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Old 06-23-2008, 03:41 AM
"Krsnendu dasa"
 
Default Continued network problems

Yes. It's me again.
Still bugged with network problems.

The main problem is that dhcp sometimes works and sometimes doesn't.
e.g. Sometimes 5 terminals boot up at once and then the 6th won't.
Then later it will boot.
Dhcp also takes a long time to restart when I do it from the command
line. Like 2 mins or so.

(It is running from eth3 because eth0 and eth1 are from the previous
motherboard setup.)

Any ideas where to look for these kind of problems?

Thanks.
Krsnendu dasa

Background:

I have an Intel quad core 6600 processor. I started with Feisty on an
Intel motherboard. It was working fine for a few months then the
network went intermittent. SSH, port 80, dhcp etc all went flakey.

The network problems even affect the vmware machines running on the
same machine.

Since my problems began, I have tried isolating the server from the
network for testing with just one client, changing network cards,
transferring the hard drives to an AMD xp2500 system, and now finally
I have changed from an Intel motherboard to an ASUS motherboard. In
all cases the problem seems to persist.

When I did a fresh install on the AMD there was not network problem,
but it was sloooow.

I am guessing that because I have transfered the hard drive directly
from one motherboard to another that may be why the problem persists.
I may need to do (another) fresh install.

In a week's time I will get a replacement of my original motherboard,
so I am not sure if I should wait till I get it before I do a fresh
install or try out the new motherboard now (for testing.)

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Old 06-24-2008, 11:27 AM
Gavin McCullagh
 
Default Continued network problems

Hi,

On Mon, 23 Jun 2008, Krsnendu dasa wrote:

> The main problem is that dhcp sometimes works and sometimes doesn't.
> e.g. Sometimes 5 terminals boot up at once and then the 6th won't.
> Then later it will boot.

If you run this on the client:

sudo tcpdump -i eth3 port 67 or port 68

you should be able to see the dhcp requests from the client and responses.
You can therefore see if your server is responding to each request it gets
and how quickly.

> Dhcp also takes a long time to restart when I do it from the command
> line. Like 2 mins or so.

- If you stop it and then separately start it, which takes the time or is
it split between the two?
- Are there any logs in /var/log/syslog which suggest a problem with
dhcpd.
- What is the load on the machine (the output of the uptime command will
tell you)?
- During the minute, if you run "top" does dhcpd appear near the top?

> (It is running from eth3 because eth0 and eth1 are from the previous
> motherboard setup.)

You probably need to comment out the entries in /etc/iftab to solve this.
Then things will fall back to eth0. eth1, etc.

Gavin


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Old 06-25-2008, 10:39 PM
"Krsnendu dasa"
 
Default Continued network problems

2008/6/24 Gavin McCullagh <gmccullagh@gmail.com>:
> Hi,
>
> On Mon, 23 Jun 2008, Krsnendu dasa wrote:
>
>> The main problem is that dhcp sometimes works and sometimes doesn't.
>> e.g. Sometimes 5 terminals boot up at once and then the 6th won't.
>> Then later it will boot.
>
> If you run this on the client:
>
> sudo tcpdump -i eth3 port 67 or port 68
>
> you should be able to see the dhcp requests from the client and responses.
> You can therefore see if your server is responding to each request it gets
> and how quickly.
>

First I ran the command you gave. Then I started a terminal.
I repeatedly started the terminal until it booted about 5 mins later.

