# SSL Expiration Checker

This utility checks the SSL certificate expiration dates for a list of domains. It helps system administrators monitor their websites and renew certificates before they expire.

**Modules Used:**
*   `ssl`: To wrap sockets and retrieve certificate information.
*   [[programming/python/modules/socket-module|socket]]: To establish connections to the servers.
*   `datetime`: To parse dates and calculate the remaining time.
*   [[programming/python/modules/argparse-module|argparse]]: To handle command-line arguments.

## The Code

Save this as `ssl_check.py`.

```python
import ssl
import socket
import datetime
import argparse
import sys

def get_ssl_expiry_date(hostname, port=443):
    context = ssl.create_default_context()
    
    try:
        # Create a connection to the host
        with socket.create_connection((hostname, port), timeout=5) as sock:
            # Wrap the socket with SSL
            with context.wrap_socket(sock, server_hostname=hostname) as ssock:
                # Retrieve the certificate
                cert = ssock.getpeercert()
                
                # Extract the 'notAfter' date
                # Format is usually: 'May 25 12:00:00 2024 GMT'
                not_after = cert['notAfter']
                
                # Parse the date string into a datetime object
                expiry_date = datetime.datetime.strptime(not_after, r'%b %d %H:%M:%S %Y %Z')
                return expiry_date
    except Exception as e:
        # Return None if connection fails or cert is invalid
        return None

def check_domains(domains):
    print(f"{'Domain':<30} {'Expiry Date':<25} {'Days Left':<10} {'Status'}")
    print("-" * 80)
    
    # Use UTC now because cert dates are in GMT/UTC
    now = datetime.datetime.utcnow()
    
    for domain in domains:
        expiry = get_ssl_expiry_date(domain)
        
        if expiry:
            days_left = (expiry - now).days
            expiry_str = expiry.strftime("%Y-%m-%d")
            
            status = "OK"
            if days_left < 0:
                status = "EXPIRED"
            elif days_left < 30:
                status = "WARNING"
                
            print(f"{domain:<30} {expiry_str:<25} {days_left:<10} {status}")
        else:
            print(f"{domain:<30} {'ERROR':<25} {'-':<10} {'Connection Failed'}")

if __name__ == "__main__":
    parser = argparse.ArgumentParser(description="SSL Expiration Checker")
    parser.add_argument("domains", nargs='+', help="List of domains to check (e.g., google.com github.com)")
    
    args = parser.parse_args()
    
    check_domains(args.domains)
```

## Usage

```bash
python ssl_check.py google.com github.com expired.badssl.com
```

[[programming/python/python]]