[Lancaster] Firewall problem

[andy baxter]

Ken Hough wrote:
> Hi Guys,
>
> Can anyone help me with a firewall problem.
>
> I'm trying use my T42 Thinkpad to access an ftp server that is running on my 
> desktop PC. The T42 runs Windows XP (yes, I know, but I need it to run some 
> astro software). The desktop PC runs openSUSE v11.1.
>
> I'm using vsftp which is clearly configured OK and can be accessed from the 
> T42, provided that I turn off the firewall on the Linux machine.
>
> OpenSUSE includes a nifty utility for setting up the firewall, but doesn't 
> seem to be setting up correctly to allow for vsftp.
>
> Can someone please tell me what ports must be left open for vsftp operation?
>
> According to the firewall utility, for vsftp, port 20 should be open. 
> According to lists of recognised TCPIP ports, 21 should also be open, and 
> I've tried this but with no success.
>   
The only thing I know about this is there are two different FTP modes 
(Passive and active). One uses both ports, using 21 for setting up the 
transfer and 20 for moving data, whereas the other uses only one port 
(21 I think). Some ftp clients let you choose which mode to use.

I.e. you definitely want both ports open, but it sounds like you've 
already tried that.

You could try doing 'telnet <ftp host name> 21' from the client machine, 
and see what response you get with the firewall up and down. This might 
give you a clearer idea of whether the firewall is configured right. (If 
it is, the response should be the same in both cases)

andy