[SOLVED] Iptables is blocking bluetooth/hci0 connection

xj25vm · 10-16-2011, 07:40 AM

Hi all,

I have an HP Deskjet 460btw portable printer - which can connect over usb and bluetooth. I've just setup the printer in Slackware using bluetooth after an upgrade - and it only works if I stop my iptables firewall. Otherwise, if the firewall is up, the printer will output a line of garbled text - and nothing else. All works fine if the firewall is stopped. There is no reference/setting in my rc.firewall to /dev/hci0 yet.

I used this printer before, but because of circumstances, there was no firewall involved in the past. So I don't think it is a new problem specific to Slackware 13.37.

My questions are:

1. Is iptables interfering with the hci0 (or other interface)? Even for non network protocols, such as printing over bluetooth? I can't find any references in Google about this - unless I'm searching for the wrong thing.

2. If the answer to the above question is "yes" - what is the best way to proceed? Do I just add rules in rc.firewall to allow all inbound and outbound traffic on hci0? I take it I can't be more selective (limit to certain ports) - as I don't imagine bluetooth is using tcp or udp for printing - or am I wrong?

3. Will iptables interfere just the same if I connect a bluetooth headset for example?

4. After bluez/bluetoothd starts and the printer is connected, there is no /dev/hci0 like it used to be in older versions of Slackware. I can only find an hci0 under the /sys folder. What is the reason for that? No corresponding udev rule?

Please note that I am not using any form of networking over Bluetooth - as far as I know.

Thanks in advance for any answers.

Sebastian

CTM · 10-17-2011, 07:11 AM

I don't have a definitive answer for questions 1-3, but assuming your default policy is to drop packets, appending this to rc.firewall will log all dropped packets to a new chain named LOGGING (the log message will be sent to syslog):

Code:

/usr/sbin/iptables -N LOGGING
/usr/sbin/iptables -A INPUT -j LOGGING
/usr/sbin/iptables -A FORWARD -j LOGGING
/usr/sbin/iptables -A LOGGING -m limit -j LOG --log-prefix "packet dropped: " --log-level 7
/usr/sbin/iptables -A LOGGING -j DROP

The verbosity level is high enough that you should be able to tell which interface is affected, and the source/destination IPs should tell you whether that traffic was destined for your printer (and therefore whether it's being intercepted).

xj25vm · 10-27-2011, 04:46 AM

I'm afraid I have to mark this thread as solved - without providing a definite answer. The printer just started working over bluetooth, with the firewall on - for no reason whatsoever. I have not amended the firewall in anyway (it is a manually generated rc.firewall, using the Slackware firewall generator here: http://connie.slackware.com/~alien/efg/). As far as I know, I haven't changed anything else to do with cups, bluetooth or firewall.

That night when I posted the OP, it would definitely work with the firewall down, and not work with the firewall up. I tried it several times both ways just to make sure. Now it is working all the time. I've scratched my head but can't come up even with a wild guess as to the cause of this. At least it is working now.

Thanks for the reply anyway.

unSpawn · 10-27-2011, 05:01 AM

Please post your thread in only one forum. Posting a single thread in the most relevant forum will make it easier for members to help you and will keep the discussion in one place. This thread is being closed because it is a duplicate.