[Nix-dev] Internet Issue

Taeer Bar-Yam tb442 at cornell.edu
Thu Sep 29 03:02:17 CEST 2016


Hey, sorry it took a while to reproduce (it doesn't happen all the time)

Indeed my computer is at that IP address, and I don't see anything suspicious on netstat (though I'm not entirely sure what I'm looking for)
running ```sudo systemctl restart network-manager``` fixes the problem temporarily, so I don't have a real issue anymore (I don't really mind running that every once in a while)
Still, this seems to be a problem with nixos' networkmanager, so probably a real fix should be found, no?
netstat output reproduced below (the last part of it may have been after the networkmanager restart):

```
➜  ~ sudo netstat --all --udp -4 --program
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
udp        0      0 192.168.0.19:45871      209.18.47.61:domain     ESTABLISHED 23086/nscd          
udp        0      0 192.168.0.19:54065      209.18.47.61:domain     ESTABLISHED 23086/nscd          
udp        0      0 192.168.0.19:45917      209.18.47.61:domain     ESTABLISHED 11093/astroid       
udp        0      0 192.168.0.19:38207      209.18.47.61:domain     ESTABLISHED 11093/astroid       
udp        0      0 192.168.0.19:54745      209.18.47.62:domain     ESTABLISHED 1071/xmobar         
udp        0      0 192.168.0.19:54887      209.18.47.62:domain     ESTABLISHED 11093/astroid       
udp        0      0 192.168.0.19:47019      209.18.47.62:domain     ESTABLISHED 23086/nscd          
udp        0      0 192.168.0.19:47614      209.18.47.62:domain     ESTABLISHED 23086/nscd          
udp        0      0 192.168.0.19:39696      209.18.47.61:domain     ESTABLISHED 11093/astroid       
udp        0      0 192.168.0.19:56471      209.18.47.61:domain     ESTABLISHED 23086/nscd          
udp        0      0 *:bootpc                *:*                                 23027/dhclient      
udp        0      0 192.168.0.19:ntp        *:*                                 589/ntpd            
udp        0      0 localhost:ntp           *:*                                 589/ntpd            
udp        0      0 *:ntp                   *:*                                 589/ntpd            
udp        0      0 *:49433                 *:*                                 16773/firefox       
udp        0      0 192.168.0.19:49798      209.18.47.62:domain     ESTABLISHED 23086/nscd          
udp        0      0 192.168.0.19:33435      209.18.47.61:domain     ESTABLISHED 15350/skype         
udp        0      0 192.168.0.19:49922      209.18.47.61:domain     ESTABLISHED 23086/nscd          
udp        0      0 192.168.0.19:41809      209.18.47.61:domain     ESTABLISHED 1071/xmobar         
udp        0      0 192.168.0.19:58523      209.18.47.62:domain     ESTABLISHED 11093/astroid       
udp        0      0 192.168.0.19:58695      209.18.47.62:domain     ESTABLISHED 11093/astroid       
udp        0      0 192.168.0.19:50588      209.18.47.62:domain     ESTABLISHED 11093/astroid       
udp        0      0 192.168.0.19:58926      209.18.47.62:domain     ESTABLISHED 23086/nscd          
udp        0      0 192.168.0.19:35389      209.18.47.62:domain     ESTABLISHED 23086/nscd          
udp        0      0 192.168.0.19:35431      209.18.47.61:domain     ESTABLISHED 23086/nscd          
udp        0      0 *:52443                 *:*                                 23027/dhclient      
udp        0      0 192.168.0.19:52585      209.18.47.62:domain     ESTABLISHED 11093/astroid       
udp        0      0 localhost:52851         *:*                                 15350/skype         
udp        0      0 192.168.0.19:36500      209.18.47.61:domain     ESTABLISHED 15350/skype         
udp        0      0 *:28501                 *:*                                 15350/skype         
```

Excerpts from Pavel Chuprikov's message of September 27, 2016 9:11 am:
> Hi,
> 
> Am I correct, that your computer's IP is 192.168.0.19 (you can check it
> with *ip addr*)? It doesn't seems so, since there are no ARP replies from
> (presumably) your router.
> If it is, then for starters I would suggest to find the guy who sends UDP
> broadcast on port 75. To do this you can use *netstat* and check for any
> suspicious activity*:*
> *# sudo netstat --all --udp -4 --program*
> 
> Also, check that your computer doesn't run dhcp server, that could misguide
> other clients.
> 
> At home you can try to run wireshark to find out what happens with HTTP
> requests or you better follow some basic network troubleshooting guides
> like this <https://ubuntuforums.org/showthread.php?t=25557> one or this
> <http://searchnetworking.techtarget.com/tip/Wireless-network-troubleshooting-Connectivity>
> one, or, maybe, this
> <http://www.linuxhomenetworking.com/wiki/index.php/Quick_HOWTO_:_Ch04_:_Simple_Network_Troubleshooting#.V-pukXV95vA>
> one.
> 
> --
> Pavel
> 
> 
> вт, 27 сент. 2016 г. в 10:05, Taeer Bar-Yam <tb442 at cornell.edu>:
> 
>> Okay, I got wireshark. I ran it (with sudo) and hit analyze on the wifi
>> network. I've attached a screenshot of the results. There are definitely
>> some fishy things going on. Let me know if you need other diagnostic
>> information. Sorry, I've never done much with network connections before.
>> Thanks for the help!
>>   --Taeer
>>
>> Excerpts from Tomasz Czyż's message of September 23, 2016 11:51 am:
>> > whireshark is your friend
>> >
>> > 2016-09-23 16:46 GMT+01:00 Taeer Bar-Yam <tb442 at cornell.edu>:
>> >
>> >> It *seems* as though my computer is breaking the internet for other
>> >> people. Sometimes at home the internet cuts out (not the wifi, that
>> still
>> >> connects; but webpages do not load on anyone's computers). This also
>> >> happens at my friend's house, but not the on-campus wifi network. It
>> >> appears to only happen when I am there and try to connect to the
>> internet,
>> >> but it doesn't always happen when I try to connect to the internet.
>> >>
>> >> Is it possible that my computer is responsible? What would be causing
>> that?
>> >>
>> >> I am using NixOS 16.03 stable and my internet setup is:
>> >> ```
>> >> networking.hostName = "rebel";
>> >> networking.networkmanager.enable = true;
>> >> ```
>> >> and I'm using ```nmtui connect``` to connect to the wifi network
>> >>
>> >> let me know if there's any other relevant information I should send.
>> >>
>> >>  --Taeer
>> >> _______________________________________________
>> >> nix-dev mailing list
>> >> nix-dev at lists.science.uu.nl
>> >> http://lists.science.uu.nl/mailman/listinfo/nix-dev
>> >>
>> >
>> >
>> >
>> > --
>> > Tomasz Czyż
>> >
>> _______________________________________________
>> nix-dev mailing list
>> nix-dev at lists.science.uu.nl
>> http://lists.science.uu.nl/mailman/listinfo/nix-dev
>>
> 

  --Taeer


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