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Spool directory

Spool directory holds encrypted packets received from remote nodes and queued for sending to them. It has the following example structure with just single outbound (tx) packet LYT64MWSNDK34CVYOO7TA6ZCJ3NWI2OUDBBMX2A4QWF34FIRY4DQ to the node 2WHBV3TPZHDOZGUJEH563ZEK7M33J4UESRFO4PDKWD5KZNPROABQ:


directory contains various temporary files that under normal circumstances are renamed to necessary files inside other directories. All directories in spool have to be on the same filesystem for working renaming.


is an example Base32-encoded neighbour identifier.

rx, tx

directories are for incoming and outgoing encrypted packets. rx contains currently unfinished, non-checked, unprocessed, etc packets.

toss.lock, rx.lock, tx.lock

Lock files. Only single process can work with rx/tx directories at once.


is an example encrypted packet. Its filename is Base32 encoded Merkle Tree Hashing hash of the whole contents. It can be integrity checked anytime.


is an example partly received file. It can appear only when online transfer is used. Its filename is sent by remote side and until file is fully downloaded – it plays no role.


non-checksummed (NoCK) fully received file. Its checksum is verified against its filename either by nncp-check, or by working online daemons. If it is correct, then its extension is trimmed.


nncp-toss utility can be invoked with -seen option, leading to creation of seen/ files, telling that the file with specified hash has already been processed before. It could be useful when there are use-cases where multiple ways of packets transfer available and there is possibility of duplicates reception. You have to manually remove them, when you do not need them (probably because they are expired).


If no nohdr option is enabled in configuration file, then hdr/ files are automatically created for every ordinary (fully received and checksummed) packet. It literally contains just the header of the corresponding packet. It will be automatically created even during simple nncp-stat call. On filesystems with big blocksize (ZFS for example) it can greatly help listing the packets in directories, because it prevents unnecessary read-amplification. On other filesystems probably it won’t help at all, or even harm performance.

There is a hack: you can create more dense hdr/ allocation by removing all hdr/ files and then running nncp-stat, that will recreate them. In many cases many hdr/ files will be allocated more or less linearly on the disk, decreasing listing time even more.


If tossing was performed with -gen-ack option, then for each generated ACKnowledgements packet there will be corresponding empty ack/ file. ACK outbound packets needs to be deleted after the transmission, but since they are stored encrypted in the spool, there needs to be some kind of knowledge what packets are ACK ones. Both ACK and corresponding ack/ files are removed by nncp-rm -ack command.

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