ubuntu help

[Matt Graham]

After a long battle with technology, Dazed_75 wrote:
> On 10/3/07, Matt Graham <danceswithcrows at usa.net> wrote:
>> That's what the "assign default route to this interface" checkbox in kppp
>> is for.  Check it, and the PPP interface becomes the default gateway. 
>> This is what most PPP users want, though there are specialized situations
>> when you don't want this.
> Thanks Matt, that's news to me, but then I have never done dial-up in
> Linux.  Also, from a quick web search it looks like kppp is a KDE thing. 
> Is there a gnome equivalent (for future reference only)?

There is, but I don't know what it's called.

> > Destination     Gateway         Genmask   Flags Metric Ref    Use Iface
> > 0.0.0.0         192.168.1.1     0.0.0.0   UG    0      0        0 eth0
> >
> > ...packets that are not destined for the local (192.168.1.0, 127.0.0.0)
> > nets are sent to the gateway.  Betty would probably see something similar,
> > but it'd be ppp0 instead of eth0, and the gateway address would probably
> > be a routable IP corresponding to the device on the other end of the PPP 
> Cool.  I did not know this either.  But can you give an example of what it 
> would look like if broken by two interfaces to the same gateway?

IIRC, you can have only one default gateway, that is, one route with 
destination 0.0.0.0.  If you add another one with "route add default gw 
x.y.z.w", it *should* replace the existing route.  So: your machine is hooked 
up to 802.11b, gateway is 10.0.0.1.  Then you connect to a PPP link using 
kppp with "make this the default route" set, and the gateway changes to 
141.211.125.17 (or whatever) and packets that aren't destined for 10/8 or 
127/8 are routed through the PPP gateway instead of the 802.11 gateway.  At 
least that's what should happen.  Most workstation-ish machines tend to have 
3 or 4 routing table entries:  loopback, local net, (additional local net if 
they have 802.11 in addition to wired net), and default.  As such, it's much 
less complex than what you get if you have a box that's got 3 NICs and is 
acting as a router for 3 nets.

I heard of one guy who set his default gateway to 127.0.0.1 by accident.  That 
utterly b0rked his network, but was easy enough to fix given route -n output.

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