FidoNet

The BBS can be a node (or point) of FidoNet or any other FTN network (fsxNet, AgoraNet, or a network of your own). A message area becomes an echo when it is given an echo tag, users send netmail by addressing mail to Name@zone:net/node, and the BBS exchanges packets with its links over binkp, both calling them and answering their calls. The BBS is its own tosser, scanner and mailer, so no other FTN software is needed.

bbs area echo General FSX_GEN       ; General is the echo FSX_GEN
bbs area echo General -             ; no longer an echo
bbs fido poll                       ; call the links now (also: poll LINK)
bbs fido scan                       ; pack new mail into the outbound
bbs fido toss                       ; take in what has come
bbs filearea echo Nodediff NODEDIFF ; a file area is the file echo NODEDIFF
bbs fido node 21:1/100              ; a system in the nodelist
bbs fido nodes Wellington           ; systems by name, place or sysop
bbs fido subs downlink              ; what a link has, echoes and file echoes
bbs fido link downlink FSX_GEN      ; link it to echoes (unlink; filelink,
                                    ; fileunlink for file echoes)
bbs fido areafix hub +FSX_* %LIST   ; ask the hub's AreaFix (filefix: FileFix)

; bbs.conf
[fido]
address = 21:1/999              ; ours; more after it are AKAs
origin = D-Modem BBS, by phone and telnet
dir = /var/lib/bbs/fido          ; inbound, outbound, bad packets
charset = cp437                  ; or utf-8
nodelist = /var/lib/bbs/fido/nodelist/FSXNET.*   ; the newest of each

[binkp]                          ; answer calls (port 24554)
address = :24554

[link hub]                       ; our hub: a link per system
address = 21:1/100
host = hub.example.net:24554       ; to call it ("": it calls us)
password = secret                ; the session password
echoes = FSX_*                   ; the echoes exchanged, a wildmat
route = yes                      ; netmail for anywhere goes by it
poll = 3600                      ; call every hour, mail or not
fileechoes = FSX_*               ; the file echoes exchanged (none if unset)
tic_password = secret            ; the TICs' password, both ways
areafix_password = FIXIT         ; to ask its AreaFix and FileFix
create = yes                     ; make the echoes and file echoes it sends
packer = zip                     ; or arc, arj, lha; none: bare packets

[link downlink]                  ; a node that has its echoes from us
address = 21:1/200
password = other
echoes = *                       ; what it may have...
fileechoes = *
areafix = yes                    ; ...and asks for, by AreaFix and FileFix
areafix_password = FIXIT2

Echomail

Messages users post in an echo are packed for each link that carries it (with MSGID, REPLY for threads, PID, TZUTC, CHRS, tear and origin lines, SEEN-BY and PATH). Messages that links send are tossed into the echo, decoded from their character set according to their CHRS kludge (CP437 and the other DOS code pages, Latin-1, KOI8, Windows code pages, UTF-8), and cleaned like anything else a caller writes. With more than one link, the BBS passes echomail on between them by SEEN-BY, as a hub does. Each message is taken only once (by its MSGID, or by a digest for messages without one), and never if this system is already in its PATH.

Netmail

On the text BBS and on a 3270, mail to Name@1:2/3 (or Name@1:2/3.4) is netmail. It is sent through the link with that address, or the link of that point's node, or otherwise the link with route = yes. Netmail for this system goes to the user of that name (or to the sysop), from Name@zone:net/node, so Reply answers it as netmail (with a REPLY kludge). The BBS does not route anyone else's netmail: it is a leaf.

binkp

The mailer speaks binkp (FTS-1026) with CRAM-MD5 passwords (FTS-1027). Links are recognised by their address and password, and other systems are turned away. A password is never sent in the clear unless plain_password = yes.

Packets are Type 2+, sent as ARCmail bundles (packer = zip, the default, or arc, arj, lha) or as bare packets (none). Received bundles of any of the four kinds (whatever they are called; the BBS reads their contents to tell) and bare packets are tossed, and broken packets go to dir/bad. Files without a TIC that are a day old (such as file requests, or a file a sysop sent by hand) are set aside in dir/in/LINK/files.

