1 IP Many Interal Devices

[Henry Martel]

I was looking for some guidance on a scenario that came up at a customer site.

A little background first: The site has 1 public ip address with an 1841 and five 3750 switches behind it. They want me to help configure a telnet/ssh sessions for one of their outside admins who will need to access the switches from time to time.  

The goal is to use the 1 ip address for outside access to their router and switches.

example:
router 1 telnet 1.1.1.1

switch 1 telnet 1.1.1.1 6661
switch 2 telnet 1.1.1.1 6662
switch 3 telnet 1.1.1.1 6663
and so on.

Can anyone advise on the best method for this?

[rvarelac]

Hi Henry,

I guess a static translation would fit here well.

http://www.cisco.com/c/en/us/support/docs/long-reach-ethernet-lre-digital-subscriber-line-xdsl/asymmetric-digital-subscriber-line-adsl/12905-827spat.html

If you want to use internally the same IP with different lines, you need to set up a terminal server or reverse SSH. 

Hope it helps

-Randy-

[Henry Martel]

P.Dath thank you for your response, same to you Randy. P.Dath - Your suggestion is how the site is currently setup. From the outside they can login and remotely access the various switches. However, for their monitoring application they need to have their one public IP address with a different port assignments for each switch. As Randy suggested, i was thinking of using some type of natting that would allow ip address 1.1.1.1 port 6661 to be statically assigned to switch 1 ip address 10.1.1.1. Thank your for the suggestions, I am be onsite tomorrow with the customer and we'll see how this goes. -Henry

[Philip D'Ath]

What is their monitoring application?  Many monitoring applications like PRTG have agents you install inside the network to resolve this exact issue, simply.

I highly recommend PRTG for monitoring ...

[Philip D'Ath]

I assume the Cisco 1841 is the Internet facing device?

Allow them to log into the 1841 remotely (no NAT required), and from there they can telnet/ssh to the internal Cisco devices.

Simple.