iptables v1.4.14: can't initialize iptables table `nat': Table does not exist (do you need to insmod?)

I had the same problem with Debian 8. I fixed it by restarting the system. It seems that the error can occur if the kernel image was updated and the system was not restarted thereafter.

I had the same problem and this worked:

sudo modprobe ip_tables
sudo echo 'ip_tables' >> /etc/modules

http://www.howtoforge.com/forums/showthread.php?t=3196

It maybe useful to add that if you're seeing this error message and you're not using some kind of restricted container based hosting (e.g. OpenVZ) then the problem maybe that the kernel is missing the nat modules. To check run:

modinfo iptable_nat

Which should print out the location of the module, if it prints an ERROR then you know that is your problem. There are also dependent modules like nf_nat which might be missing so you'll have to dig deeper if the iptable_nat module is there but fails. If it is missing you'll need to get another kernel and modules, or if you're rolling your own ensure that the kernel config contains CONFIG_IP_NF_NAT=m (for IPv4 NAT).

For info the relevant kernel module is usually found in one of these locations:

ls /lib/modules/`uname -r`/kernel/net/netfilter/
ls /lib/modules/`uname -r`/kernel/net/ipv4/netfilter/

And if you're running IPv6 also look here:

ls /lib/modules/`uname -r`/kernel/net/ipv6/netfilter/