Guide to the Secure Configuration of Red Hat Enterprise Linux CoreOS 4
Rules, Groups, and Values defined within the XCCDF Benchmark
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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.ssgproject.content_value_var_postfix_root_mail_ali...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 "root". <pre>$ sudo grep "postmaster:\s*root$" /etc/al...Rule Medium Severity -
Configure System to Forward All Mail through a specific host
Set up a relay host that will act as a gateway for all outbound email. Edit the file <code>/etc/postfix/main.cf</code> to ensure that only the following <code>relayhost</code> line appears: <pre>re...Rule Medium Severity -
Rlogin, Rsh, and Rexec
The Berkeley r-commands are legacy services which allow cleartext remote access and have an insecure trust model.Group -
Disable netfs if Possible
To determine if any network filesystems handled by netfs are currently mounted on the system execute the following command: <pre>$ mount -t nfs,nfs4,smbfs,cifs,ncpfs</pre> If the command did not re...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</code> option from the file <code>/etc/exports</co...Rule Low Severity -
Remove Rsh Trust Files
The files <code>/etc/hosts.equiv</code> and <code>~/.rhosts</code> (in each user's home directory) list remote hosts and users that are trusted by the local system when using the rshd daemon. To re...Rule High Severity -
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 unpredictably on unmanaged systems. Central time protocols can...Group -
Vendor Approved Time Servers
The list of vendor-approved time serversValue -
Maximum NTP or Chrony Poll
The maximum NTP or Chrony poll interval number in seconds specified as a power of two.Value -
Install the ntp service
The ntpd service should be installed.Rule High Severity -
Disable chrony daemon from acting as server
The <code>port</code> option in <code>/etc/chrony.conf</code> can be set to <code>0</code> to make chrony daemon to never open any listening port for server operation and to operate strictly in a c...Rule Low Severity -
Disable network management of chrony daemon
Thecmdport
option in/etc/chrony.conf
can be set to0
to stop chrony daemon from listening on the UDP port 323 for management connections made by chronyc.Rule Low Severity -
Configure Time Service Maxpoll Interval
The <code>maxpoll</code> should be configured to <xccdf-1.2:sub idref="xccdf_org.ssgproject.content_value_var_time_service_set_maxpoll" use="legacy"></xccdf-1.2:sub> in <code>/etc/ntp.conf</code> o...Rule Medium Severity -
Specify a Remote NTP Server
Depending on specific functional requirements of a concrete production environment, the Red Hat Enterprise Linux CoreOS 4 system can be configured to utilize the services of the <code>chronyd</code...Rule Medium Severity -
Ensure Chrony is only configured with the server directive
Check that Chrony only has time sources configured with theserver
directive.Rule Medium Severity -
Specify Additional Remote NTP Servers
Additional NTP servers can be specified for time synchronization in the file <code>/etc/ntp.conf</code>. To do so, add additional lines of the following form, substituting the IP address or hostna...Rule Unknown Severity -
Specify a Remote NTP Server
To specify a remote NTP server for time synchronization, edit the file <code>/etc/ntp.conf</code>. Add or correct the following lines, substituting the IP or hostname of a remote NTP server for <em...Rule Medium Severity
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