Re: avoiding overload on port 587
- Am 30.11.2012 11:52, schrieb Tomas Macek:
> If the Postfix's behaviour on port 587 is the same as with 25, it seemsplease reread the doku why and how using submission
> to me to be better to let the MUAs to send their mail to 25. In the
> postscreen the mynetworks are automatically whitelisted and on 25 they
> have better chance to send their mails, because 25 should not be
> overloaded because of postscreen used.
> Using firewall on 587 is useless, because our clients travel with their
> computers even around Europe and want to send their mails.
as its used with auth only, no spammer will ever deliver mail unless he
has a valid auth via submission, most attacks running against submission
are brute force attacks ,try finding user and auth accouts combination
to hack in
for brute force fail2ban or simular is good enough,
process limits or mail send limits are managed by other stuff i.e
postfix parameters and/or policy servers
MfG Robert Schetterer
[*] sys4 AG
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- On Tue, Dec 04, 2012 at 07:46:10AM -0600, /dev/rob0 wrote:
> On Tue, Dec 04, 2012 at 11:59:01PM +1300, Peter wrote:Or better yet: replace it with postscreen.
> > I would still also set up port 587 on the mail.example.com
> > IP as submission as well and try to encourage your users (at
> > least the ones you can) to use port 587 from now on.
> What I would do, on Linux with IPv4 only, is create the submission
> port and use an iptables redirect for the alternate IP address:
> # iptables -vt nat -A PREROUTING -p tcp --dport smtp -d \
> mail.example.com -j REDIRECT --to-port submission
> This saves the overhead (system and administrative) of running
> another smtpd on [mail.example.com]:25; he can leave his "smtp ...
> smtpd" service alone in master.cf.
> I should also add as a reply to Stan in the other subthread: lookTo clarify, I meant that if those Outlook Expresses are not yet
> above at the first quoted paragraph: "Outlook Expresses setup with
> ... default configuration."
> Yikes, bad news, very bad. If not doing content filtering nor
> policy limitation of submission now, he will be soon. And possibly
> losing his job in any case. Tomas is not in a good place right now.
compromised by malware, they will be, soon.
http://rob0.nodns4.us/ -- system administration and consulting
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