What were you trying to do that didn't work?

When test iptables -j TRACE,
I noticed that xtables-monitor report error message:
 
ip netns exec S bash -c "ip6tables -t raw -A PREROUTING -i s_c -p tcp --dport 9999 -j TRACE"
xtables-monitor 1.8.10
ip netns exec S bash -c "stdbuf -oL xtables-monitor -t > trace.log &"
ip netns exec S bash -c "ncat -6 -l 2001:db8:ffff:11::1 9999 &"
ip netns exec S bash -c "wait_start ncat"
ip netns exec C bash -c "ncat -w 1 -6 2001:db8:ffff:11::1 9999 <<<abc"
abc
Error: unsupported layer 4 protocol value
xtables-monitor v1.8.10 (nf_tables): Parsing nftables rule failed
Perhaps xtables-monitor or your kernel needs to be upgraded.

Please provide the package NVR for which bug is seen:

iptables-nft-1.8.10-2.el9.x86_64

How reproducible:

always

Steps to reproduce

1. https://gitlab.cee.redhat.com/kernel-qe/kernel/-/blob/master/networking/firewall/netfilter/xtables/ip6tables/target/tg_TRACEv6.sh
2.  
3.  

Expected results

Actual results