GPRS and bad DNS servers like 10.11.12.13
Mikko Rapeli
I've seen a number of users here and on other Linux user forums
complaining that GPRS (mobile broadband, 3G, UMTS, EDGE, what ever
different names this has) modems give bad DNS server names over PPP
negotiations making the otherwise working PPP link useless.
I have experiences with Vodafone branded Huawei E220 and an Option PC
card with GSM and 3G GPRS support (can't remember the exact version, has
no WLAN, looks like USB device from Linux). They both give DNS server
names like 10.11.12.13, 10.11.12.14 and 10.11.12.15 if the GPRS pppd
scripts fire connection setup AT commands right after the device has
been connected to the PC card or USB slot.
If the connection is setup manually, and slowly, it works and proper DNS
names are returned. If an udev script automatically fires up 'ifup ppp0'
which in turn does 'pppd call gprs' etc when the device is connected,
then bad DNS server names are always returned.
I've found two somewhat working workarounds:
- setup DNS servers manually in the connection setup scripts, or
- or add 30-120 second sleep before activating the GPRS connection,
good place to do this is for example the connect chat script
Now, today I tried calling a few Finnish GSM/GPRS operators if they know
about this and if they know how query the modem, if it is in a sane
state. But they naturally don't know.
So, does anyone here know how to verify that a GPRS usb/PC card modem is
in a sane state and ready for a GPRS connection?
I haven't had time yet to check the Linux version of Vodafone Mobile
Connect, or newer versions of Network Manager which are supposed to have
working PPP support unlike the version in Debian Etch.
-Mikko
Chris Davies
> I have experiences with Vodafone branded Huawei E220 and an Option PC
> card with GSM and 3G GPRS support (can't remember the exact version, has
> no WLAN, looks like USB device from Linux). They both give DNS server
> names like 10.11.12.13, 10.11.12.14 and 10.11.12.15 if the GPRS pppd
> scripts fire connection setup AT commands right after the device has
> been connected to the PC card or USB slot.
Yes, I can vouch for that. There seems to be about a two minute window
before the card is stable.
> I haven't had time yet to check the Linux version of Vodafone Mobile
> Connect, or newer versions of Network Manager which are supposed to have
> working PPP support unlike the version in Debian Etch.
I use VMC version 1.99.17 with a Huawei E870 (E220 lookalike). If VMC
gets the "bad" DNS servers it warns the user to disconnect and try again,
or to put static entries in /etc/resolv.conf. Unfortunately its ppp
configuration replaces /etc/resolv.conf and does NOT restore it on exit.
Chris
Günther Schwarz
> So, does anyone here know how to verify that a GPRS usb/PC card modem
> is in a sane state and ready for a GPRS connection?
Sorry, I do not know that. But I can add that on connections to German
Servers by O2 I have similar problems. This is not limited to
GPRS/EDGE, but occurs when connecting in 3G/HPDPA mode also. Simply
terminating the connection and trying a second time works for me most
times. Was anybody successfull with static DNS IPs outside the ISPs
network?
Günther
Mikko Rapeli
> I have experiences with Vodafone branded Huawei E220 and an Option PC
> card with GSM and 3G GPRS support (can't remember the exact version, has
> no WLAN, looks like USB device from Linux).
I guess the common denominator for these cards, and perhaps others as
well, is that they all use Qualcomm wireless chipsets.
-Mikko
Clifford Kite
> Hello
> I've seen a number of users here and on other Linux user forums
> complaining that GPRS (mobile broadband, 3G, UMTS, EDGE, what ever
> different names this has) modems give bad DNS server names over PPP
> negotiations making the otherwise working PPP link useless.
> I have experiences with Vodafone branded Huawei E220 and an Option PC
> card with GSM and 3G GPRS support (can't remember the exact version, has
> no WLAN, looks like USB device from Linux). They both give DNS server
> names like 10.11.12.13, 10.11.12.14 and 10.11.12.15 if the GPRS pppd
> scripts fire connection setup AT commands right after the device has
> been connected to the PC card or USB slot.
> If the connection is setup manually, and slowly, it works and proper DNS
> names are returned. If an udev script automatically fires up 'ifup ppp0'
> which in turn does 'pppd call gprs' etc when the device is connected,
> then bad DNS server names are always returned.
> I've found two somewhat working workarounds:
> - setup DNS servers manually in the connection setup scripts, or
> - or add 30-120 second sleep before activating the GPRS connection,
> good place to do this is for example the connect chat script
A Google search for "GPRS PPP DNS 10.11.12.13" yielded this:
http://www.archivum.info/linux-...@vger.kernel.org/2008-07/msg00238.html
The pppd patch seems to be a "try and try again until you get real DNS
server IPs" approach. Checkout this later post in the thread by the same
poster to see why:
http://www.archivum.info/linux-...@vger.kernel.org/2008-07/msg09189.html
Patching pppd seems a bit extreme to me. Once the DNS servers are known
I would personally prefer to manually put them in /ect/resolv.conf and
seek out and remove the usepeerdns pppd option. That option would likely
in the script /etc/ppp/peers/gprs (as in 'pppd call gprs') or something
called by it.
> Now, today I tried calling a few Finnish GSM/GPRS operators if they know
> about this and if they know how query the modem, if it is in a sane
> state. But they naturally don't know.
> So, does anyone here know how to verify that a GPRS usb/PC card modem is
> in a sane state and ready for a GPRS connection?
The pppd patch appears to effectively do that.
--
Clifford Kite
/* In his wisdom RMS decided that people need no man pages when they can
use GNU's beautiful info system.
Unfortunately, everybody I know greatly prefers man pages.
- From the man-pages-1.55/man1/README */
Mikko Rapeli
> A Google search for "GPRS PPP DNS 10.11.12.13" yielded this:
>
> http://www.archivum.info/linux-...@vger.kernel.org/2008-07/msg00238.html
>
> The pppd patch seems to be a "try and try again until you get real DNS
> server IPs" approach. Checkout this later post in the thread by the same
> poster to see why:
>
> http://www.archivum.info/linux-...@vger.kernel.org/2008-07/msg09189.html
>
> Patching pppd seems a bit extreme to me. Once the DNS servers are known
> I would personally prefer to manually put them in /ect/resolv.conf and
> seek out and remove the usepeerdns pppd option. That option would likely
> in the script /etc/ppp/peers/gprs (as in 'pppd call gprs') or something
> called by it.
I tried the patch and it works with a Huawei USB and an Option PC card
modems. I can remove all sleeps and pppd call gprs with success straight
from udev scripts when the modems are connected.
If I got it right, the patch forces pppd to use the latest received DNS
configuration from the peer instead of the first one. That would be the
correct thing to do with these modems, but I'm not sure what else this
might break. A quick look at the PPP rfc does not say this would be
wrong.
For comparison I took AT command and PPP logs from a Vista machine which
uses the Vodafone connection manager:
http://koti.kapsi.fi/~mcfrisk/gprs_debug/qualcomm_ppp/vista_ModemLog_HUAWEI%20Mobile%20Connect%20-%203G%20Modem.txt
http://koti.kapsi.fi/~mcfrisk/gprs_debug/qualcomm_ppp/vista_ppp.log
Here are successfull connection setups with and without the patch:
http://koti.kapsi.fi/~mcfrisk/gprs_debug/qualcomm_ppp/ppp_log_huawei_fixed_pppd.txt
http://koti.kapsi.fi/~mcfrisk/gprs_debug/qualcomm_ppp/ppp_log_success_without_ppp_fix.txt
I will host failing cases too when I manage to copy some older log files
from the host in question.
-Mikko