On 05/21/2012 03:06 PM, [email protected] wrote:
Hello Eric, thanks for your reply.
We do not have spam issues with our customers, what we have is a high
volume due to large clients number.
With so many clients, the probability of compromised passwords is fairly
high. I wouldn't be very quick to dismiss this as a possibility. Do your
anti-spam measures have any effect on authenticated smtp sessions?
All meassures to void spam sending are taken, but the blocks are being
generated for large volume send from just a bunch of IPs (5) which are
the number of mta's qmt in our cluster. As all you may know, having 9k
clients with at least 4 email accounts per client and a limit of 350 per
hour per account, it is still a big traffic generated.
350 per hour per account seems like a high limit to me for typical email
use. In any case, how are you enforcing this limit?
So I am looking forward to have better service on delivery having in
mind that custmer number is growing fast and anti-spam messures do its
job preatty good. But of the lack of IP on each mta in cluster, it is
affecting delivery.
Hope someone around may share a solution.
Are all machines in the cluster going out on the the same public IP? If
so, I presume you have NAT in effect. If that's the case, you should
look into implementing SNAT along with NAT, so the source IP changes
according to which machine behind the NAT is the source of the packets.
This is something your NAT router needs to do.
Thanks.
A little more detailed description of your current setup might be
helpful for us to know what might be most effective for you.
--
-Eric 'shubes'
On lun 21/05/12 4:55 PM , Eric Shubert [email protected] sent:
I don't know if rotating addresses is the best solution or not. It's
certainly not practical for small QMT installations.
I think in many (if not all or most) of these cases, the user's
password
has been compromised. This is especially likely if it's possible to
configure a client insecurely (plain text password with no TLS/SSL).
I've seen this happen on more than one occasion, on a small domain.
Password sniffing does happen.
First step is to ensure that clients cannot attempt to authenticate
with
clear text passwords. This can be enforced with dovecot, but we don't
have a way yet to enforce it on the sending/smtp side. I'm hopeful that
Sam will get this feature built into spamdyke in the near future.
Another good defensive weapon is a script I came across on the spamdyke
list today, and hope to make available in some form with QTP in the
future. It's a script that periodically checks the logs for accounts
which have sent more messages in a given interval than some allowed
limit. When it finds such an account, it changes the password, removes
messages from that account still in the queue, and notifies the
postmaster with an email. I think this is very practical, because
passwords do become compromised on occasion, even with full encryption
(human action). The script is written in python, and will need a little
tweaking for the QMT environment, as it's presently written to scan a
spamdyke log (the author wasn't using the submission port at all). I
think it'd be better to scan the send log if that's feasible.
Anywise, I
think this approach is promising.
If anyone has any thoughts on this, please chime in. It's in everyone's
interest to be protecting our public IP addresses so they don't get
blacklisted.
Thanks.
--
-Eric 'shubes'
On 05/21/2012 01:42 PM, [email protected]
<mailto:[email protected]> wrote:
> Hello everyone
>
>
> I am the owner of a growing hosting enterprise in my country
(Perú), and
> we are facing big rise on our client number.
>
> As an efect of this we are seeying a rise in mail outbound in our
> servers. Even thoug we put limits to hourly sending, having more
than 9k
> clients, all delivering through the same cluster, it lacks of
> efectiveness because each server in cluster uses only one ip for
sending
> tasks. We are now seeying blocking issues because of the many clents
> generated traffic.
>
> We talked to some people at godaddy and hostgator, as we know they
use a
> cluster system that includes on each server a list of IPs that rotates
> in a random fashion, so even with high demand quality service on mail
> delivery from client accounts is always achieved.
>
> I would like to ask for some guidance and help to this comunity on how
> can we could implement such solution to rotate in a random or
other way
> the IPs for sending clients mails.
>
> I hope you people can see my situation and can help me with this. We
> used to work with exim, but since we changed to QMT it was the best
> desition we ever made on this matters. Now we need to push it to a
next
> level.
>
>
>
> Thanks a lot.
>
>
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If you need professional help with your setup, contact them today!
---------------------------------------------------------------------------------
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