Check certificate expiry using Python

 Following python script can use to check HTTPS certifcate expiry.

import ssl
import socket
import requests
from datetime import datetime

# Configuration
HOST = "mobitel.lk"  # Change to your domain
PORT = 443
THRESHOLD_DAYS = 30  # Alert before expiry (days)
API_URL = "https://your-api.com/alert"  # REST API to notify

def get_ssl_expiry(host, port):
    context = ssl.create_default_context()
    with socket.create_connection((host, port)) as sock:
        with context.wrap_socket(sock, server_hostname=host) as ssock:
            cert = ssock.getpeercert()
            expiry_date = datetime.strptime(cert['notAfter'], "%b %d %H:%M:%S %Y %Z")
            return expiry_date

def send_alert():
    data = {"message": f"SSL certificate for {HOST} is expiring soon!"}
    response = requests.post(API_URL, json=data)
    print(f"Alert sent: {response.status_code}")
# Check expiry

expiry_date = get_ssl_expiry(HOST, PORT)
days_left = (expiry_date - datetime.now()).days
if days_left <= THRESHOLD_DAYS:
    send_alert()
    print(f"Certificate expiring in {days_left} days. Alert sent!")
else:
    print(f"Certificate is valid for {days_left} more days.")

Weblogic certificate issues

"The loading of the trusted certificate list raised a certificate parsing exception PKIX: Unsupported OID in the AlgorithmIdentifier object:"

"javax.net.ssl.SSLKeyException: FATAL Alert:BAD_CERTIFICATE - A corrupt or unuseable certificate was received"

Above error was raised while accessing https URL in application server. To avoid this error, we have following options.

1. Install certificate in cacert to trust the certificate (JAVA_HOME/jre/lib/security)
2. Install certificate in a key store and refer it
3. Install certificate in Linux server

For the option 3, you can download https URL in server. Following commands can be used to download page using curl or wget.

curl - k https://www.google.com
wget https://www.google.com

Since, this is a valid http request server will install certificate in Linux server and validate requests against it.