Bind credentials to trusted ground.
Restrict access to trusted networks or machines, applied equally to API keys and high-privileged user sessions. Bind sensitive credentials to known address ranges so a leaked key is useless from anywhere else.
1. The idea: a credential should have a home
Most credentials are portable by default — a leaked API key works from anywhere on the internet, which is precisely the attacker’s advantage. An application-layer IP firewall removes that portability for the credentials that matter most, binding a sensitive key or a high-privileged session to the network ranges it is actually expected to come from. A key exfiltrated to an attacker’s infrastructure then authenticates from the wrong place and is rejected.
2. Why at the application layer
Network firewalls protect the perimeter, but the application is the only layer that knows which credential should be allowed from which range. A platform may legitimately accept traffic from the whole internet for its public endpoints while insisting that an administrative key or a partner integration appear only from a registered allowlist. That per-credential granularity lives in the app, beside the identity it constrains.
3. Keys and sessions alike
The same control protects two very different things: machine credentials, where it pins integrations to their known egress addresses, and high-privileged human sessions, where it confines administrative actions to trusted offices or VPN ranges. Applying it equally is what closes the gap an attacker looks for — the privileged path someone forgot to constrain.
4. How B5 Secure handles it
B5 Secure makes IP restriction a configurable property of a credential and a session, evaluated in the same pipeline as authentication and authorization. Sensitive keys can be locked to address ranges; privileged sessions can require a trusted network; and because it is policy rather than scattered code, the constraint is consistent and auditable. It is a direct expression of least-privilege: access is limited not just to an action and a record, but to a place.