Problem switching to use Pi-hole DHCP

stirbitch · January 22, 2022, 3:51pm

Expected Behaviour:

Raspbian GNU/Linux 10 (buster)
Pi-hole v5.8.1 FTL v5.13 Web Interface v5.10.1
Using Pi-hole for DHCP, because Virgin Hub DHCP will not let me change the DNS server.
I expect the Pi-hole DHCP to take over when I disable the DHCP server on the Virgin Hub, and the Pi-hole DNS to by used.

Actual Behaviour:

This was working perfectly, but I had problems with one WiFi access point on my Raspi (there is no ethernet socket) - poor signal so could not connect to the Internet. So I changed to another access point. Internet connection from the Raspi now works fine.

When I enable DHCP on the Virgin Hub, and I can see use the Internett and see my Raspi from other machines on my local network, and can use the Pi-hole web interface.

But when I disable DHCP on my Virgin Hub, I cannot ping my Raspi, and cannot use the Internet from other machines. Yes, DHCP is enabled in Pi-hole.

Apart from what I described above, I don't believe I changed anythting. No idea how to start diagnosing the problem. Any help gratefully received.

Debug Token:

https://tricorder.pi-hole.net/O0Qt8OvU/
This was generated with DHCP enabled on the Virgin Hub

jfb · January 22, 2022, 3:57pm

Your debug log shows two active DHCP servers. The router is offering DNS servers other than Pi-hole, and Pi-hole DHCP was active as well. Multiple DHCP servers cause problems.

Disable the router DHCP server and renew the DHCP leases on all clients.

*** [ DIAGNOSING ]: Discovering active DHCP servers (takes 10 seconds)
   Scanning all your interfaces for DHCP servers
   Timeout: 10 seconds
   
   * Received 548 bytes from wlan0:192.168.0.1
     Offered IP address: 192.168.0.18
     Server IP address: 192.168.0.1
     Relay-agent IP address: N/A
     BOOTP server: (empty)
     BOOTP file: (empty)
     DHCP options:
      Message type: DHCPOFFER (2)
      server-identifier: 192.168.0.1
      lease-time: 86400 ( 1d )
      netmask: 255.255.255.0
      router: 192.168.0.1
      dns-server: 194.168.4.100
      dns-server: 194.168.8.100
      --- end of options ---
    
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (3382653620) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (2091975346) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (394580103) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (2711127372) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (171946573) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (2825658380) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (2929005625) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (368974275) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (2719409427) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (2388090917) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (2867709982) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (3973221436) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 310 bytes from wlan0:192.168.0.3
     Offered IP address: 192.168.0.233
     Server IP address: 192.168.0.3
     Relay-agent IP address: N/A
     BOOTP server: (empty)
     BOOTP file: (empty)
     DHCP options:
      Message type: DHCPOFFER (2)
      server-identifier: 192.168.0.3
      lease-time: 86400 ( 1d )
      renewal-time: 43200 ( 12h )
      rebinding-time: 75600 ( 21h )
      netmask: 255.255.255.0
      broadcast: 192.168.0.255
      dns-server: 192.168.0.3
      domain-name: "lan"
      hostname: "RaspberryPi"
      router: 192.168.0.1
      --- end of options ---
    
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (3373633685) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (3245937954) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (2602071145) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (1728933944) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (952094385) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (2734823146) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (856507954) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (4245740510) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (1990106410) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (715895390) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (3762424712) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (3452862290) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (1967024406) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (4195595428) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (467508671) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (1706573104) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (3940554471) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (1108803026) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (3072972288) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (219830030) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (1872934108) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (3643573618) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (789106535) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (1625293010) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (2874191981) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (1156469249) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (519738336) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (2058766849) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (2425154198) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (2133100424) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (160150022) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (87211543) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   * Received 548 bytes from wlan0:192.168.0.1
     DHCPOFFER XID (2493521178) does not match our DHCPDISCOVER XID (1857241393) - ignoring packet (not for us)
   
   DHCP packets received on interface wlan0: 2
   DHCP packets received on interface lo: 0

Edit - in addition, you have this dnsmasq warning as a result:

not using configured address 192.168.0.3 because it is in us

See our documentation page for dnsmasq warnings:

https://docs.pi-hole.net/ftldns/dnsmasq_warn/

Handing out addresses used by known critical infrastructure (like the DHCP server or a relay) is prevented to avoid IP address duplication issues.

This can happen when you have configured a static address assignment for the IP address of your Pi-hole. As this could result in an IP address conflict, Pi-hole offers a different free address from your configured DHCP pool. As this means Pi-hole behaves differently than you configured it to, it issues a warning.

The solution would be to either remove the static reservation for the Pi-hole itself (see ADDRESS in the warning) or simply accept this warning as it should only happen during debug log generation. When this warning appears outside of a running DHCP test, check that your Pi-hole is indeed using a static address.

stirbitch · January 23, 2022, 10:27am

Thank you for your help and the quick reply.

