imds-filterd (pronounced "I M D S Filter D") is a pair of utilities which
work together to intercept and filter requests to the EC2 Instance Metadata
Service -- or theoretically any other service at 169.254.169.254:80.

It validates requests against a configured ruleset which specifies whether
given users and groups should be allowed or denied access to certain prefixes
in the Instance Metadata Service.  For example, "root" could be granted
access to everything; most unprivileged users granted access to everything
except IAM role credentials; but the www user denied access to the entire
Instance Metadata Service in order to guard against SSRF and similar attacks.