[Kea-users] Lose Connection every 5 to 10 minitues when working.

[Shane Kerr]

Quang Trieu,

At 2016-01-12 08:21:18 +0700
"Quang. Trieu Minh" <quangtm at vng.com.vn> wrote:

> We have used kea 1.0.0 for a week. Sometime, our users lose connection
> every 5 to 10 minutes when working. After we saw lose ip on their computer.
> 
> Our config as bellow :
> 
> "valid-lifetime": 9200,
> 
> #    "renew-timer": 1000,
> 
> #   "rebind-timer": 2000,
> 
> Please help us to solve the issue.

I don't know what the problem is, but what I would do in such a case is
start a tcpdump and capture the traffic:

$ sudo tcpdump -n -s0 -v port 67 or port 68

You can then confirm that clients are requesting addresses as well as
answers going back. You may need to specify "-i" to get the correct
interface, although on my system leaving the "-i" off captures packets
from all interfaces.

If packets are not arriving, then there is probably something wrong
with the network, for example a badly-configured firewall or NAT box or
something like that.

If packets are arriving, but no answers are being sent, then there is
something wrong with either the OS or Kea.

If packets are arriving, and answers are being sent, but the clients
are still timing out, then it might be useful to look at the contents
of the packets. The "-v" option on the tcpdump above should give you
a lot of information. If not, then you might have more luck with
capturing the packets to a file and then using Wireshark to look at the
results. Something like this:

$ sudo tcpdump -n -s0 -U -w dhcp.pcap port 67 or port 68

This will write all of the DHCP packets to a file called "dhcp.pcap".

Cheers,

--
Shane