Guide to the Secure Configuration of Debian 11
Rules, Groups, and Values defined within the XCCDF Benchmark
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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 -
The Postfix package is installed
A mail server is required for sending emails. Thepostfix
package can be installed with the following command:$ apt-get install postfix
Rule Medium Severity -
Configure SMTP For Mail Clients
This section discusses settings for Postfix in a submission-only e-mail configuration.Group -
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.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 -
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 circumstances under which it is possible to disable NF...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 subsystems required by NFS.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 -
Disable SSH Server If Possible
The SSH server service, sshd, is commonly needed. However, if it can be disabled, do so. This is unusual, as SSH is a common method for encrypted and authenticated remote access.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 -
Install the ntp service
The ntpd service should be installed.Rule High Severity -
The Chronyd service is enabled
chrony is a daemon which implements the Network Time Protocol (NTP) is designed to synchronize system clocks across a variety of systems and use a source that is highly accurate. More information o...Rule Medium Severity -
Enable the NTP Daemon
Thentp
service can be enabled with the following command:$ sudo systemctl enable ntp.service
Rule High Severity -
Ensure Chrony is only configured with the server directive
Check that Chrony only has time sources configured with theserver
directive.Rule Medium Severity -
A remote time server for Chrony is configured
<code>Chrony</code> is a daemon which implements the Network Time Protocol (NTP). It is designed to synchronize system clocks across a variety of systems and use a source that is highly accurate. M...Rule Medium Severity
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