first commit

example_config.json

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+{
+  "ip_server":"https://api.ipify.org",
+  "dns_endpoint":"https://dns.eu.ovhapis.com/nic/update",
+  "username":"username",
+  "password":"password",
+  "domains":[
+    "example.com"
+  ],
+  "delay":3600
+}

readme.md

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+# VYDNS
+
+A simple DynDNS v2 client written in Python, compatible with providers such as OVH DynHost.
+
+## Features
+
+- Periodically checks the public IP address
+- Updates DNS records only when the IP changes
+- Uses a local cache to avoid unnecessary updates
+- No external dependencies except `requests` module
+
+## Usage
+
+Run the script with Python. It will periodically:
+
+- Query a web endpoint that returns the public IP in plain text
+- Compare it with the cached IP
+- If the IP has not changed, sleep for the configured delay
+- If the IP has changed, update the DNS records and refresh the cache
+- If no cache exists, create it and perform an initial update
+
+## Configuration
+
+The script relies on a JSON configuration file named `config.json` located in the working directory.
+
+It must contain the following keys:
+
+- `ip_server`: URL of the endpoint used to retrieve the public IP (must return plain text)
+- `dns_endpoint`: DynDNS v2 API endpoint of the provider
+- `username`: DynDNS account username
+- `password`: DynDNS account password
+- `domains`: list of domain names to update
+- `delay`: interval in seconds between checks
+
+You can find an example configuration file in this repo. 
+**Warning:** the password is stored in plain text. Changing config file permissions is recommended.
+
+## Supported DynDNS providers
+
+To this day, these DynDNS providers have been found to work well with the script:
+- OVH
+
+## License
+
+This script and the provided examples are under the MIT license.

vydns.py

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+import requests
+import os
+import json
+import ipaddress
+import time
+def recreate_cache(ip_server:str):
+  print("[VYDNS] Obtaining public IP using server '"+ip_server+"'")
+  ip=""
+  try:
+    ip=requests.get(ip_server,timeout=10).text.strip()
+    ipaddress.ip_address(ip)
+  except Exception as e:
+    print("[VYDNS] Error: counldn't obtain IP or IP isn't valid. Exception: "+str(e))
+    exit()
+  print("[VYDNS] "+ip)
+  cache={"ip":ip}
+  with open("cache.json","w") as f:
+    json.dump(cache,f)
+  print("[VYDNS] Succesfully obtained IP.")
+  return ip
+def obtain_ip(ip_server:str):
+  print("[VYDNS] Obtaining public IP using server '"+ip_server+"'")
+  ip=""
+  try:
+    ip=requests.get(ip_server,timeout=10).text.strip()
+    ipaddress.ip_address(ip)
+  except Exception as e:
+    print("[VYDNS] Error: counldn't obtain IP or IP isn't valid. Exception: "+str(e))
+    exit()
+  print("[VYDNS] "+ip)
+  print("[VYDNS] Succesfully obtained IP.")
+  return ip
+def update_ip(ip:str,dns_endpoint:str,domains:str,username:str,password:str):
+  print("[VYDNS] Updating "+str(len(domains))+" domains:")
+  for d in domains:
+    print("[VYDNS] Updating '"+d+"' :")
+    params={
+      "system":"dyndns",
+      "hostname":d,
+      "myip":ip
+    }
+    r=requests.get(dns_endpoint,params=params,auth=(username,password),timeout=10)
+    print(r.text)
+    if "good" in r.text or "nochg" in r.text:
+      print("[VYDNS] Update OK.")
+    else:
+      print("[VYDNS] Update failed.")
+conffile={}
+if os.path.exists("config.json"):
+  conffile=json.load(open("config.json","r"))
+else:
+  print("[VYDNS] Error: config file doesn't exist.")
+  exit()
+if ("ip_server" not in conffile) or ("dns_endpoint" not in conffile) or ("username" not in conffile) or ("password" not in conffile) or ("domains" not in conffile) or ("delay" not in conffile):
+  print("[VYDNS] Error: config file isn't formatted as expected.")
+  exit()
+if (conffile["ip_server"]=="") or (conffile["dns_endpoint"]=="") or (conffile["username"]=="") or (conffile["password"]=="") or (conffile["delay"]<=0):
+  print("[VYDNS] Error: one of the key is empty or invalid.")
+  exit()
+if (conffile["domains"]==[]):
+  print("[VYDNS] Error: no domains provided.")
+  exit()
+while True:
+  obtained_ip=""
+  if not os.path.exists("cache.json"):
+    print("[VYDNS] Cache file doesn't exist, recreating it.")
+    obtained_ip=recreate_cache(conffile["ip_server"])
+    update_ip(obtained_ip,conffile["dns_endpoint"],conffile["domains"],conffile["username"],conffile["password"])
+    print("[VYDNS] Sleeping for "+str(conffile["delay"])+" seconds.")
+    time.sleep(conffile["delay"])
+    continue
+  else:
+    print("[VYDNS] Cache file exist, obtaining current IP for comparaison.")
+    obtained_ip=obtain_ip(conffile["ip_server"])
+    with open("cache.json","r") as f:
+      cachefile=json.load(f)
+    if cachefile["ip"]==obtained_ip:
+      print("[VYDNS] According to cache file, IP didn't change.")
+      print("[VYDNS] Sleeping for "+str(conffile["delay"])+" seconds.")
+      time.sleep(conffile["delay"])
+      continue
+    else:
+      print("[VYDNS] According to cache file, IP did changed.")
+      update_ip(obtained_ip,conffile["dns_endpoint"],conffile["domains"],conffile["username"],conffile["password"])
+      cache={"ip":obtained_ip}
+      with open("cache.json","w") as f:
+        json.dump(cache,f)
+      print("[VYDNS] Sleeping for "+str(conffile["delay"])+" seconds.")
+      time.sleep(conffile["delay"])
+      continue