Network changing from eth0 to eth1

[Jim]

FC8, KDE
What is changing the Network settings from eth0 to eth1 ?

Even if you go into /etc/sysconfig/network-scripts/ifcfg-eth0 and setup 
as eth0, and reboot box,it will change settings to eth1.

And it is causing a unstable network.

This box only has one ethernet card in  it.

[Phil Meyer]

Jim wrote:
> FC8, KDE
> What is changing the Network settings from eth0 to eth1 ?
>
> Even if you go into /etc/sysconfig/network-scripts/ifcfg-eth0 and 
> setup as eth0, and reboot box,it will change settings to eth1.
>
> And it is causing a unstable network.
>
> This box only has one ethernet card in  it.

Now days, when Fedora detects a different NIC from one it knew (right or 
wrong), it creates a new entry in: /etc/udev/rules.d/70-persistent-net.rules

This is why you get messages in dmesg and at bootup that eth0 is being 
'moved' to eth1.

It is reasonably safe to remove this file, plus 
/etc/sysconfig/network-scripts/ifcfg-eth? and reboot.

If you are just doing DHCP, then udev will recreate the file, put the 
correct NIC into it, and set up a generic ifcfg-eth0 script.

Good luck!

[Nat Gross]

On Mon, Nov 3, 2008 at 3:09 PM, Phil Meyer  wrote:
> Jim wrote:
> > FC8, KDE
> > What is changing the Network settings from eth0 to eth1 ?
> >
> > Even if you go into /etc/sysconfig/network-scripts/ifcfg-eth0 and setup as
> > eth0, and reboot box,it will change settings to eth1.
> >
> > And it is causing a unstable network.
> >
> > This box only has one ethernet card in  it.
>
> Now days, when Fedora detects a different NIC from one it knew (right or
> wrong), it creates a new entry in: /etc/udev/rules.d/70-persistent-net.rules
>
> This is why you get messages in dmesg and at bootup that eth0 is being
> 'moved' to eth1.
>
> It is reasonably safe to remove this file, plus
> /etc/sysconfig/network-scripts/ifcfg-eth? and reboot.
>
> If you are just doing DHCP, then udev will recreate the file, put the
> correct NIC into it, and set up a generic ifcfg-eth0 script.
>
> Good luck!

Thanks for this post, it helped me a bit, but I still have nameserver problem.
Yesterday my [only]nic in a 32 bit fc8 box blew. When I replaced it,
it insisted to be eth1 and gave me eth0 errors when booting. I did an
ifconfig 192.168.... and had eth1 up and running.
No sweat, I thought. But although nfs clients were able to access
their nfs mounts, firefox can't lookup a dns entry. Also, since this
box is running squid, clients of squid can't access websites. The
/etc/resolv.conf is ok.
Also my firestarter firewall refused to start (obviously set up on eth0).
So, my goal this morning was to get it back to eth0 only, and not
worry about who-knows-what might have a problem with the subtle eth1
switch. I was happy to find your post, when goggling my gmail.
I deleted the /etc/udev/rules.d/70-persistent-net.rules file and do
not have any ifcfg-eth* files.
The good news is that now it sees it as eth0. But I still have to do
the ifconfig manually at boot and more importantly firefox cant
resolve a dns, although /etc/resolve.conf is ok.

Your help is appreciated. Thanks, and
HAPPY NEW YEAR!
nat

[Mikkel]

Nat Gross wrote:
> Thanks for this post, it helped me a bit, but I still have nameserver problem.
> Yesterday my [only]nic in a 32 bit fc8 box blew. When I replaced it,
> it insisted to be eth1 and gave me eth0 errors when booting. I did an
> ifconfig 192.168.... and had eth1 up and running.
> No sweat, I thought. But although nfs clients were able to access
> their nfs mounts, firefox can't lookup a dns entry. Also, since this
> box is running squid, clients of squid can't access websites. The
> /etc/resolv.conf is ok.
> Also my firestarter firewall refused to start (obviously set up on eth0).
> So, my goal this morning was to get it back to eth0 only, and not
> worry about who-knows-what might have a problem with the subtle eth1
> switch. I was happy to find your post, when goggling my gmail.
> I deleted the /etc/udev/rules.d/70-persistent-net.rules file and do
> not have any ifcfg-eth* files.
> The good news is that now it sees it as eth0. But I still have to do
> the ifconfig manually at boot and more importantly firefox cant
> resolve a dns, although /etc/resolve.conf is ok.

