Re: Wollongong telnet and new line processing


Jim Jensen (mtune!codas!novavax!atlas!jjensen@RUTGERS.EDU)
22 Jul 87 12:39:18 GMT


in article <25@abvax.icd.ab.com>, wrk@abvax.icd.ab.com (William R. King) says:
>
> I've been tyring to get our BSD 4.3 VAX to talk to a VAX/VMS
> system using Wollongong telnet and have discovered an interesting
> problem. Unix uses \n as the line terminator,
>[deleted about sending a \r to VMS]
> Unix translate the \r into a \n and sends it across the net
> [problems this causes on VMS deleted]
> I've modified telnet to send a \r instead of a \n for the line
> terminator. Although I think this is only a work around.
>
> I say this because if you are connect to the Unix machine
> via a direct line everything works fine. This problem only
> occurs when you are connected via a pty. We use Bridge
> cs/1 terminal servers almost exclusivly, hence you are always
> connected to a pty and never to a direct line.
>

(this is my first posting so I dont know if I am doing this right)

I just finished writing telnet for MPX (Gould's real time OS), and ran into
the same problem. The bridge box sends a \r\n which is the specifed in the
telnet rfc as the end of line character. which the unix telnet server turns
into a \n.

on telnet 4.2 the telnet task, converts this back to \r\n
which the VMS(or MPX)server converts back to a \r and everything works.

4.3 leaves it as a \n, which seems to me to be a clear violation of the
protocol. The rfc SAYS that \r\n is the end of line character, not \n.
Thats what protocols are for; To take care of differences between machines.
When a protocol is not followed problems like this happen.

I asked one of our unix people about it, and he said that
BSD did it on purpose, and it is in telnet. I was unable to convince
him it was a mistake, so he would not change it. that is until some people
in our unix group tried to use a bridge box. Thus:

 the latest patch to Gould Unix has a telnetd which has a variable that can be
set called Telnet_with_a_bridge_box(if I remember correctly) that if set fixes
the problem.

I am not a unix person, so I may have gotten something wrong about unix, but
I don't think so.
                                              Jim Jensen
                                              Gould inc. CSD
                                              6901 West Sunrise Boulevard
                                              Ft. Lauderdale Fl 33313-4499
                                              (305) 587-2900



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