centos阻挡洪水攻击

发表于 更新于 分类于

缩短SYN-Timeout时间:

1
2
iptables -A FORWARD -p tcp –syn -m limit –limit 1/s -j ACCEPT
iptables -A INPUT -i eth0 -m limit –limit 1/sec –limit-burst 5 -j ACCEPT

每秒最多3个syn封包进入表达为:

1
2
3
4
iptables -N syn-flood
iptables -A INPUT -p tcp –syn -j syn-flood
iptables -A syn-flood -p tcp –syn -m limit –limit 1/s –limit-burst 3 -j RETURN
iptables -A syn-flood -j REJECT

设置syncookies:

1
2
3
4
5
6
7
8
sysctl -w net.ipv4.tcp_syncookies=1
sysctl -w net.ipv4.tcp_max_syn_backlog=3072
sysctl -w net.ipv4.tcp_synack_retries=0
sysctl -w net.ipv4.tcp_syn_retries=0
sysctl -w net.ipv4.conf.all.send_redirects=0
sysctl -w net.ipv4.conf.all.accept_redirects=0
sysctl -w net.ipv4.conf.all.forwarding=0
sysctl -w net.ipv4.icmp_echo_ignore_broadcasts=1

防止PING:

1
sysctl -w net.ipv4.icmp_echo_ignore_all=1

拦截具体IP范围:

1
iptables -A INPUT -s 10.0.0.0/8 -i eth0 -j Drop