If you are looking in /etc/sysconfig/network-scripts for ifcfg-eth0,
and not finding it, they you are probably using NetworkManager to
manage the interface. You may have to configure it again. (If you
looked in the wrong place, make sure ifcfg-eth0 has "ONBOOT=yes".)

Mikkel

[Nat Gross]

On Thu, Jan 1, 2009 at 1:09 PM, Mikkel L. Ellertson
 wrote:
> Nat Gross wrote:
> > Thanks for this post, it helped me a bit, but I still have nameserver problem.
> > Yesterday my [only]nic in a 32 bit fc8 box blew. When I replaced it,
> > it insisted to be eth1 and gave me eth0 errors when booting. I did an
> > ifconfig 192.168.... and had eth1 up and running.
> > No sweat, I thought. But although nfs clients were able to access
> > their nfs mounts, firefox can't lookup a dns entry. Also, since this
> > box is running squid, clients of squid can't access websites. The
> > /etc/resolv.conf is ok.
> > Also my firestarter firewall refused to start (obviously set up on eth0).
> > So, my goal this morning was to get it back to eth0 only, and not
> > worry about who-knows-what might have a problem with the subtle eth1
> > switch. I was happy to find your post, when goggling my gmail.
> > I deleted the /etc/udev/rules.d/70-persistent-net.rules file and do
> > not have any ifcfg-eth* files.
> > The good news is that now it sees it as eth0. But I still have to do
> > the ifconfig manually at boot and more importantly firefox cant
> > resolve a dns, although /etc/resolve.conf is ok.
>
> If you are looking in /etc/sysconfig/network-scripts for ifcfg-eth0,
> and not finding it, they you are probably using NetworkManager to
> manage the interface. You may have to configure it again. (If you
> looked in the wrong place, make sure ifcfg-eth0 has "ONBOOT=yes".)
> Mikkel

I don't have any file that begins with ifcfg in /etc/sysconfig/network-scripts.
I took another look at the "services" gui and am not running
NetworkManager and I am running 'network'. And now I notice that in
the "status" area it sais (when network is highlighted):
--------------------------
ls: cannot access ifcfg*. No such file or directory.
Configured devices:
lo
Currently active devices:
lo eth0
--------------------------
Any clues?
Thanks;
nat

[Mikkel]

Nat Gross wrote:
> On Thu, Jan 1, 2009 at 1:09 PM, Mikkel L. Ellertson
> > If you are looking in /etc/sysconfig/network-scripts for ifcfg-eth0,
> > and not finding it, they you are probably using NetworkManager to
> > manage the interface. You may have to configure it again. (If you
> > looked in the wrong place, make sure ifcfg-eth0 has "ONBOOT=yes".)
> > Mikkel
>
> I don't have any file that begins with ifcfg in /etc/sysconfig/network-scripts.
> I took another look at the "services" gui and am not running
> NetworkManager and I am running 'network'. And now I notice that in
> the "status" area it sais (when network is highlighted):
>
> ls: cannot access ifcfg*. No such file or directory.
> Configured devices:
> lo
> Currently active devices:
> lo eth0
>
> Any clues?
> Thanks;
> nat

Definitely strange - At the very least, you should have ifcfg-lo!

If you are using hte network service and DHCP, ifcfg-eth0 should
look something like this:

DEVICE=eth0
BOOTPROTO=dhcp
ONBOOT=yes
HWADDR=<MAC address>
DHCP_HOSTNAME=<something>
TYPE=Ethernet
IPV6INIT=no
NM_CONTROLLED=no
USERCTL=no

You don't need all of this - you could get by with:

DEVICE=eth0
BOOTPROTO=dhcp
ONBOOT=yes
NM_CONTROLLED=no

You should also be able to create it using system-config-network.

