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Binding two ip addrs to one nic (different IPs, subnets,and gateways)

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mspsub

Programmer
Oct 14, 2000
17
US
Hello,

We have been sharing a T1 with another company in my building and we now have our own T1.

My dilema is that I need to keep my email up while my mail record changes propagate across the internet. I need to be able to bind two different ip addresses to my outside nic. The addresses are fully different (ip addresses, subnet mask and gateways). It the past I did port forwarding for my mail to a NATed address inside of my firewall.

I bound the additional address to my outside nic, but after I did that I could not get out to the internet (I could ping in to my net, but not out)

I may be missing a static route of other configuration.

Help me please! ;)

Mark
 
I only have one gateway defined (the confusing thing is that it is the same address as the ip address - the ELI technician configured that).
 
I think you need to add a default route out from this new IP address. something like:

route ADD 0.0.0.0 MASK 0.0.0.0 <GATEWAY IP> METRIC 1 IF <your-interface-number>
 
Bronto...thanks for the help so far...

I changed my server's (dmz) GW to point to the cisco, added the additional IP address (old mail server) and GW to the outside nic (on DMZ) and things are almost where I need them to be. Internet is up an working.

What is left is email: I can send outbound, but I am not receiving any inbound.

Currently my colocated web server is receiving messages that it cannot connect to mail.nteras.com via smtp)

Any ideas?

Mark
 
The outside nic is configured to forward ports 110 and 25 to the mail server.

That leads to my question. The outside nic has two addresses bound to it. One addr from the new T1 and my old mail address. I am not sure how the routing will be handled. Do I have to set a static route for the old mail address (where the mx record used to point) to point to the internal address, or should that happen automagically? :)

I have access to both the new T1 and the old T1. They are plugged into the same hub (just different addrs, subnet, etc).

 
that's not going to happen automatically, so yes, you'd need to set up a static mapping from the old outside T1 address to the new inside mail server address.

my head is spinning...:)
 
I do understand routing in general.... :)

Bottom line:

I have a DMZ box (Win2000 dual-homed/NATed Server).
The outside nic has two addresses bound:
1) The new ip address
2) The old mail address
In Routing and Remote Access I configured it so inbound packets (for ports 110 and 25) on the outside nic be forwarded to my mail server that is on my internal net.

I am trying to handle email for both the new and old mx records to mail functions during the change over...

BTW...I have the ability for you to connect into the server using a tool called RapidAssist (it is our product). It would let you see the server as if you were there....would you like to take a gander to see what I have mucked up?

Mark



 
I don't think that'll be necessary, and i apologize if i gave you the impression that i thought you didn't understand routing...the head spinning thing was me laughing at my own post, as I wasn't sure I understood your setup...(and I'm still not sure I do).
Anyway, when you configured the forwarding on the outside NIC, did you get an option to (or can you get an option, I'm not sure) set it for both IP's?
Also, let's make sure that the forwarding is working at least for the new IP, can you telnet to it on port 25 from outside and send an email to one of your internal accounts?
 
np on the head spinning...my bad read....

You were asking about when I configured the forwarding on the outside NIC...well I had the option to set it for &quot;this interface&quot; or &quot;by address pool entry&quot;. I set it for &quot;this interface&quot;.

I can ping the machine that is listening for that address, but I cannot connect on port 25.
 
yeah, then it's not forwarding...so I'm guessing that &quot;this interface&quot; only covers the primary address on the NIC, not both. Maybe if you configure a couple of address pools, then you'll have the option to redirect ports on both IPs...
 
I added a special port for ports 25 and 110 on the pool for the old mail addr and no go......hmmmmm

Thanks for the help and I will keep plugging away....as I get time ;)
 
Bronto...

I was able to resolve the issue by entering the old email ip address in the &quot;Address Reservations&quot; in Routing and Remote Access and pointing it to my mail server inside my firewall.

Thanks for your help.

Mark
 
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