Conntrack invalid packets may cause unexpected and subtle bugs
on esblished connections, because of that we install by default an
iptables rules that drops the packets with this conntrack state.
However, there are network scenarios, specially those that use multihoming
nodes, that may have legit traffic that is detected by conntrack as
invalid, hence these iptables rules are causing problems dropping this
traffic.
An alternative to solve the spurious problems caused by the invalid
connectrack packets is to set the sysctl nf_conntrack_tcp_be_liberal
option, but this is a system wide setting and we don't want kube-proxy
to be opinionated about the whole node networking configuration.
Kube-proxy will only install the DROP rules for invalid conntrack states
if the nf_conntrack_tcp_be_liberal is not set.
Change-Id: I5eb326931ed915f5ae74d210f0a375842b6a790e
933bcc123b