Re: [Dnsmasq-discuss] redundant/resiliant dnsmasq servers?

2016-03-26 Thread Kurt H Maier 
On Sat, Mar 26, 2016 at 11:06:39AM +0100, Matthias Andree wrote:
> Yes, but that's not the trigger for the original inquiry - it was
> explicitly about a software crash:
> 

No it wasn't.  Read the message you linked.  It's said the server
crashed; software or hardware failure is not specified.  This is a moot
point; I'm not really sure why you're offended at the idea that someone
may want redundant services.

To the original point:  it's eminently possible to run dnsmasq on a
server, have it installed on a second server, and install drbd on both
machines.  You can use heartbeat or other HA tools to fire up dnsmasq on
the secondary server if the primary fails.  This can be set up in a way
similar to https://help.ubuntu.com/community/HighlyAvailableNFS but with
dnsmasq as the service specified instead of nfs-kernel-server.

There are different approaches to this idea, obviously; I've had good
luck using CARP on OpenBSD to multiplex back to two dnsmasq instances
who both mounted a shared filesystem via iSCSI.  Again, the trick is to
be running software like heartbeat that is capable of detecting failure
of the primary node and firing up the secondary failover service.


khm

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Re: [Dnsmasq-discuss] redundant/resiliant dnsmasq servers?

2016-03-26 Thread Chris Green 
On Sat, Mar 26, 2016 at 11:06:57AM -0400, Weedy wrote:
>On 26 Mar 2016 9:50 am, "Chris Green" <[1]c...@isbd.net> wrote:
>>
>> On Fri, Mar 25, 2016 at 05:00:17PM -0400, Weedy wrote:
>> >On 25 Mar 2016 13:21, "Kurt H Maier" <[1][2]k...@sciops.net>
>wrote:
>> >>
>> >> On Fri, Mar 25, 2016 at 05:12:52PM +0100, Matthias Andree
>wrote:
>> >> > Would not it be more useful to supervise and restart the
>service in
>> >case
>> >> > of a crash? Service management is ubiquitous on the major
>> >distributions
>> >> > these days... and in case the crash isn't due to memory
>exhaustion
>> >by
>> >> > other processes, investigate why it's crashing, and have
>that
>> >fixed?
>> >>
>> >> Hardware fails.
>> >>
>> >Considering dhcp typically runs on the router in a home, I think
>> >hardware failure would cause you bigger issues then "oh crap I
>can't
>> >even DNS"
>> >
>> But dnsmasq in general *doesn't* run on a dedicated router, it's
>> something that has been installed by a user because the DNS and DHCP
>> in the router is too limited.
> 
>Uh, like every Buffalo, d-link, Linksys, netgear, tp-link, etc
>router runs dnsmasq.
> 
>And of course OpenWrt
> 
Yes, but...

I have a router running OpenWrt but I still prefer to run dnsmasq on a
Raspberry Pi.  All those routers/NAS etc. may run dnsmasq but it isn't
therefore particularly easy to configure as one wants.


-- 
Chris Green

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Re: [Dnsmasq-discuss] redundant/resiliant dnsmasq servers?

2016-03-26 Thread Weedy 
On 26 Mar 2016 9:50 am, "Chris Green"  wrote:
>
> On Fri, Mar 25, 2016 at 05:00:17PM -0400, Weedy wrote:
> >On 25 Mar 2016 13:21, "Kurt H Maier" <[1]k...@sciops.net> wrote:
> >>
> >> On Fri, Mar 25, 2016 at 05:12:52PM +0100, Matthias Andree wrote:
> >> > Would not it be more useful to supervise and restart the service
in
> >case
> >> > of a crash? Service management is ubiquitous on the major
> >distributions
> >> > these days... and in case the crash isn't due to memory
exhaustion
> >by
> >> > other processes, investigate why it's crashing, and have that
> >fixed?
> >>
> >> Hardware fails.
> >>
> >Considering dhcp typically runs on the router in a home, I think
> >hardware failure would cause you bigger issues then "oh crap I can't
> >even DNS"
> >
> But dnsmasq in general *doesn't* run on a dedicated router, it's
> something that has been installed by a user because the DNS and DHCP
> in the router is too limited.

Uh, like every Buffalo, d-link, Linksys, netgear, tp-link, etc router
runs dnsmasq.

And of course OpenWrt
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Re: [Dnsmasq-discuss] redundant/resiliant dnsmasq servers?

2016-03-26 Thread /dev/rob0 
On Sat, Mar 26, 2016 at 11:06:39AM +0100, Matthias Andree wrote:
> Regarding failover or backups, be sure to check dhcp-authoritative. 
> It does not appear that dnsmasq has facilities to share its leases 
> database with other software.  You'd probably have to cook 
> synchronization on your own with scripts or lua scripts.

And it's probably worth noting that a major design goal of dnsmasq is 
to remain simple.  It targets (and nicely fills) most common needs, 
and unlike many network services, you don't have to devote a lot of 
time to learn how to run and manage it.

