The macOS system must configure SSHD unused connection timeout to 900.

If SSHD is enabled, it must be configured with unused connection timeout set to 900. This will set the timeout when there are no open channels within a session. Note: /etc/ssh/sshd_config will be automatically modified to its original state following any update or major upgrade to the operating system. Satisfies: SRG-OS-000163-GPOS-00072, SRG-OS-000279-GPOS-00109

Verify the macOS system is configured to set the SSHD unused connection timeout to 900 with the following command: /usr/sbin/sshd -G | /usr/bin/awk '/unusedconnectiontimeout/{print $2}' If the result is not "900", this is a finding.

Configure the macOS system to set the SSHD unused connection timeout to 900 with the following command: include_dir=$(/usr/bin/awk '/^Include/ {print $2}' /etc/ssh/sshd_config | /usr/bin/tr -d '*') if [[ -z $include_dir ]]; then /usr/bin/sed -i.bk "1s/.*/Include \/etc\/ssh\/sshd_config.d\/\*/" /etc/ssh/sshd_config fi /usr/bin/grep -qxF 'unusedconnectiontimeout 900' "${include_dir}01-mscp-sshd.conf" 2>/dev/null || echo "unusedconnectiontimeout 900" >> "${include_dir}01-mscp-sshd.conf" for file in $(ls ${include_dir}); do if [[ "$file" == "100-macos.conf" ]]; then continue fi if [[ "$file" == "01-mscp-sshd.conf" ]]; then break fi /bin/mv ${include_dir}${file} ${include_dir}20-${file} done