tcp_syn_retries
Default value is 6, which corresponds to 63 seconds from first SYN packet till the last retransmission with initial RTO of 1 second.
63 seconds is 1+2+4+…+32, but the connection will not time out until another 64 seconds have passed, totaling 127 seconds. In practice, time from the last retransmission to connection timeout varies.
# nc from nmap
time nc -w 200000ms 1.1.1.1 2345
# nc
time nc -w 200 1.1.1.1 2345