Unseenet Working Group                                     A. Lorensen
UN-RFC: 0024                                              October 2026
Category: Standards Track
Status: Draft
Updates: 0023

                         Usenet Gateways

Abstract¶

This document is the network profile (UN-RFC 0023 section 9) for Usenet. It says how Usenet group names map to usenet.*, how articles convert in both directions, which Usenet messages are never imported, how articles from Unseenet are recognised on their way back, and what Usenet expects of a gateway. Everything not said here follows UN-RFC 0023.

1. Overview¶

Usenet is the network Unseenet is modelled on. Both carry articles in named groups, with RFC 5322-style headers, over NNTP; the conversion is therefore close, and the differences are in what Unseenet adds (signatures, content-derived Message-IDs, postage) and leaves out (Path, crossposting, binaries, unauthenticated cancels).

A Usenet gateway normally runs its own news server (for example INN) on the gateway host. The news server peers with Usenet, keeps the history, writes Path, and filters spam; the gateway reads new articles from it as a newsreader would and posts exported articles to it.

2. Manifest Fields¶

For Usenet, the gateway field of UN-RFC 0023 section 3.2 means:

Field	Value
`network`	`usenet`
`source`	The Usenet group name, exactly as on Usenet
`host`	The gateway's Usenet path identity (RFC 5536 section 3.1.5)
`abuse`	An e-mail address for complaints, as in `Injection-Info`

3. Names¶

The gatewayed group for the Usenet group N is named usenet. followed by N in lower case: dk.politik becomes usenet.dk.politik, comp.lang.python becomes usenet.comp.lang.python.

If the result is not a valid group name (UN-RFC 0004 section 1: characters, or more than 128 octets), the Usenet group MUST NOT be gatewayed. Usenet groups that differ only in case map to the same name; a gateway MUST gateway at most one of them.

4. Import¶

4.1 What Is Never Imported¶

In addition to UN-RFC 0023 section 4.1, a Usenet gateway MUST NOT import:

control messages: articles with a Control header, or with a Subject starting with cmsg, including newgroup, rmgroup, checkgroups and cancel;
articles whose Message-ID ends in @unseenet> (section 5.2: these came from Unseenet and are already there);
articles containing yEnc or uuencoded data, or MIME parts other than text/plain that are not a signature or a short alternative such as text/html.

A gateway SHOULD filter spam at least as strictly as a well-run Usenet text server, for example with Cleanfeed on its news server.

4.2 Conversion¶

Unseenet header	Value
`From`	The display name of the Usenet `From`, or its local part if there is none
`Subject`	The Usenet `Subject`, MIME-decoded
`Origin-Network`	`usenet`
`Origin-ID`	The Usenet Message-ID, unchanged
`Origin-Date`	The Usenet `Date`, unchanged
`Origin-From`	The Usenet `From`, unchanged
`Usenet-Newsgroups`	The Usenet `Newsgroups`, if it names more than one group
`Usenet-References`	The Usenet `References`, if any reference could not be mapped
`Usenet-Followup-To`	The Usenet `Followup-To`, if present

The other headers are set as in UN-RFC 0023 section 4.2. All other Usenet headers, including Path, Xref, NNTP-Posting-Host, Injection-Info and Organization, are dropped.

The body is decoded from its transfer encoding and charset to UTF-8. Of a MIME multipart article only the first text/plain part is kept.

4.3 References¶

For each Usenet References entry, the gateway puts the mapped Unseenet Message-ID into References, in the same order. An entry of the form <id@unseenet> maps to itself (section 5.2). Entries that cannot be mapped are left out, and the original header is then kept in Usenet-References.

4.4 Crossposts¶

Unseenet does not allow crossposting (UN-RFC 0002 section 2.1). A Usenet article posted to several groups is imported once, into the gatewayed group of the first group in its Newsgroups that this gateway gateways, and the full list is kept in Usenet-Newsgroups.

4.5 Cancels, Supersedes and No-Archive¶

Usenet cancels are not authenticated. A gateway MAY act on a Usenet cancel or Supersedes according to its stated policy, for example only for cancels issued by the server named in the target's Injection-Info. When it does, it posts an Unseenet cancel for the imported article (UN-RFC 0023 section 4.5); for Supersedes it then imports the new article.

X-No-Archive: yes and Archive: no are requests not to archive in the sense of UN-RFC 0023 section 4.5.

