Re: Network unreachable

[Jeffrey Barish <jeffbarish@starband.net>]

Marshal Wong wrote:
> On Sat, 2003-11-01 at 20:21, Jeffrey Barish wrote:
>
> > When I use the kernel that I built from the source for 2.4.18-686, I get 
> > the message:
> >
> > sendto: Network is unreachable
> >
> > when I try to ping another machine on my network.  Using ifconfig, I 
> > noticed that eth0 had no IP address assigned.  So I did
> >
> > ifconfig eth0 down
> >
> > and then
> >
> > ifconfig eth0 192.168.0.8 netmask 255.255.255.0 up
> >
> > At that point, ping worked.  So it seems as if dhcp is not working.  Is 
> > there something in the kernel configuration that is required to make 
> > dhcp work? 
> >
> > I am still not able to browse the web.  I get the message "Could not 
> > connect to host ..." no matter what URL I use.
>
>
> I've noticed that dhcp doesn't change any configurations.  If I run
> dhclient, it spews out the information for the dhcp, but that's it.  It
> doesn't change any network settings.  It's been that way for a long time
> now, but I've just worked around it...  Good to know that someone else
> is having the problem...
>
> Anyways, to help you with the "Could no connect to host..." problem, you
> probably need to add a default gateway to your routing table.
>
> Check if the default gateway is reasonable using
>
> # route (as root.  Haha!)
>
> If not, then
>
> # route add default gw <ip.address.of.gateway>
>
> Good Luck.
>
> Marshal

Your suggestion solved the problem.  I also had
  auto eth0
  iface eth0 inet dhcp
in my /etc/network/interfaces, but the routing was not correct until I 
issued the route command manually.

I still don't understand why there is a difference depending on whether 
I boot the kernel that I built from 2.4.18-686 source or use the 
standard kernel in that distribution.  The standard kernel gets 
everything right without my issuing the ifconfig and route commands. 
Also, I see dhclient running with the standard kernel.  I'm thinking 
that the problem when I run my kernel that requires the ifconfig and 
route commands arises because dhcp doesn't run, and dhcp doesn't run 
because something is not configured correctly in my kernel.  What do I 
need to turn on when I configure my kernel to get dhcp?  Is there some 
other explanation for why dhcp doesn't run with my kernel?