How to route somehost to other host with some port on linux?

Question

Say I want to route all requests to google.com to localhost:333 , how to do so?

Answer 1

Shorewall routes. (FAQ)

You want to redirect all local google.com connection requests to a server running in your local zone at 127.0.0.1 and listening on port 333. Your local interface is eth1.

Disclaimer; I've not done exactly this with Shorewall, so modified an example Squid server setup:

1. Add this entry to your /etc/shorewall/providers file.

   #NAME   NUMBER  MARK    DUPLICATE       INTERFACE       GATEWAY         OPTIONS
   foo     1       202     -               eth1            127.0.0.1     loose
   

2. In /etc/shorewall/tcrules add:

   #MARK    SOURCE              DEST        PROTO    DEST
   #                                                 PORT(S)
   202:P    net:google.com   0.0.0.0/0   tcp      80
   

3. In /etc/shorewall/interfaces :

   #ZONE   INTERFACE    BROADCAST    OPTIONS
   loc     eth1         detect       routeback          
   

4. On localhost, arrange for the following command to be executed after networking has come up

   iptables -t nat -A PREROUTING -i eth0 -d ! 127.0.0.1 -p tcp --dport 80 -j REDIRECT --to-ports 333          
   

Answer 2

If you just want to do this on a single machine, you can edit:

/etc/hosts 

and add

google.com 127.0.0.1

then restart network services

/etc/rc.d/init.d/network restart

This would redirect normal web traffic to localhost:80 though.