Date: Sun, 13 Dec 1998 18:43:50 +1100 (EST) From: Rowan Crowe <rowan@sensation.net.au> To: Dean Hollister <dean@odyssey.apana.org.au> Cc: freebsd-isp@FreeBSD.ORG Subject: Re: sendmail morons Message-ID: <Pine.BSF.4.01.9812131835450.4706-100000@velvet.sensation.net.au> In-Reply-To: <Pine.BSF.4.05.9812131529240.4741-100000@odyssey.apana.org.au>
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On Sun, 13 Dec 1998, Dean Hollister wrote:
> > If it's a machine performance issue then you could try limiting the number
^^^^^^^^^^^^^^^^^^^^^^^^^
> > of children:
> >
> > # maximum number of children we allow at one time
> > O MaxDaemonChildren=30
> >
> > If it's for a major mail server then I would _not_ recommend this, as once
> > the limit is reached all connections to port 25 will be refused. I had a
> > play with this the other day when someone decided to forward 150Mb+ of
> > their email from work to their home account, and it was severely loading
> > the system.
>
> I would *not* recommend this. It would be better to configure the child
> process to exit if the IP is in its db. I vaguely recall something at
> www.sendmail.org about it.
Note that I specified "machine performance issue". I'd rather have my
server have an absolute known limit where it no longer accepts new
connections rather than a steady decline as more and more sendmail
processes appear with each new connection. Seeing a machine run out of
swap space is not fun. ;\
This absolute limit could also be of use in something like a SYN flood
attack. (Note that limiting to 30 is probably _way_ too low, that's just
something I've started with. Still experimenting).
Also, adding in IPs requires periodic review of the database by a human.
Cheers.
--
Rowan Crowe Sensation Internet Services, Melbourne Aust
fidonet: 3:635/728 +61-3-9388-9260
http://www.rowan.sensation.net.au/ http://www.sensation.net.au/
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