Sequence and Acknowlegement number is very import in TCP protocol. They are used to detect if the packet is out of order or if there are any missing pakcets. The Seq in the SYN packet is called ISN(Initial Sequence Number)

Wireshark will calculate relative sequence nuber = real Seq - ISN ...

• block output sctp packet

iptables -A OUTPUT -p sctp -s 192.168.166.250 -d 192.168.165.86  -j DROP

• block COOKIE_ECHO of sctp

iptables  -A INPUT -i lo -p sctp --dport 10000 --chunk-types  ALL COOKIE_ECHO -j DROP