# Chapter 7. NAT & DNAT * * * ## 目錄 - [NAT](#NAT) - [DNAT](#DNAT) * * * <h3 id="NAT">NAT</h3> `sudo nano /etc/netplan/00-installer-config.yaml` gw@gw:~$ `sudo netplan generate` gw@gw:~$ `sudo netplan apply` gw@gw:~$ `ping hient.net` PING hient.net (64.131.64.91) 56(84) bytes of data. 64 bytes from server2.twdomain.com (64.131.64.91): icmp_seq=1 ttl=50 time=197 ms 64 bytes from server2.twdomain.com (64.131.64.91): icmp_seq=2 ttl=50 time=196 ms gw@gw:~$ `sudo apt update` Hit:1 http://tw.archive.ubuntu.com/ubuntu bionic InRelease Hit:2 http://tw.archive.ubuntu.com/ubuntu bionic-updates InRelease `sudo nano /etc/sysctl.conf` Find and uncomment the following line: net.ipv4.ip_forward=1 gw@gw:~$ `sysctl net.ipv4.ip_forward` net.ipv4.ip_forward = 0 gw@gw:~$ `sudo reboot` gw@gw:~$ `sysctl net.ipv4.ip_forward` net.ipv4.ip_forward = 1 `sudo iptables -t nat -A POSTROUTING -o wlx7cdd90ea4126 -j MASQUERADE` OR `sudo iptables -t nat -A POSTROUTING -s 192.168.40.0/24 -o wlx7cdd90ea4126 -j MASQUERADE` - iptables: 過濾封包 - -t: table, -A: append - -s: 來源 source - -o: output - wlx7cdd90ea4126: 連接外網的網卡 - MASQUERADE: 偽裝 設定啟動封包轉遞 (gw 電腦), 輸入 `1` 機器內封包可互傳 (預設為 0) `sudo apt-get install iptables-persistent -y` ipv4 -- yes ipv6 -- yes $ `echo 1 | sudo tee /proc/sys/net/ipv4/ip_forward` $ `sudo iptables -t nat -L -n` --- <h3 id="DNAT">DNAT</h3> `sudo iptables -t nat -A PREROUTING -p tcp --dport 2210 -j DNAT --to-destination 192.168.40.10:22` `sudo iptables -t nat -A PREROUTING -p tcp --dport 2220 -j DNAT --to-destination 192.168.40.20:22` `sudo iptables -t nat -A PREROUTING -p tcp --dport 2221 -j DNAT --to-destination 192.168.40.21:22` `sudo iptables -t nat -A PREROUTING -p tcp --dport 2222 -j DNAT --to-destination 192.168.40.22:22` `sudo iptables -t nat -A PREROUTING -p tcp --dport 2223 -j DNAT --to-destination 192.168.40.23:22` `sudo iptables -t nat -A PREROUTING -p tcp --dport 2230 -j DNAT --to-destination 192.168.40.30:22` --- <h3 id="references">參考文件</h3> - https://medium.com/@exesse/how-to-make-a-simple-router-gateway-from-ubuntu-server-18-04-lts-fd40b7bfec9 --- [返回至 - 目錄](https://github.com/xuan103/Alpine_2021)