Various recent threads about networking issues

Janina Sajka janina at
Tue Jun 27 22:25:02 UTC 2006

Matthew Saltzman writes:
> On Tue, 27 Jun 2006, Roberto Ragusa wrote:
> >My router has an internal interface eth0 and an external eth1.
> >Rebooting swaps the interfaces some times, and the pppoe points to
> >the internal LAN, with obvious results.
> >
> >I could fix the problem by using the MAC address (HWADDR variable
> >in ifcfg-eth{0,1}), but I don't want to do that because I need to
> >be able to move the disks to another machine with similar hardware
> >and power up with zero configuration change (this is done for disaster
> >recovery, and the disks are not really moved, just rsync'ed).
> FWIW, I have not found that HWADDR reliably orders the interfaces ayway. 
> Even with HWADDR parameters, interfaces would occasionally reorder 
> themselves.
> >
My experience of reordered interfaces is primarily with my laptop which
has both a wired and wireless device. In my home location, things stay
pretty stable, even though I switch between these two several times a
week depending where in my premises I use my laptop. I set the
appropriate static ip via directives in my dhcpd server under
/etc/dhcpd.conf based on mac address. This works reliably, even though
there are some 30 other wap servers in my vicinity as long as I remember
to specify essid with iwconfig. I have never succeeded adding essid to
any /etc config file in the past. I'll try again.

The problem comes when I'm on the road trolling for a dhcp address via
whatever local service might be available.I generally preferred wired,
when I can get it, but often use wired at night in the hotel and
wireless during the day around the conference table. I have frequently
seen eth0 assigned to wireless. In fact, I've seen all kinds of crazy
designations for wireless device made up of a few alpha chars and about
5 or 6 digits.

In other words, I've learned from experience, to look at the output of
iwconfig (without arguments) if I'm not getting an address off the first
try with dhclient. Oh, and yes, I still find dhclient most reliable.

Just my two cents American.

Thanks for the new scripts.


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