Solution / Private applications

Monitor Applications Behind a Firewall Without Opening Inbound Ports

Use outbound HTTPS from the application when inbound monitoring is blocked by NAT, firewall policy or private network topology.

Solution pattern; current outbound Tier 1 foundation

Why inbound monitoring is not always available

Customer-installed software, shared hosting and private services may be able to make outbound HTTPS requests while refusing inbound connections. That topology changes how monitoring should be initiated.

Outbound heartbeat model

The application sends its evidence to HeartbeatHook. The request can be authenticated with the current HMAC contract, and the receiver does not need to expose a new public endpoint just to report liveness.

Return communication through polling

When the application also needs to retrieve a signal, it can poll its authorized pending flow and ACK after processing. This keeps both directions initiated by the private application, with the trade-off of polling latency.

Advantages and limitations

  • works with outbound-only network policy;
  • avoids a public inbound webhook requirement;
  • fits intermittent or customer-controlled installations;
  • still depends on outbound DNS, TLS, credentials and a sensible polling schedule.

This pattern does not bypass a policy that blocks outbound traffic, and it does not prove that business work completed correctly.

Compare the polling model