Re: [exim] EXIM clusters and rate limiting

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Author: Brad King
Date:  
To: exim-users
Subject: Re: [exim] EXIM clusters and rate limiting
Thanks guys, looks like a bit more R&D for me.

Cheers,

Brad

On Fri, 23 Apr 2021, 06:49 Heiko Schlittermann via Exim-users, <
exim-users@???> wrote:

> Hi,
>
> Brad King via Exim-users <exim-users@???> (Mi 21 Apr 2021 23:33:20
> CEST):
> > What I am trying to find out specifically is about rate limiting. I
> > need the ability to apply different classes of service for different
> > IP addresses. That is, they will have different rate limits and
> > connection limits.
> >
> > I understand this is quite easy on a single server, but how do I
> > configure this on a cluster?
>
> Unfortunately currently Exim running on one host can't share information
> with an instance running on another host, out of the box.
>
> However: you can use a shared FS for the database files (hint files),
> where Exim stores the rates, and other hits. But I assume you'll run
> into locking issues quite fast.
>
> > For example, if IP 1.1.1.1 was assigned 2000 messages/hour. I have 10
> > EXIM servers behind my VIP.. How do I ensure that 1.1.1.1 can only
> > send max 2000 messages/hour? It would be possible, on a 'per server'
> > basis that they may make a connection to multiple EXIM servers within
> > the hour which would give them a possible volume of 20000
> > messages/hour(2000x10 EXIM servers)
>
> For most cases, if your loadbalancer balances the connections quite
> evenly, you can apply 1/nth of the rate per instance. That's by far not
> perfect, but should do the job.
>
> Alternativly you can start hacking Exim and provide memcache, redis,
> whatever for the hint databases. (It shouldn't be too hard.) If you
> can't do the hacking on your own, try asking if there is anybody you can
> pay for it.
>
>     Best regards from Dresden/Germany
>     Viele Grüße aus Dresden
>     Heiko Schlittermann
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