Re: help with how to drop connection on syntax error

On Wed, Jul 01, 2026 at 10:59:11AM +0200, Cyborg via Exim-users wrote:

> > I was hoping someone here could help me with this.  How can I make
> > exim DROP the connection faster, in response to being dos flooded
> > with gibberish.  How, and where, can I make it DROP on first
> > syntax error, instead of it sending back countless "500
> > unrecognized command" or "501 NUL characters are not allowed in
> > SMTP commands" and what not, then sitting there witting for
> > smtp_receive_timeout.

> smtp_max_synprot_errors = 0

> One false HELO etc. and they are gone.

By the way, I have a patch that adds an "event" in that code path,
which I then hook into and add such hosts into the "seen" database.
If they try reconnecting soon enough, they're blocked based on the IP
;-)

It's amazing or astonishing how many connections I get on port 25
with the other side trying to talk HTTP.

-- 
Ian

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