FTP LIST command time out on IS 6.5 SP2

I am connecting to FTPS port on IS 6.5 using Core FTP client. After successful login, ‘LIST’ command is timing out. While trying from ftp:ls command from the other IS server to this server returns successfully.

What is the reason?

In logs I could see that ftp:ls command is being shown as ‘NLST’, while list command from Core FTP client is shown as ‘LIST’.

Are your 2 IS instances load balanced? If so, sounds like the login goes to one server while the ls goes to the other. The LB device needs to be configured to make the FTP session sticky (various options for that).

Also this can happen if your going through a firewall and the data port isn’t handled correctly.

Using Passive mode rather than Active mode resolves these issues most times.

We faced a similar problem and we checked whether our clustered IS’s were in sync or not and found out that they were out of sync. Rob’s idea helped us a lot in solving this issue. Thanks Rob.