Potential Bug in 10-printing.xzm

[TimLevine]

Folks, we're using version 4.6.0 the 64 bit Porteus Kiosk.

We're experiencing what we believe to be a bug in 10-printing.xzm.

A little backstory here. In early January, we began experiencing several events wherein our corporate Cisco ASA router would lockup for unknown reasons.

In one such event, we were lucky enough to have been watching the logs in real-time and saw the following line repeated literally thousands of times:

Code: Select all

4|Jan 18 2019|11:38:27|419002|10.0.0.123|33634|10.0.0.10|631|Duplicate TCP SYN from inside:10.0.0.123/33634 to insidesecondary:10.0.0.10/631 with different initial sequence number

Our primary network is setup as inside 192.168.1.1/16 with the instances of Porteus Kiosk on insidesecondary 10.0.0.1/24. The host computers are inside and the VM instances of Porteus Kiosk connect through insidesecondary.

In the above 10.0.0.123 is a instance of Porteus Kiosk and 10.0.0.10 is a printer physically connected to the insidesecondary on the LAN with kiosk_config configured to use it as their printer for all instances of Porteus Kiosk.

We're not aware of what is causing the above error in the logs. It appears to be an error sending a print job to the printer but we're not really concerned with why it is failing. What we are concerned with is that it appears that when it tries to send a print job, it is not failing elegantly seems to be attempting to resend it to the extent that it becomes a quasi-denial of service attack with the capability of taking down a corporate Cisco router.

For the record, we did test sending a print job from the kiosk on ip 10.0.0.123 and we could not replicate the problem.

However, in real-world experience, we have had he printing module disabled all instances of Porteus Kiosk for almost a month and have not had a recurrence of the router issues we were plagued with in early January since we disabled it.

We strongly suspect that their is a bug in 10-printing.xzm such that it potentially will not fail elegantly if there are issues sending data the printer.

Thanks in advance for looking into this.

Tim Levine

[fanthom]

Hi Tim,

We got only one report which could be similar to your case so please follow this thread:
Kiosk Doing SNMP Scan on Network?

If disabling SNMP scan wont help then please upgrade to 4.8.0 release and check if it does any better.
If not then i have no other ideas at the moment.

[TimLevine]

If I customize 10-printing.xzm, embed it in a remastered iso and install from that iso burning the kiosk without including 10-printing.xzm in the kiosk-config, if I later add 10-printing.xzm to the kiosk-config for that install, is it going to use the customized one that was in the remastered iso when I installed or will it attempt to download it from the web?

[fanthom]

It will download it from our site.

You better add edited file to a separate module named as 'zz-settings.xzm' so it will be added as last one to virtual filesystem (alphanumeric insertion order) and never overridden by other files.

[TimLevine]

Do you mean the edited file within 10-printing.xzm should go in zz-settings.xzm all by itself and should load both 10-printing.xzm and zz-settings.xzm? Or do you mean that I should replace 10-printing.xzm with zz-settings.xzm?

[fanthom]

"Do you mean the edited file within 10-printing.xzm should go in zz-settings.xzm all by itself and should load both 10-printing.xzm and zz-settings.xzm?"
Yes

Aufs basics are explained here:
https://porteus-kiosk.org/file-structure.html