IP Whitelisting

IP whitelisting (also called IP allowlisting) is an access-control technique where a service accepts connections only from a defined list of trusted IP addresses. Any request coming from an address that is not on the list is automatically rejected.

How it works

An administrator registers one or more source IP addresses, or sometimes whole CIDR ranges, in a dashboard or firewall rule. When a connection arrives, the server checks the source IP against the approved list and only proceeds if there is a match. This is the opposite of a blacklist, which blocks specific bad actors but allows everyone else.

Why it matters for proxies and scraping

Proxy providers commonly offer IP whitelisting as an alternative to username/password authentication. It is convenient because you never expose credentials, but it requires a stable, predictable source IP. Scrapers running on rotating cloud instances often struggle with whitelisting because their server IP changes, breaking access until the new IP is re-added.

• Restrict API or proxy access to known servers
• Avoid leaking login credentials
• Add a strong perimeter layer for sensitive systems