Re: SMTP-SASL auth failure caching.
- Found what I think is a mistake in the documentation. "dict_del" in
"util/dict_open.c" is documented as returning non-zero on success.
This seems to be wrong, it returns greater than zero if the key does
not exist, zero if the key does exist and is deleted okay, and less
than zero on any other error.
Keean Schupke, Fry-IT Ltd.
On 30/11/2007, Wietse Venema <wietse@...> wrote:
> Victor Duchovni:
> > On Fri, Nov 30, 2007 at 06:36:49PM +0000, Keean Schupke wrote:
> > > Okay, a question about the verify service.
> > >
> > > If I do this, it seems that there will be all sorts of strange
> > > interactions with the normal verify service. You may have conflicting
> > > goals...
> > No, none at all. The verify(8) service is just a database.
> I would not use verify(8), because that solves a different problem:
> did a probe for a specific email address get bounced or deferred?
> The problem at hand is this:
> did x allow me to log in with this particular username?
> But that is the less important issue.
> The reason for a dedicated daemon is that the typical UNIX DB/DBM
> library is not suitable for concurrent updates by multiple processes.
> This is why Postfix has tlsmgr(8) for TLS cache management, and
> verify(8) for address verification management.
> Now, this dedicated daemon could be competely outside of Postfix,
> if the client side of the protocol is simple enough.
- On Tue, Dec 04, 2007 at 09:04:19PM +0000, Keean Schupke wrote:
> How about we make the key iterations a config variable, and let theYes, that's the idea. Also CPUs have historically gotten faster
> user make the balance between speed and security?
year-by-year. Moore's law is looking a bit more feeble lately, we are
getting the feature-size scaling (more cores per die) but the clock-rate
seems to have stalled for a bit.
Finally, the table will not be in the chroot jail, proxymap/proxywrite
won't be chrooted even when other processes are. So some "postfix"
processes will have less access to the table than others.
Anyway this is all coverging to something sensible. The question for
the smtp(8) side is whether making the password hash the key is the
best choice. We could make "nexthop user" the key, and stick the
password hash in the result. That way deletion will actually work.
Otherwise, new passwords will be set before the fail map entry expires,
and the table entry becomes orphaned.
If this change is made, the entry is valid only if not expired, and the
password hash matches. Looks a lot an /etc/shadow entry with a user name
and PKCS#5 v2 password hash, only it perversely records invalid passwords!
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