Guide to the Secure Configuration of Anolis OS 23
Rules, Groups, and Values defined within the XCCDF Benchmark
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Configure NFS Services to Use Fixed Ports (NFSv3 and NFSv2)
Firewalling should be done at each host and at the border firewalls to protect the NFS daemons from remote access, since NFS servers should never b...Group -
Configure NFS Clients
The steps in this section are appropriate for systems which operate as NFS clients.Group -
Disable NFS Server Daemons
There is no need to run the NFS server daemons <code>nfs</code> and <code>rpcsvcgssd</code> except on a small number of properly secured systems de...Group -
Disable Network File System (nfs)
The Network File System (NFS) service allows remote hosts to mount and interact with shared filesystems on the local system. If the local system is...Rule Unknown Severity -
Mount Remote Filesystems with Restrictive Options
Edit the file <code>/etc/fstab</code>. For each filesystem whose type (column 3) is <code>nfs</code> or <code>nfs4</code>, add the text <code>,node...Group -
Configure NFS Servers
The steps in this section are appropriate for systems which operate as NFS servers.Group -
Ensure All-Squashing Disabled On All Exports
The <code>all_squash</code> maps all uids and gids to an anonymous user. This should be disabled by removing any instances of the <code>all_squash<...Rule Low Severity -
Configure the Exports File Restrictively
Linux's NFS implementation uses the file <code>/etc/exports</code> to control what filesystems and directories may be accessed via NFS. (See the <c...Group -
Export Filesystems Read-Only if Possible
If a filesystem is being exported so that users can view the files in a convenient fashion, but there is no need for users to edit those files, exp...Group -
Use Access Lists to Enforce Authorization Restrictions
When configuring NFS exports, ensure that each export line in <code>/etc/exports</code> contains a list of hosts which are allowed to access that e...Group -
Network Time Protocol
The Network Time Protocol is used to manage the system clock over a network. Computer clocks are not very accurate, so time will drift unpredictabl...Group -
The Chrony package is installed
System time should be synchronized between all systems in an environment. This is typically done by establishing an authoritative time server or se...Rule Medium Severity -
Install the ntp service
The ntpd service should be installed.Rule High Severity -
The Chronyd service is enabled
chrony is a daemon which implements the Network Time Protocol (NTP) is designed to synchronize system clocks across a variety of systems and use a ...Rule Medium 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 -
Ensure rsyncd service is disabled
Thersyncd
service can be disabled with the following command:$ sudo systemctl mask --now rsyncd.service
Rule Medium Severity -
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 -
Disable ypserv Service
The <code>ypserv</code> service, which allows the system to act as a client in a NIS or NIS+ domain, should be disabled. The <code>ypserv</code> s...Rule Medium Severity -
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 -
Disable the CUPS Service
Thecups
service can be disabled with the following command:$ sudo systemctl mask --now cups.service
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 -
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 -
Hardware RNG Entropy Gatherer Daemon
The rngd feeds random data from hardware device to kernel random device.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 -
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 -
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 -
SNMP read-write community string
Specify the SNMP community string used for read-write access.Value -
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
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