[Techtalk] Help!

[Samantha Blackmon]

On Tuesday 05 March 2002 12:14 pm, a magikal owl from bsweeney delivered this 
message:
> Samantha wrote:
> >Please forgive the cross posting I am desperate and
> >trying to cover all bases at once.
>
> No problem!
>
> >Today I ran RH's up2date program in order to take care
> >of the security alert they emailed me about. Stayed
> >logged in all day. When I logged out of Linux tonight
> >and went over to the windows side of the box. When I
> >rebooted Grub offered me 2 versions of Linux (2.4.7-10
> >& 2.4.9-31) I assumed that the latter was the newer
> >version and booted that one. The first thing that
> >happened was I got a sound server error (cpu overload,
> >aborting) which is fine because I have an integrated
> >sound card that is not supported yet, then KNotify
> >crashed. Hmmmm. okay close that app.
>
> I've had problems with this as well, though it seems to "go away" after
> a few reboots.  Haven't had time to really troubleshoot it unfortunately.
>
> >Then I find that
> >I am not connected to the net (I have DSL) even though
> >I was and still am on the windows side. OK, reboot.
> >Boot into the old version...no sound server error.
> >Good sign or so I thought. Still no internet
> >connection! Does anyone have an idea of why this is
> >happening??
>
> First question: Is it plugged in?  This may seem silly, but trust me
> asking this question could've saved me much heartache in many
> circumstances.  Check the cabling all around.  Do you have a link light
> on your NIC and your DSL router?  If not, look no further!  Try swapping
> cables, etc.  I know, the odds of a hardware problem developing just as
> you updated the kernel are slim.  Yet, that always seems to be when I
> find mine ;-)
>
> If that doesn't work, I know RedHat did released an update for their
> init scripts to fix a problem aquiring/refreshing IP addresses.  I
> believe it was only for systems whos ip changes often (like my laptop,
> jumping from home lan to work lan), but I'm not sure.  In any case, the
> update didn't fix the issue for me.  The only thing that did was to
> issue a pump command manually.
>
> So, as I believe someone else suggested, type an ifconfig -a command and
> see what the status of your network interfaces is.  If the network
> interface does not show up when you run ifconfig -a (ie, you don't see
> anything besides the "lo" interface), things get a bit more interesting
> as for whatever reason you're nic card isn't being recognized.  But I
> doubt that's it; if it is, post again.
>
> If it is there, try executing the command "pump -i <interface>" where
> interface is the name of your network interface (most likely eth0,
> though it could be eth1, eth2 etc if you have more than one network card
> in your system; it's NOT 'lo' though).  At that point, recheck your
> network interfaces, but this time just type ifconfig without the -a.
>  That'll show only the interfaces which are "up", along with ip,
> netmask, broadcast info, etc.  If you see your interface there with an
> ip address, and you still can't get network activity, try narrowing down
> the issue.  Ping an ip address on the net to see if it's a general
> networking failure or just a DNS issue; 216.239.51.101 and
> 216.239.33.101are google ip addresses, and should respond.  Type "ping
> <ip>" to ping those hosts.  If that works, then type "ping
> www.google.com".  If THAT works, then general networking and DNS are
> working!  At that point, any inability to surf the web, check email,
> etc, would most likely be an application issue.  If pinging the ip
> addresses works, but pinging the names doesn't, check your
> /etc/resolv.conf file.  There will be listed your current nameservers.
>  Try pinging their ip addresses; do they respond?  If not, you've got
> issues contacting your name server.  Try calling your ISP to let them know.
>
> If pinging the google ip addresses failed, type "netstat -rn" to get a
> list of your systems' routing information.  It should look something
> like this:
>
> Kernel IP routing table
> Destination            Gateway         Genmask         Flags   MSS
> Window  irtt Iface
> <your-network>    0.0.0.0             <your-netmask>U        40
>  0              0   eth0
> 127.0.0.0                0.0.0.0             255.0.0.0
> U        40      0              0   lo
> 0.0.0.0                    <gateway-ip>   0.0.0.0            UG       40
>      0              0    eth0
>
> The first line tells linux to address any systems on your subnet locally
> via eth0 (or whatever the name of your network interface is), sending
> information directly to them.  The second line tells your system to
> address itself via the loopback interface.  The third line tells your
> system to send any information not destined for one of the first two
> through your default gateway, whos ip address will be <gateway-ip> .
>  Try pinging this ip address.   If you can't, but you're sure you have a
> linklight, I'm not entirely sure where you should go from there.
>  Perhaps replace the nic?  If you have no line like the third line above
> in your routing table that has a destination of 0.0.0.0 with the flags
> "UG", then for whatever reason you didn't get routing information from
> your dhcp server.  Try '/etc/rc.d/init.d/network restart', and if that
> doesn't work, 'pump -i <interface>' again.   If again you get an ip
> address but not a router, your ISP may be having issues.
>
> As a final general troubleshooting note, try checking your log files for
> strangeness.  Use grep on /var/log/messages and /var/log/boot.log ("grep
> -i '<words-your-looking-for>' <filename>"; check out man grep for more
> info or ask here!)  Words I usually search for when troubleshooting an
> unknown problem include fail, error, panic, unable, timed out; in this
> case I would add dhcp to that list.
>
> One last thing that just occured to me: are you running a firewall on
> this machine? I doubt that would be the problem, but just in case run
> '/etc/rc.d/init.d/ipchains status' and see if you've got a bunch of
> firewall rules, lines with ACCEPT and/or REJECT in front.  As temporary
> troubleshooting measure, if you are running the firewall, issue
> '/etc/rc.d/init.d/ipchains stop' to turn it off and see if your network
> returns.  If so, let us know and we can try troubleshooting the firewall
> config.
>
> Hope something in that long ramble helps!
>
> -Brian
I am almost embarrassed to admit this but it seems that with the upgrade my 
config files had been wiped clean. After panicking for a while and chatting 
on #linuxchix, I calmed down enough to go in and look around to see what had 
indeed happened. Once I had it all reset I rebooted to give it a chance to 
find a new IP (I use DCHP) because I do not yet know the linux equivalent for 
"ipconfig /renew".

Thanks for all of the ideas, I am keeping a running list of responses for 
things that I am sure will pop up in the future.

Sam