Debian - I need to add a static (ipv4) route - to the secondary/static IP address on a single ethernet card.

Working: Success in adding a secondary TCP/IP address to a single ethernet card.

Working and Pinging: 192.168.1.3 & 10.22.1.3 and pinging 10.22.2.1

# Working:
# The primary network interface
allow-hotplug enp0s25
auto enp0s25:0
iface enp0s25:0 inet static
address 192.168.1.3
netmask 255.255.255.0
gateway 192.168.1.1
dns-nameservers 8.8.4.4 8.8.8.8 10.22.1.1

auto enp0s25:1
iface enp0s25:1 inet static
address 10.22.1.3
netmask 255.255.255.0
gateway 10.22.1.1
dns-nameservers 8.8.4.4 8.8.8.8 10.22.1.1

The Problem: making the new (static route below) to use the secondary IP address/pathway with this:

up route add -net 10.2.10.0 netmask 255.255.255.0 gw 10.21.1.1 dev enp0s25:1

The Problem: Debian Linux still wants to use the original gateway (192.168.1.1) on the first static IP address to find it's way to 10.2.10.0

Any suggestions on how to write my "up route add -net" syntax - to make Debian use that secondary address?

thanks,
-pete

Hi

I've set up similar things, but I didn't use more than one route. As I understand it, the gateway/route is used for ip addresses outside of the netmasks of all interfaces.

And 10.2.10.0 is outside the netmask of 10.22.1.3/255.255.255.0, so it will go to the 192.168.1.1.

I would simply drop the gateway in the secondary interface, and use 255.0.0.0 as netmask. Then all traffic to 10.* will go to the secondary interface, and isn't that ok? The gateway at 192.168.1.1 will probably reject all traffic to 10.* anyway.

Edit:

If you really need two routes, and 10.2 is a different router, you really need two routes. Here's a solution:

https://unix.stackexchange.com/quest...nd-connections

Thanks Guttorm!

Your Routing suggesting works perfectly from the Secondary IP (10.x.x.x) subnet.
I can now reach my private network (10.x.x.x) and still maintain a connection to the Internet (192.168.1.x) from the Primary IP on the single Ethernet card.
Now WHY didn't I think of that??? - change the network 10 Mask to 255.0.0.0 and remove any reference to a Network 10.x.x.x Gateway on the secondary IP.

Brilliant!

Thanks again!