我已经检查过 ufw 是否被禁用。sudo lsof -iTCP -sTCP:LISTEN -P显示如下内容：
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
sshd 1059 root 3u IPv4 15446 0t0 TCP *:22 (LISTEN)
sshd 1059 root 4u IPv6 15448 0t0 TCP *:22 (LISTEN)
mysqld 1181 mysql 20u IPv4 16775 0t0 TCP localhost:3306 (LISTEN)
redis-ser 1242 redis 4u IPv4 16537 0t0 TCP localhost:6379 (LISTEN)
node\x20/ 9098 administrator 13u IPv6 29891806 0t0 TCP *:5555 (LISTEN)
nginx 15566 root 6u IPv4 29921927 0t0 TCP *:80 (LISTEN)
nginx 15566 root 7u IPv4 29921928 0t0 TCP *:443 (LISTEN)
nginx 15570 www-data 6u IPv4 29921927 0t0 TCP *:80 (LISTEN)
nginx 15570 www-data 7u IPv4 29921928 0t0 TCP *:443 (LISTEN)
node\x20/ 21806 administrator 12u IPv6 29795008 0t0 TCP *:1341 (LISTEN)
https://www.yougetsignal.com/tools/open-ports/说 443 已关闭。
我的 nginx 配置（删除 ssl 配置后，它在端口 80 上运行良好，但在 443 上却不行）：
server {
listen 443 default_server ssl;
ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
server_name admin.....app.ch;
location / {
proxy_set_header X-Forwarded-Host $host;
proxy_set_header X-Forwarded-Server $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_pass http://127.0.0.1:5555/;
}
index index.html index.htm;
ssl_certificate /etc/letsencrypt/live/../fullchain.pem; # managed by Certbot
ssl_certificate_key /etc/letsencrypt/live/../privkey.pem; # managed by Certbot
include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot
}
iptables -L -n 的输出：
Chain INPUT (policy ACCEPT)
target prot opt source destination
ufw-before-logging-input all -- 0.0.0.0/0 0.0.0.0/0
ufw-before-input all -- 0.0.0.0/0 0.0.0.0/0
ufw-after-input all -- 0.0.0.0/0 0.0.0.0/0
ufw-after-logging-input all -- 0.0.0.0/0 0.0.0.0/0
ufw-reject-input all -- 0.0.0.0/0 0.0.0.0/0
ufw-track-input all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:443
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp spt:443
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:443
Chain FORWARD (policy ACCEPT)
target prot opt source destination
ufw-before-logging-forward all -- 0.0.0.0/0 0.0.0.0/0
ufw-before-forward all -- 0.0.0.0/0 0.0.0.0/0
ufw-after-forward all -- 0.0.0.0/0 0.0.0.0/0
ufw-after-logging-forward all -- 0.0.0.0/0 0.0.0.0/0
ufw-reject-forward all -- 0.0.0.0/0 0.0.0.0/0
ufw-track-forward all -- 0.0.0.0/0 0.0.0.0/0
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
ufw-before-logging-output all -- 0.0.0.0/0 0.0.0.0/0
ufw-before-output all -- 0.0.0.0/0 0.0.0.0/0
ufw-after-output all -- 0.0.0.0/0 0.0.0.0/0
ufw-after-logging-output all -- 0.0.0.0/0 0.0.0.0/0
ufw-reject-output all -- 0.0.0.0/0 0.0.0.0/0
ufw-track-output all -- 0.0.0.0/0 0.0.0.0/0
Chain ufw-after-forward (1 references)
target prot opt source destination
Chain ufw-after-input (1 references)
target prot opt source destination
Chain ufw-after-logging-forward (1 references)
target prot opt source destination
Chain ufw-after-logging-input (1 references)
target prot opt source destination
Chain ufw-after-logging-output (1 references)
target prot opt source destination
Chain ufw-after-output (1 references)
target prot opt source destination
Chain ufw-before-forward (1 references)
target prot opt source destination
Chain ufw-before-input (1 references)
target prot opt source destination
Chain ufw-before-logging-forward (1 references)
target prot opt source destination
Chain ufw-before-logging-input (1 references)
target prot opt source destination
Chain ufw-before-logging-output (1 references)
target prot opt source destination
Chain ufw-before-output (1 references)
target prot opt source destination
Chain ufw-reject-forward (1 references)
target prot opt source destination
Chain ufw-reject-input (1 references)
target prot opt source destination
Chain ufw-reject-output (1 references)
target prot opt source destination
Chain ufw-track-forward (1 references)
target prot opt source destination
Chain ufw-track-input (1 references)
target prot opt source destination
Chain ufw-track-output (1 references)
target prot opt source destination
详细：
Chain INPUT (policy ACCEPT 708K packets, 375M bytes)
pkts bytes target prot opt in out source destination
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Chain OUTPUT (policy ACCEPT 677K packets, 280M bytes)
pkts bytes target prot opt in out source destination
Chain ufw-after-forward (0 references)
pkts bytes target prot opt in out source destination
Chain ufw-after-input (0 references)
pkts bytes target prot opt in out source destination
Chain ufw-after-logging-forward (0 references)
pkts bytes target prot opt in out source destination
Chain ufw-after-logging-input (0 references)
pkts bytes target prot opt in out source destination
Chain ufw-after-logging-output (0 references)
pkts bytes target prot opt in out source destination
Chain ufw-after-output (0 references)
pkts bytes target prot opt in out source destination
Chain ufw-before-forward (0 references)
pkts bytes target prot opt in out source destination
Chain ufw-before-input (0 references)
pkts bytes target prot opt in out source destination
Chain ufw-before-logging-forward (0 references)
pkts bytes target prot opt in out source destination
Chain ufw-before-logging-input (0 references)
pkts bytes target prot opt in out source destination
Chain ufw-before-logging-output (0 references)
pkts bytes target prot opt in out source destination
Chain ufw-before-output (0 references)
pkts bytes target prot opt in out source destination
Chain ufw-reject-forward (0 references)
pkts bytes target prot opt in out source destination
Chain ufw-reject-input (0 references)
pkts bytes target prot opt in out source destination
Chain ufw-reject-output (0 references)
pkts bytes target prot opt in out source destination
Chain ufw-track-forward (0 references)
pkts bytes target prot opt in out source destination
Chain ufw-track-input (0 references)
pkts bytes target prot opt in out source destination
Chain ufw-track-output (0 references)
pkts bytes target prot opt in out source destination