Re: How can I direct TELNET to use specific NIC card

Hi John,

Typically, you'd do this:

1) Assign a separate IP address to each network interface. For example, you might give 192.168.0.1 to one of them, and 192.168.0.2 to another.

2) In your DNS server, set up a name like 'telnet.example.com' (or ftp.example.com for FTP, or www.example.com for Web.) Or if you have more than one server, you might have telnetProd.example.com, telnetTest.example.com or whatever makes sense. Anyway... have this DNS entry point to the proper IP address... such as 192.168.0.1

3) Configure all of your telnet clients (Client Access, Mochasoft, whatever) to connect to 'telnet.example.com'. Presto... all telnet is now going to the 192.168.0.1 network interface!

4) If you ever want to change it, just change 'telnet.example.com' to point to 192.168.0.2 instead.


If you don't want to do the above, and you're asking "I must always use IP address 192.168.0.1, but I want incoming telnet to use a different interface with the same IP address", then no, I don't think it's possible. The system won't know if the connection is telnet or not until it has received at least a packet or two off the network... and the packet has to be received via one or the other network interface...

I suppose you could do it by putting a NAT gateway or load balancer in front of the machine. Some different appliance that changes the packet to go to the right IP address based on it's port number. So I guess that's an alternative, if the users aren't connecting from within the same subnet.



On 4/8/2011 9:57 AM, John Allen wrote:

I have two NIC cards.

I need to direct a telnet session to use a specific card (it needs to go out
from a specific IP address)



Is this possible and if so what do I need to do?



Thanks in advance



John