Document: FSC-0049
Version:  001
Date:     03-Jul-90

                               A Proposal for
                         Passing Domain Information
                         During an FTS-0006 Session

                                Bob Hartman
                                July 3, 1990

Status of this document:

     This FSC suggests a proposed protocol for the FidoNet(r) community,
     and requests discussion and suggestions for improvements.
     Distribution of this document is unlimited.

     Fido and FidoNet are registered marks of Tom Jennings and Fido

FSC-0045 proposes a method for sending five dimensional FidoNet addresses
(ie, zone:net/node.point@domain) via the type 2 packet header.  This
document describes a proposed method for sending the same five dimensional
address in the Hello packet of an FTS-0006 session, with the additional
advantage of being able to utilize the full Internet recognized domain name
for various Fidonet technology networks.  This proposal, combined with
FSC-0045 will help to solve one of FidoNet's most pressing problems: How to
recognize alternative networks without the need of some centralized
management looking at all of them and what they are doing with Zone numbers,
etc.  Like FSC-0045, this proposal remains backwards compatible with what it
is replacing.

Currently FTS-0006 has provisions for zone, net, node, and point information
to be passed in the Hello packet.  To extend this to allow the domain name
to be passed, an extra capability bit is used.  This bit corresponds to the
0x4000 bit, and will be called the DO_DOMAIN bit.  If this bit is set, it
means that the sender is domain aware, and has enclosed his domain in the
Hello packet.  The domain is stored in the system name field, after the null
that terminates the real system name.  The system name field is a maximum of
60 characters, so the sender must make the real system name, a null, the
domain name, and another null byte fit within the 60 bytes.  The domain will
start at the byte immediately after the first null byte.  The domain is
arbitrary length and should correspond to the Internet assigned domain name.
This is NOT the same as the FSC-0045 domain, and therefore there needs to be
a mapping between real Internet domains, and the FSC-0045 style domain name,
if FSC-0045 is accepted by the FTSC as a standard for use by all mailers.
This mapping is normally straightforward (for example, Internet
would correspond to FSC-0045 domain FidoNet).  Since most alternative nets
do not have a registered Internet domain, the naming convention should be
"known by" domain (ie, FSC-0045 domain name) followed by .ftn (for FidoNet
Technology Network).  So, the FSC-0045 domain "Alternet" would be converted
to alternet.ftn under this proposal.  This allows domains which are not
normally FidoNet aware to use FTS-0006 to talk to FidoNet technology mail
programs.  For example, a mailer located at Camex in Manchester, NH might
send it's mail as '' during an FTS-0006 session.  When parsing
the domain name, the parsing should try to match the domain from right to
left (Internet naming is hierarchical from right to left), so that if a
mailer knew about, that could also match something of the form  The domain name should be case
INSENSITIVE, and the FSC-0045 abbreviation of it should be unique within the
first 8 characters, and also should not include any periods ('.') or at-signs
('@') since those characters are significant in the Internet domain naming

In order for this proposal to be adopted, the FTSC would have to assign the
DO_DOMAIN bit, and have it documented in FTS-0006.  This method is fully
backwards compatible, since a domain aware mailer could send the domain
information, and if the other end was not domain aware, it would ignore it.
If the other end was domain aware, it would be able to extract the domain
information easily and would then have a full five dimensional address
available for the sender.  This proposal remains fully backward compatible
with the current uses of all FTS-0006 fields, and should not affect operation
of any mailer that has used reserved bytes in the Hello packet.