Dyn offers a free web IP detection tool for use with DynDNS services. CheckIP will return the remote socket’s IP address. If a client sends a Client-IP or a X-Forwarded-For HTTP header, CheckIP will return that value instead.
- Hostname:
checkip.dyndns.org - HTTP ports:
80, 8245
Call and Answer
CheckIP responds to valid HTTP requests for http://checkip.dyndns.com/. A valid request will result in the following sample response:
HTTP/1.1 200 OK Content-Type: text/html Server: DynDNS-CheckIP/1.0 Cache-Control: no-cache Pragma: no-cache Content-Length: 105 Connection: close <html><head><title>Current IP Check</title></head><body>Current IP Address: 123.456.78.90</body></html>
Policies
- Use the OS if possible for IP detection
- Checks must be spaced 10 minutes apart to help reduce server load
- In the case of an error while accessing CheckIP, the client should not send an update