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Re: [Astlinux-devel] [Astlinux-users] Configure DNS server in DHCP
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From: Lonnie A. <li...@lo...> - 2018-11-01 19:51:12
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Any thoughts on adding a DHCP_OPTION_DNS_SERVER rc.conf variable ? (outlined below)
Useful, or extraneous ?
Lonnie
> On Oct 24, 2018, at 9:12 AM, Lonnie Abelbeck <li...@lo...> wrote:
>
>> Does DMZ require another physical ethernet port?
>
> No, the DMZ can be a VLAN.
>
> Lonnie
>
>
>
>> On Oct 24, 2018, at 8:55 AM, David Kerr <Da...@Ke...> wrote:
>>
>> Does DMZ require another physical ethernet port? I've used up all three on my APU2.
>>
>> David
>>
>> On Wed, Oct 24, 2018 at 9:14 AM Lonnie Abelbeck <li...@lo...> wrote:
>> How about this...
>>
>> Hardware Pi-hole with AstLinux
>> ------------------------------
>>
>> Place the Pi-hole box off the DMZ interface.
>>
>> Example: DMZ is 10.10.50.1/24 and Pi-hole static IP is 10.10.50.53/24 with it's upstream DNS set to 10.10.50.1
>>
>> Network -> Firewall Configuration: {Firewall Configuration}
>> --
>> Action: [Pass DMZ->Local]
>> Source: 10.10.50.53
>> Port: 53
>> Protocol: TCP/UDP
>> Comment: Allow Pi-hole upstream DNS via Local
>> --
>>
>> Network -> Advanced Configuration: {Edit User Variables}
>> --
>> DHCP_OPTION_DNS_SERVER="10.10.50.53"
>> --
>>
>> The only code change required would be adding DHCP_OPTION_DNS_SERVER rc.conf support:
>> -- package/dnsmasq/dnsmasq.init --
>> trueDNSMASQnet()
>> ...
>> - dhcp-option=$1,option:dns-server,$gateway
>> + dhcp-option=$1,option:dns-server,${DHCP_OPTION_DNS_SERVER:-$gateway}
>> --
>> Same idea as David's, but simplified.
>>
>> FYI, in case you forgot, the default DMZ firewall rules are:
>> 1) Block all DMZ initiated connections to internal interfaces and Local AstLinux
>> 2) Allow all DMZ initiated connections via external interface.
>> 3) Allow all internal interfaces and Local AstLinux initiated connections to the DMZ
>>
>> With this scenario, AstLinux can be configured with "DNS-TLS Proxy Server" enabled to encrypt all Pi-hole upstream requests, as well as any local "DNS Hosts" can be honored via Pi-hole.
>>
>> Thoughts ?
>>
>> Lonnie
>>
>>
>>
>>
>>> On Oct 23, 2018, at 8:32 PM, David Kerr <Da...@Ke...> wrote:
>>>
>>> Hi Lonnie,
>>> Interesting thought about making pi-hole the upstream DNS for Astlinux (and therefore the whole network). You would certainly loose a lot of the metrics that pi-hole captures, though I am not sure how much I care about those. Mainly for geek interest I think. I do notice on pi-hole settings page support for DNSSEC with a note that it only works with google, norton, dns.watch and quad9 servers. I do not see a way to specify port number for pi-hole's upstream servers, but you could use iptables on Astlinux to REDIRECT traffic from pi-hole's static ip going to port 53 and send it instead to 2853, I think that might work.
>>>
>>> I do agree it is a pity that pi-hole isn't a whole lot simpler... would be great if it could just be added to AstLinux, but clearly that is not the approach they took and given cost of a Raspberry Pi it is maybe not that unreasonable for them to take the approach they did.
>>>
>>> Not at home this week so I cannot do any experimenting. I did leave pi-hole active at home, lets hope I don't return to annoyed family... I have already had to whitelist some domains just to get google sponsored search results to work.
>>>
>>> David
>>>
>>> On Sun, Oct 21, 2018 at 11:28 PM Lonnie Abelbeck <li...@lo...> wrote:
>>>> This is not a problem for standard AstLinux because that does not support DHCP for IPv6 so on a AstLinux LAN dual IPv4/IPv6 is required and DNS comes from IPv4.
