Как выполнить отладку, если /etc/sudoers не работает?

Моя ошибка:

[root@localhost ~]# systemctl status firewalld
● firewalld.service - firewalld - dynamic firewall daemon
   Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled; vendor preset: enabled)
   Active: inactive (dead) since Mon 2018-12-17 13:38:24 CST; 1min 51s ago
     Docs: man:firewalld(1)
  Process: 6491 ExecStart=/usr/sbin/firewalld --nofork --nopid $FIREWALLD_ARGS (code=exited, status=0/SUCCESS)
 Main PID: 6491 (code=exited, status=0/SUCCESS)

Dec 17 13:38:24 localhost.localdomain systemd[1]: Starting firewalld - dynamic firewall daemon...
Dec 17 13:38:24 localhost.localdomain systemd[1]: Started firewalld - dynamic firewall daemon.
Dec 17 13:38:24 localhost.localdomain firewalld[6491]: WARNING: ipset not usable, disabling ipset usage in firewall.
Dec 17 13:38:24 localhost.localdomain firewalld[6491]: ERROR: Failed to read file "/proc/sys/net/netfilter/nf_conntrack_helper": [Errno …_helper'
Dec 17 13:38:24 localhost.localdomain firewalld[6491]: WARNING: Failed to get and parse nf_conntrack_helper setting
Dec 17 13:38:24 localhost.localdomain firewalld[6491]: WARNING: iptables not usable, disabling IPv4 firewall.
Dec 17 13:38:24 localhost.localdomain firewalld[6491]: WARNING: ip6tables not usable, disabling IPv6 firewall.
Dec 17 13:38:24 localhost.localdomain firewalld[6491]: WARNING: ebtables not usable, disabling ethernet bridge firewall.
Dec 17 13:38:24 localhost.localdomain firewalld[6491]: FATAL ERROR: No IPv4 and IPv6 firewall.
Dec 17 13:38:24 localhost.localdomain firewalld[6491]: ERROR: Raising SystemExit in run_server

[root@localhost ~]# iptables -L -n
iptables v1.4.21: can't initialize iptables table `filter': Table does not exist (do you need to insmod?)
Perhaps iptables or your kernel needs to be upgraded.

Мое решение:

[root@localhost ~]# depmod
[root@localhost ~]# systemctl restart firewalld