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仅接受传入 SSH 和 ICMP 的 Iptables 策略

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仅接受传入 SSH 和 ICMP 的 Iptables 策略

我运行了以下iptables命令来允许传入的 SSH 和 ICMP 连接并阻止所有其他连接。

sudo iptables -F INPUT
sudo iptables --policy INPUT ACCEPT && sudo iptables --policy OUTPUT 
ACCEPT && sudo iptables --policy FORWARD ACCEPT
sudo iptables -I INPUT -p tcp --dport 22 -j ACCEPT
sudo iptables -I INPUT -p icmp -j ACCEPT
sudo iptables -I OUTPUT -p tcp --sport 5051  -j REJECT
sudo iptables -A INPUT -j REJECT

生成的 iptables 列表如下所示

Chain INPUT (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     icmp --  anywhere             anywhere            
ACCEPT     tcp  --  anywhere             anywhere             tcp dpt:ssh
REJECT     all  --  anywhere             anywhere             reject-with icmp-port-unreachable

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         
REJECT     tcp  --  anywhere             anywhere             match-set minuteman dst,dst tcp flags:FIN,SYN,RST,ACK/SYN reject-with icmp-port-unreachable
DOCKER-ISOLATION  all  --  anywhere             anywhere            
DOCKER     all  --  anywhere             anywhere            
ACCEPT     all  --  anywhere             anywhere             ctstate RELATED,ESTABLISHED
ACCEPT     all  --  anywhere             anywhere            
ACCEPT     all  --  anywhere             anywhere            

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination         
REJECT     tcp  --  anywhere             anywhere             tcp spt:ita-agent reject-with icmp-port-unreachable
REJECT     tcp  --  anywhere             anywhere             match-set minuteman dst,dst tcp flags:FIN,SYN,RST,ACK/SYN reject-with icmp-port-unreachable

Chain DOCKER (1 references)
target     prot opt source               destination         

Chain DOCKER-ISOLATION (1 references)
target     prot opt source               destination         
RETURN     all  --  anywhere             anywhere

我看到接受 SSH 的那一行位于拒绝所有其他流量的那一行之前。但我仍然无法通过 SSH 连接到机器。

有任何线索说明为什么这不起作用吗？

答案1

如果您只需要允许 SSH 和 ICMP

# Flush the FW Rules 
iptables -F
iptables  -X

# Block all traffic
iptables  -P INPUT DROP
iptables  -P FORWARD DROP
iptables  -P OUTPUT DROP


# Allow SSH
iptables  -A OUTPUT -p tcp --dport 22 -j ACCEPT 
iptables  -A INPUT -p tcp --dport 22 -j ACCEPT


# Allow ICMP (ping)
iptables  -A INPUT -p icmp -j ACCEPT
iptables  -A OUTPUT -p icmp -j ACCEPT

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