repeated port 21 attempts

[Jacob Wu <Wu () AUX UWM EDU>]

I'm getting port 21 connection attempts every 5 minutes from about half a
dozen of my network users.  These attempts are repeating regularly with one
computer sending out 1500+ attempts a day.  I have not seen this before and
I'm wondering if anyone else here has seen a client behave this way before?

My initial thoughts were: hacker, virus/trojan/spyware or badly configured
program.  I ruled hacker out right away when talking to the clients and
realizing they didn't even understand the concept of ports.  After receiving
the machines from the clients and doing vigorous virus/trojan/spyware scans
I have found nothing known on them.

Anyone got anything?  Is this something new or just new to me?

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