与普通转发差不多，增加了几个参数

    location /im
    {
        proxy_pass http://localhost:9902/;

        proxy_http_version 1.1;
        proxy_read_timeout 360s;
        proxy_redirect off;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
        proxy_set_header Host $host:$server_port;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header REMOTE-HOST $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }

保存后，重载配置

nginx -s reload

使用ws:域名/im 访问，转发到服务器9902端口 socket 服务