/etc/aliases" file has a defined value for "roo...
    Rule Medium Severity
  • Configure System to Forward All Mail through a specific host

    Set up a relay host that will act as a gateway for all outbound email. Edit the file <code>/etc/postfix/main.cf</code> to ensure that only the foll...
    Rule Medium Severity
  • Disable Postfix Network Listening

    Edit the file <code>/etc/postfix/main.cf</code> to ensure that only the following <code>inet_interfaces</code> line appears: <pre>inet_interfaces =...
    Rule Medium Severity
  • Configure Operating System to Protect Mail Server

    The guidance in this section is appropriate for any host which is operating as a site MTA, whether the mail server runs using Sendmail, Postfix, or...
    Group
  • Disable netfs if Possible

    To determine if any network filesystems handled by netfs are currently mounted on the system execute the following command: <pre>$ mount -t nfs,nfs...
    Group
  • Ensure Security of Postfix SSL Certificate

    Create the PKI directory for mail certificates, if it does not already exist: <pre>$ sudo mkdir /etc/pki/tls/mail $ sudo chown root:root /etc/pki/t...
    Group
  • Configure Postfix if Necessary

    Postfix stores its configuration files in the directory /etc/postfix by default. The primary configuration file is /etc/postfix/main.cf.
    Group
  • Configure Postfix Resource Usage to Limit Denial of Service Attacks

    Edit <code>/etc/postfix/main.cf</code>. Edit the following lines to configure the amount of system resources Postfix can consume: <pre>default_proc...
    Group
  • Control Mail Relaying

    Postfix's mail relay controls are implemented with the help of the smtpd recipient restrictions option, which controls the restrictions placed on t...
    Group
  • Enact SMTP Recipient Restrictions

    To configure Postfix to restrict addresses to which it will send mail, see: <a href="http://www.postfix.org/SMTPD_ACCESS_README.html#danger">h...
    Group
  • Enact SMTP Relay Restrictions

    To configure Postfix to restrict addresses to which it will send mail, see: <a href="http://www.postfix.org/SMTPD_ACCESS_README.html#danger">h...
    Group
  • Use TLS for SMTP AUTH

    Postfix provides options to use TLS for certificate-based authentication and encrypted sessions. An encrypted session protects the information that...
    Group
  • Configure Trusted Networks and Hosts

    Edit <code>/etc/postfix/main.cf</code>, and configure the contents of the <code>mynetworks</code> variable in one of the following ways: <ul> <li>I...
    Group
  • Require SMTP AUTH Before Relaying from Untrusted Clients

    SMTP authentication allows remote clients to relay mail safely by requiring them to authenticate before submitting mail. Postfix's SMTP AUTH uses a...
    Group
  • NFS and RPC

    The Network File System is a popular distributed filesystem for the Unix environment, and is very widely deployed. This section discusses the circ...
    Group
  • Disable All NFS Services if Possible

    If there is not a reason for the system to operate as either an NFS client or an NFS server, follow all instructions in this section to disable sub...
    Group
  • Disable Network File Systems (netfs)

    The netfs script manages the boot-time mounting of several types of networked filesystems, of which NFS and Samba are the most common. If these fil...
    Rule Unknown Severity
  • Disable Services Used Only by NFS

    If NFS is not needed, disable the NFS client daemons nfslock, rpcgssd, and rpcidmapd. <br><br> All of these daemons run with elevated privileges, a...
    Group
  • Disable rpcbind Service

    The rpcbind utility maps RPC services to the ports on which they listen. RPC processes notify rpcbind when they start, registering the ports they a...
    Rule Low Severity
  • Configure All Systems which Use NFS

    The steps in this section are appropriate for all systems which run NFS, whether they operate as clients or as servers.
    Group
  • Make Each System a Client or a Server, not Both

    If NFS must be used, it should be deployed in the simplest configuration possible to avoid maintainability problems which may lead to unnecessary s...
    Group
  • Configure NFS Services to Use Fixed Ports (NFSv3 and NFSv2)

    Firewalling should be done at each host and at the border firewalls to protect the NFS daemons from remote access, since NFS servers should never b...
    Group
  • Configure NFS Clients

    The steps in this section are appropriate for systems which operate as NFS clients.
    Group
  • Disable NFS Server Daemons

    There is no need to run the NFS server daemons <code>nfs</code> and <code>rpcsvcgssd</code> except on a small number of properly secured systems de...
    Group
  • Mount Remote Filesystems with Restrictive Options

    Edit the file <code>/etc/fstab</code>. For each filesystem whose type (column 3) is <code>nfs</code> or <code>nfs4</code>, add the text <code>,node...
    Group
  • Configure NFS Servers

    The steps in this section are appropriate for systems which operate as NFS servers.
    Group
  • Ensure All-Squashing Disabled On All Exports

    The <code>all_squash</code> maps all uids and gids to an anonymous user. This should be disabled by removing any instances of the <code>all_squash<...
    Rule Low Severity
  • Configure the Exports File Restrictively

    Linux's NFS implementation uses the file <code>/etc/exports</code> to control what filesystems and directories may be accessed via NFS. (See the <c...
    Group
  • Export Filesystems Read-Only if Possible

    If a filesystem is being exported so that users can view the files in a convenient fashion, but there is no need for users to edit those files, exp...
    Group
  • Use Access Lists to Enforce Authorization Restrictions

    When configuring NFS exports, ensure that each export line in <code>/etc/exports</code> contains a list of hosts which are allowed to access that e...
    Group
  • Network Time Protocol

    The Network Time Protocol is used to manage the system clock over a network. Computer clocks are not very accurate, so time will drift unpredictabl...
    Group

The content of the drawer really is up to you. It could have form fields, definition lists, text lists, labels, charts, progress bars, etc. Spacing recommendation is 24px margins. You can put tabs in here, and can also make the drawer scrollable.

Capacity
Modules