Re: dual IP

[mpradhan@healthnet.org.np]

Dear Brian Candler,

Thank you for your kind information. The problem was with the 
putting private IP in Radio modem  which was set as a gateway to 
Internet. The problem is not solved.

I want to ask one more question.

I want give to some of the users POP account but limit to them only e-
mail. How to set for this in the router?

With regards,

Sincerely yours,

Mohan Raj Pradhan
HealthNet Nepal



Date sent:      	Sat, 19 May 2001 18:27:48 +0100
From:           	Brian Candler <B.Candler@pobox.com>
To:             	mpradhan@healthnet.org.np
Copies to:      	tcpws@psg.com
Subject:        	Re: dual IP

> On Sun, May 20, 2001 at 03:36:54PM +0530, mpradhan@healthnet.org.np wrote:
> > The dual IP seems working but the problem is as follows:
> > 
> > If I use the valid IP in the IP address part of workstation for example:
> > IP address: 202.52.231.197
> > Subnet mask 255.255.255.224
> > 
> > then I can not telnet with the private IP(192.168.0.1) but I can telnet 
> > with valid IP . Earlier I could telnet with private IP even if I have put 
> > valid IP in the IP part of network neighborhood of workstation.
> 
> I am afraid you are making very little sense, and you will need to draw a
> diagram to explain what you are trying to do.
> 
> Do you have two physically separate networks, one with private IP space and
> the other with public? e.g.
> 
>                                  Internet
>                                     ^
>                                     |
>                                   Router
>              202.52.231.192/27      |<z>
>            --------------+----------+--
>                          |<x>
>                      Linux box
>                          |<y>
>            --------------+-------------
>              192.168.0.0/24
> 
> Or are you using "IP aliasing" so that some boxes have two different IP
> addresses on the same network?
> 
>                                  Internet
>                                     ^
>                                     |
>                                   Router
>                                     |202.52.231.<z>
>            -+------------+----------+--
>             |            |202.52.231.<x>
>             |            |192.168.0.<y>
>          Other        Linux box
>        workstations
> 
> If it is the latter, then how it works will depend on which IP address the
> 'other workstations' have and where they point default route.
> 
> If an 'other workstation' has a 192.168.0 address, and points defaultroute
> at the Linux box, it should be able to see both public and private networks.
> 
> If it has a public address, and points defaultroute at the router, then it
> will not be able to see the 192.168.0 network, unless you add an appropriate
> static route on the router. However in many cases you don't _want_ boxes on
> public addresses to be able to see the private network, because the NAT box
> acts as a kind of 'firewall' between the private and public networks.
> 
> Windows protocols (i.e. Netbios and SMB) may get confused if you try to NAT
> them. You could configure the Linux box to allow forwarding without NAT
> between the 192.168.0 and 202.52.231.192 networks, but then you lose any
> 'firewalling' protection you may have had. I would suggest you keep all
> Windows boxes (workstationsm, NT servers etc) on private addresses. If you
> can keep them on a physically separate network, as per the first diagram
> above, then so much the better.
> 
> Sorry I can't give a specific answer to your problem unless you are more
> specific about how your network is constructed.
> 
> Brian.