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README.md

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+# pretense
+
+Server that listens on arbitary TCP ports and logs connections.
+Connections are immediately closed once opened.
+
+It logs connection attempts to stdout.
+Additionally, prometheus metrics are exposed on `/metrics`.
+
+## Configuration
+
+Configuration is done via environment variables:
+- `PRETENSE_PORTS` (required): Comma-separated list of TCP ports (u16 integers) to listen on.
+  Example: `23,1234`
+- `PRETENSE_METRICS_PORT`: TCP Port (u16 integer) to serve the `/metrics` HTTP endpoint on.
+  If not set, no metrics are served.
+  Example: `2000`
+
+## Note about privileged ports
+
+When listening on a privileged port (on UNIX-like systems, 1-1023), you need permissions to bind on that port.
+On Linux, this can be achieved by giving the binary the `CAP_NET_BIND_SERVICE` capability.