TCP Three-Way Handshake & State Machine
Protocol walkthroughProtocol walkthrough of RFC 9293 connection establishment, POSIX socket transitions, and sequence/acknowledgment numbers. State: STUDIED.
Derived state: STUDIED
Handshake RTT14.20 ms
Payload Sizen/a
ProtocolPOSIX
TTLn/a
Socket StateSYN_SENT
ProvenanceRFC 9293 walkthrough
Protocol Execution Trace (Scrubbable Sequence)
00.000 msAppApp invokes socket(AF_INET, SOCK_STREAM, 0)
00.024 msKernelApp invokes connect(fd, 93.184.216.34:443)
00.048 msWireClient transmits [SYN] Seq=1000 Win=65535 MSS=1460
14.210 msWireServer replies [SYN, ACK] Seq=5000 Ack=1001
14.240 msKernelClient sends [ACK] Seq=1001 Ack=5001
14.300 msAppwrite(fd, request) transmits [PSH, ACK]
Active Step: App invokes socket(AF_INET, SOCK_STREAM, 0)POSIX
Kernel allocates file descriptor fd=5 and initializes TCP sock struct (CLOSED)
Wireshark TCP Segment Inspector (Wire Spec / RFC 9293)
Wireshark Segment Hex Dump (TCP SYN)
0000 00 15 5d 01 02 03 00 1c 42 11 22 33 08 00 45 00
0010 00 3c d4 31 40 00 40 06 7c 2a c0 a8 01 64 5d b8
0020 d8 22 d4 31 01 bb 00 00 03 e8 00 00 00 00 a0 02
0030 ff ff 7f 1a 00 00 02 04 05 b4 04 02 08 0a 00 00
Wire Spec Decoded Header
Source / Dest Port:54321 → 443 (HTTPS)
Sequence Number:1000 (Initial Seq Num)
Flags:0x002 (SYN=1, ACK=0)
Window Size:65535 (Window Scale 7)
Options:MSS 1460, SACK Permitted
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