Mikkel

[Nat Gross]

On Thu, Jan 1, 2009 at 3:59 PM, Mikkel L. Ellertson
 wrote:
> Nat Gross wrote:
> > On Thu, Jan 1, 2009 at 1:09 PM, Mikkel L. Ellertson
> > > If you are looking in /etc/sysconfig/network-scripts for ifcfg-eth0,
> > > and not finding it, they you are probably using NetworkManager to
> > > manage the interface. You may have to configure it again. (If you
> > > looked in the wrong place, make sure ifcfg-eth0 has "ONBOOT=yes".)
> > > Mikkel
> >
> > I don't have any file that begins with ifcfg in /etc/sysconfig/network-scripts.
> > I took another look at the "services" gui and am not running
> > NetworkManager and I am running 'network'. And now I notice that in
> > the "status" area it sais (when network is highlighted):
> >
> > ls: cannot access ifcfg*. No such file or directory.
> > Configured devices:
> > lo
> > Currently active devices:
> > lo eth0
> >
> > Any clues?
> > Thanks;
> > nat
>
> Definitely strange - At the very least, you should have ifcfg-lo!
>
> If you are using hte network service and DHCP, ifcfg-eth0 should
> look something like this:

Once you told me that I need these two files, I grabbed them from
another fedora 8 box on the same lan, adjusted the static ip address,
and... voila! It works!
Thank you!
& Happy New Year!
nat

[Bill Davidsen]

Nat Gross wrote:
> On Mon, Nov 3, 2008 at 3:09 PM, Phil Meyer  wrote:
> > Jim wrote:
> > > FC8, KDE
> > > What is changing the Network settings from eth0 to eth1 ?
> > >
> > > Even if you go into /etc/sysconfig/network-scripts/ifcfg-eth0 and setup as
> > > eth0, and reboot box,it will change settings to eth1.
> > >
> > > And it is causing a unstable network.
> > >
> > > This box only has one ethernet card in  it.
> >
> > Now days, when Fedora detects a different NIC from one it knew (right or
> > wrong), it creates a new entry in: /etc/udev/rules.d/70-persistent-net.rules
> >
> > This is why you get messages in dmesg and at bootup that eth0 is being
> > 'moved' to eth1.
> >
> > It is reasonably safe to remove this file, plus
> > /etc/sysconfig/network-scripts/ifcfg-eth? and reboot.
> >
> > If you are just doing DHCP, then udev will recreate the file, put the
> > correct NIC into it, and set up a generic ifcfg-eth0 script.
> >
> > Good luck!
>
> Thanks for this post, it helped me a bit, but I still have nameserver problem.
> Yesterday my [only]nic in a 32 bit fc8 box blew. When I replaced it,
> it insisted to be eth1 and gave me eth0 errors when booting. I did an
> ifconfig 192.168.... and had eth1 up and running.

You did change the MAC address in the config, to reflect the change right? 
Otherwise eth0 will go to the old MAC address even if not present, and the next 
NIC found will be eth1, eth2, etc.

[Bill Davidsen]

