The description of tcp_retries2 in tcp.7 reads:
The default value is 15, which corresponds to a duration of approximately between 13 to 30 minutes, depending on the retransmission timeout.
I'm not a networking expert, but I think this description is outdated. See these kernel commits: https://git.kernel.org/linus/6fa12c85031485df https://git.kernel.org/linus/5d7892298a819743 -- Jakub Wilk
