Guide to the Secure Configuration of Fedora
Rules, Groups, and Values defined within the XCCDF Benchmark
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Force frequent session key renegotiation
The <code>RekeyLimit</code> parameter specifies how often the session key of the is renegotiated, both in terms of amount of data that may be trans...Rule Medium Severity -
Ensure SSH LoginGraceTime is configured
The <code>LoginGraceTime</code> parameter to the SSH server specifies the time allowed for successful authentication to the SSH server. The longer ...Rule Medium Severity -
Set LogLevel to INFO
The INFO parameter specifices that record login and logout activity will be logged. <br> The default SSH configuration sets the log level to INFO. ...Rule Low Severity -
Set SSH Daemon LogLevel to VERBOSE
The <code>VERBOSE</code> parameter configures the SSH daemon to record login and logout activity. To specify the log level in SSH, add or correct t...Rule Medium Severity -
Set SSH authentication attempt limit
The <code>MaxAuthTries</code> parameter specifies the maximum number of authentication attempts permitted per connection. Once the number of failur...Rule Medium Severity -
Set SSH MaxSessions limit
The <code>MaxSessions</code> parameter specifies the maximum number of open sessions permitted from a given connection. To set MaxSessions edit <co...Rule Medium Severity -
Ensure SSH MaxStartups is configured
The MaxStartups parameter specifies the maximum number of concurrent unauthenticated connections to the SSH daemon. Additional connections will be ...Rule Medium Severity -
Enable Certmap in SSSD
SSSD should be configured to verify the certificate of the user or group. To set this up ensure that section like <code>certmap/testing.test/rule_...Rule Medium Severity -
Distribute the SSH Server configuration to multiple files in a config directory.
Make sure to have the <code>Include /etc/ssh/sshd_config.d/*.conf</code> line in the <code>/etc/ssh/sshd_config</code> file. Ideally, don't have an...Rule Medium Severity -
Enable Use of Privilege Separation
When enabled, SSH will create an unprivileged child process that has the privilege of the authenticated user. To enable privilege separation in SSH...Rule Medium Severity -
SSH server uses strong entropy to seed
To set up SSH server to use entropy from a high-quality source, edit the <code>/etc/sysconfig/sshd</code> file. The <code>SSH_USE_STRONG_RNG</code>...Rule Low Severity -
Prevent remote hosts from connecting to the proxy display
The SSH daemon should prevent remote hosts from connecting to the proxy display. <br> The default SSH configuration for <code>X11UseLocalhost</code...Rule Medium Severity -
Strengthen Firewall Configuration if Possible
If the SSH server is expected to only receive connections from the local network, then strengthen the default firewall rule for the SSH service to ...Group -
System Security Services Daemon
The System Security Services Daemon (SSSD) is a system daemon that provides access to different identity and authentication providers such as Red H...Group -
SSSD certificate_verification option
Value of the certificate_verification option in the SSSD config.Value -
SSSD memcache_timeout option
Value of the memcache_timeout option in the [nss] section of SSSD config /etc/sssd/sssd.conf.Value -
SSSD ssh_known_hosts_timeout option
Value of the ssh_known_hosts_timeout option in the [ssh] section of SSSD configuration file /etc/sssd/sssd.conf.Value -
Install sssd-ipa Package
Thesssd-ipapackage can be installed with the following command:$ sudo dnf install sssd-ipa
Rule Medium Severity -
Enable the SSSD Service
The SSSD service should be enabled. The <code>sssd</code> service can be enabled with the following command: <pre>$ sudo systemctl enable sssd.ser...Rule Medium Severity -
Certificate status checking in SSSD
Multifactor solutions that require devices separate from information systems gaining access include, for example, hardware tokens providing time-ba...Rule Medium Severity -
Enable Smartcards in SSSD
SSSD should be configured to authenticate access to the system using smart cards. To enable smart cards in SSSD, set <code>pam_cert_auth</code> to ...Rule Medium Severity -
Configure SSSD's Memory Cache to Expire
SSSD's memory cache should be configured to set to expire records after <code><xccdf-1.2:sub idref="xccdf_org.ssgproject.content_value_var_sssd_mem...Rule Medium Severity -
Configure SSSD to Expire Offline Credentials
SSSD should be configured to expire offline credentials after 1 day. To configure SSSD to expire offline credentials, set <code>offline_credential...Rule Medium Severity -
Configure SSSD to run as user sssd
SSSD processes should be configured to run as user sssd, not root.Rule Medium Severity -
Configure SSSD to Expire SSH Known Hosts
