Re: FTP Forwarding

["TestMail" <testmail@peterpaul.com.ph>]

----- Original Message -----
From: "Jason Opperisano" <opie@817west.com>
To: <netfilter@lists.netfilter.org>
Sent: Friday, January 14, 2005 10:23 PM
Subject: Re: FTP Forwarding


> On Fri, 2005-01-14 at 03:57, Test Mail wrote:
> > Hi!Can i have a follow up question regarding FTP server inside internal
LAN
> > which can be seen in the internet.....
> > now what if the scenario is i want to restrict a specific Public IP
Address
> > in using my FTP what will be the rules that i should  apply?
> >
> > I was thinking of setting up a rule that will filter incomming Public IP
> > Address request for ftp before it forwards it into my internal FTP
Server.
> >
> > Below are the sample entry in my iptables:
> > iptables -t filter -A INPUT -p tcp -s $PublicIPAdd --dport 20:21 -j
ACCEPT
> > <--- is this correct?
> > iptables -t filter -A INPUT -j DROP
> >
> > Below are the previous solution that you gave.
> >
> > modprobe ip_conntrack_ftp
> > modprobe ip_nat_ftp
> >
> >  iptables -t nat -A PREROUTING -i $EXT_IF -p tcp -d 202.147.167.99 \
> >    --dport 21 -j DNAT --to-destination 192.168.0.5
> >
> >  iptables -A FORWARD -i $EXT_IF -o $INT_IF -p tcp --syn -d 192.168.0.5 \
> >    --dport 21 -j ACCEPT
>
> change that rule to something like:
>
>   iptables -A FORWARD -i $EXT_IF -o $INT_IF -p tcp --syn \
>     -s $PublicIPAdd -d 192.168.0.5 --dport 21 -j ACCEPT
>
> repeat for multiple instances of $PublicIPAdd.
>
> -j
>
> --
> "It's not easy to juggle a pregnant wife and a troubled child, but
>  somehow I managed to fit in eight hours of TV a day."
> --The Simpsons
>

I'm sorry but i think this rule will not be the solution to my problem cause
my ftp server is inside my internal network and automatically my gateway
will "only" be the source from the -s $PublicIPAdd Forward rule parameter...
i think???

Below is my schematic on how i want it to be ..
    1. only 202...1 ip address in my branch office should be allowed to use
my ftp server in my head office

        so incoming ftp request should be filtered and only 202....1 ip
address that is coming from my branch office should be allowed.

| Branch | eth0 202. .1       < external
       |
       |
| WAN  |
       |
       |
|gateway:firewall:FCore2|  eth0 192.168...  < internal <<<<<<
       |                                 eth1 202........    <external
       |
       |
|Ftp Server:FCore2| eth0 192.168.0.5 < Internal
--------CUT ----------------------------------------------------------------
:::::2nd Question:::::
if i apply a policy >>>> iptables -P INPUT DROP
                                    iptables -t filter -A INPUT -p tcp -s
192.168.0.1 -d 192.168.0.2 --dport 20:21 ACCEPT

means only 192.168.0.1 will only be allowed to use ftp and the rest will be
drop ???? am i correct??

--------CUT-----------------------------------------------------------------

Thanks in advance.

Still learning iptables..
Milo