AlmaLinux OS 9 SSH daemon must not allow Generic Security Service Application Program Interface (GSSAPI) authentication.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-269161	SRG-OS-000364-GPOS-00151	ALMA-09-009370	SV-269161r1050043_rule	2025-02-20	1

Description
GSSAPI authentication is used to provide additional authentication mechanisms to applications. Allowing GSSAPI authentication through SSH exposes the system's GSSAPI to remote hosts, increasing the attack surface of the system.

ℹ️ Check
Verify the SSH daemon does not allow GSSAPI authentication with the following command: $ /usr/sbin/sshd -dd 2>&1 \| awk '/filename/ {print $4}' \| tr -d '\r' \| tr '\n' ' ' \| xargs sudo grep -iH '^\s*gssapiauthentication' gssapiauthentication no If the value is returned as "yes", the returned line is commented out, no output is returned, and the use of GSSAPI authentication has not been documented with the information system security officer (ISSO), this is a finding. If the required value is not set, this is a finding.

ℹ️ Check

Verify the SSH daemon does not allow GSSAPI authentication with the following command: $ /usr/sbin/sshd -dd 2>&1 | awk '/filename/ {print $4}' | tr -d '\r' | tr '\n' ' ' | xargs sudo grep -iH '^\s*gssapiauthentication' gssapiauthentication no If the value is returned as "yes", the returned line is commented out, no output is returned, and the use of GSSAPI authentication has not been documented with the information system security officer (ISSO), this is a finding. If the required value is not set, this is a finding.

✔️ Fix
Configure the SSH daemon to not allow GSSAPI authentication. Add the following line to "/etc/ssh/sshd_config", or uncomment the line and set the value to "no": GSSAPIAuthentication no Alternatively, add the setting to an included file if the line "Include /etc/ssh/sshd_config.d/*.conf" is found at the top of the "/etc/ssh/sshd_config" file: GSSAPIAuthentication no Restart the SSH daemon for the settings to take effect: $ systemctl restart sshd.service

✔️ Fix

Configure the SSH daemon to not allow GSSAPI authentication. Add the following line to "/etc/ssh/sshd_config", or uncomment the line and set the value to "no": GSSAPIAuthentication no Alternatively, add the setting to an included file if the line "Include /etc/ssh/sshd_config.d/*.conf" is found at the top of the "/etc/ssh/sshd_config" file: GSSAPIAuthentication no Restart the SSH daemon for the settings to take effect: $ systemctl restart sshd.service