开启转发支持

修改文件/etc/default/ufw，将默认转发策略修改为ACCEPT。

DEFAULT_FORWARD_POLICY="ACCEPT"

修改文件/etc/ufw/sysctl.conf，开启系统转发支持。

net/ipv4/ip_forward=1

端口转发配置

添加NAT到/etc/ufw/before.rules的配置。将以下内容添加到过滤器规则（*filter）之前

*nat
:PREROUTING ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]

# Port Forwardings
-A PREROUTING -p tcp --dport 端口号 -j DNAT --to-destination 远程IP:端口号
-A POSTROUTING -j MASQUERADE

# don't delete the 'COMMIT' line or these rules won't be processed
COMMIT

重启ufw

ufw disable && ufw enable

测试

nmap -Pn xxx.xxx.xxx.xxx -p xxxxx
Starting Nmap 7.80 ( https://nmap.org ) at 2024-05-02 14:20 CST
Nmap scan report for xxx.xxx.xxx.xxx
Host is up (0.13s latency).

PORT      STATE SERVICE
xxxxx/tcp open  unknown

Nmap done: 1 IP address (1 host up) scanned in 1.81 seconds