how to check which application uses FTP port 21 on W2008?

Hi;

I need to check which application uses FTP port 21 on W2008?

When I telnet the application, I saw the result as "Microsoft FTP Service" as a result. But  how can i be sure that any other application is not using port 21 (e.g. Filezilla).

Note that I am unable install anything but can run commands on cmd.

Br.
LVL 12
jazzIIIloveAsked:
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

x
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

nociSoftware EngineerCommented:
ports are free to choose..., but there are conventions...
port 21 = FTP (+port 20 for transfer).
port 22 = SSH
port 23 = TELNET
port 80 = HTTP
etc. etc.

btw, FTP also needs another port to transfer the data with, that port is negotiated through port 21.
There is only a configuration to start HTTP on port 21..., it will confuse the world... (or rather they can't communicate with you) but it can be configured & used.
So using a non-standard services isn't done often.

If a port is used by a process, another process CANNOT use that port as well.
So once the FTP runs, no other processes can use it.

That said on windows netstat -b should show you all ports with processes running on them.
giltjrCommented:
Do the following:

netstat -an | findstr /c:":21"
net stop "Microsoft FTP Service"
netstat -an | findstr /c:":21"
net start "Microsoft FTP Service"
netstat -an | findstr /c:":21"

My guess is that after the net stop you will not see anything listening on port 21.

As noci stated, FTP also uses port 20, but this is only used when an active mode data transfers are done.  Today most ftp data transfers use passive mode.  This is because passive mode is friendlier with firewalls.

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
Greg HejlPrincipal ConsultantCommented:
I would caution against using straight FTP - you will get a man-in-the-middle attack.

Setup SFTP per MS's recommendations.

Here's the link for security settings for IIS FTP service:
http://www.iis.net/learn/publish/using-the-ftp-service/cse-curated-view-ftp-security-settings
nociSoftware EngineerCommented:
best is to NOT use FTP, unless for anonymous access. as FTP transmits passwords without encryption over the internet. Best is to use scp (part of ssh), that also prevents the necessity for firewall to monitor the port 21 channel to be able to open the right ports.
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
SSH / Telnet Software

From novice to tech pro — start learning today.