Firewall and FTP

Oliver Eickenberg oliver at eickenberg.de
Sat Nov 9 07:50:19 PST 2002


Hello,

With my firewall working for a few weeks now (thanks again for the help 
i received here) i discovered one problem left:

I tried to grant access to Internet-FTP-sites for my LAN whith enabling 
port 21 exactly as i had enabled port 80 for http. I could connect to 
sites and login successfully but then got timed out every time on any site.

I searched the net and found out, that this is not a surprise, because 
port 21 is only used as a kind of ftp-handshaking and that the 
data-transfer is handled on a separate port. For that port is not always 
the same, how can one now build a firewall with ftp going through ? That 
question, the sites i found haven't answered understandable for me.

Is somebody here who knows a solution ?

Thanks, Oliver

P.S.: Here is my actual "FTP-enabling"

iptables -A OUTPUT -p tcp -s $myLAN --dport 21 -j ACCEPT
iptables -A INPUT  -p tcp -s $myLAN --sport 21 -m state --state 
-ESTABLISHED -j ACCEPT

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