sysctl -P error solution
Problem Symptom
Modify linux kernel file
#vi /etc/sysctl.conf and execute sysctl -P error
error: “net.bridge.bridge-nf-call-ip6tables” is an unknown key
error: “net.bridge.bridge-nf-call-iptables” is an unknown key
error: “net.bridge.bridge-nf-call-arptables” is an unknown key

Solution:
modprobe bridge
lsmod|grep bridge