Public IP's and routers

[dhaywood]

I have got 4 public Ips, two are used by the modem/router (etec adsl modem router) and the other two I was goin to use as mail and http servers. How do I configure the servers/modem router to use the public ips, everything I have tries so far does not seem to work.

 

[manarth]

you'll have to specify makes/models/OpSys etc. it varies according to system spec.



<marc> i wonder what will happen if i press this...[ul][li]please give feedback on what works / what doesn't[/li][li]need some help? how to get a better answer: faq581-3339[/li][/ul]

 

[dhaywood]

Sorry about that.

router is epic adsl modem/router 4 port ethernet which is assigned two public ip

I have one linux 8 box which I want to use as a web server, I have tried to assign it a public ip, but didnt work.

I have a W2003 Server which I want to use for mail (exchange 2003).

The main rpblem I have is that when I have assigned the public ip to the linux box I cant ping anything. But when it has a private ip everything works fine. But not as I want it to ie web server.

Does this Help

 

[pansophic]

Generally you don't actually &quot;assign&quot; the public IP to the box that is behind the router. You normally assign a static NAT rule, that translates incoming connections on the public IP address to the private IP address of the server.

So your router will have 2 public IPs assigned to it, and it will have static rules to send connection requests bound for public_IP_1 port 80 and port 443 to linux_private_IP, and public_IP_2 port 25 and 110 to 2003_private_IP.

You can actually do this using a single public IP address, and boy does it confuse vulnerability scanners and port scanners. They expect a single OS on a given IP. Having some ports point to a machine with one OS, and other ports point to a machine with another OS is really beyond the scope of their capabilities.

This does mean that you will have to statically address the two servers that are behind your router. Some routers will let you define them in DHCP by MAC address, but others require that you reduce the scope of the DHCP pool and statically address outside that pool.

Couldn't find any details on your router, so I can't say for sure.


pansophic

 

[dhaywood]

I know what your are saying and it makes sense, but trying to configure the router to do this is another story, I dont even know if it its capable of doing this. If you want this is the link to the manual which is pretty much spot on for my router.

http://www.nvk.co.th/Support/Manual/CN-6R11.pdf

If you could take a look and see what you think.

Thanks loads, this has been driving me up the wall for ages.

 

[pansophic]

OK, in spending almost a whole minute reading the manual, it appears that your router does not support multiple public IPs.

But that is not the end of the world. You can use the Virtual Server configuration to define your port forwarding rules. You need 4 rules to get your configuration working as you described:

ID     Public Port   Private Port   Type  Host IP
smtp    25            25             TCP   2003_IP
pop    110           110             TCP   2003_IP
www     80            80             TCP   linux_IP
https  443           443             TCP   linux_IP

That should give you what you need, but it doesn't allow you to use your second IP.


pansophic