Windows & DOS: Issues & Discussions

Hi,

I know tcp port tunneling can be done using ssh/putty. how about udp?

I have a scenario where a license server handsout licenses to machines in that network ONLY. I have a windows machine in a different subnet and even though the client software can see license server, while using the software the lic. server denies the permission because the windows machine is not in the same subnet as that of license server.

The license server here is windows. The service runs on port_a ( I think this should be 2047 UDP for opnet)

There are solaris / linux machines in the same network as that of license server which can be used for tcp/udp tunneling but I don;t know how I should make use of that. I do have account on those unix/linux machines and tcp forwarding/gateway ports is enabled in sshservers.

Is there anyway from client(windows), I can specify " localhost : port_a "as license server and so software will query to localhost:2047(udp). Can we forwards 2047 UDP to localhost:2047(tcp)?

Then do ssh tcp forwarding to linux machine for tcp port 2047. Then on remote linux machine forward tcp 2047 to localhost:2047(udp) and forward that udp 2047 to license server 2047 (udp)?

Is this technically possible? May be using nc(netcat) or udp_redirect?

or if there is any other way to let such users use the lic. servers successfully?

Please help..
Thanks in advance!

ssh doesn't support UDP tunneling, just TCP. Maybe you should investigate a VPN solution.

That's right, ssh does not support udp. problem with our VPN is that it can not provide an IP from license server's network. So VPN is also not really useful. May be configuring openvpn will be a good idea?

since we don't know how the license server works it's not really possible for this problem to be solved. does the client send a request first? or does the server just "hand out" licenses? does the server use broadcast to send out the replies or does it reply directly to the IP of the client? if it does indeed just broadcast then you're stuck either moving the machine or adding a NIC to it or rearranging your VLAN or some such.

Thanks for your inputs. Makes sense. I really don't know how lic. works because vendor has made least documentation available in this regard. Had it been Flexlm, it would have been better. My only hope was if someone knew how Opnet license service works. Having said that, I ran wireshark on client and checked what the application is doing and saw that there were attempts to connect to port 2047 (udp) on server IP but it seems when Lic. server checks the client IP and finds that not being in the same network, rejects it. The application has a configuration to provide IP of lic. server.

Thanks again

Here is a nice tutorial for UDP on port 53:

Performing UDP tunneling through an SSH connection

For some reason I did not get message about updated thread. Thanks, I was able to do what I wanted to using udp-tunnel program but I am curious about the link you have posted. I'll go through it

Thank you!