RFCOMM channel 1 behavior differences

RFCOMM channel 1 behavior differences

[Isaiah Sarju]

Hello,

Does Ubuntu, linux kernel 2.6.38.10, running bluez 4.91-0ubuntu1 have a 
special security policy for incoming rfcomm connections on channel 1, 
and not other channels?

I ask this because I can create rfcomm connections between two computers 
on other channels (2, 3, 11, 13, etc.) but the listening computer 
refuses connections when connection requests come in for channel 1.

I use the following commands:

on listening computer:
	sudo rfcomm listen hci0 <channel>

on connecting computer:
	sudo rfcomm connect hci0 <BD_ADDR> <channel>

When <channel> does not equal 1 both computers connect no with no 
problem. When <channel> equals 1 I receive the error "Can't connect 
RFCOMM socket: Connection refused"

I tried this in to two different environments. 1) in a X-session and 2) 
in command line

1) in GUI on the listing computer a dialogue box pops up requesting a 
pin for pairing. When I click cancel on the dialogue box of the 
listening machine the error "Can't connect RFCOMM socket: Connection 
refused" appears on the command line of the connecting machine.

2) in command line mode on the listening computer nothing appears and I 
immediately receive the error "Can't connect RFCOMM socket: Connection 
refused" on in the command line of the connecting machine

These problems do not arise when attempting to connect on any other 
channels.

I have searched Google, looked at multiple forum posts on rfcomm 
connections, looked at forum posts on peoples' problems with rfcomm 
connections, reviewed this mailing list's archives, and I cannot find my 
specific problem.

Thank you for any advice you can provide or resources to which you can 
point me.

Regards,
Isaiah

Re: RFCOMM channel 1 behavior differences

[Vinicius Costa Gomes]

Hi Isaiah,

On 19:23 Fri 12 Aug, Isaiah Sarju wrote:
> Hello,
> 
> Does Ubuntu, linux kernel 2.6.38.10, running bluez 4.91-0ubuntu1
> have a special security policy for incoming rfcomm connections on
> channel 1, and not other channels?
> 

Most probably this is caused by a problem in how Ubuntu packages
BlueZ. 

Could you try this: edit /etc/bluetooth/main.conf and add "pnat-server"
to the DisabledPlugins field (perhaps you will need to uncomment that
line). Restart bluetoothd and see if it works.

> I ask this because I can create rfcomm connections between two
> computers on other channels (2, 3, 11, 13, etc.) but the listening
> computer refuses connections when connection requests come in for
> channel 1.
> 
> I use the following commands:
> 
> on listening computer:
> 	sudo rfcomm listen hci0 <channel>
> 
> on connecting computer:
> 	sudo rfcomm connect hci0 <BD_ADDR> <channel>
> 
> When <channel> does not equal 1 both computers connect no with no
> problem. When <channel> equals 1 I receive the error "Can't connect
> RFCOMM socket: Connection refused"
> 
> I tried this in to two different environments. 1) in a X-session and
> 2) in command line
> 
> 1) in GUI on the listing computer a dialogue box pops up requesting
> a pin for pairing. When I click cancel on the dialogue box of the
> listening machine the error "Can't connect RFCOMM socket: Connection
> refused" appears on the command line of the connecting machine.
> 
> 2) in command line mode on the listening computer nothing appears
> and I immediately receive the error "Can't connect RFCOMM socket:
> Connection refused" on in the command line of the connecting machine
> 
> These problems do not arise when attempting to connect on any other
> channels.
> 
> I have searched Google, looked at multiple forum posts on rfcomm
> connections, looked at forum posts on peoples' problems with rfcomm
> connections, reviewed this mailing list's archives, and I cannot
> find my specific problem.
> 
> Thank you for any advice you can provide or resources to which you
> can point me.
> 
> Regards,
> Isaiah
> --
> To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in
> the body of a message to majordomo@vger.kernel.org
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Cheers,
-- 
Vinicius

Re: RFCOMM channel 1 behavior differences

[Johan Hedberg]

Hi,

On Fri, Aug 12, 2011, Vinicius Costa Gomes wrote:
> On 19:23 Fri 12 Aug, Isaiah Sarju wrote:
> > Hello,
> > 
> > Does Ubuntu, linux kernel 2.6.38.10, running bluez 4.91-0ubuntu1
> > have a special security policy for incoming rfcomm connections on
> > channel 1, and not other channels?
> > 
> 
> Most probably this is caused by a problem in how Ubuntu packages
> BlueZ. 
> 
> Could you try this: edit /etc/bluetooth/main.conf and add "pnat-server"
> to the DisabledPlugins field (perhaps you will need to uncomment that
> line). Restart bluetoothd and see if it works.

That could be the reason, however the plugin name is "pnat" and not
"pnat-server" (pnat-server is just the adapter driver name that the pnat
plugin registers).

Johan

Re: RFCOMM channel 1 behavior differences

[Isaiah Sarju]

On 8/13/11 4:26 AM, Johan Hedberg wrote:
> Hi,
>
> On Fri, Aug 12, 2011, Vinicius Costa Gomes wrote:
>> On 19:23 Fri 12 Aug, Isaiah Sarju wrote:
>>> Hello,
>>>
>>> Does Ubuntu, linux kernel 2.6.38.10, running bluez 4.91-0ubuntu1
>>> have a special security policy for incoming rfcomm connections on
>>> channel 1, and not other channels?
>>>
>>
>> Most probably this is caused by a problem in how Ubuntu packages
>> BlueZ.
>>
>> Could you try this: edit /etc/bluetooth/main.conf and add "pnat-server"
>> to the DisabledPlugins field (perhaps you will need to uncomment that
>> line). Restart bluetoothd and see if it works.
>
> That could be the reason, however the plugin name is "pnat" and not
> "pnat-server" (pnat-server is just the adapter driver name that the pnat
> plugin registers).

Thank you both for the advice. Adding "pnat" to the comma separated list 
worked for me.

main.conf now contains line:
DisablePlugins = network,input,pnat

What I could find on pnat-server in the archives stated that it has a 
use on some Nokia device. What function does the pnat plugin serve?

Thank you,
Isaiah