Ubuntu 20.04 port forwarding

 ubuntu port forwarding

vim /etc/default/ufw

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DEFAULT_FORWARD_POLICY="ACCEPT"

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設定開啟

vim /etc/ufw/sysctl.conf

vim /etc/sysctl.conf

把 net.ipv4.ip_forward=1 都 uncomment

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# Uncomment this to allow this host to route packets between interfaces

net/ipv4/ip_forward=1

#net/ipv6/conf/default/forwarding=1

#net/ipv6/conf/all/forwarding=1

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編輯規則

vim /etc/ufw/before.rules 

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-A PREROUTING -p tcp -m tcp -d 主機IP --dport 1433 -j DNAT --to-destination 目標IP:port

舉例如下：也就是連到192.168.50.1:80，會轉發到61.168.0.212:80

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*nat

:PREROUTING ACCEPT [0:0]

-A PREROUTING -p tcp -m tcp -d 192.168.50.1 --dport 80 -j DNAT --to-destination 61.168.0.212:80

-A POSTROUTING -j MASQUERADE

COMMIT

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sudo sysctl -p

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sudo ufw allow 80/tcp

或

sudo ufw allow from any to any port 80

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sudo systemctl restart ufw

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察看與驗證

sudo ufw status

sudo iptables -t nat -L -n -v

監聽封包

tcpdump -i ens3 -c 200 port 80

網卡代號 ens3