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ZTE 931WII Issues

  • 11 December 2014
  • 7 kommenttia
  • 30 katselukertaa
M
Arvonimi
I'm having a few problems with the ZTE router.

I note it's a Linux based router, and a shell is accessible via the telnet interface. It appears to be running a modified version of linux 2.6.21.5.

My problem is that the NAT state table is misconfigured and broken.

The symptom is that various games do not function (random disconnections), sometimes websites appear to hang (easily fixed by refreshing the page).

It's caused because the conntrack timeouts are misconfigured, suggested default values can be found here:

http://www.frozentux.net/iptables-tutorial/iptables-tutorial.html#TABLE.INTERNALSTATES

Probably the most important one is the established connection timeout which is
set to 12 seconds on the router, when the recommended value by the Linux Netfilter guys is 5 days!!!!

This wouldn't be so bad because you can telnet to the router and start a Linux shell by telnetting to it and typing "sh".

Set the established timeout to 1 hour can be done by (times are in jiffies or 1/100ths of a second, refer to the documentation I linked above):

antony@blackmamba:~$ telnet 192.168.1.1
Trying 192.168.1.1...
Connected to 192.168.1.1.
Escape character is '^]'.
                   =======================
                   Welcome to ZXDSL 931WII
                   =======================

ZTE Inc., Software Release ZXDSL 931WIIV1.5.0c_Z31_FI2

Login: admin
Password:
 > sh


BusyBox v1.00 (2009.11.25-00:58+0000) Built-in shell (msh)
Enter 'help' for a list of built-in commands.

# cat /proc/sys/net/netfilter/nf_conntrack_tcp_timeout_established
1200
# echo 360000 > /proc/sys/net/netfilter/nf_conntrack_tcp_timeout_established
#


Except it doesn't work because some !!$~@&% has modified the linux kernel so that it ignores this value and sets this timeout to 30 seconds for established connections. (You can check the state of the connection tracking by reading /proc/net/ip_conntrack, and watch the established connections get timed out after 30 seconds regardless).

Even if the above worked it would only work until the modem was rebooted.

Please could Sonera also take this up with ZTE?

-Antony

7 kommenttia

A
You may find help here: http://www.ztefinland.com/

If you go to Services > Downloads you find there a link to modem's software update. It's the second one with the title ZXDSL 931WIIV1.5.0b_Z31_FI2.

I don't know if your modem already has this software version. If it doesn't and you update the software, please tell us if it helped for the problem you described.

T. Tapio
Sonera Asiakaspalvelu
A
Sonera-asiantuntija kirjoitti:
You may find help here: http://www.ztefinland.com/

If you go to Services > Downloads you find there a link to modem's software update. It's the second one with the title ZXDSL 931WIIV1.5.0b_Z31_FI2.

I don't know if your modem already has this software version. If it doesn't and you update the software, please tell us if it helped for the problem you described.

T. Tapio
Sonera Asiakaspalvelu


The version I have installed seems to be:

ZXDSL 931WIIV1.5.0c_Z31_FI2

I've installed the firmware version you've suggested, but it seems to have no effect on the issue. (exactly the same symptoms are present, ssh/telnet connections hanging, web browsing unresponsive under certain circumstances, some computer games randomly lose connections to servers).

Checking the conntrack table shows that the timeout for established tcp connections is still set to 30 seconds.

Bizarrely the version you suggested appears to be an older version of the firmware than the version which came installed on the router, assuming that 'c' comes after 'b'.

-Antony
A
The reason for the problems may be the UPnP. Disable UPnP on the modem's Advanced setup. If you are using a game console, disable UPnP also on that.

T. Tapio
Sonera Asiakaspalvelu
A
Sonera-asiantuntija kirjoitti:
The reason for the problems may be the UPnP. Disable UPnP on the modem's Advanced setup. If you are using a game console, disable UPnP also on that.

T. Tapio
Sonera Asiakaspalvelu


UPnP is already disabled as I consider it a security risk.
A
Have you tried to change the modem to bridged mode? I know it has certain cons but it might solve the problem for the time being.

T. Tapio
Sonera Asiakaspalvelu
A
Sonera-asiantuntija kirjoitti:
Have you tried to change the modem to bridged mode? I know it has certain cons but it might solve the problem for the time being.

T. Tapio
Sonera Asiakaspalvelu


I haven't tried that, I'm aware it'll solve my problems.

I guess I'll set it up and my own ddwrt or linux router to provide NAT.

ZTE should be legally required to provide the sourcecode to the router firmware (It's nearly all GPL, and quite likely just a modified version of the firmware Linksys use).

I had the same problem on a previous Linksys router, which was solved by downloading the source to the firmware and modifying it.

Thanks for your help, Antony
A
ZTE should be legally required to provide the sourcecode to the router firmware (It's nearly all GPL, and quite likely just a modified version of the firmware Linksys use).


Not only they should, but they _are required_ to provide the source code. Responsibility falls on manufacturer (ZTE) and also the distributor (Sonera) if ZTE doesn't provide the code.

Remember the license requires you make source available to your customers with the product or to include a written offer. Putting a zip of the relevant sources on the Documentation CD is a great way to do this.

If you include GPL software, include a copy of the GPL with your license documentation and make sure it is clear that your product contains GPL software.

If you make available software/firmware updates via Internet, and the update or software/firmware image contains GPL software, you have to provide the corresponding source code for every single version.

This is not legal advice, if you have doubts consult your legal counsel.

http://gpl-violations.org/faq/vendor-faq.html

If you wish you can also report GPL violations at: http://busybox.net/

Sadly this sort of disregard for licence, using someone else's code and then closing the product is quite typical for chinese companies.

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