I'm having difficulty making port redirection work

I'm having difficulty making port redirection work

[Michael Martinez]

Hi all -

I've used ipchains before, but I'm brand new to iptables, and I'm having
difficulty getting port redirection to work.

Here's what I want to do: I've got a Redhat 8.0 box running iptables
1.2.6a2. I've got a web application listening on port 8888 (on the eth0
interface) and  I'd like any web traffic coming in on port 80, to be
redirected to port 8888.

In ipchains, this is handled with the following line in
/etc/sysconfig/ipchains:

-A input -d 192.73.224.127 80 -p tcp -j REDIRECT 8888

I am using the following lines at the beginning of
/etc/sysconfig/iptables, but it does not work. I'm getting no messages
in /var/log/messages, and I don't know of any place where iptables is
logging anything:

*nat
-A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 8888
COMMIT

How do I troubleshoot and fix this?

thank you -

-- 
Michael Martinez
Linux System Administrator
Marlaw Systems Technology Inc.
CSREES/ISTM/USDA
mmartinez@csrees.usda.gov

RE: I'm having difficulty making port redirection work

[George Vieira]

http://iptables-tutorial.frozentux.net/iptables-tutorial.html

Read that tutorial very carefully and you'll pickup the differences of iptables to ipchains.

just remember that INPUT/OUTPUT are for packets going to and from the firewall ONLY, not forwarded or NATed packets unlike ipchains.. check the graphs and you'll see what I mean..

What your looking for is part of PREROUTING chain not INPUT and you forgot the -t nat switch.

iptables -A PREROUTING -i $INTDEV -t nat -p tcp --dport 80 -j REDIRECT --to-port 8888

try that.. and if all else fails.... LOG EVERYTHING!

Thanks,
____________________________________________
George Vieira
Systems Manager
georgev@citadelcomputer.com.au

Citadel Computer Systems Pty Ltd
http://www.citadelcomputer.com.au
 

-----Original Message-----
From: Michael Martinez [mailto:mmartinez@csrees.usda.gov]
Sent: Tuesday, July 01, 2003 5:37 AM
To: netfilter@lists.netfilter.org
Subject: I'm having difficulty making port redirection work


Hi all -

I've used ipchains before, but I'm brand new to iptables, and I'm having
difficulty getting port redirection to work.

Here's what I want to do: I've got a Redhat 8.0 box running iptables
1.2.6a2. I've got a web application listening on port 8888 (on the eth0
interface) and  I'd like any web traffic coming in on port 80, to be
redirected to port 8888.

In ipchains, this is handled with the following line in
/etc/sysconfig/ipchains:

-A input -d 192.73.224.127 80 -p tcp -j REDIRECT 8888

I am using the following lines at the beginning of
/etc/sysconfig/iptables, but it does not work. I'm getting no messages
in /var/log/messages, and I don't know of any place where iptables is
logging anything:

*nat
-A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 8888
COMMIT

How do I troubleshoot and fix this?

thank you -

-- 
Michael Martinez
Linux System Administrator
Marlaw Systems Technology Inc.
CSREES/ISTM/USDA
mmartinez@csrees.usda.gov

RE: I'm having difficulty making port redirection work

[Oskar Andreasson]

Hi all,

There is a postscript version as you can see, and it can be converted to 
PDF. The reason that there is no longer a PDF version is that there are 
simply too much work keeping that version alive. Too much trouble and 
weirdness simply to make it worth the effort, in my opinion. If you wish 
to feel the pain, try and download the sourcecode for the tutorial and 
follow the instructions in the README to create the PDF file.

The PS file will be gone later on as well, for the same reason, I 
think. There are other reasons as well, but I will explain those when that 
time shows up.

Have a nice day!


On 1 Jul 2003, Michael Martinez wrote:

