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Old 11-08-2010, 07:30 AM
ahmad riza h nst
 
Default large numbers of linux system user for postfix

hello,

i need to setup a mail server with postfix + dovecot + webmin +
virtualmin + virtual user with linux system user. the virtual user may
reach to thousands user from several hundreds virtual domains.

what i concern is large numbers of linux system user which used in
these setup, is it good or bad?
maybe somebody would share their experience about this setup ?

any links would be good.

postfix 2.6.7
dovecot 2.0.6
centos 5.x
webmin + virtualmin


thank you.

--
http://blog.rizahnst.org
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Old 11-08-2010, 10:12 AM
Ned Slider
 
Default large numbers of linux system user for postfix

On 08/11/10 08:30, ahmad riza h nst wrote:
> hello,
>
> i need to setup a mail server with postfix + dovecot + webmin +
> virtualmin + virtual user with linux system user. the virtual user may
> reach to thousands user from several hundreds virtual domains.
>
> what i concern is large numbers of linux system user which used in
> these setup, is it good or bad?
> maybe somebody would share their experience about this setup ?
>
> any links would be good.
>
> postfix 2.6.7
> dovecot 2.0.6
> centos 5.x
> webmin + virtualmin
>
>
> thank you.
>

Other that "centos 5.x", none of the rest is shipped by CentOS so you're
unlikely to get much help here.

Also, please don't cross post the same question to multiple lists - you
have an active thread on the postfix users list and most postfix users
on this list will also be subscribed there too.


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Old 11-08-2010, 10:42 AM
Ben McGinnes
 
Default large numbers of linux system user for postfix

On 8/11/10 7:30 PM, ahmad riza h nst wrote:
> hello,
>
> i need to setup a mail server with postfix + dovecot + webmin +
> virtualmin + virtual user with linux system user. the virtual user
> may reach to thousands user from several hundreds virtual domains.

That shouldn't be a problem. Postfix has had support for this for
well over a decade.

> what i concern is large numbers of linux system user which used in
> these setup, is it good or bad?

Virtual users with a Postfix/Dovecot installation does not equate to
real Linux/shell accounts. If the only service being provided is
mail, then there's no reason to create real accounts.

> maybe somebody would share their experience about this setup ?
>
> any links would be good.
>
> postfix 2.6.7
> dovecot 2.0.6
> centos 5.x

Is there any particular reason you've chosen these versions? That is,
are there specific functions which these versions provide that are not
in prior versions?

I ask because I'm running these versions in CentOS 5.x:

postfix-2.3.3-2.1.el5_2.i386
dovecot-1.0.7-7.el5.i386

If the only concern is security updates, these are backported to the
current versions in CentOS.

> webmin + virtualmin

I've had no experience with either of these as I edit the config files
with a text editor.


Regards,
Ben

--
Ben McGinnes http://www.adversary.org/ Twitter: benmcginnes
Systems Administrator, Writer, ICT Consultant
Encrypted email preferred - primary OpenPGP/GPG key: 0xA04AE313
http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x371AC5BFA04AE313


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Old 11-08-2010, 11:54 AM
ahmad riza h nst
 
Default large numbers of linux system user for postfix

On Mon, Nov 8, 2010 at 6:42 PM, Ben McGinnes <ben@adversary.org> wrote:
> On 8/11/10 7:30 PM, ahmad riza h nst wrote:
>> hello,
>>
>> i need to setup a mail server with postfix + dovecot + webmin +
>> virtualmin + virtual user with linux system user. the virtual user
>> may reach to thousands user from several hundreds virtual domains.
>
> That shouldn't be a problem. *Postfix has had support for this for
> well over a decade.
>
>> what i concern is large numbers of linux system user which used in
>> these setup, is it good or bad?
>
> Virtual users with a Postfix/Dovecot installation does not equate to
> real Linux/shell accounts. *If the only service being provided is
> mail, then there's no reason to create real accounts.
>

Ben,

the problem is we would use webmin + virtualmin as an interface for
costumers to manage their domain (mainly emails) on the server and
virtualmin don't use/support mysql + vpopmail yet, at least that what
i understand at this moment.

virtualmin choose to use unix system user with postfix, so if i create
an email then it create one unix system user too, this is what i'm
concern, since i don't have any information about what happen to
linux/centos if these unix system user growing bigger and bigger to
reach some thousands users for an example.

