Guide to the Secure Configuration of Ubuntu 18.04
Rules, Groups, and Values defined within the XCCDF Benchmark
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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 -
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 Ownership on SSH Server Private *_key Key Files
SSH server private keys, files that match the/etc/ssh/*_key
glob, must be group-owned byroot
group.Rule Medium Severity -
Verify Group Ownership on SSH Server Public *.pub Key Files
SSH server public keys, files that match the/etc/ssh/*.pub
glob, must be group-owned byroot
group.Rule Medium Severity -
Verify Ownership on SSH Server Private *_key Key Files
SSH server private keys, files that match the/etc/ssh/*_key
glob, must be owned byroot
user.Rule Medium Severity -
Verify Ownership on SSH Server Public *.pub Key Files
SSH server public keys, files that match the/etc/ssh/*.pub
glob, must be owned byroot
user.Rule Medium Severity -
Verify Permissions on SSH Server Private *_key Key Files
SSH server private keys - files that match the <code>/etc/ssh/*_key</code> glob, have to have restricted permissions. If those files are owned by t...Rule Medium Severity -
Verify Permissions on SSH Server Public *.pub Key Files
To properly set the permissions of/etc/ssh/*.pub
, run the command:$ sudo chmod 0644 /etc/ssh/*.pub
Rule Medium Severity -
Remove SSH Server iptables Firewall exception (Unusual)
By default, inbound connections to SSH's port are allowed. If the SSH server is not being used, this exception should be removed from the firewall ...Rule Unknown Severity -
Configure OpenSSH Client if Necessary
The following configuration changes apply to the SSH client. They can improve security parameters relwevant to the client user, e.g. increasing ent...Group -
Configure OpenSSH Server if Necessary
If the system needs to act as an SSH server, then certain changes should be made to the OpenSSH daemon configuration file <code>/etc/ssh/sshd_confi...Group -
Set SSH Client Alive Count Max to zero
The SSH server sends at most <code>ClientAliveCountMax</code> messages during a SSH session and waits for a response from the SSH client. The optio...Rule Medium Severity -
Set SSH Client Alive Count Max
The SSH server sends at most <code>ClientAliveCountMax</code> messages during a SSH session and waits for a response from the SSH client. The optio...Rule Medium Severity -
Set SSH Client Alive Interval
SSH allows administrators to set a network responsiveness timeout interval. After this interval has passed, the unresponsive client will be automat...Rule Medium Severity -
Disable Host-Based Authentication
SSH's cryptographic host-based authentication is more secure than <code>.rhosts</code> authentication. However, it is not recommended that hosts un...Rule Medium Severity -
Allow Only SSH Protocol 2
Only SSH protocol version 2 connections should be permitted. The default setting in <code>/etc/ssh/sshd_config</code> is correct, and can be verifi...Rule High Severity -
Disable Compression Or Set Compression to delayed
Compression is useful for slow network connections over long distances but can cause performance issues on local LANs. If use of compression is req...Rule Medium Severity -
Disable SSH Access via Empty Passwords
Disallow SSH login with empty passwords. The default SSH configuration disables logins with empty passwords. The appropriate configuration is used ...Rule High Severity -
Disable GSSAPI Authentication
Unless needed, SSH should not permit extraneous or unnecessary authentication mechanisms like GSSAPI. <br> The default SSH configuration disallows ...Rule Medium Severity -
Enable SSH Print Last Log
Ensure that SSH will display the date and time of the last successful account logon. <br> The default SSH configuration enables print of the date a...Rule Medium Severity
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