sysctl: cannot stat /proc/sys/net/ipv4/netfilter/ip_conntrack_max: No such file or directory
Try
net.netfilter.nf_conntrack_max = xxxx
and
net.nf_conntrack_max = xxxxx
instead.
Or maybe ip_conntrack is not loaded. Try:
lsmod |grep conntrack
If this is empty, load it with:
modprobe ip_conntrack
Try the setting net.nf_conntrack_max instead:
# sysctl net.nf_conntrack_max
net.nf_conntrack_max = 262144
Also net.netfilter.nf_conntrack_max:
# sysctl net.netfilter.nf_conntrack_max
net.netfilter.nf_conntrack_max = 262144
(There are various aliases for the same internal value).