>> maybe somebody would share their experience about this setup ?
>>
>> any links would be good.
>>
>> postfix 2.6.7
>> dovecot 2.0.6
>> centos 5.x
>
> Is there any particular reason you've chosen these versions? *That is,
> are there specific functions which these versions provide that are not
> in prior versions?
>
> I ask because I'm running these versions in CentOS 5.x:
>
> postfix-2.3.3-2.1.el5_2.i386
> dovecot-1.0.7-7.el5.i386
>
> If the only concern is security updates, these are backported to the
> current versions in CentOS.

no particular reason, i just new to postfix, currently i'm qmail +
vpopmail admin.
i read on postfix and dovecot website about latest stable release and
i installed from source
i know that centos have postfix + dovecot + mysql as a rpm package.

>
>> webmin + virtualmin
>
> I've had no experience with either of these as I edit the config files
> with a text editor.
>

these webmin + virtualmin mainly for user interface to manage their
domain on the server (just like control panel on hosting server)

>
> Regards,
> Ben
>
> --
> Ben McGinnes *http://www.adversary.org/ *Twitter: benmcginnes
> * *Systems Administrator, Writer, ICT Consultant
> Encrypted email preferred - primary OpenPGP/GPG key: 0xA04AE313
> http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x371AC5BFA04AE313
>
>
>
> _______________________________________________
> CentOS mailing list
> CentOS@centos.org
> http://lists.centos.org/mailman/listinfo/centos
>
>



--
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Old 11-08-2010, 02:25 PM
Ben McGinnes
 
Default large numbers of linux system user for postfix

On 8/11/10 11:54 PM, ahmad riza h nst wrote:
>
> the problem is we would use webmin + virtualmin as an interface for
> costumers to manage their domain (mainly emails) on the server and
> virtualmin don't use/support mysql + vpopmail yet, at least that
> what i understand at this moment.
>
> virtualmin choose to use unix system user with postfix, so if i
> create an email then it create one unix system user too, this is
> what i'm concern, since i don't have any information about what
> happen to linux/centos if these unix system user growing bigger and
> bigger to reach some thousands users for an example.

Assuming that Virtualmin doesn't have support for real virtual users
or redirecting to MySQL for that then you have three basic choices:

1a) Use a different management interface for managing the
Postfix/Dovecot configuration.

1b) Write your own extension for Virtualmin which provides this
functionality (essentially a variation on 1a).

2) Stick with the existing mail server configuration which already
works with Webmin and Virtualmin.

3) Create user accounts that do not provide an actual shell account
(e.g. /bin/noshell).

With the number of domains and users you're looking at, this could be
a real problem, especially when the usernames might conflict between
different domains.

If I were in your position I'd be looking at either 1a or 1b.


Regards,
Ben

--
Ben McGinnes http://www.adversary.org/ Twitter: benmcginnes
Systems Administrator, Writer, ICT Consultant
Encrypted email preferred - primary OpenPGP/GPG key: 0xA04AE313
http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x371AC5BFA04AE313


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Old 11-08-2010, 02:26 PM
Dan Burkland
 
Default large numbers of linux system user for postfix

On Nov 8, 2010, at 2:30 AM, ahmad riza h nst wrote:

> hello,
>
> i need to setup a mail server with postfix + dovecot + webmin +
> virtualmin + virtual user with linux system user. the virtual user may
> reach to thousands user from several hundreds virtual domains.
>
> what i concern is large numbers of linux system user which used in
> these setup, is it good or bad?
> maybe somebody would share their experience about this setup ?
>
> any links would be good.
>
> postfix 2.6.7
> dovecot 2.0.6
> centos 5.x
> webmin + virtualmin
>
>
> thank you.
>
> --
> http://blog.rizahnst.org
> _______________________________________________
> CentOS mailing list
> CentOS@centos.org
> http://lists.centos.org/mailman/listinfo/centos

I run Postfix 2.6.7 in a similar fashion (virtual domains/users/etc) and it works fine on CentOS 5.5 (even with SELinux enabled). Dovecot on the other hand threw up some errors in /var/log/audit/audit.log so I had to make a custom SELinux module to get it to work properly. Other than that you should be set.

