Networking problem
JD
jd1008 at gmail.com
Sun May 15 05:39:14 UTC 2011
On 05/14/11 22:02, Shane Dawalt wrote:
> On 05/15/2011 12:45 AM, JD wrote:
>> On 05/14/11 21:28, Shane Dawalt wrote:
>>> On 05/15/2011 12:18 AM, JD wrote:
>>>> On 05/14/11 20:59, Kevin J. Cummings wrote:
>>>>> On 05/14/2011 11:42 PM, JD wrote:
>>>>>>> Can you add a "special" static route between the 2 specifying the router
>>>>>>> as the gateway?
>>>>>>>
>>>>>>> As I recall, LAN traffic assumes that anything sent on the local
>>>>>>> interface will get directly to anything else on the local network by
>>>>>>> just sending it. I'm not sure why the router doesn't "route" those
>>>>>>> packets when it sees them unless it assumes that if receives them over
>>>>>>> the wireless and the target machine is also wireless, that that would be
>>>>>>> redundant.
>>>>>>>
>>>>>>> Sometimes I used to set up static routes between machines, guaranteeing
>>>>>>> that the route the packets take will get there. something like:
>>>>>>>
>>>>>>> On machine w.x.y.2, sending to machine w.x.y.3, using the router at
>>>>>>> w.x.y.1 as the intermediary:
>>>>>>>
>>>>>>> # route add -host w.x.y.3 gw w.x.y.1 dev eth0
>>>>>>>
>>>>>>> I'm not 100% sure this will work, because if the router is at fault, it
>>>>>>> may still fail. But its worth a try.
>>>>>>>
>>>>>> No that would not do anything because already the default route is
>>>>>> 192.168.1.254
>>>>>> which is the gateway/router.
>>>>> No. The default route is only used when there is not a route found for
>>>>> the target machine. If the target machine is on the same subnet, then
>>>>> the packets just get sent out on the local network device. While its
>>>>> true that both the target machine and the router are on this network,
>>>>> this is the configuration that is not working for you. What you want is
>>>>> to either add a specific route "before" the local network route so that
>>>>> all traffic to that machine gets sent to the router, or, remove your
>>>>> local network route from your routing table. In that case, all you
>>>>> should have is a default route (that might work).
>>>>>
>>>>> This is my laptop routing table:
>>>>>> # route
>>>>>> Kernel IP routing table
>>>>>> Destination Gateway Genmask Flags Metric Ref Use Iface
>>>>>> local.net * 255.255.255.0 U 2 0 0 eth1
>>>>>> default 192.168.6.1 0.0.0.0 UG 0 0 0 eth1
>>>>> Note that any traffic to my local network gets put on the local network.
>>>>> (This is the first routing line.) BTW, local.net is 192.168.6.0/24.
>>>>>
>>>>> If there is traffic for *anywhere* else, that's what invokes the default
>>>>> route, and that gets sent to my router.
>>>>>
>>>>> I'm suggesting that you either have:
>>>>>
>>>>> 192.168.1.108 192.168.1.254 255.255.255.0 UG wlan0
>>>>> 192.168.1.0 * 255.255.255.0 U wlan0
>>>>> 0.0.0.0 192.168.1.254 0.0.0.0 UG wlan0
>>>>>
>>>>> or you have only:
>>>>>
>>>>> 0.0.0.0 192.168.1.254 0.0.0.0 UG wlan0
>>>>>
>>>>> I think you'll see a difference....
>>>>>
>>>>> I'm also wondering if you'll have to do the something similar on the
>>>>> "other" wireless machine.... (192.168.1.108?) I'm assuming your 2
>>>>> "wireless" machines are 192.168.1.60& 192.168.1.108, and that your
>>>>> router is 192.168.1.254.
>>>>>
>>>> I do not seem to be able to alter the routing table.
>>>> Current table on Fedora pc is:
>>>> $ route -vn
>>>> Kernel IP routing table
>>>> Destination Gateway Genmask Flags Metric Ref Use
>>>> Iface
>>>> 192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0
>>>> wlan0
>>>> 0.0.0.0 192.168.1.254 0.0.0.0 UG 0 0 0
>>>> wlan0
>>>>
>>>> I removed interfaces eth0 and virbr0 (i.e. I deactivated them) so they
>>>> no longer
>>>> get configured at bootup.
>>>>
>>> It simply cannot be a default route issue. The OP is attempting to
>>> ping a device on the 192.168.1.0 network from a device on the
>>> 192.168.1.0 network. They are local. No router will get involved with
>>> this communication. The machines themselves will not use their default
>>> route. They will use 802.3 layer-2 communications to talk with one
>>> another, i.e., MAC addresses. The traffic should be bridged/switched.
>>>
>>> Shane
>>>
>>>
>> Well, that bridge is the router.
>> Wireless clients that are associated with an Access Point
>> in "infrastructure" mode cannot directly talk to each other.
>> Their traffic must flow through the router.
>> If I had set the two computers to use AdHoc mode of
>> "association" with each other, then indeed, their traffic
>> would go directly to each other without any other facility
>> in between.
> Well yes. I'm using the terms "bridge" and "router" in the operative
> sense. I think we are stumbling on semantics. But I suspect you're
> right when you say your wireless router is misbehaving, either due to
> software or due to it's configuration.
>
> Usually, firewalls don't inhibit ARP entries. To test this theory,
> try "ping 192.168.1.70" from your 192.168.1.108 box. Directly after
> that, issue the command "arp -a". If ARP works, you should see
> something like this.
>
> ? (10.1.1.1) at 00:30:ab:13:9e:3d [ether] on eth0
>
> (On my net, 10.1.1.1 is my gateway.) If it doesn't work, you'll see
> something like this:
>
> ? (10.1.1.253) at<incomplete> on eth0
>
> where 10.1.1.253 is a non-existent machine on my network. And you'll
> see ping responses such as these:
>
> PING 10.1.1.253 (10.1.1.253) 56(84) bytes of data.
> From 10.1.1.21 icmp_seq=2 Destination Host Unreachable
> From 10.1.1.21 icmp_seq=3 Destination Host Unreachable
> From 10.1.1.21 icmp_seq=4 Destination Host Unreachable
>
> You've already posted something like this, so it's a good bet ARPs
> aren't working. So the wireless router is a good bet at this point.
>
> Shane
On the Fedora Machine:
# arp -a
? (192.168.1.254) at 0:1d:1a:00:91:c1 [ether] on wlan0
On the PowerBook Machine:
# arp -na
? (192.168.1.1) at 0:28:fe:6:ef:7 on en1 [ethernet]
? (192.168.1.108) at (incomplete) on en1 [ethernet]
? (192.168.1.254) at 0:1d:1a:00:91:c1 on en1 [ethernet]
? (192.168.1.255) at ff:ff:ff:ff:ff:ff on en1 [ethernet]
Now this is really strange!
Fedora's arp reports only the gateway!
Whereas PowerBooks arp reports the gateway, the wired machine
192.168.1.1 and even the Fedora machine it cannot ping: 192.168.1.108
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