Isolating my docker container from the rest of my local network (route add reject not working)

Question

I'm just simply trying to add a route to reject any traffic to other systems on my local network from my docker container, but seems like my route add command isn't working and I'm not quite sure why.

The command I'm used to running is route add -net x.x.x.x/CIDR reject

I know I'm missing something very minor here in regards to the command, but cannot figure out what it is.

Answer 1

Create an internal network for it.

docker network  create --internal isolation
docker run --network isolation $image