Hello there,
First of let's make sure you have the following lines in your squid.conf
located here /etc/squid/squid.conf
acl FTP proto FTP
always_direct allow FTP
make sure it is located right bellow your acl where you allow all your clients to use the proxy server.
then do the following
CODE
/etc/init.d/squid stop
/etc/init.d/squid start
on your firewall do the following modifications :
add the following lines to /etc/rc.d/rc.local file
/sbin/modprobe ip_conntrack_ftp
/sbin/modprobe ip_nat_ftp
once done, save the file.
then type the following (only doing it this time, so you don't have to restart the firewall to make it work)
CODE
/sbin/modprobe ip_conntrack_ftp
/sbin/ip_nat_ftp
then type in the following :
CODE
iptables -A INPUT -i $extif -p tcp --sport 21 -m state --state ESTABLISHED -j ACCEPT
iptables -A INPUT -i $extif -p tcp --sport 20 -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A INPUT -i $extif -p tcp --sport 1024:65535 --dport 1024:65535 -m state --state ESTABLISHED -j ACCEPT
try connecting to ftp site with your client, it should work.
now you can add these iptables rules to your iptables script so that they will be there from now on, even if you restart the firewall.
$extif = your external interface, the one which is connected to the ISP
hope this helps
Sincerely
Robert B