Question:
I want to classify/match packets in OVS based on some TCP options, this is currently not supported by OVS but it is supported by netfilter. The support for ConnTrack left me wondering if I could use netfilter to match that field and then use the result of that in OVS.
Answer:
There's no native integration, but I could imagine that if Netfilter ran on the packets first then modified the skb mark field, then OVS ran later on that packet then plausibly you could match on the pkt_mark.