Troubleshooting Questions

1. How do I know if the FTP ALG is active?
   • The ALG protocol field in the conversation should display ftp.
   • There should be a valid frame count (Frm count) in the control flows.
   • A valid frame count in the data flows indicates that data transfer has taken place.
2. What do I need to check if the FTP connection is established but data transfer does not take place?
   • Most probably, the control connection is up, but the data connection is down.
   • Check the conversations output to determine whether both the control and data flows are present.
3. How do I interpret each flow? What does each flow mean?
   • FTP control flow initiator flow—flow with destination port 21
   • FTP control flow responder flow—flow with source port 21
   • FTP data flow initiator flow—flow with destination port 20
   • FTP data flow responder flow—flow with source port 20