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Old 02-08-2009, 12:10 AM
Celejar
 
Default Strange arp problem

I've posted about this before, but I still have no solution.

I have a machine with an Atheros WiFi card. From lspci:

02:0a.0 Ethernet controller: Atheros Communications Inc. AR5212/AR5213
Multiprotocol MAC/baseband processor (rev 01)

>From dmesg:

ath5k phy0: Atheros AR2414 chip found (MAC: 0x79, PHY: 0x45)

The card is supported by the in-kernel ath5k driver; I have previously
used it with Madwifi.

I frequently see that arp fails on the machine. The card continues to
function; I can access the internet via my home router, and I can even
(sometimes) ssh into it from the internet (the router forwards port 22
to that machine), but any attempt to connect to it from the local
wireless network times out, and looking at the other machine's arp
table indicates that arp is failing (table shows 'incomplete').
Manually adding an arp entry with 'arp -s ip_addr mac_addr' fixes the
problem, at least for a while. What could be causing this? I believe
that I have experienced this problem even when the card was controlled
by Madwifi. Could this be a hardware issue?

Celejar
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Old 02-08-2009, 05:13 AM
Alex Samad
 
Default Strange arp problem

On Sat, Feb 07, 2009 at 08:10:43PM -0500, Celejar wrote:
> I've posted about this before, but I still have no solution.
>
> I have a machine with an Atheros WiFi card. From lspci:
>
> 02:0a.0 Ethernet controller: Atheros Communications Inc. AR5212/AR5213
> Multiprotocol MAC/baseband processor (rev 01)
>
> >From dmesg:
>
> ath5k phy0: Atheros AR2414 chip found (MAC: 0x79, PHY: 0x45)
>
> The card is supported by the in-kernel ath5k driver; I have previously
> used it with Madwifi.
>
> I frequently see that arp fails on the machine. The card continues to
> function; I can access the internet via my home router, and I can even
> (sometimes) ssh into it from the internet (the router forwards port 22
> to that machine), but any attempt to connect to it from the local
> wireless network times out, and looking at the other machine's arp
> table indicates that arp is failing (table shows 'incomplete').
> Manually adding an arp entry with 'arp -s ip_addr mac_addr' fixes the
> problem, at least for a while. What could be causing this? I believe
> that I have experienced this problem even when the card was controlled
> by Madwifi. Could this be a hardware issue?

Not sure if I can help but.


My understanding is, that wireless networks work in 2 modes, one where
each node can see each other and the other is where they can't see each
other. But I believe the ap should have a record of each currently
connected node, maybe you machine is disassociating itself from the
wireless network ?

The AP should be able to see it at all times


>
> Celejar
> --
> mailmin.sourceforge.net - remote access via secure (OpenPGP) email
> ssuds.sourceforge.net - A Simple Sudoku Solver and Generator
>
>
> --
> To UNSUBSCRIBE, email to debian-user-REQUEST@lists.debian.org
> with a subject of "unsubscribe". Trouble? Contact listmaster@lists.debian.org
>
>

--
"I try to go for longer runs, but it's tough around here at the White House on the outdoor track. It's sad that I can't run longer. It's one of the saddest things about the presidency. "

- George W. Bush
interview with Runners World, Aug. 2002
 
Old 02-08-2009, 05:20 AM
Celejar
 
Default Strange arp problem

On Sun, 8 Feb 2009 17:13:11 +1100
Alex Samad <alex@samad.com.au> wrote:

> On Sat, Feb 07, 2009 at 08:10:43PM -0500, Celejar wrote:
> > I've posted about this before, but I still have no solution.
> >
> > I have a machine with an Atheros WiFi card. From lspci:
> >
> > 02:0a.0 Ethernet controller: Atheros Communications Inc. AR5212/AR5213
> > Multiprotocol MAC/baseband processor (rev 01)
> >
> > >From dmesg:
> >
> > ath5k phy0: Atheros AR2414 chip found (MAC: 0x79, PHY: 0x45)
> >
> > The card is supported by the in-kernel ath5k driver; I have previously
> > used it with Madwifi.
> >
> > I frequently see that arp fails on the machine. The card continues to
> > function; I can access the internet via my home router, and I can even
> > (sometimes) ssh into it from the internet (the router forwards port 22
> > to that machine), but any attempt to connect to it from the local
> > wireless network times out, and looking at the other machine's arp
> > table indicates that arp is failing (table shows 'incomplete').
> > Manually adding an arp entry with 'arp -s ip_addr mac_addr' fixes the
> > problem, at least for a while. What could be causing this? I believe
> > that I have experienced this problem even when the card was controlled
> > by Madwifi. Could this be a hardware issue?
>
> Not sure if I can help but.
>
>
> My understanding is, that wireless networks work in 2 modes, one where
> each node can see each other and the other is where they can't see each
> other. But I believe the ap should have a record of each currently
> connected node, maybe you machine is disassociating itself from the
> wireless network ?
>
> The AP should be able to see it at all times

Thanks, but I don't think that's it. The problematic machine remains
connected to the AP; as I mentioned, it can access the internet fine.

