I was reading this: https://help.ubuntu.com/community/IptablesHowTo#Allowing_Established_Sessions
It says "If the line above doesn't work, you may be on a castrated VPS whose provider has not made available the extension".
So how do I tell if the extension is actually available and enabled? Just because an extension is listed in the
iptables-extensions manpage doesn't mean it's actually available and enabled, does it?