Server slow in the network

biio · 2006-02-23 00:36:28

Hi boys and girls.
I have a little problem. My server (router, ftp, http etc.) is realy slow when Im connecting within my network to it. If I connect to it with ftp I only get a speed at around 20kb/s, and thats in the same network, not over internet! Same thing with ssh, and so on.
Whats the problem?

Im using vsftpd 2.0.3, openssh 4.2pl, Arch's kernel 2.6.13, and a iptablesscript called firewall-jay (dont think that makes any difference).
And no, I have no real load on it, so that should matter either. I have tried using different computers with different os's and diffrent ftp-clients.

Please ask if you need more information.

EDIT
Something I forgot to mention and mentioned in my second post, from the internet I get around 2MB/s (~20mbps), with that computer acting as a router. That makes it even wierder in my eyes.
And I can also add that I can find nothing that is worth mentioning in dmesg.

cactus · 2006-02-23 01:28:33

Things to check.
1) mii-tool. Is the nic auto detecting at 100baseTx-FD?
That is 100MBit Ethernet, full duplex.

2) What is between you and the box? If you have a switch in between..try using a X-over cable, and addressing them both statically, and trying a direct file pull. If that is significantly faster, then it could be your switch is just going bad.

Check those..then work from there..

biio · 2006-02-23 08:07:44

1) [root@serenity biio]# mii-tool
eth0: negotiated 100baseTx-FD flow-control, link ok
SIOCGMIIPHY on 'eth1' failed: Operation not supported
eth2: negotiated 100baseTx-FD, link ok

I am at eth2, eth1 is to my sisters computer, and eth0 is for internet.

2) Right now I have a switch, but have tried using a x-overcable directly.

Something I forgot to mention in the first post. I can download in highspeed (2MB/s) from the internet, with that computer as my router.

cactus · 2006-02-23 16:35:33

hmm. that is very odd indeed.
What are you iptables rules? Do you have flood prevention or rate limit for local connection in your rules?

Try to dump some traffic with tcpdump, and look for odd behavior. This is a weird one..

biio · 2006-02-23 17:30:39

Do you know whats even wierder?
Nobody got my rootpassword (if I'm not hacked ), nd now its working pretty good without me chaning anything. If or when the problems return I will do
as you said and report back here.
And what I know, I dont have either floodcontrol or ratelimit.
Thanks.

biio · 2006-02-24 06:16:52

(Two posts in a row!)
Now its slow again.
I used tcpdump as you said, but couldnt find any intressting things (I anybody intressted I can post a couple of minutes worth of dump later today?).
And if anyone tell me how, I can post my iptables rules to, dont remember what flag it is, and I'm off for school right now.
What to do now?

cactus · 2006-02-24 07:32:21

to snag iptables output: iptables -nvL > iptables_output.txt
if you want to post a tcpdump, have it write out in pcap format, so people can look at it in ethereal
tcpdump -w tcpdump.dump

no idea why it would be slow sometimes..and not others.. nutty

biio · 2006-02-24 10:41:07

cactus wrote:

to snag iptables output: iptables -nvL > iptables_output.txt
if you want to post a tcpdump, have it write out in pcap format, so people can look at it in ethereal
tcpdump -w tcpdump.dump
no idea why it would be slow sometimes..and not others.. nutty

Iptables: http://gigabit.nu/~biio/iptables.txt
I'll edit this post later today with tcpdump, when I'm home again.
EDIT
Now I'm back home.
Started downloading a file from my server (20kb/s this time), and started tcpdump in about a minute, here you go:
http://gigabit.nu/~biio/tcpdump.dump
EDIT2
Could a broken nic result in this things? In my opinion it should be problem with both internet and lan then? I changed nic to eth1 (that's the one my sisters computer is on usualy). And now my computers get a decent speed.
I'll wait for some people to coment my iptables and tcpdump before trying to buy a new NIC (I need one anyway...)

cactus · 2006-02-24 22:19:38

whoah biio
Looks like one side of your "conversation" (192.168.0.1) is generating frames larger than 1500 bytes.
Are you using gigabit ethernet on both devices? If not, then this *will* cause some poor network performance.
This isn't such an issue when connecting *through* the node, as packets coming from upstream will already be of the appropriate size (and are just being routed).

Check the mtu on the machine in question, and on your 'router'.

On *nix, you can check the mtu with...
ifconfig

ie. ifconfig eth0

do that on both machines, and report back with your mtu sizes..

biio · 2006-02-25 09:44:01

Finaly we are going somewhere!
My computer 192.168.0.99: MTU:1500
My router, 192.168.0.1: eth2 (thats the one going to my room), MTU: 1500, but lo has MTU:16436, could that make a difference?
EDIT
Forgot to mention, all my NICs (except eth1 on my router) is 100Mbit cards.

cactus · 2006-02-25 19:06:19

No. lo should have a large mtu..that is normal.

100mbit on everything..,that is fine.. hmm...

It is very odd then that the 0.1 machine is sending packets larger than 1500 bytes..
Let me take a look at your tcpdump output again...
<takes another look>

biio · 2006-02-26 15:52:04

Hmmm...new NIC, but still aint working...
I wonder if its something like its sending all the data over the internet (eth0) to my computer? Now its going in 100kb/s, and my upload on my dsl is around 100kb/s.
Could that be the problem or something?

cactus · 2006-02-26 17:36:28

hmm.. try this:
unplug your internet connection, and flush you iptables ruleset. Then set default allow..
Just to make sure that your flag checking/flood checking isn't causing a problem.

biio · 2006-02-28 11:41:41

Heya, just so you know. I havent forgotten about this. I've just been busy. Last 2-3 times I have tried it works good. But next time I'll get some of these problems I will do as you said, and report the result.
Btw. you remember that you said to me to change MTU? After that I had problems accesing the internet so I changed it back. So now we know the result of that

cactus · 2006-02-28 16:58:42

likely you just needed to lower the mtu on both machines.. one was probably sending larger packets than the other was allowing..

Arch Linux

#1 2006-02-23 00:36:28

Server slow in the network

#2 2006-02-23 01:28:33

Re: Server slow in the network

#3 2006-02-23 08:07:44

Re: Server slow in the network

#4 2006-02-23 16:35:33

Re: Server slow in the network

#5 2006-02-23 17:30:39

Re: Server slow in the network

#6 2006-02-24 06:16:52

Re: Server slow in the network

#7 2006-02-24 07:32:21

Re: Server slow in the network

#8 2006-02-24 10:41:07

Re: Server slow in the network

#9 2006-02-24 22:19:38

Re: Server slow in the network

#10 2006-02-25 09:44:01

Re: Server slow in the network

#11 2006-02-25 19:06:19

Re: Server slow in the network

#12 2006-02-26 15:52:04

Re: Server slow in the network

#13 2006-02-26 17:36:28

Re: Server slow in the network

#14 2006-02-28 11:41:41

Re: Server slow in the network

#15 2006-02-28 16:58:42

Re: Server slow in the network

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