krsnendu@hks1:~$ sudo tcpdump -i eth4 port 67
[sudo] password for krsnendu:
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth4, link-type EN10MB (Ethernet), capture size 96 bytes
10:17:51.262022 IP hks1.harekrishna.school.nz.bootps >
255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
10:18:16.294813 IP hks1.harekrishna.school.nz.bootps >
255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
10:18:25.295097 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548
10:18:26.275469 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548
10:18:28.252868 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548
10:18:32.207705 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548
10:18:36.310819 IP hks1.harekrishna.school.nz.bootps >
255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
10:18:40.117345 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548
10:18:46.338814 IP hks1.harekrishna.school.nz.bootps >
255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
10:18:56.346829 IP hks1.harekrishna.school.nz.bootps >
255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
10:19:01.450391 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548
10:19:02.445640 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548
10:19:04.423045 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548
10:19:06.354837 IP hks1.harekrishna.school.nz.bootps >
255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
10:19:08.377880 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548
10:19:16.287526 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548
10:19:26.370829 IP hks1.harekrishna.school.nz.bootps >
255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
10:19:41.382823 IP hks1.harekrishna.school.nz.bootps >
255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
10:19:51.391352 IP hks1.harekrishna.school.nz.bootps >
255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
10:20:01.399365 IP hks1.harekrishna.school.nz.bootps >
255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
10:20:16.567358 IP hks1.harekrishna.school.nz.bootps >
255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
10:20:36.583341 IP hks1.harekrishna.school.nz.bootps >
255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
10:20:46.591360 IP hks1.harekrishna.school.nz.bootps >
255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
10:20:56.630858 IP hks1.harekrishna.school.nz.bootps >
255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
10:21:06.686840 IP hks1.harekrishna.school.nz.bootps >
255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
10:24:13.318782 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548
10:24:14.001725 IP hks1.harekrishna.school.nz.bootps >
255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
10:24:14.300081 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548
10:24:14.300162 IP hks1.harekrishna.school.nz.bootps >
255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
10:24:16.277507 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548
10:24:16.277695 IP hks1.harekrishna.school.nz.bootps >
255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
10:24:20.232346 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548
10:24:20.239244 IP hks1.harekrishna.school.nz.bootps >
255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
10:24:37.655990 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 271

# Here it finally gets an ip address and boots.
# I don't know what has changed?????

10:24:37.656114 IP hks1.harekrishna.school.nz.bootps >
192.168.0.94.bootpc: BOOTP/DHCP, Reply, length 309
10:24:37.656447 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 283
10:24:37.664520 IP hks1.harekrishna.school.nz.bootps >
192.168.0.94.bootpc: BOOTP/DHCP, Reply, length 309
10:24:39.664229 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 283
10:24:41.865815 IP hks1.harekrishna.school.nz.bootps >
192.168.0.94.bootpc: BOOTP/DHCP, Reply, length 309

>> Dhcp also takes a long time to restart when I do it from the command
>> line. Like 2 mins or so.
>
> - If you stop it and then separately start it, which takes the time or is
> it split between the two?
It stops and starts slowly. About equal.

> - Are there any logs in /var/log/syslog which suggest a problem with
> dhcpd.
> - What is the load on the machine (the output of the uptime command will
> tell you)?

krsnendu@hks1:~$ uptime
10:36:52 up 1:09, 6 users, load average: 0.06, 0.05, 0.09

> - During the minute, if you run "top" does dhcpd appear near the top?

No. Can't see it anywhere and the overall load is not high.
>
>> (It is running from eth3 because eth0 and eth1 are from the previous
>> motherboard setup.)
>
> You probably need to comment out the entries in /etc/iftab to solve this.
> Then things will fall back to eth0. eth1, etc.

I am now on eth0 because I am on a new motherboard. Couldn't find /etc/iftab
is there another file?

Thanks for the help. Hopefully we can get to the bottom of it.

Krsnendu dasa

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Old 06-30-2008, 11:24 AM
Gavin McCullagh
 
Default Continued network problems

Hi,

On Thu, 26 Jun 2008, Krsnendu dasa wrote:

> > sudo tcpdump -i eth3 port 67 or port 68
> First I ran the command you gave. Then I started a terminal.
> I repeatedly started the terminal until it booted about 5 mins later.

> krsnendu@hks1:~$ sudo tcpdump -i eth4 port 67
> [sudo] password for krsnendu:
> tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
> listening on eth4, link-type EN10MB (Ethernet), capture size 96 bytes

> 10:17:51.262022 IP hks1.harekrishna.school.nz.bootps > 255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
> 10:18:16.294813 IP hks1.harekrishna.school.nz.bootps > 255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300

these are broadcast replies.

