FTP problem on a client pc

[walle]

Hi,

I've installed a Mandrake 8.1 linux-router, to share my internet connection using ipchains and a bastille-firewall.
Everything works on the client pc's except ftp.
Is there anything I should check?

thanks!

Walle

 

[ifincham]

Hi,

I don't know how sophisticated that Mandrake firewall is but 'regular' ftp can be quite tricky to masquerade. This is due to the two connections : the client connects to the server's port 21 as the control channel but to transfer data the ftp server initiates a connection using port 20 back to the client. Because this is initiated by the server it maybe firewalled out by syn bit protection (don't allow inbound packets that ask to initiate connections rather than just participate in an established session) .

The easy solution is to use passive ftp . Almost all clients / ftp servers support this - there is probably an active vs passive setting in the client ftp software. The difference is that the second connection (data) is initiated by the client based on a packet sent by the server telling it which port to connect to. So both control and data channels are initiated by the client side and firewalls will generally be a lot happier.

Hope this helps

 

[walle]

Thaks a lot, this is the solution!!

Walle