TCP Connect Timeout (Server Side)

Introduction

The tcp_synack_retries variable. Since Linux 2.2.

The maximum number of times a SYN/ACK segment for a passive TCP connection will be retransmitted. This number should not be higher than 255. See tcp_synack_retries - Debian Manpages

OS Configuration

$ cat /proc/sys/net/ipv4/tcp_synack_retries
5
$ sysctl net.ipv4.tcp_synack_retries
net.ipv4.tcp_synack_retries = 5

sysctl -w net.ipv4.tcp_synack_retries = 2

// linux kernel 2.6.32
icsk->icsk_rto = min(icsk->icsk_rto << 1, TCP_RTO_MAX)

timeout = 1
while tcp_synack_retries:
    tcp_synack_retries -= 1
    timeout += 2 ** (tcp_synack_retries - r)
return timeout

Python Examples or Recipes

References