TCP FLAGS
tcpのflagのTYPE別
TCP Flags Continued: CWR + ECE | Catchpoint
to warn senders of congestion in the network thereby avoiding packet drops and retransmissions.
CWR(congestion window reduced) congested
ECE( Explicit Congestion Notification)
TCP Flags: PSH and URG - PacketLife.net
URG(urgent)
PSH(push)
基本的なもの
ACK
SYN
FIN
RST(廃棄する ReSeTする)
tcp 3way handshake
tcpdump の　pcap filter expressionで、特定のFLAGで絞り込む
tcp - How to capture ack or syn packets by Tcpdump? - Server Fault
tcpdump "tcp[tcpflags] & (tcp-syn|tcp-ack) != 0"