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Debian 8.5 networking quits working every couple of hours

Posted on 2016-08-31
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Last Modified: 2016-10-06
Running Freeradius on Debian 8.5. system loses the ability to ping the default gateway every couple of hours. The system can still ping the local network.

~$ sudo route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         10.X0.0.1       0.0.0.0         UG    1024   0        0 eth0
10.X0.0.0       *               255.255.0.0     U     0      0        0 eth0

 sudo ifconfig
eth0      Link encap:Ethernet  HWaddr 00:0c:29:80:4c:82
          inet addr:10.X0.0.200  Bcast:10.X0.255.255  Mask:255.255.0.0
          inet6 addr: fe80::20c:29ff:fe80:4c82/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1102 errors:0 dropped:0 overruns:0 frame:0
          TX packets:207 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:101879 (99.4 KiB)  TX bytes:24485 (23.9 KiB)

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:27 errors:0 dropped:0 overruns:0 frame:0
          TX packets:27 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:3077 (3.0 KiB)  TX bytes:3077 (3.0 KiB)

Any clues on how to fix this? Other debian install do not have this problem. All have static addresses.
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Question by:jimmylew52
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by:Duncan Roe
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Is the default route still there when the problem occurs?
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by:jimmylew52
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yes, I altered it to read

default         10.X0.0.1       0.0.0.0         UG    0   0        0 eth0

and it started working but quit again in a couple of hours. When I reboot the server, this is the route I get.
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by:Duncan Roe
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Just to be clear, are you saying the default route had disappeared or altered when you lost access to the default gateway? If so, which?

(I would expect it had done one of those. The task would be then to discover what process was responsible).

And if the default route changed, what was its new value?
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by:jimmylew52
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The route only changes if I make a change, otherwise it remains the same. The access to the default gateway stops after a few hours no matter what the entries are in the route. Changing the entries regains a access to the dfg, but in a couple of hours the access to the dfg is gone again.

I do not see any log entries that explain the issue. No errors at all. Right now I am rebooting the system every 3 hours to keep the radius access working.

Sequence of events, boot system, I can ping the dfg an Internet. In a few hours I cannot ping the dfg or Internet. Check system and Freeradius logs, no errors. Reboot system, access to dfg an Internet regained. In a few hours, less than 4 hours, access to dfg and Internet are not possible again. Reboot system, access to dfg and Internet regained.
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by:ArneLovius
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how did you configure the network interface ?
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by:Duncan Roe
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Perhaps X changed? Why are you X-ing out an internal address anyway? No-one outside your organisation can get to it, or are you hiding it from your colleagues?

When you say Changing the entries regains a access to the dfg, what entries do you change and from what to what? Please post entire route before and after: I would prefer that you would use ip route list to show it rather than route; here's a comparison
09:59:04$ route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         dullstar.local. 0.0.0.0         UG    1      0        0 eth0
local.net       *               255.255.255.0   U     0      0        0 eth0
loopback        *               255.0.0.0       U     0      0        0 lo
09:59:34$ ip route list
default via 10.255.255.3 dev eth0  metric 1 
10.255.255.0/24 dev eth0  proto kernel  scope link  src 10.255.255.1 
127.0.0.0/8 dev lo  scope link 

Open in new window

Note that ip route list shows the source address presented by the NIC in addition to everything route shows.
Of course remove any entries referencing real actual external addresses as you wish.
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by:jimmylew52
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Substitute X with 8 and you have the actual address.

I will have wait for the networking to fail to send the ip fount list.

I have tried configurintnhetworking through the network namager and by editing the files. Both quit working in less than 4 hours.
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by:Duncan Roe
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Fine - look forward to it
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by:jimmylew52
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Working ip route list

default     via    10.80.0.1   dev   eth0   proto   static   metric    1024
10.80.0.0/16   dev   eth0   proto   kernel   scope   link   src   10.80.0.200

non-working ip route list

default     via    10.80.0.1   dev   eth0   proto   static   metric    1024
10.80.0.0/16   dev   eth0   proto   kernel   scope   link   src   10.80.0.200


Both look the same to me
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by:Duncan Roe
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Indeed they do look the same. And you say that if you re-issue a route command specifying the same route, then you get access again?

As a work-around, can you set up a cron job to re-do the route every hour or so?

I have no idea what is going on here. Maybe the route command interacts with Freeradius somehow - I have no experience of the latter. If my work-around keeps your system going, you could maybe investigate why it  works.
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by:jimmylew52
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Found a second system with the Sam IP address. Problem solved
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Duncan Roe earned 500 total points
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Good catch!
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by:jimmylew52
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Thanks for hanging in there with me. I will have to keep better tabs on my assistant.
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