ftplib problems with firewall

[Kent Polk]

On Tue, 01 Aug 2000 22:18:06 GMT, "lance wrote:
>David Bolen wrote:
>
>> (Oh, and I'm presuming you mean a real FTP client and not a web
>> browser to an FTP: URL, right?  The latter can be proxied differently
>> than a pure FTP client)
>
>No browser, just the standard FTP client.
>
>>
>> Since you mention tcpdump - it would be really interesting to see what
>> was happening with your other FTP client that works, when for example,
>> you do a directory listing, since that might give a hint as to how it
>> could possibly work with outbound rules only, since that's sort of
>> perplexing.  Maybe the IP filter is looking for a specific format of
>> the PORT command which is different with ftplib.  I'm just guessing
>> though :-)

ftp and firewalls can get interesting because there are 'active'
and 'passive' ftp clients.

It's not an issue of 'real' or 'pure' or fake. Older 'real' ftp
clients may still use active mode (solaris' ftp client for example).
Most browsers (all?) and most modern ftp clients use passive mode
ftp.

http://www.proftpd.org/proftpd-l-archive/99-08/msg00028.html
http://help.netscape.com/kb/consumer/19960513-36.html