[TUHS] [COFF] Pondering the hosts file

Paul Ruizendaal pnr at planet.nl
Fri Mar 12 20:53:05 AEST 2021

BBN’s TCP implementation contained something akin to the hosts file, called hostmap there:

I have not looked at the code for a while, but if I remember correctly the BBN kernel code also read in this file (pre-processed into a binary form) to build its internal routing table.

I do not recall having seen an equivalent file with UoI's NCP Unix in any of the surviving docs or sources - but that does not exclude a library having existed to do lookups in a local copy the SRI-NIC host file. In fact there is some evidence for that in the 2.9 BSD source.

The only surviving copy of the 4.1a (network) source code that I know is in the back-port of this code to 2.8/2.9 BSD. This code includes #ifdef’ed code for accessing the SRI-NIC online host table via NCP:

This source also contains tools to convert the SRI-NIC data into - inter alia - a hosts file:

It would seem that the modern host.txt on Unix evolved late ’81 (BBN code) to early ’82 (4.1a BSD). Possibly NCP Unix has prior work.


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