The SUSE operating system SSH daemon must be configured with a timeout interval.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-77459	SLES-12-030190	SV-92155r1_rule		Medium

Description
Terminating an idle session within a short time period reduces the window of opportunity for unauthorized personnel to take control of a management session enabled on the console or console port that has been left unattended. In addition, quickly terminating an idle session will also free up resources committed by the managed network element. Terminating network connections associated with communications sessions includes, for example, deallocating associated TCP/IP address/port pairs at the SUSE operating system level, and deallocating networking assignments at the application level if multiple application sessions are using a single SUSE operating system-level network connection. This does not mean that the SUSE operating system terminates all sessions or network access; it only ends the inactive session and releases the resources associated with that session. Satisfies: SRG-OS-000126-GPOS-00066, SRG-OS-000163-GPOS-00072, SRG-OS-000279-GPOS-00109

Description

Terminating an idle session within a short time period reduces the window of opportunity for unauthorized personnel to take control of a management session enabled on the console or console port that has been left unattended. In addition, quickly terminating an idle session will also free up resources committed by the managed network element. Terminating network connections associated with communications sessions includes, for example, deallocating associated TCP/IP address/port pairs at the SUSE operating system level, and deallocating networking assignments at the application level if multiple application sessions are using a single SUSE operating system-level network connection. This does not mean that the SUSE operating system terminates all sessions or network access; it only ends the inactive session and releases the resources associated with that session. Satisfies: SRG-OS-000126-GPOS-00066, SRG-OS-000163-GPOS-00072, SRG-OS-000279-GPOS-00109

STIG	Date
SLES 12 Security Technical Implementation Guide	2020-06-30

Details

Check Text ( C-77017r1_chk )
Verify the SUSE operating system SSH daemon is configured to timeout idle sessions. Check that the "ClientAliveInterval" parameter is set to a value of "600" with the following command: # sudo grep -i clientalive /etc/ssh/sshd_config ClientAliveInterval 600 If "ClientAliveInterval" is not set to "600" in "/etc/ssh/sshd_config", this is a finding.

Fix Text (F-84099r1_fix)
Configure the SUSE operating system SSH daemon to timeout idle sessions. Add or modify (to match exactly) the following line in the "/etc/ssh/sshd_config" file: ClientAliveInterval 600 The SSH daemon must be restarted in order for any changes to take effect.