Local Port Forwarding.

Local Port Forwarding.

[Alejandro Villarroel]

Hello:
	I'm kind of new to IpTables, and I'm having problems to do this kind of
port forwarding in my Fedora Core 3:

Suppose I have some user trying to access Host X:Port X on the Internet
from my Linux, but Instead of that I want to forward this traffic to the
localhost:Port Y, what rule I have to apply?

Thanks in advance,
	Alejandro

Re: Local Port Forwarding.

[Jason Opperisano]

On Fri, Apr 22, 2005 at 05:41:38PM -0400, Alejandro Villarroel wrote:
> Hello:
> 	I'm kind of new to IpTables, and I'm having problems to do this kind of
> port forwarding in my Fedora Core 3:
> 
> Suppose I have some user trying to access Host X:Port X on the Internet
> from my Linux, but Instead of that I want to forward this traffic to the
> localhost:Port Y, what rule I have to apply?

your kernel needs to be compiled with the option to nat local
connections:

  CONFIG_IP_NF_NAT_LOCAL=y

(i *believe* that FC3 includes this in their kernel--don't quote me on
that)

with that, you can DNAT local connections in the nat table, OUTPUT
chain:

  iptables -t nat -A OUTPUT -p tcp -d $HostX --dport $PortY \
    -j DNAT --to-destination $LocalHost:$PortY

HTH...

-j

--
"Diane: Tom, you're so deep in the closet you're finding Christmas
 presents."
        --Family Guy

Re: Local Port Forwarding.

[Taylor, Grant]

> Hello:
> 	I'm kind of new to IpTables, and I'm having problems to do this kind of
> port forwarding in my Fedora Core 3:
> 
> Suppose I have some user trying to access Host X:Port X on the Internet
> from my Linux, but Instead of that I want to forward this traffic to the
> localhost:Port Y, what rule I have to apply?
> 
> Thanks in advance,
> 	Alejandro

Alejandro, are you wanting to redirect the traffic of someone (or something / some daemon) running locally on the box that will be doing the redirection?  Or are you wanting to redirect the traffic from an internet connected client to a different system?  From what I read of your question the situation is the former.  As such I'm going to answer that question.

iptables -t nat -A OUTPUT -d $HostX -p tcp --dport $PortX -j REDIRECT --to-ports $PortY



Grant. . . .

Re: Local Port Forwarding.

[Taylor, Grant]

>   iptables -t nat -A OUTPUT -p tcp -d $HostX --dport $PortY \
>     -j DNAT --to-destination $LocalHost:$PortY

Slight typo

iptables -t nat -A OUTPUT -p tcp -d $HostX --dport $PortX -j DNAT --to-destination $LocalHost:$PortY



Grant. . . .

Re: Local Port Forwarding.

[Jason Opperisano]

On Fri, Apr 22, 2005 at 05:02:04PM -0500, Taylor, Grant wrote:
> >  iptables -t nat -A OUTPUT -p tcp -d $HostX --dport $PortY \
> >    -j DNAT --to-destination $LocalHost:$PortY
> 
> Slight typo
> 
> iptables -t nat -A OUTPUT -p tcp -d $HostX --dport $PortX -j DNAT 
> --to-destination $LocalHost:$PortY

whoops.  nice catch.

-j

--
"Brian: You got anything on that remote lower than Mute?"
        --Family Guy

Re: Local Port Forwarding.

[Alejandro Villarroel]

Thanks Taylor and Jason, both solutions worked just fine,
Thanks for your help,
	Alejandro

iptables -t nat -A OUTPUT -d $HostX -p tcp --dport $PortX -j REDIRECT --
to-ports $PortY

On Fri, 2005-04-22 at 17:02 -0500, Taylor, Grant wrote:
> >   iptables -t nat -A OUTPUT -p tcp -d $HostX --dport $PortY \
> >     -j DNAT --to-destination $LocalHost:$PortY
> 
> Slight typo
> 
> iptables -t nat -A OUTPUT -p tcp -d $HostX --dport $PortX -j DNAT --to-destination $LocalHost:$PortY
> 
> 
> 
> Grant. . . .

Re: Local Port Forwarding.

[Nick Drage]

On Fri, Apr 22, 2005 at 06:07:15PM -0400, Jason Opperisano wrote:
> On Fri, Apr 22, 2005 at 05:02:04PM -0500, Taylor, Grant wrote:
> > >  iptables -t nat -A OUTPUT -p tcp -d $HostX --dport $PortY \
> > >    -j DNAT --to-destination $LocalHost:$PortY
> > 
> > Slight typo
> > 
> > iptables -t nat -A OUTPUT -p tcp -d $HostX --dport $PortX -j DNAT 
> > --to-destination $LocalHost:$PortY
> 
> whoops.  nice catch.

iptables -t nat -A OUTPUT -p udp -d 192.168.13.43 --dport 161 -j
REDIRECT --to-ports 32789

Makes no difference to the traffic I sent out on port 161 to host
192.168.14.43, any ideas on what I could be missing out?

I'm using iptables version 1.2.8 if that makes a difference....

-- 
http://tinyurl.com/7xyt2

Re: Local Port Forwarding.

[Jason Opperisano]

On Wed, Apr 27, 2005 at 09:48:59PM +0100, Nick Drage wrote:
> iptables -t nat -A OUTPUT -p udp -d 192.168.13.43 --dport 161 -j
> REDIRECT --to-ports 32789
> 
> Makes no difference to the traffic I sent out on port 161 to host
> 192.168.14.43, any ideas on what I could be missing out?

speaking of typos--your rule has "-d 192.168.13.43" and you say it
doesn't affect traffic destined for 192.168.14.43.  typo in the email,
or in the rule?

> I'm using iptables version 1.2.8 if that makes a difference....

and your kernel is compiled with:

  CONFIG_IP_NF_NAT_LOCAL=y

-j

--
"Stewie: Damn it! I want pancakes! God! You people understand every
 language except English. Yo quiero pancakes. Donnez-moi pancakes.
 Click-click-bloody click pancakes!
        --Family Guy