linux: OpenVz: docker: iptables nat issue: iptables v1.8.7 (legacy): can't initialize iptables table `nat': Table does not exist (do you need to insmod?)

 >PROBLEM

Common scenarios:

1. Docker installation fails on Linux distributions,

 or  

2. Attempt to run "iptables -t nat -L -n" command fails.

Both scenarios return the same message:

iptables v1.8.7 (legacy): can't initialize iptables table `nat': Table does not exist (do you need to insmod?)
Perhaps iptables or your kernel needs to be upgraded.

Reason:

Docker uses iptables during installations where the S.O. has this firewall command by default.

>SOLUTION

Make sure that is the case by running the following command:

iptables -t nat -L -n

If it fails, there are two main possibilities.
Choose first the easier one.

- If using a cloud hosting, check with the support service to "enable NatFilter".

or

- Maybe a system upgrade is required, sometimes even the kernel.

A successful test, when the NatFilter is enabled shall return something like this:

$ iptables -t nat -L -n

Chain PREROUTING (policy ACCEPT)

target     prot opt source               destination

Chain INPUT (policy ACCEPT)

target     prot opt source               destination

Chain OUTPUT (policy ACCEPT)

target     prot opt source               destination

Chain POSTROUTING (policy ACCEPT)

target     prot opt source               destination

>ENV

cloud hosting

OpenVz/debian 9-11/Ubunto18-22

MYREF: 
y;faq-iptables v1.8.7 (legacy): can't initialize iptables table `nat': Table does not exist (do you need to insmod?)<memo<linux;.