Mikkel L. Ellertson wrote:
> Nat Gross wrote:
> > On Thu, Jan 1, 2009 at 1:09 PM, Mikkel L. Ellertson
> > > If you are looking in /etc/sysconfig/network-scripts for ifcfg-eth0,
> > > and not finding it, they you are probably using NetworkManager to
> > > manage the interface. You may have to configure it again. (If you
> > > looked in the wrong place, make sure ifcfg-eth0 has "ONBOOT=yes".)
> > > Mikkel
> >
> > I don't have any file that begins with ifcfg in /etc/sysconfig/network-scripts.
> > I took another look at the "services" gui and am not running
> > NetworkManager and I am running 'network'. And now I notice that in
> > the "status" area it sais (when network is highlighted):
> >
> > ls: cannot access ifcfg*. No such file or directory.
> > Configured devices:
> > lo
> > Currently active devices:
> > lo eth0
> >
> > Any clues?
> > Thanks;
> > nat
>
> Definitely strange - At the very least, you should have ifcfg-lo!
>
> If you are using hte network service and DHCP, ifcfg-eth0 should
> look something like this:
>
> DEVICE=eth0
> BOOTPROTO=dhcp
> ONBOOT=yes
> HWADDR=<MAC address>
> DHCP_HOSTNAME=<something>
> TYPE=Ethernet
> IPV6INIT=no
> NM_CONTROLLED=no
> USERCTL=no
>
> You don't need all of this - you could get by with:
>
> DEVICE=eth0
> BOOTPROTO=dhcp
> ONBOOT=yes
> NM_CONTROLLED=no

I really suggest using the MAC field, it prevents learning about Plauger's Law 
(law of least astonishment) the hard way... Of course the O.P. was using the MAC 
field (I suspect) and didn't know it.
> You should also be able to create it using system-config-network.

Indeed. And I believe that should be part of the default install again.
> Mikkel

[Nat Gross]

On Thu, Jan 1, 2009 at 6:19 PM, Bill Davidsen  wrote:
> Nat Gross wrote:
> > On Mon, Nov 3, 2008 at 3:09 PM, Phil Meyer 
> > wrote:
> > > Jim wrote:
> > > > FC8, KDE
> > > > What is changing the Network settings from eth0 to eth1 ?
> > > >
> > > > Even if you go into /etc/sysconfig/network-scripts/ifcfg-eth0 and setup
> > > > as
> > > > eth0, and reboot box,it will change settings to eth1.
> > > >
> > > > And it is causing a unstable network.
> > > >
> > > > This box only has one ethernet card in  it.
> > >
> > > Now days, when Fedora detects a different NIC from one it knew (right or
> > > wrong), it creates a new entry in:
> > > /etc/udev/rules.d/70-persistent-net.rules
> > >
> > > This is why you get messages in dmesg and at bootup that eth0 is being
> > > 'moved' to eth1.
> > >
> > > It is reasonably safe to remove this file, plus
> > > /etc/sysconfig/network-scripts/ifcfg-eth? and reboot.
> > >
> > > If you are just doing DHCP, then udev will recreate the file, put the
> > > correct NIC into it, and set up a generic ifcfg-eth0 script.
> > >
> > > Good luck!
> >
> > Thanks for this post, it helped me a bit, but I still have nameserver
> > problem.
> > Yesterday my [only]nic in a 32 bit fc8 box blew. When I replaced it,
> > it insisted to be eth1 and gave me eth0 errors when booting. I did an
> > ifconfig 192.168.... and had eth1 up and running.
>
> You did change the MAC address in the config, to reflect the change right?
> Otherwise eth0 will go to the old MAC address even if not present, and the
> next NIC found will be eth1, eth2, etc.

In the network gui, there is a "probe" button. I used that and saw it
magically change the MAC.
nat

[Mikkel]

Bill Davidsen wrote:
> Mikkel L. Ellertson wrote:
> > If you are using the network service and DHCP, ifcfg-eth0 should
> > look something like this:
> >
> > DEVICE=eth0
> > BOOTPROTO=dhcp
> > ONBOOT=yes
> > HWADDR=<MAC address>
> > DHCP_HOSTNAME=<something>
> > TYPE=Ethernet
> > IPV6INIT=no
> > NM_CONTROLLED=no
> > USERCTL=no
> >
> > You don't need all of this - you could get by with:
> >
> > DEVICE=eth0
> > BOOTPROTO=dhcp
> > ONBOOT=yes
> > NM_CONTROLLED=no
>
> I really suggest using the MAC field, it prevents learning about
> Plauger's Law (law of least astonishment) the hard way... Of course the
> O.P. was using the MAC field (I suspect) and didn't know it.
> > You should also be able to create it using system-config-network.
>
> Indeed. And I believe that should be part of the default install again.
> > Mikkel

With /etc/udev/rules.d/70-persistent-net.rules, you are probably not
going to run into it if you do not use HWADDR in ifcfg-eth? On the
other hand, I do tend to use something like the first example I gave
- you don't need to, but it can prevent surprises.

