Unable to resume FTP transfer using the FTP client on the LAN PC

Unable to resume FTP transfer using the FTP client on the LAN PC

 

FTP client on the LAN PC is unable to resume file tranfer.

If user stops and resume file tranfer client asking for re-naming or overwrighting the file as below

Pic(1) User interrupting file tranfer

Pic(2) User trying to resume but FTP client asking for overwriting

Troubleshooting:

Step 1:

Packet capture on sonicwall Shows as below

In Packet number 516 client PC is sending a correct restart command(REST) but in packet number 517(NATed packet) firewall changing the ftp command REST to RE*T and sending it to server

In packet 525 FTP server says  (500 'RE*T 0': command not understood),since ftp command is getting truncated server is unable to understand the command

Also SonicWall log says

 

Gateway Anti-Virus | Configure Gateway AV Settings | Enable FTP 'REST' requests with Gateway AV(Check the box)

 

Testing & verification

Manually interrupting the file tranfer

After resuming file transfer successfully