> Woah ... great tutorial. (Do you have a pdf version ?)
> 
> mike
> 
> On Mon, 2003-06-30 at 18:59, George Vieira wrote:
> > http://iptables-tutorial.frozentux.net/iptables-tutorial.html
> > 
> > Read that tutorial very carefully and you'll pickup the differences of iptables to ipchains.
> > 
> > just remember that INPUT/OUTPUT are for packets going to and from the firewall ONLY, not forwarded or NATed packets unlike ipchains.. check the graphs and you'll see what I mean..
> > 
> > What your looking for is part of PREROUTING chain not INPUT and you forgot the -t nat switch.
> > 
> > iptables -A PREROUTING -i $INTDEV -t nat -p tcp --dport 80 -j REDIRECT --to-port 8888
> > 
> > try that.. and if all else fails.... LOG EVERYTHING!
> > 
> > Thanks,
> > ____________________________________________
> > George Vieira
> > Systems Manager
> > georgev@citadelcomputer.com.au
> > 
> > Citadel Computer Systems Pty Ltd
> > http://www.citadelcomputer.com.au
> >  
> > 
> > -----Original Message-----
> > From: Michael Martinez [mailto:mmartinez@csrees.usda.gov]
> > Sent: Tuesday, July 01, 2003 5:37 AM
> > To: netfilter@lists.netfilter.org
> > Subject: I'm having difficulty making port redirection work
> > 
> > 
> > Hi all -
> > 
> > I've used ipchains before, but I'm brand new to iptables, and I'm having
> > difficulty getting port redirection to work.
> > 
> > Here's what I want to do: I've got a Redhat 8.0 box running iptables
> > 1.2.6a2. I've got a web application listening on port 8888 (on the eth0
> > interface) and  I'd like any web traffic coming in on port 80, to be
> > redirected to port 8888.
> > 
> > In ipchains, this is handled with the following line in
> > /etc/sysconfig/ipchains:
> > 
> > -A input -d 192.73.224.127 80 -p tcp -j REDIRECT 8888
> > 
> > I am using the following lines at the beginning of
> > /etc/sysconfig/iptables, but it does not work. I'm getting no messages
> > in /var/log/messages, and I don't know of any place where iptables is
> > logging anything:
> > 
> > *nat
> > -A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 8888
> > COMMIT
> > 
> > How do I troubleshoot and fix this?
> > 
> > thank you -
> > 
> > -- 
> > Michael Martinez
> > Linux System Administrator
> > Marlaw Systems Technology Inc.
> > CSREES/ISTM/USDA
> > mmartinez@csrees.usda.gov
> > 
> > 
> 

-- 
----
Oskar Andreasson
http://www.frozentux.net
http://iptables-tutorial.frozentux.net
http://ipsysctl-tutorial.frozentux.net
mailto:blueflux@koffein.net

RE: I'm having difficulty making port redirection work

[Michael Martinez]

Woah ... great tutorial. (Do you have a pdf version ?)

mike

On Mon, 2003-06-30 at 18:59, George Vieira wrote:
> http://iptables-tutorial.frozentux.net/iptables-tutorial.html
> 
> Read that tutorial very carefully and you'll pickup the differences of iptables to ipchains.
> 
> just remember that INPUT/OUTPUT are for packets going to and from the firewall ONLY, not forwarded or NATed packets unlike ipchains.. check the graphs and you'll see what I mean..
> 
> What your looking for is part of PREROUTING chain not INPUT and you forgot the -t nat switch.
> 
> iptables -A PREROUTING -i $INTDEV -t nat -p tcp --dport 80 -j REDIRECT --to-port 8888
> 
> try that.. and if all else fails.... LOG EVERYTHING!
> 
> Thanks,
> ____________________________________________
> George Vieira
> Systems Manager
> georgev@citadelcomputer.com.au
> 
> Citadel Computer Systems Pty Ltd
> http://www.citadelcomputer.com.au
>  
> 
> -----Original Message-----
> From: Michael Martinez [mailto:mmartinez@csrees.usda.gov]
> Sent: Tuesday, July 01, 2003 5:37 AM
> To: netfilter@lists.netfilter.org
> Subject: I'm having difficulty making port redirection work
> 
> 
> Hi all -
> 
> I've used ipchains before, but I'm brand new to iptables, and I'm having
> difficulty getting port redirection to work.
> 
> Here's what I want to do: I've got a Redhat 8.0 box running iptables
> 1.2.6a2. I've got a web application listening on port 8888 (on the eth0
> interface) and  I'd like any web traffic coming in on port 80, to be
> redirected to port 8888.
> 
> In ipchains, this is handled with the following line in
> /etc/sysconfig/ipchains:
> 
> -A input -d 192.73.224.127 80 -p tcp -j REDIRECT 8888
> 
> I am using the following lines at the beginning of
> /etc/sysconfig/iptables, but it does not work. I'm getting no messages
> in /var/log/messages, and I don't know of any place where iptables is
> logging anything:
> 
> *nat
> -A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 8888
> COMMIT
> 
> How do I troubleshoot and fix this?
> 
> thank you -
> 
> -- 
> Michael Martinez
> Linux System Administrator
> Marlaw Systems Technology Inc.
> CSREES/ISTM/USDA
> mmartinez@csrees.usda.gov
> 
> 
-- 
Michael Martinez
Linux System Administrator
Marlaw Systems Technology Inc.
CSREES/ISTM/USDA
(202) 720-6223
mmartinez@csrees.usda.gov