migration to new isp - now private addresses showing up publicly?

[Kaya Saman]

On 5/23/23 20:18, Sten Carlsen wrote:
>
>
>> On 23 May 2023, at 19.46, Kaya Saman <kayasaman at gmail.com> wrote:
>>
>>
>> On 5/23/23 18:07, Sten Carlsen wrote:
>>>> On 23 May 2023, at 19.00, Kaya Saman<kayasaman at gmail.com>  wrote:
>>>>
>>>> 
>>>>> On 5/23/23 12:47, Matus UHLAR - fantomas wrote:
>>>>>> On 23.05.23 12:22, Kaya Saman wrote:
>>>>>> I've got a very strange problem that has emerged somehow after migrating my isp.
>>>>>>
>>>>>>
>>>>>> My setup previously used 2x servers in master/slave configuration for my public "view" and then had 3x servers for the "internal" view. This was working fine for years and I have been regularly testing using online dns healthcheck sites such as mxtoolbox etc...
>>>>>>
>>>>>>
>>>>>> Now when I try to run any type of check from mxtoolbox or other site eg.https://dnschecker.org/  I am getting my private IP's showing instead of the public ones?
>>>>>>
>>>>>>
>>>>>> Initially it started off by my external zone files not transferring which I managed to see that the information was trying to traverse my NAT (I know, not the best practice to have all dns servers on the same network).
>>>>>>
>>>>>>
>>>>>> As a result external emails from my mail server are not working too well with a hit and miss type thing going on right now.
>>>>>>
>>>>>>
>>>>>> Just to go over, my zone files are fine as the 'external' ones only have public ip addresses in them and do not include any type of internal addressing whatsoever.
>>>>>>
>>>>>>
>>>>>> Here's an example of the config in named.conf for the master:
>>>>>> view "external" {
>>>>>>      match-clients { !internals; any; };
>>>>> [...]
>>>>>> view "external" {
>>>>>>      match-clients { !internals; any; };
>>>>> I don't see your definition of "internals".
>>>>> Also, I don't see your definition of internal view.
>>>>> if internal IP addresses are visible on the internet, obviously the internet sources fall into your internal view, not into this one.
>>>>>
>>>>>
>>>> Finally, I understand what is going on and things get stranger....
>>>>
>>>>
>>>> The internal IP addressing is being served up by the slave servers. They seem to have pulled the file domain.db and renamed it to domain-external.db???
>>>>
>>>>
>>>> Of course the 'master' machine is already serving up domain-external.db to the public domain. This has the correct IP addressing with everything else such as dkim and dmarc.
>>>>
>>>>
>>>> So, currently I think the whole problem is stemming from the fact that the zone transfers are not working correctly for my external view between 'master' and 'slave' servers.
>>>>
>>>>
>>>> How can I do that without needing to traverse my NAT?
>>>>
>>> When migrating ISP, are you sure that there is not another NAT in the ISP router?
>>> That would explain this. The internet would present itself as 192.168.xx.xx and match your internals.
>>
>>
>> I can certainly ask. Though I am on a business package with multiple 
>> static public IPv4 addresses. I think I have a /28 block if memory 
>> serves me well....
>>
>>
> You might find that it has some kind of address translation built-in 
> "to protect your business" or whatever. To me it still smells that way.
> You might look at the IP address for the port you think is the 
> internet - if that has an 192.168.x.x. or 172.16.x.x. or 10.x.x.x it 
> would be clear that is what your problem is. It can still be solved 
> but other setup details will be needed.


I'm not sure what you mean by "port to the internet"?


The actual DNS servers themselves don't have a public IP address. They 
are all running internal addressing and have been for many years, 
another words the address on the NIC itself is private. What I am doing 
is using NAT/PAT to translate the public address to the private address 
of the server itself.


So essentially on my side I am doing int_dns -> ext_dns -> internet

Reverse then becomes internet -> ext_dns (port 53 udp/tcp) -> int_dns 
(port 53 udp/tcp)


That's how I am handling things. I wonder if that is the cause or if 
there is something that my ISP has in place? Hence the fact that I'm 
using "views" to differentiate between 'internal' and 'external' addresses.

Actually I did run a tcpdump on the server and my firewall/gateway both 
and the addresses coming in are both from public domain. No internal 
addressing hitting the server WAN side, even when my NAT/PAT translates 
my ext_ip to int_ip, the public address of say the mxtoolbox checker is 
still there.


I should know in a few days if there is anything my ISP is doing in the 
middle. But* I really am not sure if it is something that I am doing 
within the config, though I have posted pretty much all of my named.conf 
file up. Though it still doesn't explain how the IP addresses keep 
'flapping' - especially in mxtoolbox using the DNS Check. Sometimes I 
see internal addresses and sometimes I see external addresses?? It just 
seems like random occurrence really unless I badly misconfigured something?
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