Network service crashes periodically

Network service crashes periodically

Post by Chase Casanov » Sat, 06 Oct 2001 11:53:05



Hi,

I have an old 486/33 running as a firewall/gateway/router for my home
network.  I have unhooked the monitor from and the only way that I access it
is over the network.  On occassion something will happen and I lose all
connectivity to it and the Internet.  I'm assuming that the network service
crashes.  So the only way to get it back is to cycle the power on it and
then wait as it slowly comes back.  So now that I have given a little
background let me layout my questions.

First, what could cause the network service to crash like that? ping of
death?

Next, what could I run on the box to restart the network service if this is
what happens? some kind of script?

Any help or comments would be appreciated.

-C3

 
 
 

Network service crashes periodically

Post by Dean Thompso » Sat, 06 Oct 2001 15:53:34


Hi!,

Quote:> I have an old 486/33 running as a firewall/gateway/router for my home
> network.  I have unhooked the monitor from and the only way that I access
> it is over the network.  On occassion something will happen and I lose all
> connectivity to it and the Internet.  I'm assuming that the network service
> crashes.  So the only way to get it back is to cycle the power on it and
> then wait as it slowly comes back.  So now that I have given a little
> background let me layout my questions.

> First, what could cause the network service to crash like that? ping of
> death?

Anything, there is just not enough information here to make a judgement.  It
could be anything from a faulty motherboard, bad network connection to a power
spike.  If your system kept losing the connection in a particular set of
circumstances, then it might lead to something like APM but I doubt that your
486/33 has got APM support in it.  Additionally, I am pretty sure that your
Linux distribution probably doesn't have APM working on it.

Quote:> Next, what could I run on the box to restart the network service if this is
> what happens? some kind of script?

Depends on what sort of fault it is.  Does the computer continue to respond,
such as whether or not the caps lock light flashes when you connect the
keyboard or does it come to a complete halt.

If it is just the link that fails, all you need to do is right a quick script
which tries to ping some outside site.  If it gets 100% packet loss or some
other error message, just do a /etc/rc.d/init.d/network restart and that
should solve the problem.

See ya

Dean Thompson

--
+____________________________+____________________________________________+

| Bach. Computing (Hons)     | ICQ     - 45191180                         |
| PhD Student                | Office  - <Off-Campus>                     |
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+----------------------------+--------------------------------------------+

 
 
 

Network service crashes periodically

Post by Chase Casanov » Sun, 07 Oct 2001 07:15:12


It has stopped responding before and I simply connect the monitor and I see
that the network service has just stopped.  I restart it and it is fine
again until it happens again for some reason.

This box doesn't seem to be affected by brownouts nearly as much as my other
machines.  If the power even flickers they go down but my good  ol' 486
stays up and when the others finish coming back up the connection to my
linux box is still up.  This is why I feel that something is happening to
the network service.  Perhaps I am getting attacked and the service goes
down as a result.  How can I tell what is going on is there some kind of log
file or something that keeps track of when a service dies.

And if you have an example of a script that I could run that would restart
the network service when the pings start failing that would be great.

Thanks,
C3


Quote:

> Hi!,

> > I have an old 486/33 running as a firewall/gateway/router for my home
> > network.  I have unhooked the monitor from and the only way that I
access
> > it is over the network.  On occassion something will happen and I lose
all
> > connectivity to it and the Internet.  I'm assuming that the network
service
> > crashes.  So the only way to get it back is to cycle the power on it and
> > then wait as it slowly comes back.  So now that I have given a little
> > background let me layout my questions.

> > First, what could cause the network service to crash like that? ping of
> > death?

> Anything, there is just not enough information here to make a judgement.
It
> could be anything from a faulty motherboard, bad network connection to a
power
> spike.  If your system kept losing the connection in a particular set of
> circumstances, then it might lead to something like APM but I doubt that
your
> 486/33 has got APM support in it.  Additionally, I am pretty sure that
your
> Linux distribution probably doesn't have APM working on it.

