configure bind in chroot jail
Greg Choules
gregchoules+bindusers at googlemail.com
Wed Aug 6 10:05:09 UTC 2025
Hi Renzo.
The Linux distros package their own versions of BIND, which they obtain
from ISC and patch over the years, hence it is almost guaranteed to not be
the latest. That may be OK for you. But see here for how to install it
directly if you choose: https://kb.isc.org/docs/isc-packages-for-bind-9
Whether you think that chroot is worth the effort is your decision. I can't
tell you not to do it, just advise that many don't use chroot and have no
issues. BIND needs to write to certain folders, depending on which features
you use. But as it is running as a normal user, if the OS won't let it, it
can't.
Maybe you should ask RedHat and its users (there must be a RH forum) what
they recommend and make your decision once you have gathered opinions from
various sources.
Hope that helps.
Cheers, Greg
On Wed, 6 Aug 2025 at 10:35, Renzo Marengo <buckroger2011 at gmail.com> wrote:
> Hi greg,
> I'm replacing old DNS virtual server with old Bind with new one.
> So I thought to build the same box with the same chroot which gives me
> jail environment where *Bind is not able to access system files or
> outside data.*
> But your words are making me think...*if you say it's not necessary.*
> I installed Oracle Linux 9 with 9.16.23-RH rpm package because it's latest
> available one.
>
>
>
> Il giorno ven 1 ago 2025 alle ore 10:08 Greg Choules <
> gregchoules+bindusers at googlemail.com> ha scritto:
>
>> Hi Renzo.
>> This is not intended to sound negative. But why are you stuck on chroot?
>> What benefit do you think it will bring you? It used to be the case (many
>> years ago) that if you started BIND as root, it ran as root and chroot made
>> sense then. But not anymore. It starts with some privilege, to scan
>> interfaces etc. but then drops to a normal user, subject to the usual
>> restrictions an OS should provide.
>>
>> I would suggest that, if you are really worried about losing control of a
>> process, or it being used for remote access to your machine, or
>> something (are either of these why you think you need chroot?) you should
>> either/both run BIND in a VM or take a good look at your server and network
>> security. But many people run BIND natively, without chroot, and have no
>> problems.
>>
>> Cheers, Greg
>>
>> On Thu, 31 Jul 2025 at 20:46, Renzo Marengo <buckroger2011 at gmail.com>
>> wrote:
>>
>>> i know what I want. I asked myself these questions many years ago when I
>>> build this server. I am replacing this cache dns server with newer os.
>>>
>>> Il giorno 31 lug 2025, alle ore 09:57, Ondřej Surý <ondrej at isc.org> ha
>>> scritto:
>>>
>>> Perhaps the question that you should explore first would be “Why?” and
>>> not “How?”.
>>>
>>> Ondrej
>>> --
>>> Ondřej Surý — ISC (He/Him)
>>>
>>> My working hours and your working hours may be different. Please do not
>>> feel obligated to reply outside your normal working hours.
>>>
>>> On 31. 7. 2025, at 8:58, Renzo Marengo <buckroger2011 at gmail.com> wrote:
>>>
>>>
>>> Thank you very much but my issue is to understand what first step I have
>>> to do, considering that the following rpm are just installed:
>>>
>>> bind.x86_64
>>> bind-chroot.x86_64
>>> bind-dnssec-doc.noarch
>>> bind-dnssec-utils.x86_64
>>> bind-libs.x86_64
>>> bind-license.noarch
>>> bind-utils.x86_64
>>>
>>> e.g.
>>> chroot folder structure is just set ?
>>> what service I have to enable at boot ? Bind or bind-chroot ?
>>>
>>>
>>>
>>> Il giorno mer 30 lug 2025 alle ore 20:55 Danjel Jungersen via bind-users
>>> <bind-users at lists.isc.org> ha scritto:
>>>
>>>>
>>>> On 7/30/2025 1:11 PM, Renzo Marengo wrote:
>>>> > I want to install latest rpm of Bind (9.16.23-31) for Oracle Linux 9
>>>> > to create only cache DNS server which is running in chroot jail.
>>>> > I installed several Bind packages included bind-chroot.
>>>> > What document do you suggest me to follow to configure bind in chroot
>>>> > jail ?
>>>> > Thanks
>>>> >
>>>> Setting up as caching / forwarder is pretty straight forward:
>>>>
>>>> In named.conf.options :
>>>> recursion yes;
>>>> allow-query { trusted; };
>>>> allow-transfer { none; };
>>>>
>>>> forwarders { // From here
>>>> 192.168.20.10; // Replace with the servers you want to
>>>> use
>>>> 192.168.20.11; // Same here
>>>> };
>>>> forward only; // to here - must be left out if you do
>>>> not wish to use forwarders, ie the system will do all the work itself.
>>>>
>>>> dnssec-validation auto; // Check this setting before going
>>>> online, may not suit your setup.
>>>>
>>>> listen-on-v6 { any; };
>>>>
>>>>
>>>> In named.conf.local:
>>>> acl "trusted" {
>>>> 192.168.1.0/24; // Replace with your own ip's
>>>> 192.168.20.15/32; // Replace with your own ip's
>>>> 127.0.0.1/32;
>>>> localhost;
>>>> };
>>>>
>>>> I do not know anything about redhat, but as I understand, debian also
>>>> uses chroot.
>>>> I run debian and have had zero issues with using the default setup.
>>>>
>>>> Best of luck!
>>>> Danjel
>>>> --
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>>
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