Mikkel

[Bill Davidsen]

Mikkel L. Ellertson wrote:
> Bill Davidsen wrote:
> > Mikkel L. Ellertson wrote:
> > > If you are using the network service and DHCP, ifcfg-eth0 should
> > > look something like this:
> > >
> > > DEVICE=eth0
> > > BOOTPROTO=dhcp
> > > ONBOOT=yes
> > > HWADDR=<MAC address>
> > > DHCP_HOSTNAME=<something>
> > > TYPE=Ethernet
> > > IPV6INIT=no
> > > NM_CONTROLLED=no
> > > USERCTL=no
> > >
> > > You don't need all of this - you could get by with:
> > >
> > > DEVICE=eth0
> > > BOOTPROTO=dhcp
> > > ONBOOT=yes
> > > NM_CONTROLLED=no
> >
> > I really suggest using the MAC field, it prevents learning about
> > Plauger's Law (law of least astonishment) the hard way... Of course the
> > O.P. was using the MAC field (I suspect) and didn't know it.
> > > You should also be able to create it using system-config-network.
> >
> > Indeed. And I believe that should be part of the default install again.
> > > Mikkel
>
> With /etc/udev/rules.d/70-persistent-net.rules, you are probably not
> going to run into it if you do not use HWADDR in ifcfg-eth? On the
> other hand, I do tend to use something like the first example I gave
> you don't need to, but it can prevent surprises.

There are valid arguments both ways, as long as you have only one NIC. After 
that you really want to have them called by the same names.  ;-)

[Bill Davidsen]

Nat Gross wrote:
> On Thu, Jan 1, 2009 at 6:19 PM, Bill Davidsen  wrote:
> > Nat Gross wrote:
> > > On Mon, Nov 3, 2008 at 3:09 PM, Phil Meyer 
> > > wrote:
> > > > Jim wrote:
> > > > > FC8, KDE
> > > > > What is changing the Network settings from eth0 to eth1 ?
> > > > >
> > > > > Even if you go into /etc/sysconfig/network-scripts/ifcfg-eth0 and setup
> > > > > as
> > > > > eth0, and reboot box,it will change settings to eth1.
> > > > >
> > > > > And it is causing a unstable network.
> > > > >
> > > > > This box only has one ethernet card in  it.
> > > >
> > > > Now days, when Fedora detects a different NIC from one it knew (right or
> > > > wrong), it creates a new entry in:
> > > > /etc/udev/rules.d/70-persistent-net.rules
> > > >
> > > > This is why you get messages in dmesg and at bootup that eth0 is being
> > > > 'moved' to eth1.
> > > >
> > > > It is reasonably safe to remove this file, plus
> > > > /etc/sysconfig/network-scripts/ifcfg-eth? and reboot.
> > > >
> > > > If you are just doing DHCP, then udev will recreate the file, put the
> > > > correct NIC into it, and set up a generic ifcfg-eth0 script.
> > > >
> > > > Good luck!
> > >
> > > Thanks for this post, it helped me a bit, but I still have nameserver
> > > problem.
> > > Yesterday my [only]nic in a 32 bit fc8 box blew. When I replaced it,
> > > it insisted to be eth1 and gave me eth0 errors when booting. I did an
> > > ifconfig 192.168.... and had eth1 up and running.
> >
> > You did change the MAC address in the config, to reflect the change right?
> > Otherwise eth0 will go to the old MAC address even if not present, and the
> > next NIC found will be eth1, eth2, etc.
>
> In the network gui, there is a "probe" button. I used that and saw it
> magically change the MAC.

That should do it.

