hummingbird and internal dns servers

[dr_kristau 4]

Hello!

I've been running an airvpn config file via openvpn on my 'homebrew' ubuntu 'router' for years and it's great. I use isc-dhcp-server to broadcast the 'internal' dns address of the airvpn server (10.4.0.1) to all the clients on my network, so when tun0 is up all the clients can use it. This has been working for years too.

I thought I'd try hummingbird 1.0.2 on my ubuntu box instead of openvpn, as the performance gain seemed interesting. Hummingbird constructs the tun0 correctly for me, however, the 'internal' dns server doesn't seem to be working. Using openvpn, dig gives me:
 

dig @10.4.0.1 google.com

; <<>> DiG 9.16.1-Ubuntu <<>> @10.4.0.1 google.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 13228
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;google.com.            IN    A

;; ANSWER SECTION:
google.com.        83    IN    A    216.58.211.238

;; Query time: 12 msec
;; SERVER: 10.4.0.1#53(10.4.0.1)
;; WHEN: Thu May 21 14:42:02 UTC 2020
;; MSG SIZE  rcvd: 55

whereas when I use hummingbird I get:
 

dig @10.4.0.1 google.com

; <<>> DiG 9.16.1-Ubuntu <<>> @10.4.0.1 google.com
; (1 server found)
;; global options: +cmd
;; connection timed out; no servers could be reached

This means that I can't use isc-dhcp-server to push 10.4.0.1 to the clients on my network anymore. Could anybody please tell me if this is expected behavior? Thanks.

EDIT:
more information: I call hummingbird with the network lock off (I use my own custom iptables for this)

sudo hummingbird --network-lock off /etc/openvpn/AirVPN.ovpn

 

[eburom 16]

Hello,
Not sure what your problem might be but hummingbird also changes the machines DNS settings as opposite as openvpn, so you could try to call it with --ignore-dns-push option.
Not sure if this will help though.

[dr_kristau 4]

2 minutes ago, eburom said:

Hello,
Not sure what your problem might be but hummingbird also changes the machines DNS settings as opposite as openvpn, so you could try to call it with --ignore-dns-push option.
Not sure if this will help though.

Thank you for the suggestion! That one had occurred to me and I tried it; unfortunately it didn't work.

[OpenSourcerer 1359]

One word: Logs.

[dr_kristau 4]

52 minutes ago, giganerd said:

One word: Logs.

Thank you for your reply!

My question is about expectations - should I expect hummingbird to find the 10.4.0.1 DNS server or not? Certainly openvpn finds it, which seems to indicate that it is a problem with hummingbird itself. Before I spend more time on the issue, given that I already have a working system, I thought I'd ask if not finding it was expected behaviour.

Which logs did you have in mind?

[OpenSourcerer 1359]

1 hour ago, dr_kristau said:

Which logs did you have in mind?

Hummingbird.

Also, I'm wondering why you publish 10.4.0.1 as the DNS server instead of your router's IP.

[dr_kristau 4]

14 minutes ago, giganerd said:

Hummingbird.

Also, I'm wondering why you publish 10.4.0.1 as the DNS server instead of your router's IP.

I can't find any reference to logs in the hummingbird readme, and I've done a grep for 'hummingbird' in the syslogs but found nothing. Could you please indicate to me where the hummingbird logs are?

I use 10.4.0.1 firstly because it's in the airvpn specs, and secondly because it means I don't have to reconfigure my isc-dhcp-server (and have all my clients reset their DNS) every time I change the airvpn server my router connects to. 

[OpenSourcerer 1359]

1 hour ago, dr_kristau said:

I can't find any reference to logs in the hummingbird readme, and I've done a grep for 'hummingbird' in the syslogs but found nothing. Could you please indicate to me where the hummingbird logs are?

They are written to STDOUT. So you kinda copy and paste.

[dr_kristau 4]

1 hour ago, giganerd said:

They are written to STDOUT. So you kinda copy and paste.

Okay, thank you.

The issue is, however, that hummingbird connects successfully; it correctly constructs my tun0. From my router, I can ping addresses as expected. What I can't do, however, is connect to 10.4.0.1. as I can when I successfully connect using openvpn, as my calls to dig show.