[ih] Internet-history Digest, Vol 65, Issue 23

[Dave Crocker]

On 4/21/2025 8:23 AM, John Shoch via Internet-history wrote:
> But none of the networking protocols enforced data
> integrity and this problem had,
> apparently, gone on for months."


Heh. Apologies.  I thought I'd worded that more carefully.  And thanks 
for providing the background treatise this needed.

I did indeed only mean to comment on the implementation only.  I was 
tempted to review the actual protocol specs, which is something I 
probably did back then. But I'm a lot lazier now.

Anyhow, cutting corners by implementers doing proprietary 
implementations was not that unusual in those days. In the emerging 
commercial Internet space, I especially liked marketing blurbs for 
Internet protocols that said 'based on' TCP/IP, since it inevitably 
meant the product did not interoperate with other people's.

At U-B, we had a telnet client implementation that was fairly aggressive 
about setting up telnet options with the other side, as soon as the TCP 
connection was set up. One day, a friendly, knowledgeable customer 
called to say that it did not interoperate with another company´s telnet 
server.  This was a surprise, since we interoperated with plenty of 
others and had had no problem reports before this.

I sent them the packet-tracing package and had them capture a session.  
What I saw from it was that the other side received the TCP connection 
and then immediately passed it off to their terminal driver, with no 
telnet server mediating. So their system just echoed back our telnet 
option requests!

Best of all was that after I explained this to the customer they then 
asked me what we were going to do about it.  I sputtered that the 
problem was the other company's implementation.  The customer said they 
understood this, and would certainly talk with the other folks, but we 
were more responsive....

Later, at Wollongong, we had a PC TCP/IP stack that suddenly started 
flooding the LAN.  Turned out the engineer had built it in a LAN-only 
environment (before I got there) which was a lot quicker and a lot more 
reliable than the open Internet. So they chose to avoid the hassle of 
implementing the specified retransmission code and just had a fixed, 
very-short timer....

d/

-- 
Dave Crocker

Brandenburg InternetWorking
bbiw.net
bluesky: @dcrocker.bsky.social
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