[Mikkel]

Bill Davidsen wrote:
> Mikkel L. Ellertson wrote:
> > With /etc/udev/rules.d/70-persistent-net.rules, you are probably not
> > going to run into it if you do not use HWADDR in ifcfg-eth? On the
> > other hand, I do tend to use something like the first example I gave
> > you don't need to, but it can prevent surprises.
>
> There are valid arguments both ways, as long as you have only one NIC.
> After that you really want to have them called by the same names.  ;-)

The 70-persistent-net.rules file will take care of that. It keeps
tract of the MAC addresses, and assures that the same device name is
always assigned to that MAC address. What I have found with HWADDR
is that the interface will not come up if the MAC address is wrong,
but it can not guaranty that the NICs will be assigned the correct
device.

It does make changing a NIC a bit more work - you end up with 2
places you have to change the MAC address. (I don't know if the
network config GUI will change the entry in 70-persistent-net.rules...)

Mikkel

[Roberto Ragusa]

Mikkel L. Ellertson wrote:
> The 70-persistent-net.rules file will take care of that. It keeps
> tract of the MAC addresses, and assures that the same device name is
> always assigned to that MAC address. What I have found with HWADDR
> is that the interface will not come up if the MAC address is wrong,
> but it can not guaranty that the NICs will be assigned the correct
> device.
>
> It does make changing a NIC a bit more work - you end up with 2
> places you have to change the MAC address. (I don't know if the
> network config GUI will change the entry in 70-persistent-net.rules...)

FWIW, I just discovered how useful can be a manually modified
70-persistent-net.rules file.

You can map MAC addresses to interface names and completely remove
the HWADDR from ifcfg-eth? files.

In my case this is perfect because I want to have *two* different
NICs as eth0 (not at the same time, obviously), two NICs as eth1,
two NICs as eth2.

I didn't think it could be so easy to have a configuration with
3 NICs (it's a firewall machine) and have the ability, in case of
a hardware problem, to just remove the disk from the failed machine,
put it into a backup machine and have the new 3 NICs automatically
assigned to the correct interface names so everything works with
no reconfiguration.

Best regards.

[Mikkel]

Roberto Ragusa wrote:
> FWIW, I just discovered how useful can be a manually modified
> 70-persistent-net.rules file.
>
> You can map MAC addresses to interface names and completely remove
> the HWADDR from ifcfg-eth? files.
>
> In my case this is perfect because I want to have *two* different
> NICs as eth0 (not at the same time, obviously), two NICs as eth1,
> two NICs as eth2.
>
> I didn't think it could be so easy to have a configuration with
> 3 NICs (it's a firewall machine) and have the ability, in case of
> a hardware problem, to just remove the disk from the failed machine,
> put it into a backup machine and have the new 3 NICs automatically
> assigned to the correct interface names so everything works with
> no reconfiguration.

Thanks - that is one I didn't think of. I can use that on my USB
drive so that it uses eth0 on any known computer I plug it in to. I
will have to try doing the same thing for CD/DVD drives.

Mikkel

[Bill Davidsen]

Mikkel L. Ellertson wrote:
> Roberto Ragusa wrote:
> > FWIW, I just discovered how useful can be a manually modified
> > 70-persistent-net.rules file.
> >
> > You can map MAC addresses to interface names and completely remove
> > the HWADDR from ifcfg-eth? files.
> >
> > In my case this is perfect because I want to have *two* different
> > NICs as eth0 (not at the same time, obviously), two NICs as eth1,
> > two NICs as eth2.
> >
> > I didn't think it could be so easy to have a configuration with
> > 3 NICs (it's a firewall machine) and have the ability, in case of
> > a hardware problem, to just remove the disk from the failed machine,
> > put it into a backup machine and have the new 3 NICs automatically
> > assigned to the correct interface names so everything works with
> > no reconfiguration.
>
> Thanks - that is one I didn't think of. I can use that on my USB
> drive so that it uses eth0 on any known computer I plug it in to. I
> will have to try doing the same thing for CD/DVD drives.

Interesting thought, I could put my firewall install on the USB key, and for 
failover just move it to another machine.