> > Next, what could I run on the box to restart the network service if this
is
> > what happens? some kind of script?

> Depends on what sort of fault it is.  Does the computer continue to
respond,
> such as whether or not the caps lock light flashes when you connect the
> keyboard or does it come to a complete halt.

> If it is just the link that fails, all you need to do is right a quick
script
> which tries to ping some outside site.  If it gets 100% packet loss or
some
> other error message, just do a /etc/rc.d/init.d/network restart and that
> should solve the problem.

> See ya

> Dean Thompson

> --

+____________________________+____________________________________________+

|
> | Bach. Computing (Hons)     | ICQ     - 45191180
|
> | PhD Student                | Office  - <Off-Campus>
|
> | School Comp.Sci & Soft.Eng | Phone   - +61 3 9903 2787 (Gen. Office)
|
> | MONASH (Caulfield Campus)  | Fax     - +61 3 9903 1077
|
> | Melbourne, Australia       |
|

+----------------------------+--------------------------------------------+
 
 
 

Network service crashes periodically

Post by Karl Heye » Sun, 07 Oct 2001 09:09:23




> It has stopped responding before and I simply connect the monitor and I see
> that the network service has just stopped.  I restart it and it is fine
> again until it happens again for some reason.

> This box doesn't seem to be affected by brownouts nearly as much as my other
> machines.  If the power even flickers they go down but my good  ol' 486
> stays up and when the others finish coming back up the connection to my
> linux box is still up.  This is why I feel that something is happening to
> the network service.  Perhaps I am getting attacked and the service goes
> down as a result.  How can I tell what is going on is there some kind of log
> file or something that keeps track of when a service dies.

I concur with Dean, you need to get more information about the state of the
box when this happens.  run the ifconfig and route commands to see if the
system thinks the network is there. If that seems ok run procinfo or cat
/proc/interrupts to see if the interrupts increase for the NIC. Then look to
see in packets can be seen with tcpdump.

If power flickers are the cause then it could effect the hardware in subtle
ways, one thing you can check up on is resetting the hub/switch.

karl.

 
 
 

Network service crashes periodically

Post by Dean Thompso » Sun, 07 Oct 2001 19:33:38


Hi!,

Quote:> It has stopped responding before and I simply connect the monitor and I see
> that the network service has just stopped.  I restart it and it is fine
> again until it happens again for some reason.

> This box doesn't seem to be affected by brownouts nearly as much as my
> other machines.  If the power even flickers they go down but my good  ol'
> 486 stays up and when the others finish coming back up the connection to my
> linux box is still up.  This is why I feel that something is happening to
> the network service.  Perhaps I am getting attacked and the service goes
> down as a result.  How can I tell what is going on is there some kind of
> log file or something that keeps track of when a service dies.

> And if you have an example of a script that I could run that would restart
> the network service when the pings start failing that would be great.

A simple script which detects network failures shouldn't be too hard for you
to write.  Basically just do a ping, capture the output and see whether or not
you get any errors which ping can return.  If you get an error, then just
restart the network.

See ya

Dean Thompson

--
+____________________________+____________________________________________+

| Bach. Computing (Hons)     | ICQ     - 45191180                         |
| PhD Student                | Office  - <Off-Campus>                     |
| School Comp.Sci & Soft.Eng | Phone   - +61 3 9903 2787 (Gen. Office)    |
| MONASH (Caulfield Campus)  | Fax     - +61 3 9903 1077                  |
| Melbourne, Australia       |                                            |
+----------------------------+--------------------------------------------+

 
 
 

Network service crashes periodically

Post by Karl Heye » Sun, 07 Oct 2001 21:26:22




> A simple script which detects network failures shouldn't be too hard for you
> to write.  Basically just do a ping, capture the output and see whether or
> not you get any errors which ping can return.  If you get an error, then
> just restart the network.

another possibility is to run tcpdump and capture 1 packet. If it hasn't done
so within 1 minute restart networking.   This is all assuming the hub/switch
isn't the problem.

karl.

 
 
 

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