1// SPDX-License-Identifier: GPL-2.0 2// 3// Minimal passive open. 4// Peer is first to close. 5 6`./defaults.sh` 7 8 // Open listener socket 9 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3 10 +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0 11 +0 bind(3, ..., ...) = 0 12 +0 listen(3, 1) = 0 13 14 // Incoming connection: passive open: three-way handshake 15 +0 < S 0:0(0) win 65535 <mss 1000,sackOK,nop,nop,nop,wscale 8> 16 +0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8> 17 +0 < . 1:1(0) ack 1 win 257 18 19 // Open connection socket and close listener socket 20 +0 accept(3, ..., ...) = 4 21 +0 close(3) = 0 22 23 // Peer sends data: acknowledge and receive 24 +0 < P. 1:1001(1000) ack 1 win 257 25 +0 > . 1:1(0) ack 1001 26 +0 recv(4, ..., 1000, 0) = 1000 27 28 // Peer initiates connection close 29 +0 < F. 1001:1001(0) ack 1 win 257 30 +.04 > . 1:1(0) ack 1002 31 32 // Local socket also closes its side 33 +0 close(4) = 0 34 +0 > F. 1:1(0) ack 1002 35 +0 < . 1002:1002(0) ack 2 win 257 36