port forwaring from localhost to inet

port forwaring from localhost to inet

[Oran G]

hello,

I want to forward local requests to a mashine on the network.

I have a few hundred cgi scripts running on the webserver and using a 
mysql-server on the same host. now i have set up a separate 
mysql-linux-box and since it would be to much work to rewrite all the 
scripts, im trying to redirect all trafic from localhost:3306 to 
somepublicip:3306.

i used:
iptables -t nat -A PREROUTING -p tcp --dport 3306 -j DNAT --to 195.x.x.x

which works well form inet to inet but if I put '-o lo' to the line it 
doesnt.

i understand that this could be becouse the source of the packets would 
also require some rewriting, but i dont know how to do this. is there a 
way to solve this with iptables or shoud i try it with ssh-tunels?

thax, oran g

Re: port forwaring from localhost to inet

[Jörg Harmuth]

Oran G schrieb:
> hello,
> 
> I want to forward local requests to a mashine on the network.

This is done in nat table with OUTPUT chain. This chain is for natting
locally generated packages. If you don't have this chain, you have to
recompile the kernel with appropriate settings.

Have a nice time

Joerg

Re: port forwaring from localhost to inet

[Oran G]

>
>
>Oran G schrieb:
>  
>
>>hello,
>>
>>I want to forward local requests to a mashine on the network.
>>    
>>
>
>This is done in nat table with OUTPUT chain. This chain is for natting
>locally generated packages. If you don't have this chain, you have to
>recompile the kernel with appropriate settings.
>
>Have a nice time
>
>Joerg
>  
>

that was it, thanx!

iptables -t nat -A OUTPUT -o lo -p tcp --dport 8111 -j DNAT --to-destination 192.168.0.11:80

this leadts me to my second question, maybe little offtopic:

i can realize the same functionality with an ssh tunnel. since encryption is a nice extra but not neccesary i wonder about how it would affect the performance of the communikation line. 

both of my mashines have 2-3 GigH CPUs, and as i described befor, one runs apache the another mysql, both under heavy use.

oran G