how can i know what is blocking one of my ports?

[ventrox]

hey guys

i'm using a laptop here

and it doesn't allow me to connecto to FTP sites/servers when the port is 21

i guess it is some program pre-installed in my laptop that blocks access to this port

how can i know which one is blocking it?

thank you very much

[+BudMan MVC]

Check your anti-virus software, its quite possible it could block ftp by default, or you enable it to do so, etc.

example here is where it would be done in mcafee 8.5

[ventrox]

thank you for your response

my laptop used to have Norton Antivirus

but because it expired

i uninstalled it and changed to NOD32

I'm using NOD32 on my PC and it doesn't block FTP access

so, I'm guessing it's not NOD32

and even if it is, I've tried turning it off, but still without any access to FTP

any other suggestions?

[+BudMan MVC]

when you say it "doesn't" do you mean you check the settings and its not setup to block it, or that you believe it does not have the ability to block it?

The crappy ass manual for nod32 does not seem to go into any details about the protocol filtering - but just looking at the menu's it seems quite possible it "could be" blocking it.

Are you running any other security/firewall software -- what OS are you on? Vista or XP -- vista for sure is quite possible to be blocking outbound access on 21. Even with XP or 2k its possible to use tcp filtering to control what ports you can access outbound.

You sure your laptop is doing it - it could be your router blocking outbound on 21. It could be the network you on -- schools have been known to block outbound access on 21, etc. etc.

How many ftp sites have you tried? Its possible the site is down? Or did you try accessing it from another machine on the same network as your laptop - and that works? Or that site is being blocked by IP, etc. etc.

[witalit]

budman always comes with the worthwhile posts. Thumbs up dude! Yea try what he said LOL :)

[pengiranijam]

In this link, find the Quick Start Guide so that you can understand more about the configurations usage...

[ventrox]

thank you for all your responses

first, sorry i didn't explain myself more detailed

so, i'll try to explain myself better

I'm using NOD32 2.7 here, so, my interface looks kind of differently

i don't see the part where BudMan says "Protocol filtering"

My Laptop is an IBM laptop, IBM ThinkPad R60e

besides from this, the only firewall I'm running is the one integrated with Windows

I use Windows XP SP2

I am NOT behind any router and I'm indeed in a school's network

I've tried accesing other sites with the same port 21 but it doesn't work

I've accesed the same sites with my PC with the same NOD32 installed and using the same Firewall (Windows Firewall) and having no problems connecting to those servers, so, I am sure it's not the FTP server but my Laptop and both, my Laptop and my PC are connected to the same exact network

besides, I have a friend that also has an IBM laptop (forgot the model)

and it also cannot connect to any ftp server that uses port 21

so, I was guessing it's something pre-installed that comes with IBM laptops?

thank you again

[ventrox]

ehhh

already found the problem

because my laptop came with Symantec Antivirus

I uninstalled it and didn't get totally removed

so, somehow, it was blocking it (i don't know how, is it even possible?)

so, i cleaned symantec totally

and now it works fine

thank you