I share a network with other flatmate; and lately I encounter a problem that sometimes the accessing to the internet (e.g. open a web page) seems to be slow, but I do not know the reason why.

So my question: is there any tool I can use to check who is downloding large files or open too many connections, etc.?

Or where there is any resource related to this issue?


I appreciate any help.

Environment I use: Debian unstable

Thanks for help.

If you control the Access Point then it is a relatively simple matter to open the web interface and look at "connections". Some AP's will offer remedial statistics on user activity.

If you know *WHO* is connected, you can sniff traffic for the user, checking to see if what you suspect is true.

I can't advise on the best way to do your sniffing, but perhaps another expert will chime in...

You could use wireshark on your lan to sniff data. It actually shows you the amount of traffic by IP/Protocol + loads of other information.
We use wireshark plenty of times in office network when we suspect network congestions. Definitely worth a try.

Your internet connection can be slow without someone downloading large files or there being too many open connections, so it is possible that you will find nothing.

I do agree that wireshark is worth a go, but what are you going to do next?

Thanks all your reply.

If I am lucky, the problem is just that e.g. someone downloads using bt, I can talk to them not to use it heavily. But honestly I have no idea if the problem is not obviously to be detected (such as open too many connection).

Would you please kindly to give some suggestion on what I should do would be better? or point me to resource (books or tutorial) where I am able to obtain/ learn related information.

Thanks all your help.

I appreciate it.

If you pay for the Internet connection and control the gateway, install a proxy and restrict the other user's access.

http://www.faqs.org/docs/securing/chap28sec232.html

That being said, you might just ask the roommate to obey the rules of good Netiquette.

bt = bluetooth????

The issue is that seem to have decided that it is other users or a number of open connections and that isn't necessarily the case, or at least, you haven't given the rest of us any reason to believe that its true.

Does the system ever work well (eg at some time at which it can be reliably assumed that there is a low level of other usage)? If it never works well, even when no one else it using it, then there is probably something completely different wrong. That could be

• you isp isn't giving you the data rate that you think (maybe they've even limited your rate due to excessive usage from the other users)
• your isps nameservers are slow
• you have both ipv4 and ipv6 set up or you have a 'bad' nameserver set up somewhere and you are waiting for it to time out
• something else about your network setup is bad (wireless with a poor signal level) or are you using wired?
• interference on you wireless (if you are using it) and consequent slow data rates
• wired ethernet set to a slow bit rate and/or half duplex
• bad setup of your router..or modem ...or modem router whatever you have (and it may well do a trivial level of caching of name look ups, so if that is set up badly that could be a performance issue)
• whatever browser you are using badly set up and not really using caching (or just a poor browser)

amongst other things.

It would be helpful if you could get some actual information (do you have decent ping times to your networking kit, or to your isps nameservers, or to google, do you have a sensible looking traceroute to google..or to your isp's name servers, what does the about of dig look like), what about signal strength on your wireless connection (if that's what you are using) and then the rest of us could maybe try to focus on something rather than 'trying to focus on everything' which could take a while.