linux tcp ip 協議棧 最佳化

下面為最佳化linux 網路(network tuning )經常提及的參數

setup in /etc/sysctl.conf

# Network tunning
net.ipv4.tcp_fin_timeout = 35
net.ipv4.tcp_keepalive_time = 1800
net.ipv4.tcp_keepalive_intvl = 35
net.ipv4.tcp_tw_recycle = 1

net.ipv4.tcp_tw_reuse = 1

A better explanation:

/proc/sys/net/ipv4/tcp_fin_timeout
Time to hold socket in state FIN-WAIT-2, if it was closed by our side. Peer can be broken and never close its side, or even died unexpectedly. Default value is 60sec. Usual value used in 2.2 was 180 seconds, you may restore it, but remember that if your machine
is even underloaded WEB server, you risk to overflow memory with kilotons of dead sockets, FIN-WAIT-2 sockets are less dangerous than FIN-WAIT-1, because they eat maximum 1.5K of memory, but they tend to live longer. Cf. tcp_max_orphans.

/proc/sys/net/ipv4/tcp_keepalive_time
How often TCP sends out keepalive messages when keepalive is enabled. Default: 2hours.

/proc/sys/net/ipv4/tcp_keepalive_intvl
How frequent probes are retransmitted, when a probe isn't acknowledged. Default: 75 seconds.

/proc/sys/net/ipv4/tcp_tw_recycle
Enable fast recycling TIME-WAIT sockets. Default value is 1. It should not be changed without advice/request of technical experts.

/proc/sys/net/ipv4/tcp_tw_reuse
This allows reusing sockets in TIME_WAIT state for new connections when it is safe from protocol viewpoint. Default value is 0 (disabled). It is generally a safer alternative to tcp_tw_recycle