Re:History of 127/8 as localhost/loopback addresses (2021)
by DonHopkins on Wednesday May 25, 2022 @12:35PM
(#31506869)
In the days of NCP, before TCP/IP (aka ipv4), the original ARPANET TIP manual "Users Guide to the Terminal Imp" (originally written in 1971 by William Crowther, one of the authors of Adventure) documents on page 5-4 the procedure for connecting an input and output socket of one TIP to an input and output socket of another TIP, through an unsuspecting host, so you could chat back and forth directly between two TIP dial-ups, without actually logging into the host.
It went something like @HOST #, @SEND TO SOCKET #, @RECEIVE FROM SOCKET #, @PROTOCOL BOTH, making sure the sockets were different parity so as not to violate the Anita Bryant clause with homosocketuality:
You could also add the octal device port number of any other TIP user on your same TIP after the @ and before the command, to execute those commands on their session. (See page 5-7, "Setting Another Terminal's Parameters".) BBN wrote such great documentation and would mail copies of it for free to anyone who asked (that's how I got mine), you couldn't even call it security by obscurity!
https://archive.org/details/bitsavers_bbntipADA0eTerminalIMP...
It went something like @HOST #, @SEND TO SOCKET #, @RECEIVE FROM SOCKET #, @PROTOCOL BOTH, making sure the sockets were different parity so as not to violate the Anita Bryant clause with homosocketuality:
https://news.ycombinator.com/item?id=12422813
You could also add the octal device port number of any other TIP user on your same TIP after the @ and before the command, to execute those commands on their session. (See page 5-7, "Setting Another Terminal's Parameters".) BBN wrote such great documentation and would mail copies of it for free to anyone who asked (that's how I got mine), you couldn't even call it security by obscurity!