No DoS attack. I'm not the one hosting the ftp server and I can connect to the ftp server with the same credentials using an ftp client on a different machine so I don't think the DoS is on the server side either.
The good news is tcpkill did the trick
This is the command I used for those interested
tcpkill -i eth0 -9 ip host local_ip and remote_ip
Of course substitute remote_ip and local_ip with the actual IP's
The connections dropped right off however it didn't resolve the problem i'm having with not being able to connect to the ftp server. But after telneting to the server on port 21 I got an error saying something about "too many open connection" and "connection closed by foreign hosts". So I'm filing a ticket with the guys on the server side.
Thanks for you help!