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5.1.15 Ensure sshd LoginGraceTime is configured

Information

The LoginGraceTime parameter specifies the time allowed for successful authentication to the SSH server. The longer the Grace period is the more open unauthenticated connections can exist. Like other session controls in this section the Grace Period should be limited to appropriate organizational limits to ensure the service is available for needed access.

Setting the LoginGraceTime parameter to a low number will minimize the risk of successful brute force attacks to the SSH server. It will also limit the number of concurrent unauthenticated connections. While the recommended setting is 60 seconds (1 minute), set the number based on site policy.

Solution

Edit the /etc/ssh/sshd_config file to set the LoginGraceTime parameter to 60 seconds or less above any Include entry as follows:

LoginGraceTime 60

Impact:

Reducing LoginGraceTime shortens the window in which a connecting client must complete authentication. On slow or high-latency links, or where interactive multi-factor prompts take time to complete, legitimate users may occasionally exceed a very low grace time and have to reconnect; set the value in line with site policy.

See Also

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

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-6

Plugin: Unix

Control ID: 0136d6339d2957456cff5d24e4872784eef8e8222e7ecb968f26f0bd67a43f0e