[Babel-users] Unable to ping, intermittent connectivity

c g truegrael at yahoo.com
Mon Feb 2 22:23:15 UTC 2015


Thank you for your reply Juliusz.
It is definitely an interesting project, I am learning a lot, though there is an awful lot to learn and understand.  I appreciate any help or insight you have to offer.
Since sending the original email, we have moved to a Buildroot Linux using kernel 3.12.28.  The ralink driver is rt5370sta version 2.5.0.3.  We are seeing the same things on Buildroot that we saw on Raspbian, namely the ip addresses being handed out, some talk via ipv6 showing up in the logs using debug, but periodically losing the ability to ping, ssh, or any other communication. 
We have not included a firewall in the build root, so there shouldn't be one there to disable.  We are not using Avahi.  
The output of ifconfig -a for the ahcpd server (manually assigned to 128) is:
eth0      Link encap:Ethernet  HWaddr B8:27:EB:1A:18:A4            inet addr:10.0.2.50  Bcast:10.0.2.255  Mask:255.255.255.0          inet6 addr: fe80::ba27:ebff:fe1a:18a4/64 Scope:Link          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1          RX packets:331 errors:0 dropped:0 overruns:0 frame:0          TX packets:188 errors:0 dropped:0 overruns:0 carrier:0          collisions:0 txqueuelen:1000           RX bytes:37180 (36.3 KiB)  TX bytes:27033 (26.3 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:0 errors:0 dropped:0 overruns:0 frame:0          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0          collisions:0 txqueuelen:0           RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
ra0       Link encap:Ethernet  HWaddr C8:3A:35:C5:38:A8            inet addr:10.10.2.128  Bcast:0.0.0.0  Mask:255.255.255.128          inet6 addr: fe80::ca3a:35ff:fec5:38a8/64 Scope:Link          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1          RX packets:0 errors:0 dropped:0 overruns:0 frame:0          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0          collisions:0 txqueuelen:1000           RX bytes:238470 (232.8 KiB)  TX bytes:19371 (18.9 KiB)
for a sample client it is:
 eth0      Link encap:Ethernet  HWaddr B8:27:EB:1F:CF:AE            inet addr:10.0.2.74  Bcast:10.0.2.255  Mask:255.255.255.0          inet6 addr: fe80::ba27:ebff:fe1f:cfae/64 Scope:Link          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1          RX packets:66 errors:0 dropped:0 overruns:0 frame:0          TX packets:58 errors:0 dropped:0 overruns:0 carrier:0          collisions:0 txqueuelen:1000           RX bytes:8725 (8.5 KiB)  TX bytes:7884 (7.6 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:0 errors:0 dropped:0 overruns:0 frame:0          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0          collisions:0 txqueuelen:0           RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
ra0       Link encap:Ethernet  HWaddr C8:3A:35:C9:1D:B2            inet addr:10.10.2.132  Bcast:0.0.0.0  Mask:255.255.255.255          inet6 addr: fde6:20f5:c9ac:358:ca3a:35ff:fec9:1db2/128 Scope:Global          inet6 addr: fe80::ca3a:35ff:fec9:1db2/64 Scope:Link          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1          RX packets:0 errors:0 dropped:0 overruns:0 frame:0          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0          collisions:0 txqueuelen:1000           RX bytes:17600 (17.1 KiB)  TX bytes:5021 (4.9 KiB)
route -n output
~# route -nKernel IP routing tableDestination     Gateway         Genmask         Flags Metric Ref    Use Iface0.0.0.0         10.0.2.1        0.0.0.0         UG    0      0        0 eth010.0.2.0        0.0.0.0         255.255.255.0   U     0      0        0 eth010.0.2.50       10.10.2.128     255.255.255.255 UGH   0      0        0 ra010.0.2.71       10.10.2.131     255.255.255.255 UGH   0      0        0 ra010.10.2.128     10.10.2.128     255.255.255.255 UGH   0      0        0 ra010.10.2.129     10.10.2.129     255.255.255.255 UGH   0      0        0 ra010.10.2.131     10.10.2.131     255.255.255.255 UGH   0      0        0 ra0
iptables -vnL output:
~# iptables -vnL Chain INPUT (policy ACCEPT 0 packets, 0 bytes) pkts bytes target     prot opt in     out     source               destination         
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes) pkts bytes target     prot opt in     out     source               destination         
Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes) pkts bytes target     prot opt in     out     source               destination         
At the moment of this output, 128, 130, and 131 were able to ping and communicate.  However we could not reach 129 via ping or ssh, but it received its 129 address through AHCPD.  This is not typical of our problem, usually when there is no communication it is where nobody can ping anybody else, though we have had it like this several times.
All these devices are within 15 feet of each other spanning two desks.  There shouldn't be any range or line of sight limitations. 
I can provide the above information from each of the nodes if that is more helpful.  I am not sure how much of it you need. 
Again, thank you very much for your time.      From: Juliusz Chroboczek <jch at pps.univ-paris-diderot.fr>
 To: c g <truegrael at yahoo.com> 
Cc: "babel-users at lists.alioth.debian.org" <babel-users at lists.alioth.debian.org> 
 Sent: Friday, January 30, 2015 7:25 PM
 Subject: Re: [Babel-users] Unable to ping, intermittent connectivity
   
> I am just the guy whose lap this landed on.

Enjoy the situation!  You've been tasked with an exciting project.



> I am at a loss as to why these nodes can clearly see each other and
> communicate enough to pass out addresses, but be unable to ping or do other
> kinds of communication.  

1. Disable the firewall.  Perhaps the ping packets are being dropped at
  that level?

2. If that doesn't help, please post the output of

    route -n
    iptables -vnL
    ifconfig -a

There's no way we can debug you issue wiithout that information.

-- Juliusz


  
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