CentOS - May 2015 - Strange network failure on C6

Hi all!

I'm running C6 (up to date) on x86-64. have been running on the same
system for over a year.

a couple of times lately access to the outside network has suddenly
stopped working for reasons that I didn't figure out until it happened
again yesterday.

I had the time to fool with it, yesterday, so after quite a bit of
head-banging I found that it had no default route set up (to make this
story less long...).

An appropriate route command "fixed" it and all was well, but...
I had rebooted several times, among other drastic actions, such as
rebooting the router and cable modem, and none of those things helped.
so whatever it was that lost the default route was persistent across
boots, while the manual route command to re-add it was NOT persistent
across boots.

At some point in fooling with it, I did something--and right now I have
no idea what it was--that suddenly caused routes to persist across boots.
I know I did not change any of /etc/sysconfig/network*, but I did look
at them and saw that ifcfg-eth0 DID contain a line for default route,
even though the route command did not reflect it.

So, if anyone has any good guesses on what the heck happened here, I'd
like to hear them.

thanks in advance!

-- 
---- Fred Smith -- fredex at fcshome.stoneham.ma.us
-----------------------------
               But God demonstrates his own love for us in this: 
                         While we were still sinners, 
                              Christ died for us.
------------------------------- Romans 5:8 (niv) ------------------------------

On 05/15/2015 08:09 AM, Fred Smith wrote:
> Hi all!
>
> I'm running C6 (up to date) on x86-64. have been running on the same
> system for over a year.
I've been running mine for three + years and have had this randomly 
occur only over the last year or so
> a couple of times lately access to the outside network has suddenly
> stopped working for reasons that I didn't figure out until it happened
> again yesterday.
>
> I had the time to fool with it, yesterday, so after quite a bit of
> head-banging I found that it had no default route set up (to make this
> story less long...).
>
> An appropriate route command "fixed" it and all was well, but...
> I had rebooted several times, among other drastic actions, such as
> rebooting the router and cable modem, and none of those things helped.
> so whatever it was that lost the default route was persistent across
> boots, while the manual route command to re-add it was NOT persistent
> across boots.
>
> At some point in fooling with it, I did something--and right now I have
> no idea what it was--that suddenly caused routes to persist across boots.
> I know I did not change any of /etc/sysconfig/network*, but I did look
> at them and saw that ifcfg-eth0 DID contain a line for default route,
> even though the route command did not reflect it.
Not sure what I did to fix it but check these:
Do you have a GATEWAY=192.168.1.1 in the /etc/sysconfig/network file?
plus in the ifcfg-eth0 file
make sure DEFROUTE=yes
I actually have a GATEWAY line in this file too plus DNS1= and DNS2and in case
it wasn't obvious NM_CONTROLLED="no"

After all this my network comes up about 29 times out of 30, randomly it 
doesn't and then I just "sudo service network restart" and all is
well.
Just fyi, I also find randomly that the gnome login list sometimes sorts 
alphabetically rather than the default of by UID, no major difficulty 
but I am sure this kind of randomness is a fairly recent
occurrence.
>
> So, if anyone has any good guesses on what the heck happened here, I'd
> like to hear them.
>
> thanks in advance!
>