> 10:18:25.295097 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548
> 10:18:26.275469 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548
> 10:18:28.252868 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548
> 10:18:32.207705 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548

These are requests from a client with mac 00:08:c7:a3:cb:8e (I presume your
client) between 10:18:25 and 10:18:32.

> 10:18:36.310819 IP hks1.harekrishna.school.nz.bootps > 255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300

This is a reply at 10:18:36. That is a bit of a slow reply alright. It's
possible the client timed out waiting.

> 10:18:40.117345 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548

request at 10:18:40

> 10:18:46.338814 IP hks1.harekrishna.school.nz.bootps > 255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
> 10:18:56.346829 IP hks1.harekrishna.school.nz.bootps > 255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300

responses at 10:18:46, 10:18:56.

> 10:19:01.450391 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548
> 10:19:02.445640 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548
> 10:19:04.423045 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548

3 requests

> 10:19:06.354837 IP hks1.harekrishna.school.nz.bootps > 255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300

a response within 2 seconds of the last request.

> 10:19:08.377880 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548
> 10:19:16.287526 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: > BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548

2 requests

> 10:19:26.370829 IP hks1.harekrishna.school.nz.bootps > 255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
> 10:19:41.382823 IP hks1.harekrishna.school.nz.bootps > 255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
> 10:19:51.391352 IP hks1.harekrishna.school.nz.bootps > 255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
> 10:20:01.399365 IP hks1.harekrishna.school.nz.bootps > 255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
> 10:20:16.567358 IP hks1.harekrishna.school.nz.bootps > 255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
> 10:20:36.583341 IP hks1.harekrishna.school.nz.bootps > 255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
> 10:20:46.591360 IP hks1.harekrishna.school.nz.bootps > 255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
> 10:20:56.630858 IP hks1.harekrishna.school.nz.bootps > 255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
> 10:21:06.686840 IP hks1.harekrishna.school.nz.bootps > 255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300

9 replies.

> 10:24:13.318782 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548
> 10:24:14.001725 IP hks1.harekrishna.school.nz.bootps > 255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
> 10:24:14.300081 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548
> 10:24:14.300162 IP hks1.harekrishna.school.nz.bootps > 255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
> 10:24:16.277507 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548
> 10:24:16.277695 IP hks1.harekrishna.school.nz.bootps > 255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
> 10:24:20.232346 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 548
> 10:24:20.239244 IP hks1.harekrishna.school.nz.bootps > 255.255.255.255.bootpc: BOOTP/DHCP, Reply, length 300
> 10:24:37.655990 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 271

These seem to be slightly more prompt replies.

> # Here it finally gets an ip address and boots.
> # I don't know what has changed?????
>
> 10:24:37.656114 IP hks1.harekrishna.school.nz.bootps > 192.168.0.94.bootpc: BOOTP/DHCP, Reply, length 309
> 10:24:37.656447 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 283
> 10:24:37.664520 IP hks1.harekrishna.school.nz.bootps > 192.168.0.94.bootpc: BOOTP/DHCP, Reply, length 309
> 10:24:39.664229 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:08:c7:a3:cb:8e (oui Unknown), length 283
> 10:24:41.865815 IP hks1.harekrishna.school.nz.bootps > 192.168.0.94.bootpc: BOOTP/DHCP, Reply, length 309

The replies appear to be a bit quicker maybe.

> >> Dhcp also takes a long time to restart when I do it from the command
> >> line. Like 2 mins or so.
> >
> > - If you stop it and then separately start it, which takes the time or is
> > it split between the two?
> It stops and starts slowly. About equal.

It's not clear what's wrong, but there seems to be something wrong with the
dhcp server. It's pretty slow to respond and very slow to restart.

> > - Are there any logs in /var/log/syslog which suggest a problem with
> > dhcpd.

You didn't answer this one. Can you check through the logs (syslog,
daemon.lod, messages) and see if there's anything?

> > - What is the load on the machine (the output of the uptime command will
> > tell you)?
>
> krsnendu@hks1:~$ uptime
> 10:36:52 up 1:09, 6 users, load average: 0.06, 0.05, 0.09

So it's probably not that the server is too busy to answer requests.

Gavin


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