From LinuxBender @ HN
Create /etc/modprobe.d/nf_conntrack.conf:
options nf_conntrack expect_hashsize=256400 hashsize=256400
And then in /etc/sysctl.conf:
# from /etc/sysctl.conf: increase state table limits.
# Requires 1/4 mem to hash table plus 400 overhead because I am the cargo culting king:
# cat /etc/modprobe.d/nf_conntrack.conf
# options nf_conntrack expect_hashsize=256400 hashsize=256400
net.nf_conntrack_max = 1024000