下面iptables规则是我现在用的，是从linode上看来的，然后加了几行从其他地方看来的规则。-A -I 混合在一起，请问这样有问题吗？

*filter

# Allow all loopback (lo0) traffic and drop all traffic to 127/8 that doesn't use lo0
-A INPUT -i lo -j ACCEPT
-A INPUT -d 127.0.0.0/8 -j REJECT

# Accept all established inbound connections
-A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT

# Allow all outbound traffic - you can modify this to only allow certain traffic
-A OUTPUT -j ACCEPT

# Allow HTTP and HTTPS connections from anywhere (the normal ports for websites and SSL).
-A INPUT -p tcp --dport 80 -j ACCEPT
-A INPUT -p tcp --dport 443 -j ACCEPT

# Allow SSH connections
#
# The -dport number should be the same port number you set in sshd_config
#
-A INPUT -p tcp -m state --state NEW --dport 22 -j ACCEPT

# limit 80 port
-I INPUT -p tcp --dport 80 -m connlimit --connlimit-above 20 -j DROP

-I INPUT -p tcp --dport 80 --syn -m recent --name badboy --rcheck --seconds 60 --hitcount 20 -j LOG --log-prefix "DDOS: " --log-ip-options

-I INPUT -p tcp --dport 80 --syn -m recent --name badboy --rcheck --seconds 60 --hitcount 20 -j DROP

-I INPUT -p tcp --dport 80 --syn -m recent --name badboy --set -j ACCEPT

# Allow ping
-A INPUT -p icmp -j ACCEPT

# Log iptables denied calls
-A INPUT -m limit --limit 5/min -j LOG --log-prefix "iptables denied: " --log-level 7

# Drop all other inbound - default deny unless explicitly allowed policy
-A INPUT -j DROP
-A FORWARD -j DROP

COMMIT
有人愿意指导一下吗^_^

iptables -L -vn 最终效果看看呢

-A和-I添加的位置不一样
以最终形成的chain为准