Graphite's pickle receiver — the batched, binary sibling of 2003.
IANA registers 2004/tcp as mailbox, a name with no live meaning. In practice it is carbon's pickle receiver, which Graphite documents as running on port 2004 by default and which accepts batches of metrics in Python's pickle serialization instead of one line at a time. It is what carbon-relay and high-volume senders use, so it usually appears alongside 2003 on the same monitoring host.
Do not expose
Unauthenticated like 2003, and it deserializes attacker-supplied pickle data — keep it strictly on the private network.
$ nc -vz TARGET 2004Seen this on your network? Beige Box scans your Wi-Fi and shows every open port on every device — and its Ports tool links straight back here.
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Corrections or a missing port? Reply @rimrocksystems.