FTP connection in FTD

[Muhammed Midlaj]

Hello Brothers,

I have a query regarding the FTP connections behaviour in Cisco FTDs.

We have allowed TCP/21 (& few others TCP/80, TCP/443, TCP/22) in a rule from a specific source to destination for FTP traffic.

But after allowing this TCP/21, I can see that the traffic from the source to destination with destination ports within 3000-4000 are allowed, but we have not allowed those traffic. looking at the logs, we can see the 'application protocol' as 'FTP Data'.

Can some one explain this behaviour please?

Warm Regards

[MHM Cisco World]

https://www.cisco.com/c/en/us/support/docs/content-networking/file-transfer-protocol-ftp/200194-ASA-9-x-Configure-FTP-TFTP-Services.html