[Xymon] IPv6 debugging on xymon 4.4 (was Re: Roadmap/GitHub?/IPv6)

[Japheth Cleaver]

On 4/15/2019 11:28 PM, Christian Herzog wrote:
> For the short term, testing xymonclient messaging
>>> meaning client reports to IPv6 XYMONSERVERS?
> specifying IPv6 XYMONSERVERS on the client doesn't work. No reports coming in.

Thanks.

> also, any hosts.cfg entry seems to get resolved to IPv4 only, even if the host
> entry is IPv6. As soon as I cut IPv4 connectivity on a dual stack host, conn
> turns red even if IPv6 is working fine. Probably xymonnet <-> xymonnet2 again.
>
>
>> Would be good to disable BFQ too if it's enabled, since local components
>> will short-circuit to using that for message submission instead of TCP in
>> 4.x
> this [1] BFQ? *confused*

Sorry, the "backfeed queue" :)

See README.backfeed: 
https://sourceforge.net/p/xymon/code/HEAD/tree/branches/4.x-master/README.backfeed

The short of it is that it provides an alternate way of submitting 
messages to xymond for local processes, using SysV-IPC instead of 
localhost TCP connections. It's much more efficient for injecting lots 
of messages, but sort of obviates the testing of xymond submissions over 
IPv6 :)


> I've also been thinking about how I would like xymon to behave on dual stack
> hosts: in my experience, IPv4 networks are still quite a bit more stable than
> IPv6 (I've seen sporadic PD issues, sudden IPv6 routing problems in the middle
> of Europe etc), so ideally we would have v4/v6 tests on supported services on
> dual stack hosts. I don't know if this means splitting each tests into two
> halves or duplicate the whole host entry or something else entirely, but we
> need to be able to deal with "v4 is working but v6 isn't" or vice versa....

Looking into this more, I believe we'll be able to use the existing 
"conn" framework for handling multiple IP addresses, but we may need a 
default set of flags for how to handle priority and fallbacks on DNS lookup.

I'd envision something along the lines of:
IPv4 Only
IPv4 Mandatory/IPv6 Optional
IPv4 Optional/IPv6 Mandatory
IPv6 Only

xymonnet can have a set of flags, but this we'd also want the ability to 
set flags for for each host.

For non-http checks, a "testip" combined with the choice of dedicated 
address (of either type) in hosts.cfg should keep checks hitting only 
one protocol or the other.

Regards,
-jc