Bandwidth between linodes
Can I use private addresses between linodes on different accounts? For company structure/billing purposes we have a couple of different linode accounts with containers in them. Can I use private addresses to communicate between containers in the different accounts?
As long as you're using the private network IPs, then yes, it's free.
There's a bunch of internal services that you can use from others like that:
In fact, there are a number of people (myself included) who offer various services (NTP, apt caches, etc) to other Linode customers via the private network.