Topic: Odd network performance issue

[ddougan]

I have a version 7.4 system that's been running solidly for a long time. This evening, I noticed Internet connectivity was very slow so called my ISP. After resetting the modem and being told that they had no known issues, I plugged my laptop into the cable modem and pings which on the server were taking over a second were returning in 30 - 40 ms on my laptop.

So it looks like the performance issue is on the server, which runs in server/gateway mode. There is nothing untoward in the logs and running ifconfig on the external adapter shows no dropped packets and no errors at all. I've restarted the server, just to check from a known clean position, and am seeing the same poor response.

In fact, one ping attempt returned "unknown host" - trying it again just afterwards saw it resolved correctly (the host I was trying is telus.net. Telus is the phone company in western Canada).

Running "top" shows low CPU utilization.

I'd appreciate any thoughts as to why this is happening - I'm having a hard time trying to figure out what's causing this.


Thanks,

Des

[janet]

ddougan

Firstly I'd advise you to update to the latest release as there may be fixes released already that relate to your problem.

There are numerous possibilities. Here are a couple.

Spam & virus filtering can be VERY processor & memory intensive. Check log files etc, or disable spam & virus scanning temporarily to see if there is any change. Of course the slowness factor will depend on how much spam & how many viruses are being detected & scanned at any moment in time

Your system may be sending out loads of spam if a workstation has been compromised, thus slowing the connection.

[Stefano]

I would also check for clients activity.. slowliness is due, most of the times, to outgoing band saturation.. check for p2p..

[ddougan]

Thanks for all the suggestions. The problem was caused by a script kiddie in China trying to hack into my Asterisk server. I managed to resolve it by installing Fail2Ban on the Asterisk box. It looks a very useful tool and would make a positive difference if included in SME Server.

Des

[piran]

Was it so unfeasible to resolve using stuff native to SME7?
For the wider benefit could you display what it was that
the rest of us might need to similarly handle on our sites?
If it's not too private of course;-)