New mail is packed within a minute (netmail at once). A link with a host is called when mail is waiting for it (and again every five minutes while calls fail), and every poll seconds. The first scan for a new link only marks where to start, so the link is not sent the whole history.

Gateways to newsgroups

An area that is both an echo and a newsgroup is a gateway. Echomail is served to newsreaders as articles (From Name <Name@f1.n2.z3.fidonet.org>, with the Message-ID made from the MSGID as other gateways do), and articles from news peers go out as echomail. Most FidoNet echoes do not want gated traffic, so ask first.

Bundles

Nearly every hub sends ARCmail as ZIP, but older systems send ARC, ARJ or LHA. The BBS reads all four itself, so there are no archivers to install: ZIP's stored and deflated methods; ARC's stored, packed, squeezed, crunched and squashed; ARJ's methods 1 to 4; and LHA's -lh0- and -lh4- to -lh7-, with header levels 0 to 2. Bundles it writes with packer = arc, arj or lha are stored uncompressed, so every unpacker can read them. The same readers list archives in the file areas and find their FILE_ID.DIZ.

Nodelists

nodelist in [fido] names nodelists (FTS-5000) by path or pattern, or as area:NAME for the file area that the NODELIST file echo fills. The BBS reads the newest file of each, plain or in an archive, and reads it again when a newer one arrives. With a nodelist:

• netmail to a node it lacks, or has as down, is refused as it is written, and the writer is told the system's name and place when it is sent;
• host = nodelist has a link called where its nodelist entry says (its IBN flag's host, or its INA);
• bbs fido node and bbs fido nodes look systems up, and callers can too: N (PF5 on a 3270) in their mailbox searches the nodelist.

Only zones that the nodelists cover are checked. Netmail for other zones, and for links, is sent without a check.

AreaFix and FileFix

A link with areafix = yes manages its own echoes. Out of the echoes that echoes (and fileechoes) allow, it gets the ones it asks for, by sending netmail to AreaFix (or AreaMgr) and FileFix (or FileMgr, AllFix, Raid, TicFix) with its areafix_password as the subject and one command per line:

+FSX_GEN        link it (a pattern too: +FSX_*)
-FSX_GEN        unlink it; -ALL unlinks every one
%LIST           what it may have, * where linked
%QUERY          what it has linked
%UNLINKED       what it has not
%HELP           this

The answer comes back by netmail. The sysop can do the same from the command line (bbs fido link, unlink, filelink, fileunlink) and see what a link has (bbs fido subs). A link without areafix gets every echo that echoes allows.

In the other direction, bbs fido areafix hub COMMAND... (or filefix) writes to a link's robot with areafix_password. With create = yes on that link, the echoes and file echoes it then sends are created here (as a message area, or a sysop-upload file area, named by the tag) instead of being dropped.

File echoes

A file area becomes a file echo with bbs filearea echo AREA TAG. Files arrive with TICs (FTS-5006). Each file is checked (that it came from the link with its tic_password, its size and CRC-32, that it is not a duplicate, and that it has not already passed this system), put in the area with its description, and passed on with its own TIC to the other links that carry the echo and are not in its SEEN-BY. A TIC's Replaces removes the older files it names, among those that came by a file echo. Files uploaded here (by callers, by FTP or with bbs file add) are hatched, which means sent to every link that carries the echo. A file that does not match its TIC goes to dir/bad, and a TIC waits a day for its file. As with echomail, the first scan for a link only marks where to start.

Testing

The BBS was tested against binkd 1.1a and CrashMail II 1.7, with echomail and netmail in both directions, both calling binkd and being called by it, with ZIP bundles and CRAM-MD5. Bundles made by the real arc, arj and jlha are tossed correctly, and those tools unpack what the BBS writes.

Not supported

File requests (FREQ), routing other systems' netmail, binkp's NR mode, CRYPT and multiple batches (the BBS speaks binkp/1.0, which every mailer accepts), and EMSI for mailers calling by modem.

See also: Newsgroups and NNTP, Security