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From Eric Lee Green <eric.lee.gr...@gmail.com>
Subject Re: DNS quit working when I updated to 4.11.2
Date Fri, 24 May 2019 19:12:36 GMT
On 5/24/19 10:16 AM, Andrija Panic wrote:
> Eric,
>
> your BIND9 servers is on a "Public" network (trying to talk to the Public
> IP of the VR during forwarding DNS requests) or a VM inside an Isolated
> network behind VR)?

It's on *a* public network, but not *the* public network. I don't have 
any Isolated networks, though I have them enabled from VLAN 1000-2000. I 
am using "Advanced Networking" but for my own purposes -- I have one 
"Shared" guest network at VLAN 102, and then several isolated specialty 
physical "Shared" networks like "Security Cameras" (VLAN 103) and 
"Storage Network" (VLAN 200) that are attached to virtual machines that 
need access to those things. The "Shared" guest network (VLAN 102) is 
routed by my layer 3 switch with the rest of my network's public VLANs 
so if I am on e.g. 10.31.1.2 (VLAN 31), which is similarly a routed 
public VLAN (but not one that Cloudstack is allowed to directly talk to 
or manage, it has to go thru the layer 3 switch) or 10.120.0.5 (VLAN 
120), I can talk directly to 10.102.199.148 since all are routed into 
the common fabric via the layer 3 switch.  I only care about the VM's 
that are VLAN 102, which are supposed to be publicly available to my 
users, thus why my quicky script hack to generate a zone file out of the 
database does

select v.name, n.ip4_address from vm_instance as v, nics as n where v.removed is null and
n.instance_id = v.id and n.ip4_address like '10.102.%'  and type = 'User'  order by n.ip4_address;

in order to select out the name and IP address of virtual machines with 
NIC's on that VLAN. (Which, if it's a different list from the last list 
that was queried, then gets massaged into a zone file for 
name.cloud.mydomain.com by the script, which then scp's to my master 
domain server and does a reload to reload the zone file from the new 
version).

Both of my BIND9 servers can talk directly to 10.102.199.148 (the IP of 
the virtual router for the 10.102.xxx.xxx network, VLAN 102) if I use 
'host' to directly query 10.102.199.148 for an API address like, say, 
'api-default1.cloud.mydomain.com' but when I try to put a forward domain 
there, nope. This was working, but now is not. I suspect it's got to do 
with the recent changes in DNS software, both bind9 and dnsmasq,  to 
deal with multiple attacks on the domain name system, but I'm having 
trouble figuring out why, or what my solution should be.

Note that it's quite reasonable / feasible / viable to put a DNS server 
actually inside the Cloudstack constellation if that's necessary and 
then do a two-stage hop if necessary. I'm just trying to figure out the 
"right" way to do this right now so I can retire my hack script.

> On Fri, 24 May 2019 at 02:15, Eric Lee Green <eric.lee.green@gmail.com>
> wrote:
>
>> I had this working under 4.9. All I did was, on my main BIND9 servers,
>> point a forward zone at 'cloud.<mydomain>.com' to the virtual router
>> associated with all VM's that were publicly available. I could then
>> resolve all foo.cloud.<mydomain>.com names on my global network.
>>
>> Somehow, though, this quit working after I updated to 4.11. I'm not
>> quite sure why.
>>
>> The 'Guest Network' is defined with domain 'cloud.mydomain.com'.
>>
>> Okay, so my router for the 'Guest Network' advanced networking is
>> located at 10.102.199.148. In my master BIND9 DNS server at 10.31.1.2 I
>> have this:
>> zone "cloud.mydomain.com" IN {
>>      type forward;
>>      forward only;
>>      forwarders {
>>           10.102.199.148;
>>       };
>> };
>>
>> If I send a NAMED request directly to the virtual router while logged
>> into my main name server, it works:
>>
>> [root@ypbind ~]# host eric-gui.cloud.mydomain.com 10.102.199.148
>> Using domain server:
>> Name: 10.102.199.148
>> Address: 10.102.199.148#53
>> Aliases:
>>
>> eric-gui.cloud.mydomain.com has address 10.102.199.234
>>
>> If I try to use the name server however, it doesn't work:
>>
>> [root@ypbind logs]# host eric-gui.cloud.mydomain.com
>> Host eric-gui.cloud.viakoo.com not found: 3(NXDOMAIN)
>>
>> I'm baffled, because this *was* working.
>>
>> So I disabled any dnssec in the {options} on bind9  and gave all
>> permissions to see if that was the problem (note that this is internal
>> to my infrastructure, so DNS amplification isn't an issue):
>>
>>           dnssec-enable no;
>>           dnssec-validation no;
>>           dnssec-lookaside auto;
>>           recursion yes;
>>           allow-recursion { any; };
>>           allow-query { any; };
>>           allow-query-cache { any; };user
>>
>> Still nope. Still baffled.
>>
>> Anybody got any clues as to what I may be doing wrong? I'm thinking it
>> has to be on the BIND9 side, because I can resolve the host name if I
>> talk to the virtual router directly, but for some reason it's not
>> allowing me to get any records from the router.
>>
>> Right now I've temporarily worked around this with a script that
>> directly queries the MySQL database every few minutes and generates a
>> revised zone file on my master DNS server when the list of virtual
>> machines queried out of the database changes, but that's clearly not the
>> right way to do it. The question is, what *is* the right way to do it?
>>
>> -Eric
>>
>>
>>


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