Celejar
--
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Old 02-08-2009, 09:25 PM
Celejar
 
Default Strange arp problem

[back on list]

On Mon, 9 Feb 2009 09:06:16 +1100
Alex Samad <alex@samad.com.au> wrote:

> On Sun, Feb 08, 2009 at 01:20:58AM -0500, Celejar wrote:
> > On Sun, 8 Feb 2009 17:13:11 +1100
> > Alex Samad <alex@samad.com.au> wrote:
> >
> > > On Sat, Feb 07, 2009 at 08:10:43PM -0500, Celejar wrote:
>
> [snip]
>
> > >
> > > The AP should be able to see it at all times
> >
> > Thanks, but I don't think that's it. The problematic machine remains
> > connected to the AP; as I mentioned, it can access the internet fine.
>
> Okay, what about then you can't access from the local lan, have you
> tried running a tcpdump on the wireless link to see if the arp requests
> are making it to the machine ?

That's certainly a good suggestion; ISTR that I tried that last time I
had the problem, but I'll have to try it again and report back.

Celejar
--
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ssuds.sourceforge.net - A Simple Sudoku Solver and Generator


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Old 02-09-2009, 01:05 AM
Alex Samad
 
Default Strange arp problem

On Sun, Feb 08, 2009 at 05:25:55PM -0500, Celejar wrote:
> [back on list]
>
> On Mon, 9 Feb 2009 09:06:16 +1100
> Alex Samad <alex@samad.com.au> wrote:
>
> > On Sun, Feb 08, 2009 at 01:20:58AM -0500, Celejar wrote:
> > > On Sun, 8 Feb 2009 17:13:11 +1100
> > > Alex Samad <alex@samad.com.au> wrote:
> > >
> > > > On Sat, Feb 07, 2009 at 08:10:43PM -0500, Celejar wrote:
> >
> > [snip]
> >
> > > >
> > > > The AP should be able to see it at all times
> > >
> > > Thanks, but I don't think that's it. The problematic machine remains
> > > connected to the AP; as I mentioned, it can access the internet fine.
> >
> > Okay, what about then you can't access from the local lan, have you
> > tried running a tcpdump on the wireless link to see if the arp requests
> > are making it to the machine ?
>
> That's certainly a good suggestion; ISTR that I tried that last time I
> had the problem, but I'll have to try it again and report back.

when I am trying to track problems like this I usually like to have
tcpdump running on the 2 machines and if possible on the wireless router


I am guessing you don't have openwrt or ddwrt on some linux distro on
the ap. But if you can see the arp request leaving the lan box and not making
it to the wireless box then it might be a ap problem

>
> Celejar
> --
> mailmin.sourceforge.net - remote access via secure (OpenPGP) email
> ssuds.sourceforge.net - A Simple Sudoku Solver and Generator
>
>
> --
> To UNSUBSCRIBE, email to debian-user-REQUEST@lists.debian.org
> with a subject of "unsubscribe". Trouble? Contact listmaster@lists.debian.org
>
>

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08/23/2002
Stockton, CA
 
Old 02-09-2009, 01:50 AM
Celejar
 
Default Strange arp problem

On Mon, 9 Feb 2009 13:05:36 +1100
Alex Samad <alex@samad.com.au> wrote:

> On Sun, Feb 08, 2009 at 05:25:55PM -0500, Celejar wrote:
> > [back on list]
> >
> > On Mon, 9 Feb 2009 09:06:16 +1100
> > Alex Samad <alex@samad.com.au> wrote:
> >
> > > On Sun, Feb 08, 2009 at 01:20:58AM -0500, Celejar wrote:
> > > > On Sun, 8 Feb 2009 17:13:11 +1100
> > > > Alex Samad <alex@samad.com.au> wrote:
> > > >
> > > > > On Sat, Feb 07, 2009 at 08:10:43PM -0500, Celejar wrote:
> > >
> > > [snip]
> > >
> > > > >
> > > > > The AP should be able to see it at all times
> > > >
> > > > Thanks, but I don't think that's it. The problematic machine remains
> > > > connected to the AP; as I mentioned, it can access the internet fine.
> > >
> > > Okay, what about then you can't access from the local lan, have you
> > > tried running a tcpdump on the wireless link to see if the arp requests
> > > are making it to the machine ?
> >
> > That's certainly a good suggestion; ISTR that I tried that last time I
> > had the problem, but I'll have to try it again and report back.
>
> when I am trying to track problems like this I usually like to have
> tcpdump running on the 2 machines and if possible on the wireless router

Yes, I tried that previously, but as you surmise, I can't run it on the
AP, which is running proprietary firmware, and the hardware doesn't
support an open fw . I'm actually playing with openwrt on two spare
routers that I have, but I have not yet switched out my
production one.

> I am guessing you don't have openwrt or ddwrt on some linux distro on
> the ap. But if you can see the arp request leaving the lan box and not making
> it to the wireless box then it might be a ap problem

I currently don't have access to the wireless network in question, but
I'll be playing with tcpdump next time I do. Thanks for the help.

Celejar
--
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