[ubuntu-za] ppp not replacing default gateway route when using bluetooth modem

Panayiotis panayk at gmail.com
Mon Feb 25 23:14:42 GMT 2008

Sorry to reply to this rather old message.

On Fri Sep 21 12:42:37 BST 2007, CM Schoonbee wrote:
> Hi there,
> I have previously gotten a GPRS internet connection working with a 
> Bluetooth Nokia  phone modem largely per the instructions on the 
> Ubuntu-ZA wiki. However I  subsequently  changed to using a  Vodacom 
> USB  modem to  connect to the internet.
> My Dad's Dell  laptop became unusably slow under Windows XP and he has 
> decided to give Linux another bash.  He will be taking the laptop on 
> holiday for connectivity using his cellphone and Bluetooth.  Having 
> gotten it to work on my computer previously I was confident that this 
> would not be an issue but soon ran into a snag which I do not know how 
> to overcome.
> The problem is that I had set up his laptop to access his ADSL router 
> over the network to get Feisty updates etc.  The default gateway is 
> therefore set to the ADSL router.  But the Bluetooth ppp script has the 
> 'defaultroute' option so my understanding is that this option should 
> temporarily replace the default route with the ppp one.  However, when 
> activating the ppp connection, the log gives a message about "not 
> replacing existing default route to eth"  This means that if I 
> unplug the network cable, there is no working connection default route 
> to the internet although there is a connection with the phone.
> Can someone please tell me why does the defaultroute option does not 
> seem to work or how to fix this problem?  If I do a 'route del default 
> gateway' before connecting then all is well, but this seems an 
> unnecessary kludge as a permanent solution and does not improve my 
> understanding as to what is broken.
> Thanks,
> Chris

You probably need to specify 'replacedefaultroute' in addition to
'defaultroute'. From the pppd manpages:

        Add a default route to the system routing tables, using the peer
as the gateway, when IPCP negotiation is successfully completed. This
entry is removed when the PPP connection is broken. [...]

        This option is a flag to the defaultroute option. If
defaultroute is set and this flag is also set, pppd replaces an existing
default route with the new default route.

 - Panayiotis

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