>>>
>>> Indeed, and is why I like the idea of only supporting DHCPv4 on internal interfaces, it just works, and works consistently.
>>>
>>>
>>>> The changes to support that (IPv4 only for standard AstLinux) can be found here..
>>>> https://github.com/dkerr64/astlinux/commit/d20a4f40571258bbbf8725bfde6ec5a4254630ec
>>>
>>> David, nicely done (I have a few quibbles) but you put your finger on where it would go.
>>>
>>>
>>> Taking a step back, if a dedicated Raspberry Pi was performing DNS for the whole network, wouldn't it be better for AstLinux to just use it as it's static DNS source ? like ...
>>>
>>> Network -> DNS: ____
>>>
>>> In this case all the requests would be coming from AstLinux itself, would you be loosing any interesting statistics on the pi-hole web interface ?
>>>
>>> More importantly, the pi-hole should offer DNS-TLS upstream (via stubby like we do), I'm not sure if that has been implemented (lots of requests for it by DuckDuckGo'ing it).
>>>
>>> If you have a simple single LAN, then I can see tweaking the DHCP "option:dns-server" would be a reasonable choice, but when you have multiple LAN's/VLAN's and a single pi-hole it would require adding a bunch of firewall rules for DNS to be accessed across subnets. Not to mention requiring dnsmasq setup tweaks like what David proposed above.
>>>
>>> I would imagine that pi-hole should support DNS-TLS upstream at some point. I suppose we could optionally have our stubby daemon listen on 0.0.0.0@2853 instead of 127.0.0.1@2853 so a local pi-hole could direct DNS to it's internal gateway at port 2853 ... bypassing dnsmasq's DNS altogether. It would take some testing, assuming pi-hole can forward upstream to both address and port.
>>>
>>> Sadly the pi-hole project basically requires a full "Linux system" rather than just a single daemon, the later could be easily incorporated into AstLinux directly.
>>>
>>> Lonnie
>>>
>>>
>>>
>>>
>>>> On Oct 21, 2018, at 7:57 PM, David Kerr <da...@ke...> wrote:
>>>>
>>>> Moving this to developer list...
>>>>
>>>> I decided to go the same route as Michael. I found a old Raspberry Pi lying around and set it up as a pi-hole server. Then I went the route of setting dnsmasq option to replace the DNS server pushed out to DHCP clients.
>>>>
>>>> As I did this I found a quirk of dnsmasq...
>>>> NOTE... following does NOT apply to standard AstLinux, only to my version, but it is worth documenting.
>>>> For IPv4 all is fine. The dhcp-option statement in dnsmasq.static seems to replace/overwrite that in dnsmasq.conf.
>>>> However for IPv6 it was not as clean cut as that. On iOS devices both the IPv6 address in dnsmasq.conf and that in dnsmasq.static was getting picked up by the IPv6 network stack on iOS devices. This did not appear to be happening on MacOS devices however, very odd.
>>>> This is not a problem for standard AstLinux because that does not support DHCP for IPv6 so on a AstLinux LAN dual IPv4/IPv6 is required and DNS comes from IPv4. I have implemented much richer IPv6 support for local networks but this has not been incorporated back into the standard AstLinux (yet?).
>>>>
>>>> I decided therefore that it would make sense to allow for manual configuration of DNS servers in Astlinux, so that it would be done by the system into dnsmasq.conf and not require setting in dnsmasq.static. I therefore implemented support for...
>>>> INTDNS="192.168.1.1"
>>>> that can be set in user.conf.
>>>> And of course all the other interfaces as well... INT2DNS, INT3DNS, INT4DNS, DMZDNS and EXTDNS
>>>> These can be a space or comma separated list of IP addresses, so if you want to push a primary and secondary you can...
>>>> INT2DNS="8.8.8.8 8.8.4.4"
>>>>
>>>> The changes to support that (IPv4 only for standard AstLinux) can be found here..
