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Old 01-23-2007, 10:04 AM   #1
Thasat
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Registered: Sep 2005
Distribution: Debian
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Network access time is very long.


Hi

I have a pc with Debian Etch installed. It acts mainly as a router to my home network and a few services like ftp, http, etc.
About two months ago I noticed that its reaction for incoming local network traffic is slower than before. By the time it was getting worse and worse, now it sometimes almost takes ages to connect to it. I even sometimes get timeouts when trying to access some web pages (on the internet, and on the apache installed on the router). The most strange thing is that it sometimes works like it should for a while, without slowdowns at all.
To describe my problem better:
- While trying to connect to it via ssh it takes about one minute to see the "Password:" after that it works ok, and its responsive for other not network related commands.
- FTP connections are even worse. Connecting takes ages, copying files is almost impossible because of constant "connection stalled" messages that my FTP client (gFTP) gives me. The more small files I would like to move (from/to), the longer it takes to move them.
The list is much longer but I think you will get the point

First thing that i thought about was that the damn thing ran out of free space but there is about 18Gb of free space on /
I compiled a new kernel (2.6.19-2) but it didn't help, system is updated recently so packages are up to date.

Hardware:
CPU Celeron 400MHz
256 Mb RAM
Ethernet based on Realtek 8139
Modem connected via USB

I tried replacing the ethernet card (also realtek 8739) but it didn't work. I tested RAM with memtest86+ and it didn't show any errors after about 14 hours of tests.

Some things that might help:
There is also a torrent client installed and it utilizes my 2 Mbit connection without any problems, so i think the problem is only related to local connections.
Back to the ssh thing I recently discovered with another ssh session open that when I type the command to connect to the router, the process appears immediately on the router but I have to wait for the password question from it.


I have no idea where to look for the source of my problem. I hope you could help me.
 
Old 01-24-2007, 11:28 AM   #2
unSpawn
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I'd start with checking the basics like CPU, network, memory and swap utilisation. If they don't show unhealthy values right now (which I doubt) you could measure and log using any form of SAR like Dstat or Atop while you go about your business. I'd say 256 RAM is low considering the network tasks it has to perform.
 
Old 01-24-2007, 03:20 PM   #3
Thasat
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I don't have Dstat or Atop, I tried to install dstat but apt cant connect to the server, I'll try later.
I have htop installed, it doesn't show network utilisation, but it shows CPU, swap and memory. I'm not really sure what SAR means.

What htop tells me is:
CPU - 0% - 3% (it varies)
memory - 69MB
swap - 0MB

When I try to open a new connection, like new ssh session, the CPU usage jumps to about 5-6% for a moment and after that it's back to normal.
The same situation is while accessing the web site, but obviously CPU and memory usage jumps to highier values than for the ssh but it's all temporary.

I was trying to diagnose what's causing it by watching htop before a few times but I came out with nothing.

About the network usage right now I can tell You only that the leds on the switch aren't blinking when other computers are not trying to access http etc. When my pc will manage to connect and download the dstat package I'll hopefully be able to tell more about the network usage.
 
Old 01-26-2007, 10:43 AM   #4
unSpawn
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So you haven't been able to come up with more stats yet?
 
Old 01-26-2007, 04:03 PM   #5
Thasat
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I'm sorry you have had to wait so long for my answer, I have some very busy time at my studies.

The fact is that I trully haven't been able to download dstat. It's right now not even able to ping any address outside the local network (i tried IP, its not a DNS problem).

Strangely enough yesterday routing internet connections to local pc's started to work normally. At least it's much faster than a week ago.

To be honest I gave up on this, every time I want to do something with it, it actually only irritates me.
Maybe unstable distribution was a bad idea for these tasks. I've been having some ideas on my mind for some time, and they couldn't be implemented without reinstalling the system so it's not that bad after all.

Anyway, I'm really glad that you tried to help me!
 
Old 01-26-2007, 06:22 PM   #6
unSpawn
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NP, that's what we're here for.
 
Old 01-27-2007, 05:59 PM   #7
snuffy115
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Have you checked your DNS? Could the delay's be caused by name resolution issues?
 
Old 01-29-2007, 12:04 PM   #8
Thasat
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Hello.

Today I have had some time and I decided to give it a try for the last time and apt finally connected and installed dstat.

I was looking on dstat output for a while and i didn't notice anything bad or unusual at all. Maybe I missed something so here is a screenshot from dstat while I was trying to connect via ssh.
SCREENSHOT

I also replaced network wires and switch but nothing changed.

@snuffy115 are you talking about the DNS servers in the /etc/resolv.conf file? I checked them and they are correct.
 
Old 01-29-2007, 12:26 PM   #9
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I was looking on dstat output for a while and i didn't notice anything bad or unusual at all.
Uh. I usually make Dstat output to CSV format, then chart it in OpenOffice.org.
Easier to spot spikes 'n such when you let it run for a usable minimum sampling period of say 24hrs.
 
  


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