500 miles

_data/navigation.csv

@@ -8,6 +8,7 @@ link dump,/linklink
 timezone,/oneshot/timezone
 coding bibble,/oneshot/codingbible
 footgun,/oneshot/footgun
+500 miles,/oneshot/500miles
 guestbook,http://users3.smartgb.com/g/g.php?a=s&i=g36-36498-b6
 direct message me,/personal/qa
 thanks page,/thanks

oneshot/500miles.md

@@ -0,0 +1,147 @@
+---
+title: 500 miles
+---
+## Sourced from <https://web.mit.edu/jemorris/humor/500-miles>
+
+From: Trey Harris <trey@sage.org>
+
+Here's a problem that *sounded* impossible...  I almost regret posting
+the story to a wide audience, because it makes a great tale over drinks
+at a conference. :-)  The story is slightly altered in order to protect
+the guilty, elide over irrelevant and boring details, and generally make
+the whole thing more entertaining.
+
+I was working in a job running the campus email system some years ago
+when I got a call from the chairman of the statistics department.
+
+"We're having a problem sending email out of the department."
+
+"What's the problem?" I asked.
+
+"We can't send mail more than 500 miles," the chairman explained.
+
+I choked on my latte.  "Come again?"
+
+"We can't send mail farther than 500 miles from here," he repeated.  "A
+little bit more, actually.  Call it 520 miles.  But no farther."
+
+"Um... Email really doesn't work that way, generally," I said, trying
+to keep panic out of my voice.  One doesn't display panic when speaking
+to a department chairman, even of a relatively impoverished department
+like statistics.  "What makes you think you can't send mail more than
+500 miles?"
+
+"It's not what I *think*," the chairman replied testily.  "You see, when
+we first noticed this happening, a few days ago--"
+
+"You waited a few DAYS?" I interrupted, a tremor tinging my voice.  "And
+you couldn't send email this whole time?"
+
+"We could send email.  Just not more than--"
+
+"--500 miles, yes," I finished for him, "I got that.  But why didn't
+you call earlier?"
+
+"Well, we hadn't collected enough data to be sure of what was going on
+until just now."  Right.  This is the chairman of *statistics*. "Anyway,
+I asked one of the geostatisticians to look into it--"
+
+"Geostatisticians..."
+
+"--yes, and she's produced a map showing the radius within which we can
+send email to be slightly more than 500 miles.  There are a number of
+destinations within that radius that we can't reach, either, or reach
+sporadically, but we can never email farther than this radius."
+
+"I see," I said, and put my head in my hands.  "When did this start?
+A few days ago, you said, but did anything change in your systems at
+that time?"
+
+"Well, the consultant came in and patched our server and rebooted it.
+But I called him, and he said he didn't touch the mail system."
+
+"Okay, let me take a look, and I'll call you back," I said, scarcely
+believing that I was playing along.  It wasn't April Fool's Day.  I
+tried to remember if someone owed me a practical joke.
+
+I logged into their department's server, and sent a few test mails.
+This was in the Research Triangle of North Carolina, and a test mail to
+my own account was delivered without a hitch.  Ditto for one sent to
+Richmond, and Atlanta, and Washington.  Another to Princeton (400 miles)
+worked.
+
+But then I tried to send an email to Memphis (600 miles).  It failed.
+Boston, failed.  Detroit, failed.  I got out my address book and started
+trying to narrow this down.  New York (420 miles) worked, but Providence
+(580 miles) failed.
+
+I was beginning to wonder if I had lost my sanity.  I tried emailing a
+friend who lived in North Carolina, but whose ISP was in Seattle.
+Thankfully, it failed.  If the problem had had to do with the geography
+of the human recipient and not his mail server, I think I would have
+broken down in tears.
+
+Having established that -- unbelievably -- the problem as reported was
+true, and repeatable, I took a look at the sendmail.cf file.  It looked
+fairly normal.  In fact, it looked familiar.
+
+I diffed it against the sendmail.cf in my home directory.  It hadn't been
+altered -- it was a sendmail.cf I had written.  And I was fairly certain
+I hadn't enabled the "FAIL_MAIL_OVER_500_MILES" option.  At a loss, I
+telnetted into the SMTP port.  The server happily responded with a SunOS
+sendmail banner.
+
+Wait a minute... a SunOS sendmail banner?  At the time, Sun was still
+shipping Sendmail 5 with its operating system, even though Sendmail 8 was
+fairly mature.  Being a good system administrator, I had standardized on
+Sendmail 8.  And also being a good system administrator, I had written a
+sendmail.cf that used the nice long self-documenting option and variable
+names available in Sendmail 8 rather than the cryptic punctuation-mark
+codes that had been used in Sendmail 5.
+
+The pieces fell into place, all at once, and I again choked on the dregs
+of my now-cold latte.  When the consultant had "patched the server," he
+had apparently upgraded the version of SunOS, and in so doing
+*downgraded* Sendmail.  The upgrade helpfully left the sendmail.cf
+alone, even though it was now the wrong version.
+
+It so happens that Sendmail 5 -- at least, the version that Sun shipped,
+which had some tweaks -- could deal with the Sendmail 8 sendmail.cf, as
+most of the rules had at that point remained unaltered.  But the new
+long configuration options -- those it saw as junk, and skipped.  And
+the sendmail binary had no defaults compiled in for most of these, so,
+finding no suitable settings in the sendmail.cf file, they were set to
+zero.
+
+One of the settings that was set to zero was the timeout to connect to
+the remote SMTP server.  Some experimentation established that on this
+particular machine with its typical load, a zero timeout would abort a
+connect call in slightly over three milliseconds.
+
+An odd feature of our campus network at the time was that it was 100%
+switched.  An outgoing packet wouldn't incur a router delay until hitting
+the POP and reaching a router on the far side.  So time to connect to a
+lightly-loaded remote host on a nearby network would actually largely be
+governed by the speed of light distance to the destination rather than by
+incidental router delays.
+
+Feeling slightly giddy, I typed into my shell:
+
+$ units
+1311 units, 63 prefixes
+
+You have: 3 millilightseconds
+You want: miles
+        * 558.84719
+        / 0.0017893979
+
+"500 miles, or a little bit more."
+
+Trey Harris
+-- 
+I'm looking for work.  If you need a SAGE Level IV with 10 years Perl,
+tool development, training, and architecture experience, please email
+me at trey@sage.org.  I'm willing to relocate for the right opportunity.
+
+
+