Debian系统关闭iptables的conntrack跟踪

测试脚本

#!/bin/bash
# /opt/iptables-switch.sh status | disable | enable
ipt_mod_conf="/etc/modprobe.d/iptables.conf"
ipt_mod_list="ip_vs iptable_nat nf_nat_ipv4 ipt_MASQUERADE nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack iptable_filter ip_tables xt_tcpudp xt_multiport xt_length xt_addrtype x_tables"
nf_max=$(sysctl -e -n net.nf_conntrack_max)
nf_cur=$(sysctl -e -n net.netfilter.nf_conntrack_count)
ipt_hsize=$(grep 'MemTotal' /proc/meminfo | awk '{printf("%d",$2/16)}')
fuck_ipt_mod(){
echo '# disable iptables conntrack modules' > ${ipt_mod_conf}
for ipt_mod in ${ipt_mod_list}; do
echo "blacklist ${ipt_mod}" >> ${ipt_mod_conf}
modprobe -r ${ipt_mod}
done
}
clean_ipt_rule(){
iptables -F
iptables -Z
iptables -X
for ipt_table in $(cat /proc/net/ip_tables_names 2>/dev/null); do
iptables -t ${ipt_table} -F
iptables -t ${ipt_table} -Z
iptables -t ${ipt_table} -X
done
iptables -P INPUT ACCEPT
iptables -P OUTPUT ACCEPT
iptables -P FORWARD ACCEPT
}
ipt_enable(){
echo "options nf_conntrack hashsize=${ipt_hsize}" > ${ipt_mod_conf} # /sys/module/nf_conntrack/parameters/hashsize
for ipt_mod in ${ipt_mod_list}; do
modprobe -q -r ${ipt_mod} && modprobe -a ${ipt_mod}
done
dmesg --reltime | grep nf_conntrack | tail -2 2>/dev/null
sysctl -e -w net.nf_conntrack_max=4194304
sysctl -e -w net.ipv4.netfilter.ip_conntrack_max=4194304
sysctl -e -w net.netfilter.nf_conntrack_max=4194304
sysctl -e -w net.netfilter.nf_conntrack_tcp_timeout_established=1200
sysctl -e -w net.netfilter.nf_conntrack_tcp_timeout_close_wait=60
sysctl -e -w net.netfilter.nf_conntrack_tcp_timeout_fin_wait=120
sysctl -e -w net.netfilter.nf_conntrack_tcp_timeout_time_wait=120
}
case "$1" in
status)
if [[ -z ${nf_max} ]]; then
echo 'nf_conntrack disabled.'
else
echo "nf_conntrack used: ${nf_cur}/${nf_max}."
fi
;;
disable)
clean_ipt_rule
fuck_ipt_mod
$0 status
;;
enable)
ipt_enable
$0 status
;;
*)
echo "Usage: $0 {status|disable|enable}"
exit 2
;;
esac
exit 0

开启防火墙

nf_conntrack

/opt/iptables.sh enable
watch -n 1 -d '/opt/iptables.sh status'

施加压力

ssh

watch -n 0.1 -d 'curl -s demo.higkoo.com:22'

故障重现

nf_conntrack_max

sysctl -w net.netfilter.nf_conntrack_max=20

disable

enable

iptables

sudo /opt/iptables.sh status
sudo /opt/iptables.sh enable
sudo /opt/iptables.sh disable