Linux下nf_conntrack（最全面）
總結如下：
dmesg |grep nf_conntrack
連線跟蹤表nf_conntrack：如果輸出值中有“nf_conntrack: table full, dropping packet”，說明伺服器nf_conntrack表已經被打滿
如果伺服器上跑著iptables，必須使用的情況下：
1:高併發伺服器核心調整(8核16G為例，不懂請自行百度)：
net.nf_conntrack_max = 8388608
net.netfilter.nf_conntrack_generic_timeout = 120
net.netfilter.nf_conntrack_tcp_timeout_established = 54000
模版：
net.ipv4.ip_forward = 1
net.ipv4.conf.default.accept_source_route = 0
kernel.sysrq = 0
kernel.core_uses_pid = 1
net.bridge.bridge-nf-call-ip6tables = 0
net.bridge.bridge-nf-call-iptables = 0
net.bridge.bridge-nf-call-arptables = 0
kernel.msgmnb = 65536
kernel.msgmax = 65536
kernel.shmmax = 68719476736
kernel.shmall = 4294967296
vm.swappiness = 0
net.ipv4.tcp_fin_timeout = 10
net.ipv4.tcp_keepalive_time = 1200
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_tw_recycle = 1
net.ipv4.neigh.default.gc_stale_time=120
net.ipv4.conf.all.rp_filter=0
net.ipv4.conf.default.rp_filter=0
net.ipv4.conf.default.arp_announce = 2
net.ipv4.conf.all.arp_announce=2
net.ipv4.tcp_max_tw_buckets = 90000
net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_max_syn_backlog = 2048
net.ipv4.tcp_synack_retries = 2
net.ipv4.conf.lo.arp_announce=2
net.nf_conntrack_max = 8388608
net.netfilter.nf_conntrack_generic_timeout = 120
net.netfilter.nf_conntrack_tcp_timeout_established = 54000
其他：
net.ipv4.ip_local_port_range = 10000 65000
net.core.somaxconn = 262144
*raw表下：
-A PREROUTING -p tcp -m tcp --dport 80 -j NOTRACK
-A OUTPUT -p tcp -m tcp --sport 80 -j NOTRACK
-A PREROUTING -p tcp -m tcp --sport 80 -j NOTRACK
-A OUTPUT -p tcp -m tcp --dport 80 -j NOTRACK
同時修改iptables配置檔案
vim /etc/sysconfig/iptables-config
IPTABLES_MODULES_UNLOAD="no"
二：這種方法比較徹底：直接解除安裝模組