From: Michael Tokarev (no email)
Date: Thu Jul 01 2004 - 13:55:41 EDT
Josh Marcus wrote:
> I was wondering if I could get advice on an issue I'm having.
>
> Very occasionally, on a system I administrate, I'm getting unknown user
> errors for incoming mail which should be accepted. My best guess is
> that this happening because of a less than ideal authentication scheme.
> Flat /etc/passwd and shadow files are generated from a MySQL database,
> and then copied into place after verification. My guess is that, under
> high load, there is a moment where postfix is checking a user while the
> file is being copied into place.
Ugh. NEVER, EVER, copy a file "into place". Imagine what will happen
if the copy process will fail in the middle for whatever reason -- that
should be enouth to abandom the "into place copy idea" entirely.
Use temp file instead, and use atomic rename(2) (or mv) when you're
sure the file is written ok.
/mjt
|
|
|