Skip to content

Guide to the Secure Configuration of Red Hat Enterprise Linux 9

Rules, Groups, and Values defined within the XCCDF Benchmark

  • 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
  • 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 dnf instal...
    Rule Medium Severity
  • Uninstall Sendmail Package

    Sendmail is not the default mail transfer agent and is not installed by default. The <code>sendmail</code> package can be removed with the followin...
    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
  • Ensure Mail Transfer Agent is not Listening on any non-loopback Address

    Mail Transfer Agents (MTA), such as sendmail and Postfix, are used to listen for incoming mail and transfer the messages to the appropriate user or...
    Rule Medium 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
  • 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
  • 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
  • Prevent Unrestricted Mail Relaying

    Modify the <pre>/etc/postfix/main.cf</pre> file to restrict client connections to the local network with the following command: <pre>$ sudo postcon...
    Rule Medium Severity
  • 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

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