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MLUG: Re: [MLUG] RTNETLINK answers: Network is unreachable
Re: [MLUG] RTNETLINK answers: Network is unreachable
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When you connect to your original network port (not the netgear) and
run (as root):

tcpdump -i eth0 -n

What kind of traffic do you see? If you aren't getting anything, but
your NIC has link, then your port may have been blocked or removed
from the VLAN.  It sounds like you don't manage the switch you are
connecting to.  Have you contacted the network admin(s)?  If you
changed which port you were connecting to, they may purposefully have
security mechanisms in place to prevent that change from "just
working".

If you *do* see traffic, and you changed ports, then the new port may
simply be on a different VLAN, in which case you should see broadcast
traffic that will indicate what VLAN it is.  If that happens you will
need the network admin(s) to change the VLAN membership of that port
or you will need to change your server's IP, whichever is simplest -
I'd guess the VLAN change.

If you didn't change ports then there still could be something going
on at the switch.  In general, if you have link and your interface and
routing configurations are the same, the problem will be at the
switch.  Unless it's been an exceptionally long time since the server
was rebooted, the chances that your configuration changed unexpectedly
are slim to none.

Good luck.


On 4/11/07, Cutts III, James H. <EMAIL:PROTECTED> wrote: 


Jason,

The commands you suggested did not generate any error messages, nor did they
solve the problem.

I tried the netmask and gateway you suggested - it didn't work.  :-(

Then I tried the netmask and gateway in my ifcfg-eth0 - it didn't work
either.  :-(

Michael Proctor asked about changing the changing NICs.  I have heard of
that happening.  I hadn't thought of that.  When I unplug the network cable,
the box protests that "e100: eth0 Link is Down".  This makes me believe that
I've got the right card and cable.

I have borrowed a "simple" 4 port Netgear (wireless) router.  If I plug the
box in to the router and ping something I see the lights on the router
blink.  Any suggestions of ways to use this router to see what is actually
getting shoved out of the box?







James H. Cutts III

CARES & CORI - 143C Mumford



 ________________________________
 From: EMAIL:PROTECTED
[mailto:EMAIL:PROTECTED] On Behalf Of
McIntosh Jason
Sent: Wednesday, April 11, 2007 10:33 AM
To: Members MLUG

Subject: Re: [MLUG] RTNETLINK answers: Network is unreachable


Hrmm, I re-read the original email.  If you try turning off the interface
(i.e. ifdown eth0) then try:
ifconfig  eth0 128.206.25.130 netmask 255.255.255.0 up
route add default gw 128.206.25.254


(I think that's the syntax off the top of my head) - see if that gets you up
and running.  if so, then it is an issue with your network configuration.
i.e. the syntax for the files in /etc/sysconfig/network/ have changed, or
something along those lines.  ifup and ifdown merely are shortcuts to
execute the ifconfig command with the appropriate information pulled from
those files.


Jason



/--------------------------------------|---------------------------\
| Jason McIntosh                       | CELL: 573-424-7612        |
| Webmaster, thinker, programmer, etc. | WORK: 573-884-3865        |
| http://mcintosh.poetshome.com/blog/  |
       |
|------------------------------------------------------------------|
|"How should I know if it works?  That's what beta testers are     |
|for.  I only coded it."                                           |
|(Attributed to Linus Torvalds, somewhere in a posting)            |
\--------------------------------------|---------------------------/





On Apr 11, 2007, at 10:24 AM, McIntosh Jason wrote:

They have changed, but that won't prevent a network connection from
happening.  That's just for DNS resolution (i.e. how to convert
mlug.missouri.edu to 128.206.whatever).
This issue sounds more like binding the driver to the interface.  It is
worth trying another network card though to see if it might work better.
Jason



/--------------------------------------|---------------------------\
| Jason McIntosh                       | CELL: 573-424-7612        |
| Webmaster, thinker, programmer, etc. | WORK: 573-884-3865        |
| http://mcintosh.poetshome.com/blog/  |
       |
|------------------------------------------------------------------|
|"How should I know if it works?  That's what beta testers are     |
|for.  I only coded it."                                           |
|(Attributed to Linus Torvalds, somewhere in a posting)            |
\--------------------------------------|---------------------------/





On Apr 11, 2007, at 10:22 AM, George Robb wrote:


Didn't the name servers change from 2.252 to  128.206.10.3 and 128.206.10.2?


You may want to call the op's center 4-2182 and double check me.


Worst case comment out the current nameserver entries and manually add the
new ones.


A shot in the dark...  ;)


George




On Apr 11, 2007, at 10:04 AM, Cutts III, James H. wrote:



Ah, debugging questions.  I can deal with them.


Static IP: 128.206.25.130


/etc/resolv.conf
nameserver 128.206.2.252
nameserver 128.206.2.242
search missouri.edu


Yes, I've checked the cables.


The server is on a VLAN in the MU system.  Might there be a problem
beyond my port?


Thanks,
James.




-----Original Message-----
From: EMAIL:PROTECTED
[mailto:EMAIL:PROTECTED] On Behalf Of
George Robb
Sent: Wednesday, April 11, 2007 9:51 AM
To: MLUG Members
Subject: Re: [MLUG] RTNETLINK answers: Network is unreachable


Are you static or dynamic for your IP?  What does your /etc/
resolv.conf look like?  Double checked that your cable is good?


;)


George


On Apr 11, 2007, at 9:45 AM, Cutts III, James H. wrote:



I needed to move my production server, Ronald, (running Red Hat 9
(Shrike) 2.3.20-31.9) while reconfiguring the server room.  The
room is
nicely rearranged and ready for the return of the computers.


After issuing the "halt" command Ronald, issued a few protest about
it's
inability to umount /usr2 due to a file being too large.  But
otherwise
it went down nicely (I think).


I've restarted the box and everything appears to be running nicely -
except that it can't get to nor be seen by the internet (nor campus
network for that matter).


A "/sbin/ifup eth0" produces the responses:
e100: eth0 NIC Link is Up 100 Mbps Half duplex
RTNETLINK answers: Network is unreachable
RTNETLINK answers: Invalid argument


I've been "visited" by my boss and received comments from users
that the
server is down.  Their comments haven't been helpful, hopefully MLUG
members will be more constructive.


Please!


James H. Cutts III
CARES & CORI
MU




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EMAIL:PROTECTED
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_______________________________________________
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