Guide to the Secure Configuration of Debian 11
Rules, Groups, and Values defined within the XCCDF Benchmark
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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 s...Rule Medium Severity -
Obsolete Services
This section discusses a number of network-visible services which have historically caused problems for system security, and for which disabling or...Group -
Xinetd
The <code>xinetd</code> service acts as a dedicated listener for some network services (mostly, obsolete ones) and can be used to provide access co...Group -
NIS
The Network Information Service (NIS), also known as 'Yellow Pages' (YP), and its successor NIS+ have been made obsolete by Kerberos, LDAP, and oth...Group -
Rlogin, Rsh, and Rexec
The Berkeley r-commands are legacy services which allow cleartext remote access and have an insecure trust model.Group -
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 ...Rule High Severity -
Chat/Messaging Services
The talk software makes it possible for users to send and receive messages across systems through a terminal session.Group -
Telnet
The telnet protocol does not provide confidentiality or integrity for information transmitted on the network. This includes authentication informat...Group -
TFTP Server
TFTP is a lightweight version of the FTP protocol which has traditionally been used to configure networking equipment. However, TFTP provides littl...Group -
TFTP server secure directory
Specify the directory which is used by TFTP server as a root directory when running in secure mode.Value -
Print Support
The Common Unix Printing System (CUPS) service provides both local and network printing support. A system running the CUPS service can accept print...Group -
Configure the CUPS Service if Necessary
CUPS provides the ability to easily share local printers with other systems over the network. It does this by allowing systems to share lists of av...Group -
Proxy Server
A proxy server is a very desirable target for a potential adversary because much (or all) sensitive data for a given infrastructure may flow throug...Group -
Disable Squid if Possible
If Squid was installed and activated, but the system does not need to act as a proxy server, then it should be disabled and removed.Group -
Remote Authentication Dial-In User Service (RADIUS)
Remote Authentication Dial-In User Service (RADIUS) is a networking protocol, operating on port 1812 that provides centralized Authentication, Auth...Group -
Hardware RNG Entropy Gatherer Daemon
The rngd feeds random data from hardware device to kernel random device.Group -
Network Routing
A router is a very desirable target for a potential adversary because they fulfill a variety of infrastructure networking roles such as access to ...Group -
Disable Quagga if Possible
If Quagga was installed and activated, but the system does not need to act as a router, then it should be disabled and removed.Group -
Samba(SMB) Microsoft Windows File Sharing Server
When properly configured, the Samba service allows Linux systems to provide file and print sharing to Microsoft Windows systems. There are two soft...Group -
Configure Samba if Necessary
All settings for the Samba daemon can be found in <code>/etc/samba/smb.conf</code>. Settings are divided between a <code>[global]</code> configurat...Group -
Restrict Printer Sharing
By default, Samba utilizes the CUPS printing service to enable printer sharing with Microsoft Windows workstations. If there are no printers on the...Group -
Restrict SMB File Sharing to Configured Networks
Only users with local user accounts will be able to log in to Samba shares by default. Shares can be limited to particular users or network address...Group -
Disable Samba if Possible
Even after the Samba server package has been installed, it will remain disabled. Do not enable this service unless it is absolutely necessary to pr...Group -
SNMP Server
The Simple Network Management Protocol allows administrators to monitor the state of network devices, including computers. Older versions of SNMP w...Group -
Disable SNMP Server if Possible
The system includes an SNMP daemon that allows for its remote monitoring, though it not installed by default. If it was installed and activated but...Group -
Uninstall net-snmp Package
The <code>snmp</code> package provides the snmpd service. The <code>snmp</code> package can be removed with the following command: <pre> $ apt-get...Rule Unknown Severity -
Disable snmpd Service
Thesnmpd
service can be disabled with the following command:$ sudo systemctl mask --now snmpd.service
Rule Low Severity -
Verify Group Ownership on SSH Server Private *_key Key Files
SSH server private keys, files that match the/etc/ssh/*_key
glob, must be group-owned byroot
group.Rule Medium Severity -
Configure SNMP Server if Necessary
If it is necessary to run the snmpd agent on the system, some best practices should be followed to minimize the security risk from the installation...Group -
SNMP read-only community string
Specify the SNMP community string used for read-only access.Value -
SNMP read-write community string
Specify the SNMP community string used for read-write access.Value -
Ensure Default SNMP Password Is Not Used
Edit <code>/etc/snmp/snmpd.conf</code>, remove or change the default community strings of <code>public</code> and <code>private</code>. This profil...Rule High Severity -
SSH Server
The SSH protocol is recommended for remote login and remote file transfer. SSH provides confidentiality and integrity for data exchanged between tw...Group -
SSH enabled firewalld zone
Specify firewalld zone to enable SSH service. This value is used only for remediation purposes.Value -
SSH Approved ciphers by FIPS
Specify the FIPS approved ciphers that are used for data integrity protection by the SSH server.Value -
SSH Approved MACs by FIPS
Specify the FIPS approved MACs (message authentication code) algorithms that are used for data integrity protection by the SSH server.Value -
SSH session Idle time
Specify duration of allowed idle time.Value -
SSH Server Listening Port
Specify port the SSH server is listening.Value -
SSH Max authentication attempts
Specify the maximum number of authentication attempts per connection.Value -
SSH is required to be installed
Specify if the Policy requires SSH to be installed. Used by SSH Rules to determine if SSH should be uninstalled or configured.<br> A value of 0 mea...Value -
SSH Strong KEX by FIPS
Specify the FIPS approved KEXs (Key Exchange Algorithms) algorithms that are used for methods in cryptography by which cryptographic keys are exch...Value -
SSH Max Sessions Count
Specify the maximum number of open sessions permitted.Value -
SSH Max Keep Alive Count
Specify the maximum number of idle message counts before session is terminated.Value -
Install the OpenSSH Server Package
The <code>openssh-server</code> package should be installed. The <code>openssh-server</code> package can be installed with the following command: <...Rule Medium Severity -
Remove the OpenSSH Server Package
The <code>openssh-server</code> package should be removed. The <code>openssh-server</code> package can be removed with the following command: <pre>...Rule Medium Severity -
Verify Group Ownership on SSH Server Public *.pub Key Files
SSH server public keys, files that match the/etc/ssh/*.pub
glob, must be group-owned byroot
group.Rule Medium Severity -
Verify Ownership on SSH Server Private *_key Key Files
SSH server private keys, files that match the/etc/ssh/*_key
glob, must be owned byroot
user.Rule Medium Severity -
Verify Ownership on SSH Server Public *.pub Key Files
SSH server public keys, files that match the/etc/ssh/*.pub
glob, must be owned byroot
user.Rule Medium Severity
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