Registered: Aug 2000
Location: Los Angeles, CA
Posts: 15123

Okay... being that I'm on a school network, I have to suffer with restricted ports, particularly on the ones typically used by P2P programs. Now, considering that one such program, which apparently uses random ports for such transfers, occasionally slips a transfer through at a good speed, I would be very interested in finding out which ports are allowing that speed so I can set my programs to use those ports specifically. Maybe I'll get lucky and that will solve my problems. Might not, but I figure I might as well try.

Anyway, simple question... anyone know of any programs that I can use to figure out what ports are being used?

Thanks.

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Registered: Jan 2001
Location: WDM, IA
Posts: 2963

If you want to find out what ports are being permitted outbound, nmap the appropriate perimeter devices. If you want to see what your active ports are, hell...just drop to a prompt and type "netstat".

Registered: Aug 2000
Location: Los Angeles, CA
Posts: 15123

Cool, thanks.

Any way to tell what sort of speed they're getting? Most of the ports I've got are technically accessible, but just so slow that transfers time out and everything is lagged to hell.

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Oh yeah. What's nmap, and how do I do it?

I don't know much about networking stuff.

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Registered: Jul 2000
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Why would you think that it is the port that is responsible for the good speed? I'd expect all ports to pass traffic at the same speed.

You can get nmap here http://www.nmap.org/nmap/nmap_download.html. Now with gui for windows!

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Registered: Aug 2001
Location: Hilbert Space
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quote:

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Originally posted by splAt
Now with gui for windows!

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Location: Los Angeles, CA
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I was thinking it's the ports that are the problem because most normal internet stuff (like HTTP, FTP, mail, etc) work fine. It's only p2p things, and I seem to remember someone mentioning that network admins can do something to throttle certain ports.

If you have any other idea why only the p2p programs are slow as hell, I'd love to hear it. I know next to nothing about networking stuff.

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Registered: Jan 2001
Location: WDM, IA
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"Any way to tell what sort of speed they're getting?"

- There is no easy way, in so much, that there is no easy way that is at all accurate. The only way to truly determine how much bandwidth you're using is to permiscuously sniff packets over time and manually calculate packets per second, frames per second, etc. Given those numbers, you will know how much information you're able to cram down the pipe over time. Sure, the application they are using might report (like Internet Explorer) that you are downloading at 60k/sec - but you can't prove that. The only way to accurately determine how much data you're transmitting and reciving is to sniff the packets and count them up. Otherwise, you're relying on what the application is reporting - which is not an accurate representation of ALL traffic, just traffic to that application - and under no guarantees to be accurate, anyway.

"Most of the ports I've got are technically accessible, but just so slow that transfers time out and everything is lagged to hell."

- I suspect collissions. I suspect your hub is loaded with duplex mismatching errors that the CSMA/CD processes is choaking itself and actual data transmition is being effected. While it might only be one hub, the condition is the same is overextending a single broadcast domain.


"Oh yeah. What's nmap, and how do I do it?"

- NMAP is nothing more than a port scanner plus. It's a network mapping utility. Some would argue it is the security auditing tool, dating back a long way. Well, at least as far back as the mid to late 90s. It can scan remote hosts a number of different ways. Has numerous features, such as operating system detection, etc. It has traditionaly been a Linux application but eEye Digital Security wrote a Windows-based version. It isn't updated as often as the Linux version is. This is really only an issue for OS detection...and speed. The Linux version of NMAP is much more efficient than the Windows one.

http://eeye.com/html/Research/Tools/nmapnt.html

"Why would you think that it is the port that is responsible for the good speed? I'd expect all ports to pass traffic at the same speed."

- Assuming no hardware errors, I would agree. However, I wouldn't make such an assumption given no network analysis data is available. One of the ports might have a physical issue affecting its operation. There is no way to tell at this point. Technically, none of the ports are passing traffic, anyway - all should broadcast in the same fashion to all other ports in that collision domain. Now, I'm not proposing any effects on traffic flow is at all related to the physical port, I'm suspecting client/cabling issues. I can't support my opinion, without analysis, of course.

Additionally, he mentions some protocols function without issues. Others, do not. Again, I'm sure I don't have to remind you that not all protocols are created equal. HTTP transfers look and behave, having much different qualities, etc. than FTP transfers. Even transfering the exact same 100Mb file via FTP rather than HTTP is a much thinner communcation. Perhaps, not knowing which p2p thingies he may be speaking of - those protocols are not as resilliant as say, HTTP, which isn't at all stateful - regardless if it's TCP or not.

"You can get nmap here http://www.nmap.org/nmap/nmap_download.html. Now with gui for windows!"

- Don't listen to him. Follow my links:
WINDOWS
http://eeye.com/html/Research/Tools/nmapnt.html

LINUX
http://insecure.org/nmap/index.html

"I seem to remember someone mentioning that network admins can do something to throttle certain ports."

- That opens up a whole different discussion about a network's ability to classify quality of service and frame tagging. The short answer, "Yes" - network architects do have the ability to give priority over certain communications from others. They can specific how much bandwidth is allocated on a number of different criteria. The odds of you actually existing in a network that supports actual QoS to enable these types of options, is not likely. Not likely, at all.

"If you have any other idea why only the p2p programs are slow as hell, I'd love to hear it."

- It may be as simple as it is a concious configuration on the end of the providers. I have incredible bandwidth from my cable connection, but I rarely can get a transfer speed from Grokster over a few kilobytes per second...it's like being on dialup all over again. This is due to some client-side options that can control how fast I push data from my Grokster client, meaning, the guy I'm downloading from can control what rate I can download from him - OR it may also have some ties to Grokster services, itself. The bottom line is p2p programs are almost always slow for me and I can guarantee you, it has absolutely nothing to do with the engineering of my home network.

Last edited by Paint CHiPs on 09-18-2004 at 05:09 AM

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Registered: Jul 2000
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I should have said I'd expect all traffic to be passed at the same speed regardless of the source or destination tcp port. Certainly different protocols appear to operate at different speeds to the user, but without any prioritization of traffic, they will be moving through the network at the same speed. I'd understood that he was asking about using different ports with the same application and I'd expect that it would use the same protocol(s) regardless of the port(s) he tells it to use.

I've had disgusting results with file sharing programs myself. In fact, I don't even bother with them now. You should try the newsgroups instead, Roshigoth. If you request something and somebody posts it , when you check back on your local news server, you will get much more satisfying download speeds.

I wonder why they wouldn't allow the link directly to that download page.

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Registered: Nov 2000
Location: UK
Posts: 4736

It's possible http/ftp/et al are faster due to a transparent proxy sitting around on the network.

So changing the port that the p2p software is running on won't solve the problem. I agree with splAt though. Use newsgroups/IRC to get what you're looking for. They are invariably faster and are less likely to fall foul of Uni policy.

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Registered: Aug 2000
Location: Los Angeles, CA
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Thanks for the explanations.

I use DC++ for file sharing stuff... Up until about 3 weeks ago, it worked great. Then, suddenly, it died like all the others, where most download attempts time out and those that go move at like 200 bps.

Maybe it is protocol problems. Or whatever.

I would do newsgroups, except that the school's news server is rather shitty. Even groups I know are supposed to have lots of binaries posted never have any posts on our news server. Like they filter out all the large posts or something.

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Registered: Aug 2000
Location: Los Angeles, CA
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Oh yeah, and IRC DCC transfers are likewise extremely slow. That was my first response to the other stuff failing.

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