服务端会定期发送探测报文来检测客户端的存活状态。
由三个内核参数控制：
-
首次发送探测报文时间：
net.ipv4.tcp_keepalive_time有报文传输时重置 -
探测报文的发送间隔：
net.ipv4.tcp_keepalive_intvl -
探测报文的最大重试次数：
net.ipv4.tcp_keepalive_probes
# sysctl -a | grep tcp_keepalive_
net.ipv4.tcp_keepalive_intvl = 75
net.ipv4.tcp_keepalive_probes = 9
net.ipv4.tcp_keepalive_time = 7200