I'm sure if Simon can figure out a simple way to do failover, he 
will, but I don't expect it. :)

Right now the best option for failover seems to be ISC DHCP 4.3, or 
possibly Kea for the adventurous (a failover protocol does not seem 
to be implemented yet, but lease database sharing is possible with 
another possible point of failure: mysql or PostgreSQL.)
-- 
  http://rob0.nodns4.us/
  Offlist GMX mail is seen only if "/dev/rob0" is in the Subject:

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Re: [Dnsmasq-discuss] redundant/resiliant dnsmasq servers?

2016-03-26 Thread Chris Green 
On Fri, Mar 25, 2016 at 05:00:17PM -0400, Weedy wrote:
>On 25 Mar 2016 13:21, "Kurt H Maier" <[1]k...@sciops.net> wrote:
>>
>> On Fri, Mar 25, 2016 at 05:12:52PM +0100, Matthias Andree wrote:
>> > Would not it be more useful to supervise and restart the service in
>case
>> > of a crash? Service management is ubiquitous on the major
>distributions
>> > these days... and in case the crash isn't due to memory exhaustion
>by
>> > other processes, investigate why it's crashing, and have that
>fixed?
>>
>> Hardware fails.
>>
>Considering dhcp typically runs on the router in a home, I think
>hardware failure would cause you bigger issues then "oh crap I can't
>even DNS"
> 
But dnsmasq in general *doesn't* run on a dedicated router, it's
something that has been installed by a user because the DNS and DHCP
in the router is too limited.

I used to run it on my desktop machine but now run it on a dedicated
Raspberry Pi.


-- 
Chris Green

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Re: [Dnsmasq-discuss] redundant/resiliant dnsmasq servers?

2016-03-26 Thread Matthias Andree 
Am 25.03.2016 um 22:34 schrieb Kurt H Maier:
> On Fri, Mar 25, 2016 at 05:00:17PM -0400, Weedy wrote:
>> Considering dhcp typically runs on the router in a home, I think hardware
>> failure would cause you bigger issues then "oh crap I can't even DNS"
> 
> People use dnsmasq outside of home, as well.

Yes, but that's not the trigger for the original inquiry - it was
explicitly about a software crash:


Regarding failover or backups, be sure to check dhcp-authoritative. It
does not appear that dnsmasq has facilities to share its leases database
with other software.  You'd probably have to cook synchronization on
your own with scripts or lua scripts.

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Re: [Dnsmasq-discuss] redundant/resiliant dnsmasq servers?

2016-03-25 Thread Weedy 
On 25 Mar 2016 13:21, "Kurt H Maier"  wrote:
>
> On Fri, Mar 25, 2016 at 05:12:52PM +0100, Matthias Andree wrote:
> > Would not it be more useful to supervise and restart the service in case
> > of a crash? Service management is ubiquitous on the major distributions
> > these days... and in case the crash isn't due to memory exhaustion by
> > other processes, investigate why it's crashing, and have that fixed?
>
> Hardware fails.
>
Considering dhcp typically runs on the router in a home, I think hardware
failure would cause you bigger issues then "oh crap I can't even DNS"
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Re: [Dnsmasq-discuss] redundant/resiliant dnsmasq servers?

2016-03-25 Thread Kurt H Maier 
On Fri, Mar 25, 2016 at 05:12:52PM +0100, Matthias Andree wrote:
> Would not it be more useful to supervise and restart the service in case
> of a crash? Service management is ubiquitous on the major distributions
> these days... and in case the crash isn't due to memory exhaustion by
> other processes, investigate why it's crashing, and have that fixed?

Hardware fails.

khm

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Re: [Dnsmasq-discuss] redundant/resiliant dnsmasq servers?

2016-03-25 Thread Matthias Andree 
Am 24.03.2016 um 20:34 schrieb Rick Thomas:
> 
> My home network recently suffered 5 hours of downtime because the dnsmasq 
> server crashed and took out my DNS and DHCP service.
> 
> Is it possible to run a backup instance of dnsmasq on a different server so 
> this wouldn't happen again?

Would not it be more useful to supervise and restart the service in case
of a crash? Service management is ubiquitous on the major distributions
these days... and in case the crash isn't due to memory exhaustion by
other processes, investigate why it's crashing, and have that fixed?


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[Dnsmasq-discuss] redundant/resiliant dnsmasq servers?

2016-03-24 Thread Rick Thomas 

My home network recently suffered 5 hours of downtime because the dnsmasq 
server crashed and took out my DNS and DHCP service.

Is it possible to run a backup instance of dnsmasq on a different server so 
this wouldn't happen again?

How would I configure this?

I can (and do) have two dnsmasq/DNS servers (with identical /etc/hosts files).  
That works fine.  But when I try to have two dnsmasq/DHCP servers (with 
identical /etc/ethers files) things get confused and some clients go for long 
periods without working network attachment.

Thanks!
Rick
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