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5.1.9 Ensure sshd Banner is configured

Information

The Banner parameter specifies a file whose contents must be sent to the remote user before authentication is permitted. By default, no banner is displayed.

Banners are used to warn connecting users of the particular site's policy regarding connection. Presenting a warning message prior to the normal user login may assist the prosecution of trespassers on the computer system.

Solution

Edit the /etc/ssh/sshd_config file to set the Banner parameter above any Include and Match entries as follows:

Banner /etc/issue.net

Edit the file being called by the Banner argument with the appropriate contents according to your site policy, remove any instances of \m, \r, \s, \v or references to the OS platform

Example:

# printf '%s\n' "Authorized users only. All activity may be monitored and reported." > "$(sshd -T | awk '$1 == "banner" {print $2}')"

Impact:

Configuring a banner presents a pre-authentication notice to every user before login. Automated SSH clients, scripts, or monitoring that do not expect banner text should be verified to still operate correctly, and the banner content must be maintained in line with organizational policy.

See Also

https://workbench.cisecurity.org/benchmarks/27891

Item Details

Category: CONFIGURATION MANAGEMENT, IDENTIFICATION AND AUTHENTICATION

References: 800-53|CM-1, 800-53|CM-2, 800-53|CM-6, 800-53|CM-7, 800-53|IA-5

Plugin: Unix

Control ID: 78808c00f31f511dee979bf18da61be86b077daed52691b7f5fe87f29b1a65d1