I'm a C/C++/Qt dev, and today, I have a particular need and I'm sure I'm not the only one. I need to choose with which network interface my computer app will connect to...
For example, I'm home, using a VPN to access some protected stuff (like a VPN used by my company). And I know I can't use the VPN to browse the Internet. I would like to be able to tell my FTP Client to connect to the VPN interface and my browser, to the classic interface (VPN may be a bad example, but the idea is there.)
As almost none of classical app one have on his computer, let the user choose which IP to, I would like to dev something which can do this for me and everybody who can need it, but I simply don't know where to begin. I know I'll have to hack, maybe intercept and relay the connection (Firewall like, or more NAT like), or maybe I can close and reopen the connection for the app (and STOP/CONT it to avoid it to notice, or anything else.
If you have any idea of how and where I can begin my research, it would be helpful. Thank you for your help.