Re: [tlug] Meeting Notes: TLUG Open Meeting: March 13, 2010

[Curt Sampson <cjs@example.com>]

On 2010-03-15 15:20 +0900 (Mon), Jim Grisanzio wrote:

> o Clustering and more development talks

Well, I can probably step in with some stuff there, since I go to a fair
amount of trouble to try to set up distributed, redundant systems when I
can.

Recently I've been reworking my mail systems, and this might be of
interest to the group. 

I use a set of two or three "front-end" mail servers running Postfix
that forward mail only (they do no local delivery). Most of the domains
they handle have a complete set of local address information so that
mail to invalid addresses can be rejected at this point. They also
take care of basic spam filtering. I currently just use a few popular
DNSBLs on them at the moment, combined with my own custom allow and deny
lists and header checks, but there's no reason that they couldn't run
SpamAssassin or some other content-checking system as well.

For the host that runs my mail, I currently use a Postfix instance doing
local delivery via procmail, but I'm just now experimenting with using
procmail alone as an LMTP (Local Mail Transport Protocol) server. This
is not only a simpler configuration, but in particular makes it easy
to run a standard Postfix instance (such as the one above) on the same
host. Currently I just use tcpwrappers to restrict access to it, but
clearly it should be wrapped with stunnel instead.

All of the configuration is in git repositories, with some scripts that
deal with checking that the host has the right packages available,
configuring things, and so on. On occasion you need to be a bit clever
to do what you want, rather than what your distribution wants, and also
you need some tricks to deal with handling permissions.

The front-end server config is pretty mature. It's a matter of a few
minutes to set up a new server, and all failover is automatic. The local
delivery server side of things is a bit more rough, but I'm hoping to
find some reasonable automated way to set up a hot standby, even if it
requires manual failover.

I may be able to find time to put together a presentation on this for
May, if anybody's interested. Assuming Josh hasn't kicked me out of TLUG
by then, of course. :-)

cjs
-- 
Curt Sampson         <cjs@example.com>         +81 90 7737 2974
             http://www.starling-software.com
The power of accurate observation is commonly called cynicism
by those who have not got it.    --George Bernard Shaw