[debian-lan-devel] No internet connection after converting minimal installation

[Afif Elghraoui]

On 01/16/2015 11:09 AM, Andreas B. Mundt wrote:
> Hi Afif,
Hi, Andi,
I appear to have not reversed a change to /etc/network/interfaces I made 
while debugging much earlier. I had commented out the lines enabling 
localhost as a DNS server and intern as a dns-search. Uncommenting 
those, I don't have problems with the internal interface, but my 
problems with DNS on the external interface come back. I'm sorry about 
the confusion...

Here is the current situation with the proper /etc/network/interfaces:

- I can still ssh into the mainserver from a machine on the external network
- From the mainserver, I can no longer ping or get IP addresses for 
machines on the external network.
- apt-get update now fails with "503 Service unavailable" errors for 
every source.

root at mainserver:~# host debian.org
:: connection timed out : no servers could be reached
root at mainserver:~# informatics.sdsu.edu
:: connection timed out : no servers could be reached
>
> [...]
>
>
> Hm, strange.  I have here on my test setup:
>
>     admin at mainserver:~$ host aptcache
>     aptcache.intern is an alias for mainserver.intern.
>     mainserver.intern has address 10.0.0.1
>     admin at mainserver:~$ host workstation00
>     workstation00.intern has address 10.0.0.50
>     admin at mainserver:~$ host www
>     www.intern is an alias for mainserver.intern.
>     mainserver.intern has address 10.0.0.1
>
> For some reason your DNS resolution seems to work only for external
> addresses, and the local named fails to work?!?
I'm very sorry about that confusion. This part is actually working. I 
get the same results as you for these commands (except for the 
workstation, but I never actually added one yet)
>
> Perhaps to compare, here are some more 'results':
>
>     admin at mainserver:~$ host 8.8.8.8 127.0.0.1
>     Using domain server:
>     Name: 127.0.0.1
>     Address: 127.0.0.1#53
>     Aliases:
>
>     8.8.8.8.in-addr.arpa domain name pointer
>     google-public-dns-a.google.com.
root at mainserver:~# host 8.8.8.8 127.0.0.1
:: connection timed out : no servers could be reached
>     admin at mainserver:~$ host 8.8.8.8 10.0.0.1
>     Using domain server:
>     Name: 10.0.0.1
>     Address: 10.0.0.1#53
>     Aliases:
>
>     8.8.8.8.in-addr.arpa domain name pointer
>     google-public-dns-a.google.com.
root at mainserver:~# host 8.8.8.8 10.0.0.1
:: connection timed out : no servers could be reached
>     admin at mainserver:~$ host 8.8.8.8 192.168.122.58
>     Using domain server:
>     Name: 192.168.122.58
>     Address: 192.168.122.58#53
>     Aliases:
>
>     8.8.8.8.in-addr.arpa domain name pointer google-public-dns-a.google.com.
root at mainserver:~# host 8.8.8.8 192.168.122.58
:: connection timed out : no servers could be reached
> If this works fine, is anything suspicious in the squid logs
> /var/log/squid3/access.log ?
>
Not that I can tell, but I this probably doesn't apply anymore.
>> I think we're getting closer. Thanks for bearing with me on these issues.
> No problem, I hope we can finally understand and fix this soon.
Just for your information, I also tried converting a minimal wheezy 
installation to a mainserver/gateway on virtualbox on my personal 
machine at home a few days ago (just like what I'm trying here with 
jessie), and I'm having similar issues with the external network 
interface. I had a while ago tried the fai-cd image you posted online 
for wheezy and it worked out fine for me on virtualbox. I had full 
network access and could install a workstation. I'm not sure if any of 
that information is useful to you.
>
> Regards,
>
>          Andi
Thanks and regards,
Afif