I finally remembered the syntax to force transport.  After you are done with whatever the host name is, you append a ".#" suffix followed by the name of the transport protocol.  Let's suppose there is a nickname defined in the SYSTEM:HOSTS.TXT file for MIM:: as follows:

HOST : 192.108.202.74 : MIM : PDP11 : RSX : TCP/TELNET,TCP/FTP,TCP/SMTP,TCP/FINGER :

So we can force a finger of user DEBELLIS to use a particular transport, as below.  In the output, the DCN: device is the DECnet active component (or client) and the TCP: device is for IP, where client or service are specified in the GTJFN% string.

DECNET

    FINGER>debellis@mim.#decnet
    [Fork FINGER opening DCN:MIM-117 for reading, writing]
    DEBELLIS                                
    Default directory: US00:[DEBELLIS]     CLI: DCL    SID: TDB
    Last seen May 21 2024 23:56:54 on RT0: from VENTI2::                      
    Logged on 8 times.
    No plan.

INTERNET

    FINGER>debellis@mim.#internet
    [Fork FINGER opening TCP:.30033145112-79;PERSIST:30;CONNECTION:ACTIVE for reading, writing]
    DEBELLIS                                
    Default directory: US00:[DEBELLIS]     CLI: DCL    SID: TDB
    Last seen May 21 2024 23:56:54 on RT0: from VENTI2::                      
    Logged on 8 times.
    No plan.

I did notice that the user and host name data appear to be written in fixed length fields, resulting in trailing spaces that were not trimmed.  This is unlike the other lines in the output.  Not that it really matters; who is running 300 baud these days except for museums?

On 7/20/24 7:27 PM, Thomas DeBellis wrote:

All too true, except that it isn't stupid, at least not in that particular regard.

As per my previous email, Finger uses HSTNAM to determine network transport, which has a default order, on my systems picking DECnet first.  I'm pretty sure there was a way to force the transport protocol, I just don't remember what the magic syntax is.

A number of system programs use HSTNAM to implement their protocols over multiple transports.  These include the mail system, the FTP client, finger and something else (I think).

On 6/17/24 9:22 PM, Johnny Billquist wrote:

Ugh. That notions seems risky... How do you know you should be using DECnet and not IP if you say @mim?

After all, @mim is a perfectly valid IP address as well.

On 2024-06-18 00:47, Thomas DeBellis wrote:

Updating the Tops-20 Finger client was simple enough, a table entry for DECnet and a small routine to build the JFN string, viz: