Unable to manage iptables inside OpenVZ VPS: can't initialize iptables table `nat': Table does not exist

Symptoms

• Unable to manage iptables inside OpenVZ VPS:

  # iptables -t nat -nvL
  iptables v1.4.21: can't initialize iptables table `nat': Table does not exist (do you need to insmod?)
  Perhaps iptables or your kernel needs to be upgraded

• Firewalld is not working inside the VPS as well:

  CONFIG_TEXT: firewalld[472]: ERROR: Failed to load nf_conntrack module: modprobe: ERROR: could not find mo...track'
  modprobe: ERROR: could not insert 'nf_conntrack': Function not implemented

• csf does not start inside the VPS:
  

  CONFIG_TEXT: csf: FASTSTART loading Packet Filter (IPv4)
  Error: FASTSTART: (Packet Filter IPv4) [] [iptables-restore: line 14 failed]. Try restarting csf with FASTSTART disabled, at line 5587

Cause

netfilter is not enabled for the VPS.

Resolution

1. Connect to OpenVZ node via SSH
2. Apply the following article:
   How to enable netfilter module for OpenVZ container in SolusVM?