Hello to all!


I am new to this interesting forum. My questions is not totally related to unix/linux systems, but I am not finding proper place where to make my question and this forum seems to be visited by experts and unix/linux experts are epxerts in everything

My ISP has two kinds of services: with and without real IPs that have big diference in monthly price, and usually is selected the without real IP. These clients have problems with peer internet aplications and cannot be accessed remotely eg from terminal etc. The ISP says that it does not "block" any port, but simply a specific client or better say a private IP(may be thousands) is not identified from outside, behind ISP's nat, router or firewall.
The ISP does not make static port forwarding under request, in this case it recommends the customer to take the other service.

My question is:

Knowing private and real IP, can I make a TEMPORARY port forwarding using a port that is unused at that moment, from the connection to ISP only ?

There are continuosly created IP translations and port mappings in ISP Servers during browsing, where html pages reach that IP that requested them between thousand of connected clients, how to create a such explicit rule by my own that has a temporary value time, eg it is deleted when I shut down the pc and IP is unassigned. ?

ISP may not use unix/linux,


thanks in advance

A bit of terminology: all IP addresses are real, the difference you mean is between public and private addresses.

That said, any port-mappings of your ISP can only be configured by them. The dynamic port-mapping used by your ISP is bound to a TCP session (anything between the first SYN and the final FIN/ACK), and the routers will forget about it afterwards.

One possibility to get some ports forwarded to you is if you had access to a server with a public IP. SSH supports port-forwarding from remote to local, with the limitation that you'd have to specify each port you want tunneled.