Latency on Beowulf Mailing list

pesch at pesch at
Sat Dec 6 16:50:11 EST 2003

I was planning to call Beowulf clustering the "Viagra of computing" - but after Donalds elaborations I plan to
change my mind :(((

Donald Becker wrote:

> On Fri, 5 Dec 2003, Erwan Velu wrote:
> > When I'm sending messages to beowulf mailing list, I can see them after
> > 8 hours :(
> >
> > Sometimes, my answers are too old for being intresting :(
> >
> > Any ideas? Does other users are in the same case ?
> The quick answer is "spammers and viruses".
> There are several reasons that this is the case:
>   Over 95% of Beowulf list postings are held for moderation
>   The Beowulf list alone has about 3000 addresses
> 95% might seem large, but considering only 1 in ten attempted postings
> is valid, only about 50% of the posts are held for moderation.  While I
> do sometimes wake up in the middle of the night to moderate, you
> shouldn't really expect that.
> A posting may be held for moderation by match any of about 25 patterns.
> Some of those patterns are pretty general -- even certain three digit
> numbers and two digit country codes will trigger moderation.
> Once held for moderation the posting may be automatically deleted.
> Right now there are 1439 phrases and 3298 IP address prefixes and domain
> names.  All were hand added.  My goal is over 90% automatic deletions.
> If I stop adding rules, it drops below that number in a week or two as
> spammers move machines and change tactics.
> Less common is that a post is automatically approved.  Some spammers
> have taken to including sections of web pages in their email, so don't
> expect this increasing in the future.
> The second point is also a result of spammers, albeit indirectly.  The
> list is run by mailman, which splits the list up into sections.  If your
> position is after a Teergruber, or the link is just busy, your email
> will be delayed for several hours.  Despite being very responsible
> mailers, our machine (or perhaps our IP address block) does sometimes
> end up on a RBL.
> I see this problem as only getting worse.  Our "3c509" mailing list is
> first alphabetically, and thus is the first recipient of new spam.  I've
> mostly given up on it, but leave it in place to harvest new patterns.
> It received 5 new messages in the past 30 minutes, a rate up
> substantially over just a few months ago.
> So, what can you do to avoid delays?  Nothing especially predictable,
> because predictable measures are easily defeated by spammers.  But you
> can
> - avoid posting or having a return address from free mail account services
> - have a reverse-resolving host name on all mail hops
> - don't have "adsl" or "dialup" in the header
> - avoid all mention of "personal enhancement" drugs, purchasing drugs of
>     any kind, moving money out of your sub-sahara country, mentions of
>     credit card names, sex with a farm animal, sex with multiple farm
>     animals, webcams, etc.  Talking about your cluster of webcams of
>     viagra-enhanced farm animals trying to move their lottery winnings
>     out of from Nigeria, even if they puchased the viagra at dicount
>     rates from Canadian suppliers that included a free mini-rc car could
>     conceivably be brought on-topic, but that posting will never make it.
> --
> Donald Becker                           becker at
> Scyld Computing Corporation   
> 914 Bay Ridge Road, Suite 220           Scyld Beowulf cluster systems
> Annapolis MD 21403                      410-990-9993
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