// If we close the connection before read()'ing what // the other side sent, a RST will be generated instead // of a FIN. 0.000 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3 0.000 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0 0.000 bind(3, ..., ...) = 0 0.000 listen(3, 1) = 0 0.100 < S 0:0(0) win 32792 0.100 > S. 0:0(0) ack 1 0.200 < . 1:1(0) ack 1 win 257 0.200 accept(3, ..., ...) = 4 // Receive first segment. 0.210 < P. 1:1001(1000) ack 1 win 46 // Send one ACK. 0.210 > . 1:1(0) ack 1001 // Application writes 1000 bytes. 0.250 write(4, ..., 1000) = 1000 0.250 > P. 1:1001(1000) ack 1001 // ACK 0.300 < . 1001:1001(0) ack 1001 win 257 // Client closes the connection. 0.610 < F. 1001:1001(0) ack 1001 win 260 // Respond with (delayed) ACK. 0.650 > . 1001:1001(0) ack 1002 // We close the connection. 0.700 close(4) = 0 // Since we have not read, we generate a RST instead of a FIN // conforming to RFC 1122 section 4.2.2.13. 0.701 > R. 1001:1001(0) ack 1002