Guide to the Secure Configuration of Red Hat Enterprise Linux 7
Rules, Groups, and Values defined within the XCCDF Benchmark
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Enable syslog-ng Service
The <code>syslog-ng</code> service (in replacement of rsyslog) provides syslog-style logging by default on Debian. The <code>syslog-ng</code> serv...Rule Medium Severity -
Ensure Proper Configuration of Log Files
The file <code>/etc/rsyslog.conf</code> controls where log message are written. These are controlled by lines called <i>rules</i>, which consist of...Group -
User who owns log files
Specify user owner of all logfiles specified in/etc/rsyslog.conf.Value -
Ensure cron Is Logging To Rsyslog
Cron logging must be implemented to spot intrusions or trace cron job status. If <code>cron</code> is not logging to <code>rsyslog</code>, it can b...Rule Medium Severity -
Ensure Rsyslog Authenticates Off-Loaded Audit Records
Rsyslogd is a system utility providing support for message logging. Support for both internet and UNIX domain sockets enables this utility to suppo...Rule Medium Severity -
Ensure Rsyslog Encrypts Off-Loaded Audit Records
Rsyslogd is a system utility providing support for message logging. Support for both internet and UNIX domain sockets enables this utility to suppo...Rule Medium Severity -
Ensure Rsyslog Encrypts Off-Loaded Audit Records
Rsyslogd is a system utility providing support for message logging. Support for both internet and UNIX domain sockets enables this utility to suppo...Rule Medium Severity -
Ensure Log Files Are Owned By Appropriate User
The owner of all log files written by <code>rsyslog</code> should be <code>root</code>. These log files are determined by the second part of each...Rule Medium Severity -
Enable rsyslog to Accept Messages via TCP, if Acting As Log Server
The <code>rsyslog</code> daemon should not accept remote messages unless the system acts as a log server. If the system needs to act as a central l...Rule Unknown Severity -
Ensure System Log Files Have Correct Permissions
The file permissions for all log files written by <code>rsyslog</code> should be set to 640, or more restrictive. These log files are determined by...Rule Medium Severity -
Ensure logging is configured
The <code>/etc/rsyslog.conf</code> and <code>/etc/rsyslog.d/*.conf</code> files specifies rules for logging and which files are to be used to log c...Rule Medium Severity -
systemd-journald
systemd-journald is a system service that collects and stores logging data. It creates and maintains structured, indexed journals based on logging ...Group -
Enable systemd-journald Service
The <code>systemd-journald</code> service is an essential component of systemd. The <code>systemd-journald</code> service can be enabled with the ...Rule Medium Severity -
Ensure journald is configured to compress large log files
The journald system can compress large log files to avoid fill the system disk.Rule Medium Severity -
Ensure journald is configured to send logs to rsyslog
Data from journald may be stored in volatile memory or persisted locally. Utilities exist to accept remote export of journald logs.Rule Medium Severity -
Ensure journald is configured to write log files to persistent disk
The journald system may store log files in volatile memory or locally on disk. If the logs are only stored in volatile memory they will we lost upo...Rule Medium Severity -
Ensure All Logs are Rotated by logrotate
Edit the file <code>/etc/logrotate.d/syslog</code>. Find the first line, which should look like this (wrapped for clarity): <pre>/var/log/message...Group -
Ensure logrotate is Installed
logrotate is installed by default. The <code>logrotate</code> package can be installed with the following command: <pre> $ sudo yum install logrota...Rule Medium Severity -
Ensure Logrotate Runs Periodically
The <code>logrotate</code> utility allows for the automatic rotation of log files. The frequency of rotation is specified in <code>/etc/logrotate....Rule Medium Severity -
Enable logrotate Timer
Thelogrotatetimer can be enabled with the following command:$ sudo systemctl enable logrotate.timer
Rule Medium Severity -
Configure rsyslogd to Accept Remote Messages If Acting as a Log Server
By default, <code>rsyslog</code> does not listen over the network for log messages. If needed, modules can be enabled to allow the rsyslog daemon t...Group -
net.ipv4.icmp_ignore_bogus_error_responses
Enable to prevent unnecessary loggingValue -
Enable rsyslog to Accept Messages via UDP, if Acting As Log Server
The <code>rsyslog</code> daemon should not accept remote messages unless the system acts as a log server. If the system needs to act as a central l...Rule Unknown Severity -
Ensure rsyslog Does Not Accept Remote Messages Unless Acting As Log Server
The <code>rsyslog</code> daemon should not accept remote messages unless the system acts as a log server. To ensure that it is not listening on the...Rule Medium Severity -
