Launch multiple instances of telnet application using different source ip address for each outbound

[Mike]

Hi I'm trying to make multiple instances of an application that initiates an
outbound connection use different source IP addresses. Here's my problem in
detail.

I'm using a dumb terminal product (from Ncomputing). The dumb terminals
connect to any Windows PC after you load their software on it. I have
individual Windows sessions and separate user environments just like a real
terminal server. This all works great and is beside the point, but explains
why I need to do this.

I have an application on this PC that connects to another host. We'll just
say this is a telnet application for example. User 1 launches this
application which connects to the telnet server on TCP port 23 with source
IP address 192.168.0.1 (the primary IP on the NIC). User 2 than
concurrently launches a second instance of the application which connects to
the terminal server on port 23, but since it uses the same source IP address
(192.168.0.1) it the telnet server rejects it's connection. I need the
second instance of the connection to the telnet server to use a different
source IP address such as 192.168.0.2, which could be a secondary IP on the
primary NIC.

Is it possible to assign an secondary IP address on the primary NIC (or add
a second NIC with a different IP on the same subnet), so that each
established session from this application can use a different source IP
address to connect to the telnet server with. Therefore an external host
(like a telnet server) would see the terminal server as 2 different hosts?

Thanks in advance!

Mike

 

[Pegasus \(MVP\)]

Hi I'm trying to make multiple instances of an application that initiates an
outbound connection use different source IP addresses. Here's my problem in
detail.

I'm using a dumb terminal product (from Ncomputing). The dumb terminals
connect to any Windows PC after you load their software on it. I have
individual Windows sessions and separate user environments just like a real
terminal server. This all works great and is beside the point, but explains
why I need to do this.

I have an application on this PC that connects to another host. We'll just
say this is a telnet application for example. User 1 launches this
application which connects to the telnet server on TCP port 23 with source
IP address 192.168.0.1 (the primary IP on the NIC). User 2 than
concurrently launches a second instance of the application which connects to
the terminal server on port 23, but since it uses the same source IP address
(192.168.0.1) it the telnet server rejects it's connection. I need the
second instance of the connection to the telnet server to use a different
source IP address such as 192.168.0.2, which could be a secondary IP on the
primary NIC.

Is it possible to assign an secondary IP address on the primary NIC (or add
a second NIC with a different IP on the same subnet), so that each
established session from this application can use a different source IP
address to connect to the telnet server with. Therefore an external host
(like a telnet server) would see the terminal server as 2 different hosts?

Thanks in advance!

Mike

This is a function of the telnet server you're trying to access,
not the Windows client. Try telnetting to your ISP's POP3
and SMTP servers (ports 25/110). I can do both at the same
time from different command prompts.

 

[Mike]

I'm sorry, that's not the issue, but thanks for the fast reply. I'm
telnetting to port 23 on a server that only listens on that port.

There is a specific telnet server, listening on port 23, that only accepts
one connection from each IP address. An application on a PC that initiates
the outbound connection to the telnet server can connect on port 23 on the
first instance, but in order to make a second connection to port 23 from the
same PC, the second instance would have to use a different source IP
address. I want to know how to modify the source IP address when launching
the second instance.

This is somewhat similar to what is described in the "unique network
address" section in http://support.microsoft.com/kb/186498. The only problem
is they describe using a different port. I don't have this option since I
don't control the server.

Any ideas here?
Thanks!

 

[Pegasus \(MVP\)]

Maybe nc.exe can do what you want.
http://www.securityfocus.com/data/tools/nc11nt.zip

 

[Mike]

Looks like it has some potential. I'll start testing today and report back.

Thanks!
Mike