1// Test SYN/ACK rexmit triggered 3rd ACK duplicate + CE on first data seg 2 3`./defaults.sh 4sysctl -q net.ipv4.tcp_ecn=3 5` 6 7 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3 8 +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0 9 +0 bind(3, ..., ...) = 0 10 +0 listen(3, 1) = 0 11 12 +0 < SEWA 0:0(0) win 32792 <mss 1050,nop,nop,sackOK,nop,wscale 8> 13+.002 > SW. 0:0(0) ack 1 <mss 1460,ECN e1b 1 ceb 0 e0b 1,nop,nop,nop,sackOK,nop,wscale 8> 14 15// SYN/ACK rexmitted => two 3rd ACKs in-flight 16+1.0~+1.1 > SW. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8> 17// Delivered 1st 3rd ACK 18+0.05 < [ect0] W. 1:1(0) ack 1 win 257 <ECN e0b 1 ceb 0 e1b 1,nop> 19+.002 accept(3, ..., ...) = 4 20 21// Duplicate 3rd ACK delivered 22+1.05 < [ect0] W. 1:1(0) ack 1 win 257 <ECN e0b 1 ceb 0 e1b 1,nop> 23 24+0.05 < [ce] EAP. 1:1001(1000) ack 1 win 257 <ECN e0b 1 ceb 0 e1b 1,nop> 25+.002 > [ect0] WA. 1:1(0) ack 1001 <ECN e1b 1 ceb 1000 e0b 1,nop> 26 +0 read(4, ..., 1000) = 1000 27