I did realise that the router DHCP should be disabled, but if I do that I cannot use the Internet from my Raspi, and thus cannot upload the debug information using "pihole -d". (And neither can I connect to my Raspi remotely from another machine on my lan, or connect to the Internet from any other machine.)

I could however use another mechanism to send a debug file generated when the router DHCP is disabled. Is it safe to attach the file to a message on this forum, or is there a better way?

jfb · January 23, 2022, 3:43pm

PM me the log.

stirbitch · January 23, 2022, 3:54pm

Many thanks again. PM sent. It looks like some special character(s) got lost or converted somehow, but the text remains

jfb · January 23, 2022, 5:06pm

Your debug log shows that Pi-hole cannot connect to external DNS servers.

This section of the debug log checks supported versions with this command:

dig +short -t txt versions.pi-hole.net @ns1.pi-hole.net

which should return:

"Raspbian=9,10,11 Ubuntu=16,18,20,21 Debian=9,10,11 Fedora=33,34 CentOS=7,8"

*** [ DIAGNOSING ]: Operating system
[i] dig return code:  10
[i] dig response:  dig: couldn't get address for 'ns1.pi-hole.net': failure
[?] Distro:  Raspbian
[?] Error: Raspbian is not a supported distro (https://docs.pi-hole.net/main/prerequisites/)

Your Pi was unable to make the connection to the remote nameserver.

This section of the debug log checks DNS resolution and blocking - this was also unable to connect to an external DNS server.

*** [ DIAGNOSING ]: Name resolution (IPv4) using a random blocked domain and a known ad-serving domain
[?] www.wyleczpc.pl is 0.0.0.0 on lo (127.0.0.1)
[?] www.wyleczpc.pl is 0.0.0.0 on wlan0 (192.168.0.3)
[?] Failed to resolve doubleclick.com via a remote, public DNS server (8.8.8.8)

Are you running any software on your network to block or redirect port 53 traffic?

You also have these warnings:

*** [ DIAGNOSING ]: Pi-hole diagnosis messages
   id    timestamp            type                  message                                                       blob1                 blob2                 blob3                 blob4                 blob5               
   ----  -------------------  --------------------  ------------------------------------------------------------  --------------------  --------------------  --------------------  --------------------  --------------------
   32    2022-01-22 19:36:50  DNSMASQ_WARN          interface wlan0 does not currently exist                                                                                                                                  
   33    2022-01-23 09:54:31  DNSMASQ_WARN          no address range available for DHCP request via lo

The first may be due to Pi-hole starting up before your Pi connects wirelessly to the network. You can add a startup delay for Pi-hole, to allow the wlan connection to be made prior to Pi-hole starting.

https://docs.pi-hole.net/ftldns/configfile/#delay_startup

10-15 seconds should do it.

stirbitch · January 24, 2022, 11:57am

The solution was to add a 15s delay. I have no idea why that suddenly became neceessary at a time when I was not changing anything on the Raspi, but it did the trick. Perhaps something to do with the WiFi strength or a hub upgrade sneakily applied by Virgin?

I've also removed the static IP address assigment from the Pi-hole DHCP, even though it did not seem to be causing any problems.

Thanks again!

stirbitch · January 25, 2022, 10:29pm

There is still something a little awry.

I have just found these warnings, and I seem to remember there was a tempory glitch around the time of the warnings - could not access a couple of news page in an app - which may or may not be related. Pihole wasn't starting up or anything around that time, and wlan0 is associated with the WiFi access point I am using.

After that, everything seemed to work smoothly, but it would be nice to know if there is an underlying issue I should address

Screenshot 2022-01-25 at 22-18-06 Pi-hole - raspberrypi
20220125T221545

Here's a debug file I generated a lot later than the warnings, if it is any help
https://tricorder.pi-hole.net/IxY0uxD7/

stirbitch · January 25, 2022, 10:33pm

Ooo, and a few more warnings I've just noticed, one very recent. Didn't notice any glitches this time.

20220125T223148

stirbitch · February 2, 2022, 3:04pm

I've been busy with other stuff recently, and have not had time to look at this for a while. But to conclude...

I have just found out that moving the Raspi closer to the WiFi router removed the re-occurance of any warnings found after the "solution".

However, I needed to keep the startup delay to prevent a single warning "interface wlan0 does not currently exist" on booting the machine. Maybe I have had that single warning for months, and simply not noticed?

Anyway, everything is working smoothly again now, and my conclusion is that a deterioration in the WiFi signal provoked some or all of the earlier issues.

I hope this might help someone else

yubiuser · February 6, 2022, 8:26pm

This is very likely. We just recently made this warnings appear in the web interface, but they have always been logged to /var/log/pihole.log in the past.

system · February 27, 2022, 8:26pm

This topic was automatically closed 21 days after the last reply. New replies are no longer allowed.