assign multiple ips to a network interface card so as to route some programs through a vpn in ubuntu

Question

I have a home server with several programs with web interfaces running on it.

I want to access all these web interfaces from outside my local network.

I also have a program I want to go through a vpn.

My vpn only allows one port to be forwarded however so I can't access all my web interfaces through the vpn from outside my network.

This program however allows me to bind it to an ipv4 address.

so what i want to do is somehow give my computer a second ip on my local network, make traffic on one of those ips go through my vpn, have traffic go through the non-vpn ip by default, and bind the one sensitive program to the vpn connected interface.

I currently have a workaround in place by running a virtual machine with the one sensitive program on it and it connected through vpn but that wastes resources and has a drawback. this sensitive program has a web interface as well which currently is unreachable from outside my local network. but if I am able to have different ip addresses I should be able to bind the web interface to the non-vpn but transfer the data through the vpn. any ideas on how to do this or perhaps a simpler way to solve my problem?

Answer 1

Basicall, you can configure a virtual network interface at command line (only without NetworkManager):

$ ifconfig eth0:1 192.168.177.52

If you do not use NetworkManager, you can create additional devices with :1, :2 and so on appended to the interface name in /etc/network/interfaces, so for example eth0 and then eth0:1, eth0:2, and so on. These will be displayed with ifconfig.

If you say "Ubuntu", I guess you are using NetworkManager. By use of any graphical tool for KDE or GNOME or by editing the file /etc/NetworkManager/system-connections/YOURLANCONNECTION, you can append several IP addresses.

I show you an excerpt of mine here (it is generated with the GNOME nm-applet):

[ipv4]
method=manual
dns=194.165.52.198;194.165.52.199;10.21.65.8;
dns-search=
address1=192.168.177.50/24,192.168.177.1
address2=10.21.65.206/24
address3=10.21.70.206/24
route1=192.168.10.0/24,192.168.177.1,1
route2=192.168.177.0/24,192.168.177.1,1
route3=10.21.65.0/24,0.0.0.0,1
ignore-auto-routes=true
ignore-auto-dns=true

As you can see, my PC has three different IPv4 addresses on the same interface. The interfaces are not listed with ifconfig.