两个 tpc 在同一个端口上运行，nginx 和 digitalocean

Question

我正在数字海洋上部署我的 react 应用程序。我已按照本教程进行操作，一切顺利：https://www.youtube.com/watch?v=lN0oiYqenpA&ab_channel=RyanMichaelHirst

现在每当我访问我的 ip 或域名时，都会出现以下错误：404 not found.

每当我运行 nginx 的日志时，它都会说正在使用端口 80。因此我运行这个：

sudo netstat -pan | grep ":80"

tcp        0      0 159.203.87.191:80       52.84.150.39:31164      SYN_RECV    -
tcp        0      0 159.203.87.191:80       52.84.150.39:38386      SYN_RECV    -

我知道，这是一个内部错误，但我似乎找不到那个错误。 我有两件事在同一个端口上运行，一切都崩溃了。它昨天还在工作，我受到了 nginx 页面的欢迎。

这是我的服务器配置。(nginx)

upstream my_nodejs_upstream {
        # (this is the server's ip address)
        server x.x.x.x.;
        keepalive 64;
}

server {
        listen 80;
        listen [::]:80 ipv6only=on;

        # SSL configuration
        #
        # listen 443 ssl default_server;
        # listen [::]:443 ssl default_server;
        #
        # Note: You should disable gzip for SSL traffic.
        # See: https://bugs.debian.org/773332
        #
        # Read up on ssl_ciphers to ensure a secure configuration.
        # See: https://bugs.debian.org/765782
        #
        # Self signed certs generated by the ssl-cert package
        # Don't use them in a production server!
        #
        # include snippets/snakeoil.conf;

        root /var/www/html;

        # Add index.php to the list if you are using PHP
        index index.html index.htm index.nginx-debian.html;     


server_name mmt-university;

        location / {
                # First attempt to serve request as file, then
                # as directory, then fall back to displaying a 404.
                try_files $uri $uri/ =404;
                proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
                proxy_pass http://universitymmt.com/;
                proxy_set_header Host $http_host;
                proxy_set_header X-NginX-Proxy true;
                proxy_http_version 1.1;
                proxy_set_header Upgrade $http_upgrade;
                proxy_set_header Connection "upgrade";
                proxy_redirect off;
                proxy_read_timeout 240s;
        }

        # pass PHP scripts to FastCGI server
        #
        #location ~ \.php$ {
        #       include snippets/fastcgi-php.conf;
        #
        #       # With php-fpm (or other unix sockets):
        #       fastcgi_pass unix:/var/run/php/php7.4-fpm.sock;
        #       # With php-cgi (or other tcp sockets):
        #       fastcgi_pass 127.0.0.1:9000;
        #}

        # deny access to .htaccess files, if Apache's document root
        # concurs with nginx's one
        #
        #location ~ /\.ht {
        #       deny all;
        #}
}

Answer 1

连接处于 SYN_RECV 状态，因为内核收到了一个处于 LISTENING 模式的端口的 SYN 数据包，但另一端没有回复 ACK。

通过在服务器上运行捕获来检查服务器是否接收到 ACK。捕获是在客户端还是在服务器上？

此外，相当数量的 SYN-RECV 表明可能对主机执行了 SYN Flood 攻击。欲了解更多信息： https://www.cloudflare.com/learning/ddos/syn-flood-ddos-attack/