[sf-lug] resolver problem

Alex Kleider akleider at sonic.net
Thu Apr 7 08:53:04 PDT 2016

On 2016-04-07 00:26, Michael Paoli wrote:
> A few more divide & conquer things you could try ...
> So ... works with one browser, not another, works with ping,
> but not git?  Efficient divide & conquer typically involves
> devising series of sufficiently easy/feasible tests, that
> effectively divide possible causes into two sets of
> roughly approximate probability, and results of test
> rule one set in, and the other out - or at least
> significantly assist in determining probability - after test -
> between the two sets.  One can also think of whittling it down
> to the simplest test that can show the "works" vs. "doesn't work" -
> at which point it's generally obvious what the problem is, or at least
> exactly where the problem is.
> So ... "browsers" ... & http & https.
> What about wget and/or curl?
> E.g.:
> $ curl -I https://www.google.com/
> $ curl -I https://github.com/
> and/or:
> $ wget -q -O - https://www.google.com/ | head -c 256; echo
> $ wget -q -O - https://github.com/ | head -c 256; echo

as per instructions, here are the facts:
alex at x301:~$ curl -I https://google.com
HTTP/1.1 301 Moved Permanently
Location: https://www.google.com/
Content-Type: text/html; charset=UTF-8
Date: Thu, 07 Apr 2016 15:31:07 GMT
Expires: Sat, 07 May 2016 15:31:07 GMT
Cache-Control: public, max-age=2592000
Server: gws
Content-Length: 220
X-XSS-Protection: 1; mode=block
X-Frame-Options: SAMEORIGIN
Alternate-Protocol: 443:quic
Alt-Svc: quic=":443"; ma=2592000; v="32,31,30,29,28,27,26,25"

alex at x301:~$ curl -I https://github.com
curl: (6) Could not resolve host: github.com

alex at x301:~$ wget -q -O - https://www.google.com | head -c 256; echo
<!doctype html><html itemscope="" itemtype="http://schema.org/WebPage" 
lang="en"><head><meta content="Search the world's information, including 
webpages, images, videos and more. Google has many special features to 
help you find exactly what you're looking
alex at x301:~$ wget -q -O - https://github.com/ | head -c 256; echo

alex at x301:~$

Switching users: symptoms are the same:
Chromium can resolve urls, Firefox can not, and
pat at x301:~$ ifconfig
eth2      Link encap:Ethernet  HWaddr 00:1c:25:9d:e1:f0
           inet addr:  Bcast:  Mask:
           inet6 addr: fe80::21c:25ff:fe9d:e1f0/64 Scope:Link
           RX packets:397957 errors:0 dropped:0 overruns:0 frame:0
           TX packets:343874 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:1000
           RX bytes:61678643 (61.6 MB)  TX bytes:30890987 (30.8 MB)
           Interrupt:20 Memory:f0600000-f0620000

lo        Link encap:Local Loopback
           inet addr:  Mask:
           inet6 addr: ::1/128 Scope:Host
           UP LOOPBACK RUNNING  MTU:65536  Metric:1
           RX packets:263600 errors:0 dropped:0 overruns:0 frame:0
           TX packets:263600 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:0
           RX bytes:27988121 (27.9 MB)  TX bytes:27988121 (27.9 MB)

tun0      Link encap:UNSPEC  HWaddr 
           inet addr:  P-t-P:  Mask:
           RX packets:149 errors:0 dropped:0 overruns:0 frame:0
           TX packets:49 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:100
           RX bytes:17045 (17.0 KB)  TX bytes:6174 (6.1 KB)

pat at x301:~$ ping github.com
PING github.com ( 56(84) bytes of data.
64 bytes from github.com ( icmp_seq=1 ttl=52 time=88.4 
64 bytes from github.com ( icmp_seq=2 ttl=52 time=87.2 
64 bytes from github.com ( icmp_seq=3 ttl=52 time=88.4 
--- github.com ping statistics ---
4 packets transmitted, 3 received, 25% packet loss, time 2999ms
rtt min/avg/max/mdev = 87.244/88.044/88.452/0.565 ms
pat at x301:~$ git clone https://github.com/alexKleider/debk.git
Cloning into 'debk'...
fatal: unable to access 'https://github.com/alexKleider/debk.git/': 
Could not resolve host: github.com
pat at x301:~$

Does this get us any closer to the root problem?

More information about the sf-lug mailing list