高并发之网络优化

关闭ipv6

net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1

决定检查过期多久邻居条目

net.ipv4.neigh.default.gc_stale_time=120

使用arp_announce / arp_ignore解决ARP映射问题

net.ipv4.conf.default.arp_announce = 2
net.ipv4.conf.all.arp_announce=2
net.ipv4.conf.lo.arp_announce=2 # 避免放大攻击
net.ipv4.icmp_echo_ignore_broadcasts = 1 # 开启恶意icmp错误消息保护
net.ipv4.icmp_ignore_bogus_error_responses = 1

处理无源路由的包

net.ipv4.conf.all.accept_source_route = 0
net.ipv4.conf.default.accept_source_route = 0

core文件名中添加pid作为扩展名

kernel.core_uses_pid = 1 # 开启SYN洪水攻击保护
net.ipv4.tcp_syncookies = 1

修改消息队列长度

kernel.msgmnb = 65536
kernel.msgmax = 65536

timewait的数量，默认180000

net.ipv4.tcp_max_tw_buckets = 6000
net.ipv4.tcp_sack = 1
net.ipv4.tcp_window_scaling = 1
net.ipv4.tcp_rmem = 4096 87380 4194304
net.ipv4.tcp_wmem = 4096 16384 4194304
net.core.wmem_default = 8388608
net.core.rmem_default = 8388608
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216

限制仅仅是为了防止简单的DoS 攻击

net.ipv4.tcp_max_orphans = 3276800

未收到客户端确认信息的连接请求的最大值

net.ipv4.tcp_max_syn_backlog = 262144
net.ipv4.tcp_timestamps = 0

内核放弃建立连接之前发送SYNACK 包的数量

net.ipv4.tcp_synack_retries = 1

内核放弃建立连接之前发送SYN 包的数量

net.ipv4.tcp_syn_retries = 1

启用timewait 快速回收

net.ipv4.tcp_tw_recycle = 1

开启重用。允许将TIME-WAIT sockets 重新用于新的TCP 连接

net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_mem = 94500000 915000000 927000000
net.ipv4.tcp_fin_timeout = 1

最大文件描述符

ulimit -SHn 1024000 
echo "ulimit -SHn 1024000" >> /etc/rc.d/rc.local 
source /etc/rc.d/rc.local

另外java项目看内存大小设置vm.max_map_count