Download Let's Encrypt CA-Certificates

bin/fetch_letsencrypt_ca_certs.py

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+#!/usr/bin/env python3
+
+import os
+import sys
+import requests
+from html.parser import HTMLParser
+from urllib.parse import urljoin
+
+LETSENCRYPT_CERT_PAGE = "https://letsencrypt.org/certificates/"
+DEFAULT_TARGET_DIR = "./letsencrypt-ca"
+
+
+class PemLinkParser(HTMLParser):
+    def __init__(self):
+        super().__init__()
+        self.pem_links = set()
+
+    def handle_starttag(self, tag, attrs):
+        if tag.lower() != "a":
+            return
+        for attr, value in attrs:
+            if attr == "href" and value.lower().endswith(".pem"):
+                self.pem_links.add(value)
+
+
+def fetch_certificate_page():
+    resp = requests.get(LETSENCRYPT_CERT_PAGE, timeout=15)
+    resp.raise_for_status()
+    return resp.text
+
+
+def extract_pem_links(html):
+    parser = PemLinkParser()
+    parser.feed(html)
+    return sorted(
+        urljoin(LETSENCRYPT_CERT_PAGE, link)
+        for link in parser.pem_links
+    )
+
+
+def download_and_store(url, target_dir):
+    base_name = os.path.basename(url)
+    # Zielname = .crt statt .pem
+    target_name = os.path.splitext(base_name)[0] + ".crt"
+    target_path = os.path.join(target_dir, target_name)
+
+    if os.path.exists(target_path):
+        print(f"[=] Bereits vorhanden: {target_name}")
+        return target_name
+
+    print(f"[+] Lade herunter: {base_name}")
+    resp = requests.get(url, timeout=15)
+    resp.raise_for_status()
+
+    if b"BEGIN CERTIFICATE" not in resp.content:
+        print(f"[!] Ungültiges Zertifikat: {base_name}")
+        return None
+
+    # Direkt als .crt speichern (PEM-Inhalt)
+    with open(target_path, "wb") as f:
+        f.write(resp.content)
+
+    return target_name
+
+
+def list_local_crt_files(target_dir):
+    return {
+        f for f in os.listdir(target_dir)
+        if f.lower().endswith(".crt")
+    }
+
+
+def main():
+    target_dir = sys.argv[1] if len(sys.argv) > 1 else DEFAULT_TARGET_DIR
+    os.makedirs(target_dir, exist_ok=True)
+
+    print(f"[*] Zielverzeichnis: {os.path.abspath(target_dir)}")
+    print("[*] Format: PEM-Inhalt mit .crt-Endung")
+
+    html = fetch_certificate_page()
+    pem_urls = extract_pem_links(html)
+
+    # Remote-Dateinamen im .crt-Format
+    remote_files = {
+        os.path.splitext(os.path.basename(url))[0] + ".crt"
+        for url in pem_urls
+    }
+
+    for url in pem_urls:
+        download_and_store(url, target_dir)
+
+    local_files = list_local_crt_files(target_dir)
+    orphaned = sorted(local_files - remote_files)
+
+    print("\n" + "=" * 60)
+    if orphaned:
+        print("[!] Lokal vorhanden, aber nicht mehr gelistet:")
+        for f in orphaned:
+            print(f"    - {f}")
+    else:
+        print("[✓] Keine veralteten Dateien gefunden")
+    print("=" * 60)
+    print("[✓] Fertig.")
+
+
+if __name__ == "__main__":
+    main()
+
+