Rsyslog Logs Sent To Remote Host
If system logs are to be useful in detecting malicious activities, it is necessary to send logs to a remote server. An intruder who has compromised...Group -
Remote Log Server
Specify an URI or IP address of a remote host where the log messages will be sent and stored.Value -
Ensure Logs Sent To Remote Host
To configure rsyslog to send logs to a remote log server, open <code>/etc/rsyslog.conf</code> and read and understand the last section of the file,...Rule Medium Severity -
Configure TLS for rsyslog remote logging
Configure <code>rsyslog</code> to use Transport Layer Security (TLS) support for logging to remote server for the Forwarding Output Module in <code...Rule Medium Severity -
Configure CA certificate for rsyslog remote logging
Configure CA certificate for <code>rsyslog</code> logging to remote server using Transport Layer Security (TLS) using correct path for the <code>De...Rule Medium Severity -
Network Configuration and Firewalls
Most systems must be connected to a network of some sort, and this brings with it the substantial risk of network attack. This section discusses th...Group -
net.ipv4.tcp_invalid_ratelimit
Configure the maximal rate for sending duplicate acknowledgments in response to incoming invalid TCP packets.Value -
net.ipv4.tcp_rfc1337
Enable to enable TCP behavior conformant with RFC 1337Value -
Configure Multiple DNS Servers in /etc/resolv.conf
Determine whether the system is using local or DNS name resolution with the following command: <pre>$ sudo grep hosts /etc/nsswitch.conf hosts: fi...Rule Medium Severity -
Disable Client Dynamic DNS Updates
Dynamic DNS allows clients to dynamically update their own DNS records. The updates are transmitted by unencrypted means which can reveal informati...Rule Medium Severity -
Disable Zeroconf Networking
Zeroconf networking allows the system to assign itself an IP address and engage in IP communication without a statically-assigned address or even a...Rule Unknown Severity -
Prevent non-Privileged Users from Modifying Network Interfaces using nmcli
By default, non-privileged users are given permissions to modify networking interfaces and configurations using the <code>nmcli</code> command. Non...Rule Medium Severity -
Ensure System is Not Acting as a Network Sniffer
The system should not be acting as a network sniffer, which can capture all traffic on the network to which it is connected. Run the following to d...Rule Medium Severity -
firewalld
The dynamic firewall daemon <code>firewalld</code> provides a dynamically managed firewall with support for network “zones” to assign a level of tr...Group -
Ensure network interfaces are assigned to appropriate zone
Firewall zones define the trust level of network connections or interfaces. Note: Changing firewall settings while connected over network can resul...Rule Medium Severity -
Inspect and Activate Default firewalld Rules
Firewalls can be used to separate networks into different zones based on the level of trust the user has decided to place on the devices and traffi...Group -
net.ipv4.tcp_syncookies
Enable to turn on TCP SYN Cookie ProtectionValue -
Install firewalld Package
Thefirewalldpackage can be installed with the following command:$ sudo yum install firewalld
Rule Medium Severity -
Verify firewalld Enabled
Thefirewalldservice can be enabled with the following command:$ sudo systemctl enable firewalld.service
Rule Medium Severity -
Strengthen the Default Ruleset
The default rules can be strengthened. The system scripts that activate the firewall rules expect them to be defined in configuration files under t...Group -
Configure the Firewalld Ports
Configure the <code>firewalld</code> ports to allow approved services to have access to the system. To configure <code>firewalld</code> to open por...Rule Medium Severity -
Configure firewalld To Rate Limit Connections
Create a direct firewall rule to protect against DoS attacks with the following command: <pre>$ sudo firewall-cmd --permanent --direct --add-rule i...Rule Medium Severity -
Set Default firewalld Zone for Incoming Packets
To set the default zone to <code>drop</code> for the built-in default zone which processes incoming IPv4 and IPv6 packets, modify the following lin...Rule Medium Severity -
IPSec Support
Support for Internet Protocol Security (IPsec) is provided with Libreswan.Group -
Install libreswan Package
The libreswan package provides an implementation of IPsec and IKE, which permits the creation of secure tunnels over untrusted networks. The <code>...Rule Medium Severity -
Verify Any Configured IPSec Tunnel Connections
Libreswan provides an implementation of IPsec and IKE, which permits the creation of secure tunnels over untrusted networks. As such, IPsec can be ...Rule Medium Severity
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