iptables: Unknown error 18446744073709551615
ACCEPT all opt -- in eth0 out * 0.0.0.0/0 -> 0.0.0.0/0 ctstate RELATED,ESTABLISHED
Error: iptables command [/sbin/iptables -v -A INPUT -i eth0 -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT] failed, at line 1638
Looks like you have a kernel/iptables issue on your VPS as the state module which we switched csf from to the conntrack module was deprecated some time ago. You could try checking with your VPS provider that they have indeed included the iptables conntrack module, but that error means that they (at the least) need to upgrade the kernel they are using to one that hasn't got a broken conntrack module.
In the meantime, you can work around the problem with:
I'll look at have an exception for the useless Virtuozzo kernels (their iptables implementation is dire) to use the old state module and release a new version shortly.
I have a default OVH kernel that doesn't support connlimit it looks like if you roll out this update most of there dedicated servers wont support CSF with there default custom kernels, I read on there French forum you have to re-compile to enable the module.
You can only upgrade when you have the firewall enabled, but if you are you cannot connect to the update server. If you got stuck (like me) on either 5.76 or 5.77 here is a solution:
Add this line to firewall allow IPs:
85.13.195.235 # Configserver update IP for the .com site
Then wait the timeout it takes to fetch the update, and get it