外网域名如何检测

import socket
import ssl

def check_domain(domain, port):
    try:
        # DNS解析
        ip = socket.gethostbyname(domain)
        print(f"Domain {domain} resolved to IP: {ip}")
        
        # 端口扫描
        with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
            s.settimeout(2)
            result = s.connect_ex((ip, port))
            if result == 0:
                print(f"Port {port} is open")
                
                # SSL证书检查
                if port == 443:
                    context = ssl.create_default_context()
                    with context.wrap_socket(s, server_hostname=domain) as ssl_socket:
                        cert = ssl_socket.getpeercert()
                        print(f"SSL Certificate: {cert}")
            else:
                print(f"Port {port} is closed")
    except socket.gaierror:
        print(f"Failed to resolve domain {domain}")
    except socket.error as e:
        print(f"Socket error: {e}")

# 示例调用
check_domain("example.com", 80)
check_domain("example.com", 443)