UNIX for Dummies Questions & Answers

I'm no Unix expert (so please excuse any misuse of Unix vocabulary or terminology) and I have an issue that is bugging me.

I basically have a scheduled task which uploads and then downloads some files for me using ftp. Everything was (mostly) working fine until last week. Suddenly it refuses to download or upload anything.

501 PORT command referenced an invalid destination: *.*.*.*/33160
421 Service not available, remote server has closed connection

The * represent the IP address of the Unix box. This happens when it tries to upload. It connects fine but as soon as it tries to upload the file it complains about the following.

It then does something similar when it tries to download a file from the same IP address as it uploads to.

PORT command referenced an invalid destination: *.*.*.*/33186
Lost connection
can't find list of remote files, oops
Not connected.

Again it connects fine but as soon as it attempts to download it fails.

Any ideas as to the cause? I have checked all the directory paths used and they are all correct. I can follow the steps used by my scheduled task from a command prompt on a Windows PC no problem.

Well, ftp uses two tcp connections- one for commands, and the other for the actual transfer of files.

The server-side expects the ports your ftp-client specified (33160 and 33186) to be open. Have you installed a firewall recently on your local machine?

To solve this, you can set the ftp session to run in passive mode. The command is normally 'passive' or 'pasv' depending on ftp client flavour. This will make the ftp server go passive, and it will be up to your client to actively connect to the server.

Give it a shot, tell me what happens.

Cheers