[20170504]Linux TCP keepalive timers.txt

--//上午仔细看一些文档,发现实际上netstat命令就有输出,参数--timer或者-o参数.

# netstat -otun
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address               Foreign Address             State       Timer
tcp        0      0 192.168.100.78:60479        192.168.100.78:1521         ESTABLISHED off (0.00/0/0)
tcp        0    224 192.168.100.78:22           192.168.101.6:50855         ESTABLISHED on (0.38/0/0)
tcp        0      0 192.168.100.78:1521         192.168.100.78:60479        ESTABLISHED keepalive (5864.73/0/0)
tcp        0      0 192.168.100.78:22           192.168.101.6:50817         ESTABLISHED keepalive (115.84/0/0)

The interpretation of field is, first field = timer countdown value, second field = no. of retransmissions, third field
= number of keepalive probes sent.

--//参数1记数到0发出请求检查网络.