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Auteur: info at smallinnovations dot nl
Datum:  
Aan: dng
Onderwerp: Re: [DNG] Weird network issue - slow to resolve IPs
On 12-10-18 23:35, golinux@??? wrote:
> On 2018-10-12 15:25, Rick Moen wrote:
>> Quoting info at smallinnovations dot nl (info@???):
>>
>>> I had something similar but with ssh. Some debugging learned that IPv6
>>> was preferred but my ISP connection does not have IPv6. After 60
>>> seconds
>>> ssh time out and changed back to IPv4 and made connection after all.
>>> After this discovery I disabled IPv6 on my local network.
>>
>> This is a common problem and is why you shouldn't test networking
>> problems using Web browsers, but rather with simple command-line tools
>> such as dig, ping, traceroute, and tcptracroute.
>>
>> I note that dig has flags '-4' and '-6' to limit DNS resolution to only
>> IPv4 or only IPv6, respectively.
>> _______________________________________________
>>
> Thanks for the responses. I suspect that IPv6 might indeed be the
> culprit.
>
> Let me start by posting a traceroute to google.com:
>
> $ traceroute google.com
> traceroute to google.com (74.125.129.102), 30 hops max, 60 byte packets
>  1  * * *
>  2  tge0-0-0.ausdtx2802h.texas.rr.com (66.68.2.205)  45.543 ms  46.092
> ms  46.373 ms
>  3  agg30.ausxtxir02r.texas.rr.com (24.175.42.144)  24.660 ms  25.364
> ms  25.750 ms
>  4  agg22.hstqtxl301r.texas.rr.com (24.175.41.48)  31.765 ms  36.379
> ms  35.651 ms
>  5  ae-1-0.p0.atl90.tbone.rr.com (66.109.1.218)  50.802 ms  44.462 ms 
> 39.178 ms
>  6  bu-ether12.dllstx976iw-bcr00.tbone.rr.com (66.109.6.39)  45.106
> ms  34.283 ms 107.14.19.49 (107.14.19.49)  36.338 ms
>  7  0.ae1.pr1.dfw10.tbone.rr.com (107.14.17.234)  35.058 ms
> 0.ae2.pr1.dfw10.tbone.rr.com (107.14.17.236)  27.868 ms  25.589 ms
>  8  ix-ae-23-0.tcore2.dt8-dallas.as6453.net (66.110.57.97)  32.475 ms 
> 39.941 ms  52.998 ms
>  9  74.125.50.214 (74.125.50.214)  31.421 ms  34.253 ms  38.467 ms
> 10  * * *
> 11  216.239.63.238 (216.239.63.238)  34.677 ms 108.170.226.56
> (108.170.226.56)  29.073 ms 108.170.226.182 (108.170.226.182)  29.651 ms
> 12  108.170.240.145 (108.170.240.145)  29.667 ms 108.170.240.209
> (108.170.240.209)  32.095 ms 108.170.252.130 (108.170.252.130)  34.320 ms
> 13  216.239.59.168 (216.239.59.168)  29.987 ms 108.170.233.117
> (108.170.233.117)  30.326 ms 108.170.228.84 (108.170.228.84)  31.091 ms
> 14  209.85.250.37 (209.85.250.37)  30.081 ms  38.277 ms  35.229 ms
> 15  209.85.246.182 (209.85.246.182)  56.902 ms 209.85.246.84
> (209.85.246.84)  77.541 ms 209.85.246.182 (209.85.246.182)  73.471 ms
> 16  216.239.56.175 (216.239.56.175)  63.061 ms 216.239.54.65
> (216.239.54.65)  61.564 ms 216.239.48.67 (216.239.48.67)  65.893 ms
> 17  * * *
> 18  * * *
> 19  * * *
> 20  * * *
> 21  * * *
> 22  * * *
> 23  * * *
> 24  * * *
> 25  * * *
> 26  * * *
> 27  jm-in-f102.1e100.net (74.125.129.102)  168.457 ms  171.191 ms 
> 170.337 ms
>
> Good grief!!!  Another trace route eventually got to one of my websites:
>
> $ traceroute stopcta.info
> traceroute to stopcta.info (185.203.114.117), 30 hops max, 60 byte
> packets
>  1  * * *
>  2  tge0-0-0.ausdtx2801h.texas.rr.com (66.68.2.201)  330.761 ms 
> 331.380 ms  331.773 ms
>  3  agg30.ausutxla01r.texas.rr.com (24.175.42.142)  25.345 ms  26.732
> ms  27.302 ms
>  4  agg22.dllatxl301r.texas.rr.com (24.175.41.46)  37.000 ms  33.044
> ms  37.558 ms
>  5  bu-ether14.dllstx976iw-bcr00.tbone.rr.com (66.109.6.88)  41.860 ms
> 66.109.1.216 (66.109.1.216)  40.157 ms  41.325 ms
>  6  66.109.5.121 (66.109.5.121)  31.192 ms  42.090 ms  25.595 ms
>  7  dls-b21-link.telia.net (62.115.156.208)  27.346 ms  28.104 ms 
> 27.084 ms
>  8  atl-b22-link.telia.net (80.91.246.74)  49.968 ms  58.985 ms 
> 49.461 ms
>  9  mai-b1-link.telia.net (62.115.122.53)  69.445 ms  67.043 ms 
> 59.106 ms
> 10  init7-ic-318278-mai-b1.c.telia.net (62.115.148.55)  70.009 ms 
> 77.143 ms  72.151 ms
> 11  r2nyc3.core.init7.net (193.47.153.231)  71.850 ms  70.682 ms 
> 78.191 ms
> 12  r1nyc3.core.init7.net (193.47.153.238)  80.221 ms  73.209 ms 
> 69.531 ms
> 13  r1nyc2.core.init7.net (193.47.153.234)  84.886 ms  74.355 ms 
> 70.098 ms
> 14  r1lon2.core.init7.net (77.109.128.14)  140.249 ms  140.124 ms 
> 147.072 ms
> 15  r1bsl1.core.init7.net (77.109.128.102)  173.037 ms  162.066 ms 
> 164.498 ms
> 16  r1zrh2.core.init7.net (77.109.128.129)  159.150 ms  152.605 ms
> r1bsl3.core.init7.net (82.197.168.18)  160.159 ms
> 17  r1glb1.core.init7.net (77.109.128.238)  165.343 ms
> r1zrh8.core.init7.net (82.197.168.74)  155.252 ms
> r1glb1.core.init7.net (77.109.128.238)  171.133 ms
> 18  empty.init7.net (77.109.141.139)  159.961 ms  156.963 ms  165.937 ms
> 19  * r1glb1.core.init7.net (77.109.140.205)  156.057 ms  159.736 ms
> 20  empty.init7.net (77.109.141.139)  165.136 ms
> 117-114-203-185.place5.ungleich.ch (185.203.114.117)  169.960 ms
> empty.init7.net (77.109.141.139)  161.785 ms
>
> I (or rather Evilham and Nico) recently moved my websites to a devuan
> IPv6 VPS which is set up to serve IPv4 too through some sort of
> server-side magic I don't really understand. I suspect this might be
> what triggered things. I am clueless how to test if IPv6 is actually
> enabled on my network or how to disable it if it is.  Maybe someone
> can save me some hours of searching? I really need to work on the
> refracta website a bit.
>
> golinux
>
>
> _____________


Disabling IPv6 can be done with adding in /etc/sysctl.conf:

net.ipv6.conf.all.disable_ipv6 = 1

and executing sysctl -p or reboot

Grtz.

Nick