5. Export¶

5.1 Conversion¶

The gateway builds a Usenet article (RFC 5536) from the Unseenet article:

Usenet header	Value
`Path`	`<host>!not-for-mail`, where `<host>` is the manifest's `host`
`Message-ID`	The Unseenet Message-ID, unchanged: `<id@unseenet>`
`Newsgroups`	The manifest's `source`. Never more than one group.
`Date`	The Unseenet `Date`
`From`	`"<From> (<fp4>)" <<fingerprint>@unseenet.invalid>`, where `<fp4>` is the first 4 characters of the author's fingerprint
`Subject`	The Unseenet `Subject`
`References`	Each entry mapped back: an imported article's `Origin-ID`, otherwise the Unseenet Message-ID unchanged
`Injection-Info`	`<host>; posting-account="<fingerprint>"; mail-complaints-to="<abuse>"` (RFC 5536 section 3.2.8)
`Content-Type`	`text/plain; charset=utf-8`
`Unseenet-Author-Key`	The author's `Author-Key`

No other Unseenet header is exported. In particular Signature, Proof-Of-Work, Approved-By and Approval are dropped: Usenet readers cannot verify Unseenet signatures, and Unseenet-Author-Key is informational only.

The other network has accepted the article (UN-RFC 0023 section 5.2 step 4) when the gateway's news server answers 240 or 235.

5.2 Message-IDs¶

Keeping the Unseenet Message-ID on Usenet means:

replies on Usenet reference <id@unseenet>, which import maps to the original without a table (section 4.3);
the copy that comes back through the Usenet feed is not imported (section 4.1 item 2), so there are no loops;
two gateways that export the same submission produce the same Message-ID, and Usenet's own history drops the second.

5.3 Addresses¶

A .invalid address (RFC 2606) cannot receive mail. Replies by e-mail are impossible; replies on Usenet reach the author through import.

5.4 Retractions¶

The gateway is the injecting server of every article it exports, and MAY cancel one on Usenet (UN-RFC 0023 section 6.2). A cancel in Unseenet is never turned into a Usenet cancel on its own.

6. The Other Side¶

For Usenet the other side (UN-RFC 0023 section 6.1) is the administrators of the servers the gateway's news server peers with. To Usenet the gateway is the injecting server for every exported article, and servers that inject spam or abuse lose their peers.

Peering by agreement is RECOMMENDED. Reading a public server as an ordinary user and re-publishing its groups may itself be against its terms.
Before exporting, the operator MUST tell the peers that the gateway cannot identify or trace authors, only stop keys, and MUST have a working abuse address in Injection-Info.
The pseudonymous record of UN-RFC 0023 section 6.2 is what the gateway can offer where a Usenet server would keep a log of who posted what.

7. Timing Signals¶

Usenet has no presence, typing or read signals. The only timing information is the time of injection, which UN-RFC 0023 section 5.2 blurs, and Date, which is the Unseenet Date rounded to 10 minutes.

8. Headers Defined Here¶

Header	In	Defined in
`Usenet-Newsgroups`	Unseenet	section 4.2
`Usenet-References`	Unseenet	section 4.2
`Usenet-Followup-To`	Unseenet	section 4.2
`Unseenet-Author-Key`	Usenet	section 5.1

9. Rationale¶

Why usenet.dk.politik and not dk.politik? Unseenet's dk.* is free and already in use, and the Big 8 names are reserved for communities that want to revive them in Unseenet (UN-RFC 0018 section 9). See also UN-RFC 0023 section 12.
Why keep <id@unseenet> as the Usenet Message-ID? It makes loop prevention and threading stateless, and lets several gateways export the same article without duplicates.
Why a local news server instead of speaking NNTP to peers directly? INN and its peers already solve peering, history, Path, filtering and backlog. The gateway only converts.
Why .invalid addresses? Unseenet identities have no mail address, and inventing a deliverable one would invite spam to a domain that cannot handle it. RFC 2606 reserves .invalid for exactly this, and many Usenet servers already accept it.

10. Security Considerations¶

UN-RFC 0023 section 13 applies. In addition:

Usenet servers keep text groups for years and many are archived in public. An exported article SHOULD be assumed permanent.
Usenet cancels and Supersedes are easily forged; section 4.5 leaves acting on them to the gateway's stated policy.