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strange FTP Problems

Hi,

I've got some strange problems with FTP transfair

--------FTP CLIENT-----FW----FTP SERVER----

Well, we have to establish a FTP Connection (Port 20:21) from a FTP Client to a FTP Server (WIN 2003 + Serv-U v5.0) behind the ASL Firewall (ASL 4.0.18).

Now i've got the Problem that my ftp Client (Unix Server)
want to send or to get files so files from the FTP Server behind the ASL and the ftp session freezes after around 20 Files. The Filesize is from 4 KB to max. 100 kb.

The Script from the FTP Client (Unix Maschine) looks every 5 minutes are they files on the FTP Server.

If there files on the FTP Server they get the files, but if there more den about 20 files on the server the transfairs to the 20th files and on the 21th files he hangs.

So want could that be ?
Detects ASL an intrusion an block the ip or somethink like that ?

If you need more Information please ask me.

Thanks for helping

Greetings Piet

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0 Xeno over 21 years ago

Have a look into your Packetfilterlog. Do you find some portscan detections?
By downloading a lot of small files by using FTP in passive mode it looks like a portscan for ASL. This is related to FTP's structure.

Solution: Exclude your FTP-Server from Portscan Detection.

Cheers
Xeno
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0 heckpiet over 21 years ago in reply to Xeno

Hello,

I've disabelt the portscan detections now it works!

Thanks for Helping
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0 heckpiet over 21 years ago in reply to Xeno

Hello,

I've disabelt the portscan detections now it works!

Thanks for Helping
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