anchor.diff:  Configure `pam_cracklib.so` and `pam_tally.so`.
   
   ==== 20_cron
  +CCE-27323-5, CCE-80345-2
  +
   Allow `root` to use `cron`. Mask `atd`.
   
   ==== 21_ctraltdel
  +CCE-27511-5
  +
   Disable Ctrl-alt-delete.
   
   ==== 22_auditd
  +CCE-27407-6
  +
   Configure `auditd`, use `$AUDITD_RULES`.
   
   ==== 23_disablemod
  +CCE-27327-6, CCE-27277-3
  +
   Disable `bluetooth` `firewire-core` `n_hdlc` `net-pf-31` `soundcore`
   `thunderbolt` `usb-midi` `usb-storage` kernel modules.
   
   ==== 24_aide
  +CCE-27096-7
  +
   Configure `aide`.
   
   ==== 25_rhosts
  +CCE-27406-8
  +
   Remove `hosts.equiv` and `.rhosts`.
   
   ==== 26_users
  
positive.code: Configure `/tmp/` and `/var/tmp/`. Remove floppy drivers from `/etc/fstab` and add `hidepid=2` to `/proc`.
  
  ==== 09_prelink
  Undo prelinking, and remove `prelink` package.
  
  === 10_aptget
  `apt-get` update and upgrade.
  
  ==== 11_hosts
  `/etc/hosts.allow` and `/etc/hosts.deny` restrictions.
  
  ==== 12_logindefs
  Modify `/etc/login.defs`, e.g. `UMASK`, password age limits and `SHA_CRYPT_MAX_ROUNDS`.
  
  ==== 13_sysctl
  Update `$SYSCTL` with `$SYSCTL_CONF`.
  
  ==== 14_limits
  Set hard and soft limits.
  
  ==== 15_adduser
  
negative.code: Setup script, sets APT flags and permission checks.
  
  ==== 02_firewall
  RHEL-07-040520
  
  Enable `ufw`, use `/etc/sysctl.conf`, and allow port 22 from `$FW_ADMIN`.
  
  ==== 03_disablenet
  CCE-26828-4, CCE-27106-4
  
  Disable `dccp` `sctp` `rds` `tipc` protocols.
  
  ==== 04_disablemnt
  CCE-80137-3, CCE-80138-1, CCE-80139-9, CCE-80140-7, CCE-80141-5, CCE-80142-3, CCE-80143-1
  
  Disable `cramfs` `freevxfs` `jffs2` `hfs` `hfsplus` `squashfs` `udf` `vfat` file systems.
  
  ==== 05_systemdconf
  