tcpdumpでDarwinの3way handshakeを観察。
何故か(この場合だと)ack 3947655203が2つ出てるんですが、そういうもの?
sh-3.2# tcpdump -n -S -i lo0 port 80
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on lo0, link-type NULL (BSD loopback), capture size 96 bytes
7:19:00.545638 IP 127.0.0.1.53569 > 127.0.0.1.80: S 3947655202:3947655202(0) win 65535
17:19:00.545680 IP 127.0.0.1.80 > 127.0.0.1.53569: S 1941382651:1941382651(0) ack 3947655203 win 65535
17:19:00.545690 IP 127.0.0.1.53569 > 127.0.0.1.80: . ack 1941382652 win 65535
17:19:00.545698 IP 127.0.0.1.80 > 127.0.0.1.53569: . ack 3947655203 win 65535
