> suggest how to do it only for outbound tcp6 handshakes too. Here you go: ip6tables -A OUTPUT -t mangle -m multiport -o eth0 --protocol tcp \

> suggest how to do it only for outbound tcp6 handshakes too. Here you go: ip6tables -A OUTPUT -t mangle -m multiport -o eth0 --protocol tcp \ --tcp-flags ALL SYN --dports 80,8080,443 -j MARK --set-mark 6 tc qdisc del dev eth0 root tc qdisc add dev eth0 root handle 1: htb default 1 tc class add dev eth0 parent 1: classid 1:6 htb rate 10000Mbps tc qdisc add dev eth0 parent 1:6 handle 6: netem delay 100ms tc filter add dev eth0 protocol ipv6 prio 1 handle 6 fw flowid 1:6 Although, I would personally throw in an extra class to add 200ms delay to legacy IP protocol: iptables -A OUTPUT -t mangle -o eth0 -j MARK --set-mark 4 ip6tables -A OUTPUT -t mangle -o eth0 -m multiport --protocol tcp \ --tcp-flags ALL SYN --dports 80,8080,443 -j MARK --set-mark 6 tc qdisc del dev eth0 root tc qdisc add dev eth0 root handle 1: htb default 1 tc class add dev eth0 parent 1: classid 1:4 htb rate 10000Mbps tc class add dev eth0 parent 1: classid 1:6 htb rate 10000Mbps tc qdisc add dev eth0 parent 1:4 handle 4: netem delay 200ms tc qdisc add dev eth0 parent 1:6 handle 6: netem delay 100ms tc filter add dev eth0 protocol ip prio 4 handle 4 fw flowid 1:4 tc filter add dev eth0 protocol ipv6 prio 6 handle 6 fw flowid 1:6 ...just to be compliant with draft-howard-sunset4-v4historic-00 once it becomes RFC.