Guide to the Secure Configuration of Red Hat Enterprise Linux 9
Rules, Groups, and Values defined within the XCCDF Benchmark
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Ensure tftp Daemon Uses Secure Mode
If running the Trivial File Transfer Protocol (TFTP) service is necessary, it should be configured to change its root directory at startup. To do s...Rule Medium Severity -
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 -
Uninstall CUPS Package
Thecups
package can be removed with the following command:$ sudo dnf erase cups
Rule Unknown Severity -
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 -
Uninstall squid Package
Thesquid
package can be removed with the following command:$ sudo dnf erase squid
Rule Unknown Severity -
Disable Squid
Thesquid
service can be disabled with the following command:$ sudo systemctl mask --now squid.service
Rule Unknown Severity -
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 -
Remove the FreeRadius Server Package
The <code>freeradius</code> package should be removed if not in use. Is this system a RADIUS server? If not, remove the package. The <code>freeradi...Rule Low Severity -
Hardware RNG Entropy Gatherer Daemon
The rngd feeds random data from hardware device to kernel random device.Group -
Enable the Hardware RNG Entropy Gatherer Service
The Hardware RNG Entropy Gatherer service should be enabled. The <code>rngd</code> service can be enabled with the following command: <pre>$ sudo ...Rule Low Severity -
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 -
Uninstall quagga Package
Thequagga
package can be removed with the following command:$ sudo dnf erase quagga
Rule Low Severity -
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 -
Install the Samba Common Package
The <code>samba-common</code> package should be installed. The <code>samba-common</code> package can be installed with the following command: <pre>...Rule Medium Severity -
Require Client SMB Packet Signing, if using mount.cifs
Require packet signing of clients who mount Samba shares using the <code>mount.cifs</code> program (e.g., those who specify shares in <code>/etc/fs...Rule Unknown Severity -
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 -
Uninstall Samba Package
Thesamba
package can be removed with the following command:$ sudo dnf erase samba
Rule Unknown Severity -
Disable Samba
Thesmb
service can be disabled with the following command:$ sudo systemctl mask --now smb.service
Rule Low Severity -
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>net-snmp</code> package provides the snmpd service. The <code>net-snmp</code> package can be removed with the following command: <pre> $...Rule Unknown Severity -
Disable snmpd Service
Thesnmpd
service can be disabled with the following command:$ sudo systemctl mask --now snmpd.service
Rule Low 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 -
Ensure SNMP Read Write is disabled
Edit <code>/etc/snmp/snmpd.conf</code>, remove any <code>rwuser</code> entries. Once the read write users have been removed, restart the SNMP servi...Rule Medium Severity -
Configure SNMP Service to Use Only SNMPv3 or Newer
Edit <code>/etc/snmp/snmpd.conf</code>, removing any references to <code>rocommunity</code>, <code>rwcommunity</code>, or <code>com2sec</code>. Upo...Rule Medium 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 OpenSSH client software
Theopenssh-clients
package can be installed with the following command:$ sudo dnf install openssh-clients
Rule Medium Severity -
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 -
Enable the OpenSSH Service
The SSH server service, sshd, is commonly needed. The <code>sshd</code> service can be enabled with the following command: <pre>$ sudo systemctl e...Rule Medium 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 ...Rule High Severity -
Verify Group Who Owns SSH Server config file
To properly set the group owner of/etc/ssh/sshd_config
, run the command:$ sudo chgrp root /etc/ssh/sshd_config
Rule Medium 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 byssh_keys
group.Rule Medium Severity
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