>>>> https://github.com/dkerr64/astlinux/commit/d20a4f40571258bbbf8725bfde6ec5a4254630ec
>>>> The full IPv6 version is in my "develop" branch.
>>>>
>>>> Up to Lonnie if he wants to pull the IPv4 version into the Astlinux master.
>>>>
>>>> David
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On Sat, Oct 20, 2018 at 6:00 PM Michael Keuter <li...@mk...> wrote:
>>>>
>>>>> Am 20.10.2018 um 23:50 schrieb David Kerr <da...@ke...>:
>>>>>
>>>>> So, been thinking this through. I didn't realize that primary and secondary DNS could in fact be both used in parallel. I had assumed that secondary would be used only if primary failed. If I had a dedicated DNS server for pi-hole this might be okay (raspberry pi on my network maybe?) but I have it running in a VM which is running on Astlinux and it is also my UniFi Controller. I am trying to cover the possibility of that VM not being running, even if for just a few minutes during a reboot. When Astlinux reboots the VM image also restarts but maybe delayed by a minute or two as it goes through its boot. So DNS will take longer to come back up.
>>>>>
>>>>> I think two choices. I can change DHCP to push out the IP address of pi-hole VM. Or I can put some iptables rules in place to reroute DNS requests that come in to Astlinux (using NAT rules, needs both DNAT and SNAT rules). The benefit of iptables rules is that I could apply it to entire network (even statically assigned clients) if I want and I can quickly revert the entire network to using Astlinux directly for DNS if I need to. But it is a more complex solution than just pushing out a DNS server address.
>>>>>
>>>>> Pondering over this. Any thoughts?
>>>>>
>>>>> David
>>>>
>>>> Hi David,
>>>>
>>>> I am running a real Raspi 3 Model B+ with Pi hole, and my AstLinux router does DHCP and upstream DNS.
>>>> All DHCP devices get only the Pi as DNS server, which does Ad-blocking and then forwards the requests to the AstLinux router (with the config described in my former email). The Raspi is always on.
>>>>
>>>>> On Fri, Oct 19, 2018 at 5:33 PM Lonnie Abelbeck <li...@lo...> wrote:
>>>>> Ahhh, pi-hole ....
>>>>>
>>>>> Keep in mind that depending on the DNS client, given two DNS server IP's they can be queried in parallel and not just failover as primary/secondary would imply.
>>>>>
>>>>> Can you configure AstLinux to use the pi-hole IP as the system's static DNS server ? or is there a startup chicken/egg issue ?
>>>>>
>>>>> Network -> DNS: ____
>>>>>
>>>>> Lonnie
>>>>>
>>>>>
>>>>>
>>>>>> On Oct 19, 2018, at 4:13 PM, David Kerr <Da...@Ke...> wrote:
>>>>>>
>>>>>> I'll try dnsmasq.static. As to why... I have installed pi-hole (https://pi-hole.net/) on a VM and want to point clients at it as primary DNS, astlinux as secondary in case it fails. I configured pi-hole to use my astlinux as its primary DNS so all queries will ultimately go through astlinux, after pi-hole has done its thing to filter out the unwanted. No idea if I will keep this but thought I would give it a try and see if the family notices or if anything breaks.
>>>>>>
>>>>>> David
>>>>>>
>>>>>> On Fri, Oct 19, 2018 at 4:54 PM Lonnie Abelbeck <li...@lo...> wrote:
>>>>>>
>>>>>>
>>>>>>> On Oct 19, 2018, at 3:44 PM, David Kerr <da...@ke...> wrote:
>>>>>>>
>>>>>>> I'm probably just overlooking it, but is there a way for me to define the DNS servers that get pushed to clients in DHCP responses? Say I wanted to push out 192.168.1.2 instead (or as well as) 192.168.1.1, how would I do that?
>>>>>>
>>>>>> No trivial way. Possibly you could override the "dhcp-option=lan,option:dns-server,.." value using /mnt/kd/dnsmasq.static .
>>>>>>
>>>>>> Which begs the question, Why ? :-)
>>>>>>
>>>>>> Lonnie
>>>>
>>>> Michael
>>>>
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