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服务器是centOS4.2 +apache2+php5+mysql4
突然间打开网页非常慢,top一下,发现httpd变成了zombie,查看error日志,提示说child process不存在
用netstat -na一看,发现很多ip的状态是fin-wait,怀疑是遭到了DDOS攻击
于是在/etc/rc.d/rc.local中添加
echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_all
echo 1 >/proc/sys/net/ipv4/tcp_syncookies
echo "1" > /proc/sys/net/ipv4/tcp_syn_retries
echo "1" > /proc/sys/net/ipv4/tcp_synack_retries
echo 2280 >/proc/sys/net/ipv4/tcp_max_syn_backlog
echo 1 >/proc/sys/net/ipv4/tcp_fin_timeout
在iptables里面添加
#防止別人用ACK、SYN、FIN等等的封包來掃瞄
-A RH-Firewall-1-INPUT -i eth0 -p tcp --tcp-flags SYN,FIN SYN,FIN -j DROP
#防止 port scan
# NMAP FIN/URG/PSH
-A RH-Firewall-1-INPUT -i eth0 -p tcp --tcp-flags ALL FIN,URG,PSH -j DROP
# Xmas Tree
-A RH-Firewall-1-INPUT -i eth0 -p tcp --tcp-flags ALL ALL -j DROP
# Another Xmas Tree
-A RH-Firewall-1-INPUT -i eth0 -p tcp --tcp-flags ALL SYN,RST,ACK,FIN,URG -j DROP
# Null Scan(possibly)
-A RH-Firewall-1-INPUT -i eth0 -p tcp --tcp-flags ALL NONE -j DROP
# SYN/RST
-A RH-Firewall-1-INPUT -i eth0 -p tcp --tcp-flags SYN,RST SYN,RST -j DROP
# SYN/FIN -- Scan(possibly)
-A RH-Firewall-1-INPUT -i eth0 -p tcp --tcp-flags SYN,FIN SYN,FIN -j DROP
#阻止空会话继续运行
#-A INPUT -s ! 192.168.0.0/24 -p tcp ! --syn -m state --state NEW -j DROP
-A RH-Firewall-1-INPUT -p tcp ! --syn -m state --state NEW -j DROP
#防止Dos攻击
-A RH-Firewall-1-INPUT -p tcp --dport 80 -m limit --limit 10/second --limit-burst 300 -j ACCEPT
#防止 sync flood 攻擊的設定:
-N synfoold
-A synfoold -p tcp --syn -m limit --limit 1/s -j RETURN
-A synfoold -p tcp -j REJECT --reject-with tcp-reset
-A RH-Firewall-1-INPUT -p tcp -m state --state NEW -j synfoold
-N ping
-A ping -p icmp --icmp-type echo-request -m limit --limit 1/second -j RETURN
-A ping -p icmp -j REJECT
-I RH-Firewall-1-INPUT -p icmp --icmp-type echo-request -m state --state NEW -j ping
重启服务器,发现仍然很慢
请教各位,这到底是怎么一回事?谢谢! |
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