Guide to the Secure Configuration of OpenEmbedded
Rules, Groups, and Values defined within the XCCDF Benchmark
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Disable named Service
Thenamed
service can be disabled with the following command:$ sudo systemctl mask --now named.service
Rule Medium Severity -
Isolate DNS from Other Services
This section discusses mechanisms for preventing the DNS server from interfering with other services. This is done both to protect the remainder of...Group -
Run DNS Software in a chroot Jail
Install the <code>bind-chroot</code> package: <pre>$ sudo yum install bind-chroot</pre> Place a valid named.conf file inside the chroot jail: <pre>...Group -
Run DNS Software on Dedicated Servers
Since DNS is a high-risk service which must frequently be made available to the entire Internet, it is strongly recommended that no other services ...Group -
Configure Firewalls to Protect the FTP Server
By default, <code>iptables</code> blocks access to the ports used by the web server. To configure <code>iptables</code> to allow port 21 traffic,...Rule Unknown Severity -
Restrict the Set of Users Allowed to Access FTP
This section describes how to disable non-anonymous (password-based) FTP logins, or, if it is not possible to do this entirely due to legacy applic...Group -
Limit Users Allowed FTP Access if Necessary
If there is a mission-critical reason for users to access their accounts via the insecure FTP protocol, limit the set of users who are allowed this...Rule Unknown Severity -
Use vsftpd to Provide FTP Service if Necessary
If your use-case requires FTP service, install and set-up vsftpd to provide it.Group -
Web Server
The web server is responsible for providing access to content via the HTTP protocol. Web servers represent a significant security risk because: <br...Group -
Disable Apache if Possible
If Apache was installed and activated, but the system does not need to act as a web server, then it should be disabled and removed from the system.Group -
Disable httpd Service
Thehttpd
service can be disabled with the following command:$ sudo systemctl mask --now httpd.service
Rule Unknown Severity -
Disable NGINX if Possible
If NGINX was installed and activated, but the system does not need to act as a web server, then it should be removed from the system.Group -
Install Apache if Necessary
If <code>httpd</code> was not installed and activated, but the system needs to act as a web server, then it should be installed on the system. Foll...Group -
Confirm Minimal Built-in Modules Installed
The default <code>httpd</code> installation minimizes the number of modules that are compiled directly into the binary (<code>core prefork http_cor...Group -
Secure Apache Configuration
The <code>httpd</code> configuration file is <code>/etc/httpd/conf/httpd.conf</code>. Apply the recommendations in the remainder of this section to...Group -
HTTPD Log Level
The setting for LogLevel in /etc/httpd/conf/httpd.confValue -
Maximum KeepAlive Requests for HTTPD
The setting for MaxKeepAliveRequests in httpd.confValue -
Run httpd in a chroot Jail if Practical
Running <code>httpd</code> inside a <code>chroot</code> jail is designed to isolate the web server process to a small section of the filesystem, li...Group -
Restrict File and Directory Access
Minimize access to criticalhttpd
files and directories.Group -
Configure PERL Securely
PERL (Practical Extraction and Report Language) is an interpreted language optimized for scanning arbitrary text files, extracting information from...Group -
Configure PHP Securely
PHP is a widely-used and often misconfigured server-side scripting language. It should be used with caution, but configured appropriately when need...Group -
Directory Restrictions
The Directory tags in the web server configuration file allow finer grained access control for a specified directory. All web directories should be...Group -
Minimize Web Server Loadable Modules
A default installation of <code>httpd</code> includes a plethora of dynamically shared objects (DSO) that are loaded at run-time. Unlike the aforem...Group -
httpd Core Modules
These modules comprise a basic subset of modules that are likely needed for base <code>httpd</code> functionality; ensure they are not commented ou...Group -
Minimize Modules for HTTP Basic Authentication
The following modules are necessary if this web server will provide content that will be restricted by a password. <br><br> Authentication can be p...Group -
Configure SMTP For Mail Clients
This section discusses settings for Postfix in a submission-only e-mail configuration.Group -
Postfix Network Interfaces
The setting for inet_interfaces in /etc/postfix/main.cfValue -
Minimize Configuration Files Included
The <code>Include</code> directive directs <code>httpd</code> to load supplementary configuration files from a provided path. The default configura...Group -
Minimize Various Optional Components
The following modules perform very specific tasks, sometimes providing access to just a few additional directives. If such functionality is not req...Group -
Use Appropriate Modules to Improve httpd's Security
Among the modules available for <code>httpd</code> are several whose use may improve the security of the web server installation. This section reco...Group -
Deploy mod_security
The <code>security</code> module provides an application level firewall for <code>httpd</code>. Following its installation with the base ruleset, s...Group -
Deploy mod_ssl
Because HTTP is a plain text protocol, all traffic is susceptible to passive monitoring. If there is a need for confidentiality, SSL should be conf...Group -
Restrict Web Server Information Leakage
The <code>ServerTokens</code> and <code>ServerSignature</code> directives determine how much information the web server discloses about the configu...Group -
Configure HTTPD-Served Web Content Securely
Running <code>httpd</code> inside a <code>chroot</code> jail is designed to isolate the web server process to a small section of the filesystem, li...Group -
Web Login Banner Verbiage
Enter an appropriate login banner for your organization. Please note that new lines must be expressed by the '\n' character and special characters ...Value -
Use Denial-of-Service Protection Modules
Denial-of-service attacks are difficult to detect and prevent while maintaining acceptable access to authorized users. However, some traffic-shapin...Group -
IMAP and POP3 Server
Dovecot provides IMAP and POP3 services. It is not installed by default. The project page at <a href="http://www.dovecot.org">http://www.dovec...Group -
Configure Dovecot if Necessary
If the system will operate as an IMAP or POP3 server, the dovecot software should be configured securely by following the recommendations below.Group -
Support Only the Necessary Protocols
Dovecot supports the IMAP and POP3 protocols, as well as SSL-protected versions of those protocols. Configure the Dovecot server to support only ...Group -
Disable Cyrus IMAP
If the system does not need to operate as an IMAP or POP3 server, the Cyrus IMAP software should be removed.Group -
Disable Dovecot
If the system does not need to operate as an IMAP or POP3 server, the dovecot software should be disabled and removed.Group -
Disable Dovecot Service
Thedovecot
service can be disabled with the following command:$ sudo systemctl mask --now dovecot.service
Rule Unknown Severity -
Kerberos
The Kerberos protocol is used for authentication across non-secure network. Authentication can happen between various types of principals -- users,...Group -
LDAP
LDAP is a popular directory service, that is, a standardized way of looking up information from a central database. OpenEmbedded includes software ...Group -
389 Directory Server
389 Directory Server is a popular open-source LDAP server for Linux.Group -
Configure OpenLDAP Clients
This section provides information on which security settings are important to configure in OpenLDAP clients by manually editing the appropriate con...Group -
Configure OpenLDAP Server
This section details some security-relevant settings for an OpenLDAP server.Group -
Disable LDAP Server (slapd)
The Lightweight Directory Access Protocol (LDAP) is a service that provides a method for looking up information from a central database.Rule Medium Severity -
Install and Protect LDAP Certificate Files
Create the PKI directory for LDAP certificates if it does not already exist: <pre>$ sudo mkdir /etc/pki/tls/ldap $ sudo chown root:root /etc/pki/tl...Group -
Mail Server Software
Mail servers are used to send and receive email over the network. Mail is a very common service, and Mail Transfer Agents (MTAs) are obvious target...Group
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