-Dan

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Old 11-08-2010, 06:20 PM
Mike Fedyk
 
Default large numbers of linux system user for postfix

On Mon, Nov 8, 2010 at 7:25 AM, Ben McGinnes <ben@adversary.org> wrote:
> Assuming that Virtualmin doesn't have support for real virtual users
> or redirecting to MySQL for that then you have three basic choices:
>
> 1a) Use a different management interface for managing the
> Postfix/Dovecot configuration.
>
> 1b) Write your own extension for Virtualmin which provides this
> functionality (essentially a variation on 1a).
>
> 2) Stick with the existing mail server configuration which already
> works with Webmin and Virtualmin.
>
> 3) Create user accounts that do not provide an actual shell account
> (e.g. /bin/noshell).
>
> With the number of domains and users you're looking at, this could be
> a real problem, especially when the usernames might conflict between
> different domains.
>

Unless you encode the domain in the username of the unix user. "user#domain"

I quite like the idea of having separate UIDs for each user. Let the
OS work for you...
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Old 11-08-2010, 06:36 PM
Les Mikesell
 
Default large numbers of linux system user for postfix

On 11/8/2010 1:20 PM, Mike Fedyk wrote:
> On Mon, Nov 8, 2010 at 7:25 AM, Ben McGinnes<ben@adversary.org> wrote:
>> Assuming that Virtualmin doesn't have support for real virtual users
>> or redirecting to MySQL for that then you have three basic choices:
>>
>> 1a) Use a different management interface for managing the
>> Postfix/Dovecot configuration.
>>
>> 1b) Write your own extension for Virtualmin which provides this
>> functionality (essentially a variation on 1a).
>>
>> 2) Stick with the existing mail server configuration which already
>> works with Webmin and Virtualmin.
>>
>> 3) Create user accounts that do not provide an actual shell account
>> (e.g. /bin/noshell).
>>
>> With the number of domains and users you're looking at, this could be
>> a real problem, especially when the usernames might conflict between
>> different domains.
>>
>
> Unless you encode the domain in the username of the unix user. "user#domain"
>
> I quite like the idea of having separate UIDs for each user. Let the
> OS work for you...

Or if you are really concerned about scaling beyond what the OS handles
gracefully, you might want to look at cyrus instead of dovecot as the
mail backend. I think ClearOS has a web-manged setup, but I'm not sure
how they relate email users to system users.

--
Les Mikesell@gmail.com
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Old 11-08-2010, 08:57 PM
John R Pierce
 
Default large numbers of linux system user for postfix

On 11/08/10 2:16 PM, nux@nux.ro wrote:
> ahmad riza h nst writes:
>
>> hello,
>>
>> i need to setup a mail server with postfix + dovecot + webmin +
>> virtualmin + virtual user with linux system user. the virtual user may
>> reach to thousands user from several hundreds virtual domains.
>>
>> what i concern is large numbers of linux system user which used in
>> these setup, is it good or bad?
> The large number of system users should not be a problem. Might have been an
> issue with Linux 2.4 (2^16=65536 max users), but Linux 2.6 can handle a LOT
> (2^32=4294967296)[1].
>
> I'd be more worried of the stress this number of users can inflict on a
> machine (CPU, memory, I/O etc).

indeed. if half those 1000s of users do the typical lUser thing of
checking their mail every minute, thats going to be a LOT of forks.


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Old 11-08-2010, 09:16 PM
 
Default large numbers of linux system user for postfix

ahmad riza h nst writes:

> hello,
>
> i need to setup a mail server with postfix + dovecot + webmin +
> virtualmin + virtual user with linux system user. the virtual user may
> reach to thousands user from several hundreds virtual domains.
>
> what i concern is large numbers of linux system user which used in
> these setup, is it good or bad?

The large number of system users should not be a problem. Might have been an
issue with Linux 2.4 (2^16=65536 max users), but Linux 2.6 can handle a LOT
(2^32=4294967296)[1].

I'd be more worried of the stress this number of users can inflict on a
machine (CPU, memory, I/O etc).

[1] - http://en.wikipedia.org/wiki/Linux_kernel

--
Nux!
www.nux.ro

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