グループでログイン制御することもできます。
参考情報
https://www.linux.iastate.edu/content/using-pam-kerberos-authentication-and-group-access-control
/etc/pam.d/system-authのサンプル
testgroup以外のユーザーはログインできないようにする
#%PAM-1.0
# This file is auto-generated.
# User changes will be destroyed the next time authconfig is run.
auth required pam_env.so
auth sufficient pam_unix.so nullok try_first_pass
# only allow auth for member of testgroup
auth requisite pam_succeed_if.so user ingroup testgroup
auth requisite pam_succeed_if.so uid >= 500 quiet
# for kerberos
auth sufficient pam_krb5.so use_first_pass
auth required pam_deny.so
account required pam_unix.so broken_shadow
account sufficient pam_localuser.so
account sufficient pam_succeed_if.so uid < 500 quiet
# for kerberos
account [default=bad success=ok user_unknown=ignore] pam_krb5.so
account required pam_permit.so
password requisite pam_cracklib.so try_first_pass retry=3 type=
password sufficient pam_unix.so sha512 shadow nullok try_first_pass use_authtok
# for kerberos
password sufficient pam_krb5.so use_authtok
password required pam_deny.so
session optional pam_keyinit.so revoke
session required pam_limits.so
session [success=1 default=ignore] pam_succeed_if.so service in crond quiet use_uid
session required pam_unix.so
# for kerberos
session optional pam_krb5.soingroupはグループ内のユーザーしかログインできない
notingroupはグループに所属していないユーザーしかログインできない。
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