SSSD should be configured to expire keys from known SSH hosts after <code><xccdf-1.2:sub idref="xccdf_org.ssgproject.content_value_var_sssd_ssh_kno...Rule Medium Severity -
System Security Services Daemon (SSSD) - LDAP
The System Security Services Daemon (SSSD) is a system daemon that provides access to different identity and authentication providers such as Red H...Group -
SSSD LDAP Backend Client CA Certificate Location
Path of a directory that contains Certificate Authority certificates.Value -
USBGuard daemon
The USBGuard daemon enforces the USB device authorization policy for all USB devices.Group -
Install usbguard Package
Theusbguardpackage can be installed with the following command:$ sudo dnf install usbguard
Rule Medium Severity -
Enable the USBGuard Service
The USBGuard service should be enabled. The <code>usbguard</code> service can be enabled with the following command: <pre>$ sudo systemctl enable ...Rule Medium Severity -
Log USBGuard daemon audit events using Linux Audit
To configure USBGuard daemon to log via Linux Audit (as opposed directly to a file), <code>AuditBackend</code> option in <code>/etc/usbguard/usbgua...Rule Low Severity -
Authorize Human Interface Devices in USBGuard daemon
To allow authorization of Human Interface Devices (keyboard, mouse) by USBGuard daemon, add the line <code>allow with-interface match-all { 03:*:* ...Rule Medium Severity -
Root Shell Environment Assumed
Most of the actions listed in this document are written with the assumption that they will be executed by the root user running the <code>/bin/bash...Group -
Remove the X Windows Package Group
By removing the xorg-x11-server-common package, the system no longer has X Windows installed. If X Windows is not installed then the system cannot ...Rule Medium Severity -
Disable X Windows Startup By Setting Default Target
Systems that do not require a graphical user interface should only boot by default into <code>multi-user.target</code> mode. This prevents accident...Rule Medium Severity -
Introduction
The purpose of this guidance is to provide security configuration recommendations and baselines for the Fedora operating system. Recommended settin...Group -
General Principles
The following general principles motivate much of the advice in this guide and should also influence any configuration decisions that are not expli...Group -
Encrypt Transmitted Data Whenever Possible
Data transmitted over a network, whether wired or wireless, is susceptible to passive monitoring. Whenever practical solutions for encrypting such ...Group -
Least Privilege
Grant the least privilege necessary for user accounts and software to perform tasks. For example, <code>sudo</code> can be implemented to limit aut...Group -
Minimize Software to Minimize Vulnerability
The simplest way to avoid vulnerabilities in software is to avoid installing that software. On Fedora,the RPM Package Manager (originally Red Hat P...Group -
Run Different Network Services on Separate Systems
Whenever possible, a server should be dedicated to serving exactly one network service. This limits the number of other services that can be compro...Group -
Configure Security Tools to Improve System Robustness
Several tools exist which can be effectively used to improve a system's resistance to and detection of unknown attacks. These tools can improve rob...Group -
How to Use This Guide
Readers should heed the following points when using the guide.Group -
Formatting Conventions
Commands intended for shell execution, as well as configuration file text, are featured in a <code>monospace font</code>. <i>Italics</i> are used t...Group -
Read Sections Completely and in Order
Each section may build on information and recommendations discussed in prior sections. Each section should be read and understood completely; instr...Group -
Verify File Hashes with RPM
Without cryptographic integrity protections, system executables and files can be altered by unauthorized users without detection. The RPM package m...Rule High Severity -
Verify and Correct File Permissions with RPM
The RPM package management system can check file access permissions of installed software packages, including many that are important to system sec...Rule High Severity -
Configure SSH Client to Use FIPS 140-2 Validated MACs: openssh.config
Crypto Policies provide a centralized control over crypto algorithms usage of many packages. OpenSSH is supported by system crypto policy, but the ...Rule Medium Severity -
Ensure /dev/shm is configured
The <code>/dev/shm</code> is a traditional shared memory concept. One program will create a memory portion, which other processes (if permitted) ca...Rule Low Severity -
Install cryptsetup Package
Thecryptsetuppackage can be installed with the following command:$ sudo dnf install cryptsetup
Rule Medium Severity
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